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Sample records for la-doped mg2si sn

  1. Electrical transport characterization of Al and Sn doped Mg 2 Si thin films

    KAUST Repository

    Zhang, Bo

    2017-05-22

    Thin-film Mg2Si was deposited using radio frequency (RF) magnetron sputtering. Al and Sn were incorporated as n-type dopants using co-sputtering to tune the thin-film electrical properties. X-ray diffraction (XRD) analysis confirmed that the deposited films are polycrystalline Mg2Si. The Sn and Al doping concentrations were measured using Rutherford backscattering spectroscopy (RBS) and energy dispersive X-ray spectroscopy (EDS). The charge carrier concentration and the charge carrier type of the Mg2Si films were measured using a Hall bar structure. Hall measurements show that as the doping concentration increases, the carrier concentration of the Al-doped films increases, whereas the carrier concentration of the Sn-doped films decreases. Combined with the resistivity measurements, the mobility of the Al-doped Mg2Si films is found to decrease with increasing doping concentration, whereas the mobility of the Sn-doped Mg2Si films is found to increase.

  2. High figure of merit and thermoelectric properties of Bi-doped Mg2Si0.4Sn0.6 solid solutions

    International Nuclear Information System (INIS)

    Liu, Wei; Zhang, Qiang; Yin, Kang; Chi, Hang; Zhou, Xiaoyuan; Tang, Xinfeng; Uher, Ctirad

    2013-01-01

    The study of Mg 2 Si 1−x Sn x -based thermoelectric materials has received widespread attention due to a potentially high thermoelectric performance, abundant raw materials, relatively low cost of modules, and non-toxic character of compounds. In this research, Mg 2.16 (Si 0.4 Sn 0.6 ) 1−y Bi y solid solutions with the nominal Bi content of 0≤y≤0.03 are prepared using a two-step solid state reaction followed by spark plasma sintering consolidation. Within this range of Bi concentrations, no evidence of second phase segregation was found. Bi is confirmed to occupy the Si/Sn sites in the crystal lattice and behaves as an efficient n-type dopant in Mg 2 Si 0.4 Sn 0.6 . Similar to the effect of Sb, Bi doping greatly increases the electron density and the power factor, and reduces the lattice thermal conductivity of Mg 2.16 Si 0.4 Sn 0.6 solid solutions. Overall, the thermoelectric figure of merit of Bi-doped Mg 2.16 Si 0.4 Sn 0.6 solid solutions is improved by about 10% in comparison to values obtained with Sb-doped materials of comparable dopant content. This improvement comes chiefly from a marginally higher Seebeck coefficient of Bi-doped solid solutions. The highest ZT∼1.4 is achieved for the y=0.03 composition at 800 K. - Graphical abstract: (a)The relationship between electrical conductivity and power factor for Sb/Bi-doped Mg 2.16 (Si 0.4 Sn 0.6 ) 1−y (Sb/Bi) y (0 2.16 (Si 0.4 Sn 0.6 ) 1−y Bi y (0≤y≤0.03) solid solutions. (c)Temperature dependent dimensionless figure of merit ZT of Mg 2.16 (Si 0.4 Sn 0.6 ) 1−y Bi y (0≤y≤0.03) solid solutions. - Highlights: • Bi doped Mg 2.16 Si 0.4 Sn 0.6 showed 15% enhancement in the power factor as compared to Sb doped samples. • Bi doping reduced κ ph of Mg 2.16 Si 0.4 Sn 0.6 due to stronger point defect scattering. • The highest ZT=1.4 at 800 K was achieved for Mg 2.16 (Si 0.4 Sn 0.6 ) 0.97 Bi 0.03

  3. Mg{sub 2}Sn heterostructures on Si(111) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Dózsa, L., E-mail: dozsa@mfa.kfki.hu [Institute of Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences, 1525 Budapest Pf, 49 (Hungary); Galkin, N.G. [Institute of Automation and Control Processes of FEB RAS, 5 Radio St., Vladivostok 690041 (Russian Federation); Far Eastern Federal University, 8 Sukhanova St., Vladivostok 690950 (Russian Federation); Pécz, B.; Osváth, Z.; Zolnai, Zs. [Institute of Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences, 1525 Budapest Pf, 49 (Hungary); Németh, A. [Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, 1525 Budapest, P.O.B. 49 (Hungary); Galkin, K.N.; Chernev, I.M. [Institute of Automation and Control Processes of FEB RAS, 5 Radio St., Vladivostok 690041 (Russian Federation); Dotsenko, S.A. [Institute of Automation and Control Processes of FEB RAS, 5 Radio St., Vladivostok 690041 (Russian Federation); Far Eastern Federal University, 8 Sukhanova St., Vladivostok 690950 (Russian Federation)

    2017-05-31

    Highlights: • Investigations show that the nanostructures have significant changes during the applied regular experimental investigations. • It is especially true for transmittance electron microscopy, where the investigated layers have to be thinned near to the nanostructure size. • The time order of the applied experimental investigation has a dominant effect on the experimetal results. - Abstract: Thin un-doped and Al doped polycrystalline Mg-stannide films consisting mainly of Mg{sub 2}Sn semiconductor phase have been grown by deposition of Sn-Mg multilayers on Si(111) p-type wafers at room temperature and annealing at 150 °C. Rutherford backscattering measurement spectroscopy (RBS) were used to determine the amount of Mg and Sn in the structures. Raman spectroscopy has shown the layers contain Mg{sub 2}Sn phase. Cross sectional transmission electron microscopy (XTEM) measurements have identified Mg{sub 2}Sn nanocrystallites in hexagonal and cubic phases without epitaxial orientation with respect to the Si(111) substrate. Significant oxygen concentration was found in the layer both by RBS and TEM. The electrical measurements have shown laterally homogeneous conductivity in the grown layer. The undoped Mg{sub 2}Sn layers show increasing resistivity with increasing temperature indicating the scattering process dominates the resistance of the layers, i.e. large concentration of point defects was generated in the layer during the growth process. The Al doped layer shows increase of the resistance at low temperature caused by freeze out of free carriers in the Al doped Mg{sub 2}Sn layer. The measurements indicate the necessity of protective layer grown over the Mg{sub 2}Sn layers, and a short time delay between sample preparation and cross sectionalTEM analysis, since the unprotected layer is degraded by the interaction with the ambient.

  4. Relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn: Consistent parameterization and prediction of Seebeck coefficients

    Science.gov (United States)

    Shi, Guangsha; Kioupakis, Emmanouil

    2018-02-01

    We apply density functional and many-body perturbation theory calculations to consistently determine and parameterize the relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn, and predict the Seebeck coefficient as a function of doping and temperature. The quasiparticle band gaps, including spin-orbit coupling effects, are determined to be 0.728 eV, 0.555 eV, and 0.142 eV for Mg2Si, Mg2Ge, and Mg2Sn, respectively. The inclusion of the semicore electrons of Mg, Ge, and Sn in the valence is found to be important for the accurate determination of the band gaps of Mg2Ge and Mg2Sn. We also developed a Luttinger-Kohn Hamiltonian and determined a set of band parameters to model the near-edge relativistic quasiparticle band structure consistently for all three compounds that can be applied for thermoelectric device simulations. Our calculated values for the Seebeck coefficient of all three compounds are in good agreement with the available experimental data for a broad range of temperatures and carrier concentrations. Our results indicate that quasiparticle corrections are necessary for the accurate determination of Seebeck coefficients at high temperatures at which bipolar transport becomes important.

  5. Electrical transport characterization of Al and Sn doped Mg 2 Si thin films

    KAUST Repository

    Zhang, Bo; Zheng, Tao; Sun, Ce; Guo, Zaibing; Kim, Moon J.; Alshareef, Husam N.; Quevedo-Lopez, Manuel; Gnade, Bruce E.

    2017-01-01

    Thin-film Mg2Si was deposited using radio frequency (RF) magnetron sputtering. Al and Sn were incorporated as n-type dopants using co-sputtering to tune the thin-film electrical properties. X-ray diffraction (XRD) analysis confirmed

  6. Preparation and near-infrared absorption of nano-SnO{sub 2}/SiO{sub 2} assemblies with doping and without doping

    Energy Technology Data Exchange (ETDEWEB)

    Hai Shujie [Faculty of Material Science and Chemical Engineering, China University of Geosciences, Lu Mo Road 388, Wuhan 430074 (China); Yan Chunjie, E-mail: chjyan2005@126.co [Engineering Research Center of Nano-Geomaterials, Ministry of Education, China University of Geosciences, Lu Mo Road 388, Wuhan 430074 (China); Yu Hongjie; Xiao Guoqi; Wang Duo [Faculty of Material Science and Chemical Engineering, China University of Geosciences, Lu Mo Road 388, Wuhan 430074 (China)

    2009-11-20

    The assemblies of nano-SnO{sub 2}/SiO{sub 2} and Sb- or Pd-doped nano-SnO{sub 2}/SiO{sub 2}, in which the nano-SnO{sub 2} particles are located in the pores of mesoporous SiO{sub 2} dry gels, were synthesized. Only for the Sb-doped nano-SnO{sub 2}/SiO{sub 2} assemblies, a broad near-infrared absorption step occurs in the optical absorption spectrum of the wavelength range from 300 to 1500 nm. The near-infrared absorption phenomenon is attributed to electronic transitions from the ground states to the excitation states of the impurity energy levels, which are formed by Sb doping in SnO{sub 2}. With increasing the weight ratio of SnO{sub 2}:SiO{sub 2} or the annealing temperature, the near-infrared absorption step slope side exhibits 'red shift', which is caused by the quantum confinement effect weakening due to the increased SnO{sub 2} crystalline diameter.

  7. Phase formation in Mg-Sn-Si and Mg-Sn-Si-Ca alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, A.; Groebner, J. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Schmid-Fetzer, R., E-mail: schmid-fetzer@tu-clausthal.de [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany)

    2011-02-17

    Research highlights: > The solidification paths of ternary and quaternary alloys are analyzed in detail, using the tool of thermodynamic calculations. > The precipitation sequence of phases and their amounts compare well with the microstructure of alloys. > The most efficient comparison to the experimental thermal analysis data is done by calculation of the enthalpy variation with temperature. > The viability of a procedure for the selection of multicomponent key samples is demonstrated for the development of the Mg-Ca-Si-Sn phase diagram. - Abstract: Experimental work is done and combined with the Calphad method to generate a consistent thermodynamic description of the Mg-Ca-Si-Sn quaternary system, validated for Mg-rich alloys. The viability of a procedure for the selection of multicomponent key samples is demonstrated for this multicomponent system. Dedicated thermal analysis with DTA/DSC on sealed samples is performed and the microstructure of slowly solidified alloys is analyzed using SEM/EDX. The thermodynamic description and phase diagram of the ternary Mg-Si-Sn system, developed in detail also in this work, deviates significantly from a previous literature proposal. The phase formation in ternary and quaternary alloys is analyzed using the tool of thermodynamic equilibrium and Scheil calculations for the solidification paths and compared with present experimental data. The significant ternary/quaternary solid solubilities of pertinent intermetallic phases are quantitatively introduced in the quaternary Mg-Ca-Si-Sn phase diagram and validated by experimental data.

  8. Study of Sn and Mg doping effects on TiO2/Ge stack structure by combinatorial synthesis

    Science.gov (United States)

    Nagata, Takahiro; Suzuki, Yoshihisa; Yamashita, Yoshiyuki; Ogura, Atsushi; Chikyow, Toyohiro

    2018-04-01

    The effects of Sn and Mg doping of a TiO2 film on a Ge substrate were investigated to improve leakage current properties and Ge diffusion into the TiO2 film. For systematic analysis, dopant-composition-spread TiO2 samples with dopant concentrations of up to 20.0 at. % were fabricated by RF sputtering and a combinatorial method. X-ray photoelectron spectroscopy revealed that the instability of Mg doping of TiO2 at dopant concentrations above 10.5 at. %. Both Sn and Mg dopants reduced Ge diffusion into TiO2. Sn doping enhanced the crystallization of the rutile phase, which is a high-dielectric-constant phase, although the Mg-doped TiO2 film indicated an amorphous structure. Sn-doping indicated systematic leakage current reduction with increasing dopant concentration. Doping at Sn concentrations higher than 16.8 at. % improved the leakage properties (˜10-7 A/cm2 at -3.0 V) and capacitance-voltage properties of metal-insulator-semiconductor (MIS) operation. The Sn doping of TiO2 may be useful for interface control and as a dielectric material for Ge-based MIS capacitors.

  9. Synthesis and lithium storage properties of Zn, Co and Mg doped SnO2 Nano materials

    CSIR Research Space (South Africa)

    Palaniyandy, Nithyadharseni

    2017-09-01

    Full Text Available In this paper, we show that magnesium and cobalt doped SnO2 (Mg-SnO2 and Co-SnO2) nanostructures have profound influence on the discharge capacity and coulombic efficiency of lithium ion batteries (LIBs) employing pure SnO2 and zinc doped SnO2 (Zn-Sn...

  10. Ex-situ manufacturing of SiC-doped MgB2 used for superconducting wire in medical device applications

    Science.gov (United States)

    Herbirowo, Satrio; Imaduddin, Agung; Sofyan, Nofrijon; Yuwono, Akhmad Herman

    2017-02-01

    Magnesium diboride (MgB2) is a superconductor material with a relatively high critical temperature. Due to its relatively high critical temperature, this material is promising and has the potential to replace Nb3Sn for wire superconducting used in many medical devices. In this work, nanoparticle SiC-doped MgB2 superconducting material has been fabricated through an ex-situ method. The doping of nanoparticle SiC by 10 and 15 wt% was conducted to analyze its effect on specific resistivity of MgB2. The experiment was started by weighing a stoichiometric amount of MgB2 and nanoparticles SiC. Both materials were mixed and grounded for 30 minutes by using an agate mortar. The specimens were then pressed into a 6 mm diameter stainless steel tube, which was then reduced until 3 mm through a wire drawing method. X-ray diffraction analysis was conducted to confirm the phase, whereas the superconductivity of the specimens was analyzed by using resistivity measurement under cryogenic magnetic system. The results indicated that the commercial MgB2 showed a critical temperature of 37.5 K whereas the SiC doped MgB2 has critical temperature of 38.3 K.

  11. Core shell structured nanoparticles of Eu3+ doped SnO2 with SiO2 shell: luminescence studies

    International Nuclear Information System (INIS)

    Ningthoujam, R.S.; Sudarsan, V.; Kulshreshtha, S.K.

    2005-01-01

    Re dispersible SnO 2 nanoparticles with and without Eu 3+ doping nanoparticles were prepared at 185 deg C by the urea hydrolysis of Sn 4+ in ethylene glycol medium. X-ray diffraction and 119 Sn MAS NMR studies of these particles revealed that these nanoparticles are crystalline with Cassiterite structure having an average crystallite size of 7 nm. Undoped SnO 2 gave a emission peak centered around 470 nm characteristic of the traps present in the nanoparticles. For Eu 3+ doped samples, emission around 590 and 615 nm was observed on both direct excitation as well as indirect excitation through traps, indicating that there is an energy transfer between the traps present in the nanoparticles and Eu 3+ ions. The asymmetric ratio of luminescence (relative intensity ratio of 590 to 615 nm transitions) has been found to be 1.2. For SnO 2 :Eu(5%)-SiO 2 nanoparticles, the asymmetric ratio of luminescence change significantly indicating the formation of nanoparticles with SnO 2 :Eu(5%) core covered with SiO 2 shell. (author)

  12. The effect of charge carrier and doping site on thermoelectric properties of Mg2Sn0.75Ge0.25

    International Nuclear Information System (INIS)

    Saparamadu, Udara; Mao, Jun; Dahal, Keshab; Zhang, Hao; Tian, Fei; Song, Shaowei; Liu, Weishu; Ren, Zhifeng

    2017-01-01

    Mg 2 Sn 0.75 Ge 0.25 has been recently demonstrated to be a promising thermoelectric material for power generation in the temperature range from room temperature to 723 K because of the high power factor of ∼54 μW cm −1  K −2 upon Sb doping to the Sn site. The enhanced density of states effective mass and weak electron scattering from the alloying effect are believed to be the main reasons for the high power factor (PF) and hence high figure of merit (ZT). In this study, it is shown that the right choice of carrier donor also plays an important role in obtaining high power factor. The effect of carrier donors Y and La at Mg-site and Bi and P at Sn-site in Mg 2 Sn 0.75 Ge 0.25 is systematically investigated. It is found that charge donors at the Sn-site are much more effective than at the Mg-site in enhancing PF and ZT. Bi doped Mg 2 Sn 0.73 Bi 0.02 Ge 0.25 shows a peak ZT of ∼1.4 at 673 K, a peak PF of ∼54 μW cm −1  K −2 at 577 K, which resulted in an engineering figure of merit (ZT) eng of ∼0.76 and (PF) eng of ∼2.05 W m −1  K −1 for cold side fixed at 323 K and hot side at 723 K.

  13. Thermoelectric properties of Al doped Mg{sub 2}Si material

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Kulwinder, E-mail: kulwindercmp@gmail.com; Kumar, Ranjan [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India); Rani, Anita [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India); Guru Nanak College for Girls, Sri Muktsar Sahib, Punjab (India)

    2015-08-28

    In the present paper we have calculated thermoelectric properties of Al doped Mg{sub 2}Si material (Mg{sub 2−x}Al{sub x}Si, x=0.06) using Pseudo potential plane wave method based on DFT and Semi classical Boltzmann theory. The calculations showed n-type conduction, indicating that the electrical conduction are due to electron. The electrical conductivity increasing with increasing temperature and the negative value of Seebeck Coefficient also show that the conduction is due to electron. The thermal conductivity was increased slightly by Al doping with increasing temperature due to the much larger contribution of lattice thermal conductivity over electronic thermal conductivity.

  14. In-situ synchrotron x-ray study of MgB2 formation when doped by SiC

    Science.gov (United States)

    Abrahamsen, A. B.; Grivel, J.-C.; Andersen, N. H.; Herrmann, M.; Häßler, W.; Birajdar, B.; Eibl, O.; Saksl, K.

    2008-02-01

    We have studied the evolution of the reaction xMg + 2B + ySiC → zMg1-p(B1-qCq)2 + yMg2Si in samples of 1, 2, 5 and 10 wt% SiC doping. We found a coincident formation of MgB2 and Mg2Si, whereas the crystalline part of the SiC nano particles is not reacting at all. Evidence for incorporation of carbon into the MgB2 phase was established from the decrease of the a-axis lattice parameter upon increasing SiC doping. An estimate of the MgB2 lower limit grain size was found to decrease from L100 = 795 Å and L002 = 337 Å at 1 wt% SiC to L100 = 227 Å and L002= 60 Å at 10 wt% SiC. Thus superconductivity might be suppressed at 10 wt% SiC doping due to the grain size approaching the coherence length.

  15. THERMOELECTRIC PROPERTIES OF HOT-PRESSED p-TYPE Mg2Si0.3Sn0.7 SOLID SOLUTION

    Directory of Open Access Journals (Sweden)

    G. N. Isachenko

    2014-05-01

    Full Text Available It is shown that thermoelectric energy conversion which gives the possibility for utilizing a low potential heat is one of the ways for adoption of energy-saving technologies; and semiconductor materials with p-type and n-type conductivities having high thermoelectric figure of merit are necessary for operation of thermoelectric generators. The paper deals with possibility of usage of the p-Mg2Si0.3Sn0.7 solid solution (with a nanostructured modification as a couple for the well studied thermoelectric material based on n-Mg2Si-Mg2Sn. A technological scheme for fabrication of heavily doped Mg2Si0.3Sn0.7 solid solution of p-type by hot pressing from nanopowder is developed. The given technology has made it possible to reduce duration of a homogeneous material fabrication and has improved its physical and chemical properties. The samples were made by three ways: direct fusion for polycrystals fabrication; hot pressing from microparticles; nanostructuring, i.e. hot pressing from nanoparticles. By X-ray diffraction it is shown that sizes of structural elements in the fabricated samples are about 40 nm. The probe technique is used for measurement of electric conductivity and Seebeck coefficient. The stationary absolute method is used for measurement of thermal conductivity. Thermoelectric figure of merit is defined by measured values of kinetic coefficients in the temperatures range of 77 – 800 K. It was demonstrated, that electric conductivity, Seebeck coefficient and the power factor do not depend practically on a way of solid solution preparation. Thermal conductivity of samples pressed from nanoparticles has appeared to be higher, than of samples, obtained by direct fusion; i.e. in this case nanostructuring has not led to increase of thermoelectric figure of merit. The conclusion is drawn, that polycrystalline semiconductor Mg2Si0.3Sn0.7 can be used as a p-branch for a thermoelectric generator though nanostructuring has not led to the figure of

  16. The Influence of Aluminum on the Microstructure and Hardness of Mg-5Si-7Sn Alloy

    Directory of Open Access Journals (Sweden)

    Rzychoń T.

    2016-03-01

    Full Text Available Magnesium alloys due the low density and good mechanical properties are mainly used in the automotive and aerospace industry. In recent years, magnesium alloys are extensively developed for use in high temperatures (above 120°C. Among these alloys, magnesium alloys containing tin and silicon have large possibilities of application due to the formation of thermally stable intermetallic Mg2Sn and Mg2Si. In this paper the influence of aluminum and heat treatment on the on the microstructure and hardness of Mg-7Sn-5Si alloy is reported. It was found that the microstructure of Mg-7Sn-5Si alloy consist of α-Mg solid solution, Mg2Sn and Mg2Si compounds. Addition of 2 wt% of Al to Mg-7Sn-5Si alloy causes the formation of Al2Sn phase. Moreover, Al dissolves in the α-Mg solid solution. The solution heat-treatment of tested alloys at 500°C for 24 h causes the dissolve the Mg2Sn phase in the α-Mg matrix and spheroidization of Mg2Si compound. The Mg2Si primary crystals are stable at solution temperature. After ageing treatment the precipitation process of equilibrium Mg2Sn phase was found in both alloys. The addition of aluminum has a positive effect on the hardness of Mg-7Sn-5Si alloy. In case of Mg-5Si-7Sn-2Al alloy the highest hardness was obtained for sample aged for 148 h at 250°C (88 HV2, while in case of Al-free alloy the highest hardness is 70 HV for material aged for 148 h at 250°C.

  17. Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+ ,Dy3+ co-doped Ba2 MgSi2 O7 phosphors.

    Science.gov (United States)

    Sao, Sanjay Kumar; Brahme, Nameeta; Bisen, D P; Tiwari, Geetanjali

    2016-11-01

    In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu 2 + -doped and Eu 2 + ,Dy 3 + -co-doped Ba 2 MgSi 2 O 7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba 2 MgSi 2 O 7 :Eu 2 + showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba 2 MgSi 2 O 7 :Eu 2 + Dy 3 + showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f 6 5d 1 to 4f 7 transition of Eu 2 + . TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu 2 + doping in Ba 2 MgSi 2 O 7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy 3 + ions were co-doped in Ba 2 MgSi 2 O 7 :Eu 2 + and maximum TL intensity was observed for 2 mol% of Dy 3 + . TL emission spectra of Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co-doping. The trap depths were calculated to be 0.54 eV for Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and 0.54 eV and 0.75 eV for Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors. It was observed that co-doping with small amounts of Dy 3 + enhanced the thermoluminescence properties of Ba 2 MgSi 2 O 7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The

  18. Superconductivity, critical current density, and flux pinning in MgB2-x(SiC)x/2 superconductor after SiC nanoparticle doping

    Science.gov (United States)

    Dou, S. X.; Pan, A. V.; Zhou, S.; Ionescu, M.; Wang, X. L.; Horvat, J.; Liu, H. K.; Munroe, P. R.

    2003-08-01

    We investigated the effect of SiC nanoparticle doping on the crystal lattice structure, critical temperature Tc, critical current density Jc, and flux pinning in MgB2 superconductor. A series of MgB2-x(SiC)x/2 samples with x=0-1.0 were fabricated using an in situ reaction process. The contraction of the lattice and depression of Tc with increasing SiC doping level remained rather small most likely due to the counterbalancing effect of Si and C co-doping. The high level Si and C co-doping allowed the creation of intragrain defects and highly dispersed nanoinclusions within the grains which can act as effective pinning centers for vortices, improving Jc behavior as a function of the applied magnetic field. The enhanced pinning is mainly attributable to the substitution-induced defects and local structure fluctuations within grains. A pinning mechanism is proposed to account for different contributions of different defects in MgB2-x(SiC)x/2 superconductors.

  19. Synthesis of La2O3 doped Zn2SnO4 hollow fibers by electrospinning method and application in detecting of acetone

    Science.gov (United States)

    Yang, H. M.; Ma, S. Y.; Yang, G. J.; Chen, Q.; Zeng, Q. Z.; Ge, Q.; Ma, L.; Tie, Y.

    2017-12-01

    Hollow porous pure and La2O3 doped Zn2SnO4 fibers were synthesized via single capillary electrospinning technology and used for obtaining of gas sensors. The as-prepared samples were characterized by microscopy, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy and UV-vis absorption spectra. The newly obtained gas sensors were investigated for acetone detection. Compared with pure Zn2SnO4 hollow fibers, the La2O3 doped Zn2SnO4 hollow fibers not only exhibited perfect sensing performance toward acetone with excellent selectivity, high response and fast response/recovery capability (7 s for adsorption and 9 s for desorption), but also the operating temperature was reduced from 240 °C to 200 °C. These results demonstrated that the special hollow porous La doped Zn2SnO4 fibers structures were used as the sensing material for fabricating high performance acetone sensors. The acetone sensing mechanism of La2O3 doped Zn2SnO4 hollow fibers was discussed too.

  20. Photoelectrochemical Characterization of Sprayed α-Fe2O3 Thin Films: Influence of Si Doping and SnO2 Interfacial Layer

    Directory of Open Access Journals (Sweden)

    Yongqi Liang

    2008-01-01

    Full Text Available α-Fe2O3 thin film photoanodes for solar water splitting were prepared by spray pyrolysis of Fe(AcAc3. The donor density in the Fe2O3 films could be tuned between 1017–1020 cm-3 by doping with silicon. By depositing a 5 nm SnO2 interfacial layer between the Fe2O3 films and the transparent conducting substrates, both the reproducibility and the photocurrent can be enhanced. The effects of Si doping and the presence of the SnO2 interfacial layer were systematically studied. The highest photoresponse is obtained for Fe2O3 doped with 0.2% Si, resulting in a photocurrent of 0.37 mA/cm2 at 1.23 VRHE in a 1.0 M KOH solution under 80 mW/cm2 AM1.5 illumination.

  1. Structural and optical characterization of p-type highly Fe-doped SnO2 thin films and tunneling transport on SnO2:Fe/p-Si heterojunction

    Science.gov (United States)

    Ben Haj Othmen, Walid; Ben Hamed, Zied; Sieber, Brigitte; Addad, Ahmed; Elhouichet, Habib; Boukherroub, Rabah

    2018-03-01

    Nanocrystalline highly Fe-doped SnO2 thin films were prepared using a new simple sol-gel method with iron amounts of 5, 10, 15 and 20%. The obtained gel offers a long durability and high quality allowing to reach a sub-5 nm nanocrystalline size with a good crystallinity. The films were structurally characterized through X-ray diffraction (XRD) that confirms the formation of rutile SnO2. High Resolution Transmission Electron Microscopy (HRTEM) images reveals the good crystallinity of the nanoparticles. Raman spectroscopy shows that the SnO2 rutile structure is maintained even for high iron concentration. The variation of the PL intensity with Fe concentration reveals that iron influences the distribution of oxygen vacancies in tin oxide. The optical transmittance results indicate a redshift of the SnO2 band gap when iron concentration increases. The above optical results lead us to assume the presence of a compensation phenomenon between oxygen vacancies and introduced holes following Fe doping. From current-voltage measurements, an inversion of the conduction type from n to p is strongly predicted to follow the iron addition. Electrical characterizations of SnO2:Fe/p-Si and SnO2:Fe/n-Si heterojunctions seem to be in accordance with this deduction. The quantum tunneling mechanism is expected to be important at high Fe doping level, which was confirmed by current-voltage measurements at different temperatures. Both optical and electrical properties of the elaborated films present a particularity for the same iron concentration and adopt similar tendencies with Fe amount, which strongly correlate the experimental observations. In order to evaluate the applicability of the elaborated films, we proceed to the fabrication of the SnO2:Fe/SnO2 homojunction for which we note a good rectifying behavior.

  2. Correlated vortex pinning in Si-nanoparticle doped MgB2

    OpenAIRE

    Kusevic, I.; Babic, E.; Husnjak, O.; Soltanian, S.; Wang, X. L.; Dou, S. X.

    2003-01-01

    The magnetoresistivity and critical current density of well characterized Si-nanoparticle doped and undoped Cu-sheathed MgB$_{2}$ tapes have been measured at temperatures $T\\geq 28$ K in magnetic fields $B\\leq 0.9$ T. The irreversibility line $B_{irr}(T)$ for doped tape shows a stepwise variation with a kink around 0.3 T. Such $B_{irr}(T)$ variation is typical for high-temperature superconductors with columnar defects (a kink occurs near the matching field $% B_{\\phi}$) and is very different ...

  3. Negative effects of crystalline-SiC doping on the critical current density in Ti-sheathed MgB2(SiC)y superconducting wires

    International Nuclear Information System (INIS)

    Liang, G; Fang, H; Luo, Z P; Hoyt, C; Yen, F; Guchhait, S; Lv, B; Markert, J T

    2007-01-01

    Ti-sheathed MgB 2 wires doped with nanosize crystalline-SiC up to a concentration of 15 wt% SiC have been fabricated, and the effects of the SiC doping on the critical current density (J c ) and other superconducting properties studied. In contrast with the previously reported results that nano-SiC doping with a doping range below 16 wt% usually enhances J c , particularly at higher fields, our measurements show that SiC doping decreases J c over almost the whole field range from 0 to 7.3 T at all temperatures. Furthermore, it is found that the degradation of J c becomes stronger at higher SiC doping levels, which is also in sharp contrast with the reported results that J c is usually optimized at doping levels near 10 wt% SiC. Our results indicate that these negative effects on J c could be attributed to the absence of significant effective pinning centres (mainly Mg 2 Si) due to the high chemical stability of the crystalline-SiC particles

  4. Stability of the Al/TiB2 interface and doping effects of Mg/Si

    Science.gov (United States)

    Deng, Chao; Xu, Ben; Wu, Ping; Li, Qiulin

    2017-12-01

    The Al/TiB2 interface is of significant importance in controlling the mechanical properties of Al-B4C composites and tuning the heterogeneous nucleation of Al/Si alloys in industry. Its stability and bonding conditions are critical for both purposes. In this paper, the interfacial energies were investigated by first-principles calculations, and the results support the reported grain refinement mechanisms in Al/Si alloys. Moreover, to improve the mechanical properties of the interface, Mg and Si were doped at the interface, and our simulations show that the two interfaces will both weaken after doping Mg/Si, thus the formation of TiB2 is inhibited. As a result, the processability of the Al-B4C composites may be improved. Our results provide a theoretical basis and guidance for practical applications.

  5. Scintillation properties of Zr co-doped Ce:(Gd, La)_2Si_2O_7 grown by the Czochralski process

    International Nuclear Information System (INIS)

    Murakami, Rikito; Kurosawa, Shunsuke; Shoji, Yasuhiro; Jary, Vitezslav; Ohashi, Yuji; Pejchal, Jan; Yokota, Yuui; Kamada, Kei; Nikl, Martin; Yoshikawa, Akira

    2016-01-01

    (Gd_0_._7_5,Ce_0_._0_1_5,La_0_._2_3_5)_2Si_2O_7 (Ce:La-GPS) single crystals co-doped with 0, 100, 200, 500 and 1000 ppm Zr were grown by the Czochralski process, and their scintillation properties were investigated. We investigated the co-doping effect of a stable tetravalent ion in Ce:La-GPS for the first time. The scintillation decay times in the faster component were shortened with increasing the Zr concentration. While the non-co-doped sample showed ∼63 ns day time, the Zr 100, 200, 500 and 1000 ppm co-doped samples showed ∼61, ∼59, ∼57, ∼54 ns, respectively. Additionally, light output, photon nonproportional response (PNR) and other optical properties were investigated. - Highlights: • Czochralski growth of Ce:(Gd,La)_2Si_2O_7 single crystals. • Co-doping effect of a stable tetravalent ion in Ce:(Gd,La)_2Si_2O_7 system. • Photon nonproportional response of Zr co-doped Ce:(Gd,La)_2Si_2O_7.

  6. Superparamagnetic behavior of Fe-doped SnO2 nanoparticles

    International Nuclear Information System (INIS)

    Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y.

    2014-01-01

    SnO 2 is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO 2 nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO 2 nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO 2 , were investigated. The particle size (1.8–16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO 2 single-phase structure for samples annealed at 1073–1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO 2 is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system

  7. Superparamagnetic behavior of Fe-doped SnO2 nanoparticles

    Science.gov (United States)

    Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y.

    2014-02-01

    SnO2 is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO2 nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO2 nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO2, were investigated. The particle size (1.8-16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO2 single-phase structure for samples annealed at 1073-1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO2 is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system.

  8. Enhancement of the critical current density and flux pinning of MgB2 superconductor by nanoparticle SiC doping

    Science.gov (United States)

    Dou, S. X.; Soltanian, S.; Horvat, J.; Wang, X. L.; Zhou, S. H.; Ionescu, M.; Liu, H. K.; Munroe, P.; Tomsic, M.

    2002-10-01

    Doping of MgB2 by nano-SiC and its potential for the improvement of flux pinning were studied for MgB2-x)(SiCx/2 with x=0, 0.2, and 0.3 and for 10 wt % nano-SiC-doped MgB2 samples. Cosubstitution of B by Si and C counterbalanced the effects of single-element doping, decreasing Tc by only 1.5 K, introducing intragrain pinning centers effective at high fields and temperatures, and significantly enhancing Jc and Hirr. Compared to the undoped sample, Jc for the 10 wt % doped sample increased by a factor of 32 at 5 K and 8 T, 42 at 20 K and 5 T, and 14 at 30 K and 2 T. At 20 K and 2 T, the Jc for the doped sample was 2.4 x105 A/cm2, which is comparable to Jc values for the best Ag/Bi-2223 tapes. At 20 K and 4 T, Jc was twice as high as for the best MgB2 thin films and an order of magnitude higher than for the best Fe/MgB2 tapes. The magnetic Jc is consistent with the transport Jc which remains at 20 000 A/cm2 even at 10 T and 5 K for the doped sample, an order of magnitude higher than the undoped one. Because of such high performance, it is anticipated that the future MgB2 conductors will be made using a formula of MgBxSiyCz instead of pure MgB2.

  9. Critical current density in MgB2 bulk samples after co-doping with nano-SiC and poly zinc acrylate complexes

    International Nuclear Information System (INIS)

    Zhang, Z.; Suo, H.; Ma, L.; Zhang, T.; Liu, M.; Zhou, M.

    2011-01-01

    SiC and poly zinc acrylate complexes co-doped MgB 2 bulk has been synthesized. Co-doping can cause higher carbon substitutions and the second phase particles. Co-doping can further increase the Jc value of MgB 2 bulk on the base of the SiC doping. The co-doped MgB 2 bulk samples have been synthesized using an in situ reaction processing. The additives is 8 wt.% SiC nano powders and 10 wt.% [(CH 2 CHCOO) 2 Zn] n poly zinc acrylate complexes (PZA). A systematic study was performed on samples doped with SiC or PZA and samples co-doped with both of them. The effects of doping and co-doping on phase formation, microstructure, and the variation of lattice parameters were studied. The amount of substituted carbon, the critical temperature (T c ) and the critical current density (J c ) were determined. The calculated lattice parameters show the decrease of the a-axis, while no obvious change was detected for c-axis parameter in co-doped samples. This indicates that the carbon was substituted by boron in MgB 2 . The amount of substituted carbon for the co-doped sample shows an enhancement compared to that of the both single doped samples. The co-doped samples perform the highest J c values, which reaches 3.3 x 10 4 A/cm 2 at 5 K and 7 T. It is shown that co-doping with SiC and organic compound is an effective way to further improve the superconducting properties of MgB 2 .

  10. Significant enhancement of thermoelectric properties and metallization of Al-doped Mg2Si under pressure

    International Nuclear Information System (INIS)

    Morozova, Natalia V.; Korobeinikov, Igor V.; Karkin, Alexander E.; Shchennikov, Vladimir V.; Ovsyannikov, Sergey V.; Takarabe, Ken-ichi; Mori, Yoshihisa; Nakamura, Shigeyuki

    2014-01-01

    We report results of investigations of electronic transport properties and lattice dynamics of Al-doped magnesium silicide (Mg 2 Si) thermoelectrics at ambient and high pressures to and beyond 15 GPa. High-quality samples of Mg 2 Si doped with 1 at. % of Al were prepared by spark plasma sintering technique. The samples were extensively examined at ambient pressure conditions by X-ray diffraction studies, Raman spectroscopy, electrical resistivity, magnetoresistance, Hall effect, thermoelectric power (Seebeck effect), and thermal conductivity. A Kondo-like feature in the electrical resistivity curves at low temperatures indicates a possible magnetism in the samples. The absolute values of the thermopower and electrical resistivity, and Raman spectra intensity of Mg 2 Si:Al dramatically diminished upon room-temperature compression. The calculated thermoelectric power factor of Mg 2 Si:Al raised with pressure to 2–3 GPa peaking in the maximum the values as high as about 8 × 10 −3 W/(K 2 m) and then gradually decreased with further compression. Raman spectroscopy studies indicated the crossovers near ∼5–7 and ∼11–12 GPa that are likely related to phase transitions. The data gathered suggest that Mg 2 Si:Al is metallized under moderate pressures between ∼5 and 12 GPa.

  11. Defect and phase stability of solid solutions of Mg2X with an antifluorite structure: An ab initio study

    International Nuclear Information System (INIS)

    Viennois, Romain; Jund, Philippe; Colinet, Catherine; Tédenac, Jean-Claude

    2012-01-01

    First principles calculations are done for Mg 2 X (X=Si, Ge or Sn) antifluorite compounds and their solid solutions in order to investigate their pseudo-binary phase diagram. The formation energies of the end-member compounds agree qualitatively with the experiments. For X=Si and Ge, there is a complete solubility, but we observe a miscibility gap in the pseudo-binary phase diagram Mg 2 Si–Mg 2 Sn. This agrees with the most recent experiments and phase diagram assessments. Calculated electronic properties of Mg 2 Si 1−x Sn x alloys qualitatively agree with experiments and in particular the energy bandgap decreases when Si is substituted by Sn. Supercell calculations are also done in order to determine the most stable defects and the doping induced by these defects in the three end-member compounds. We find that the intrinsic n-doping in pure Mg 2 Si can be attributed to the presence of magnesium atoms in interstitial positions. In Mg 2 Ge and Mg 2 Sn, since other defects are stable, they can be also of p-type. - Graphical abstract: Evidence of a miscibility gap from the plot of the formation energy vs x Si (silicon content) for the solid solutions Mg 2 Si–Mg 2 Sn. Highlights: ► First-principles study of the stability of Mg 2 Si–Mg 2 X alloys (X=Ge or Sn) and their defects. ► Mg 2 Si–Mg 2 Ge alloys form a complete series of solid solutions. ► Miscibility gap is found in Mg 2 Si–Mg 2 Sn alloys. ► Interstitial defects are more stable in Mg 2 Si and induce n-doping.

  12. Enhancement of H2-sensing Properties of F-doped SnO2 Sensorby Surface Modification with SiO2

    Directory of Open Access Journals (Sweden)

    S. P. Khatkar

    2006-05-01

    Full Text Available Effects of surface chemical modification with sodium silicate on the gas-sensingproperties of F-doped SnO2 gas sensor designed and fabricated employing micro-electromechanical system (MEMS technology were investigated. Gas sensing properties of thesensor were checked against combustible gases like H2, CO, CH4 and C3H8 at a heatervoltage of 0.7 V. The H2 sensitivity of the surface modified F-doped SnO2 micro sensormarkedly increased and reached S = 175 which was found to be about 40 times more thanthat of unmodified sensor (S = ~ 4.2. The increase in the sensitivity is discussed in terms ofincreased resistivity and reduced permeation of gaseous oxygen into the underlying sensinglayer due to the surface modification of the sensor. The present micro-hydrogen sensor withenhanced sensitivity due to SiO2 incorporation is a low energy consuming portable sensormodule that can be mass-produced using MEMS technology at low cost.

  13. Superparamagnetic behavior of Fe-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y. [Department of Physics, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama, Kanagawa 240-8501 (Japan)

    2014-02-20

    SnO{sub 2} is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO{sub 2} nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO{sub 2} nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO{sub 2}, were investigated. The particle size (1.8–16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO{sub 2} single-phase structure for samples annealed at 1073–1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO{sub 2} is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system.

  14. Enhancement of thermoelectric properties of Mg2Si compounds with Bi doping through carrier concentration tuning

    Science.gov (United States)

    Lee, Ji Eun; Cho, Sang-Hum; Oh, Min-Wook; Ryu, Byungi; Joo, Sung-Jae; Kim, Bong-Seo; Min, Bok-Ki; Lee, Hee-Woong; Park, Su-Dong

    2014-07-01

    The Bi-doped Mg2Si powder was fabricated with solid state reaction method and consolidated with hot pressing method and then its thermoelectric properties were investigated. The n-type transport properties were measured in all samples and temperature dependence of the electrical properties shows a behavior of degenerate semiconductors for Bi-doped samples. The electrical resistivity and the Seebeck coefficient were greatly reduced with Bi, which was mainly due to the increment of the carrier concentration. The samples have maximum carrier concentration of 8.2 × 1018 cm-3. The largest ZT value of 0.61 was achieve at 873 K for Mg2.04SiBi0.02. The Bi-doping was found to be an effective n-type dopant to adjust carrier concentration. [Figure not available: see fulltext.

  15. High-temperature thermoelectric properties of La-doped BaSnO3 ceramics

    International Nuclear Information System (INIS)

    Yasukawa, Masahiro; Kono, Toshio; Ueda, Kazushige; Yanagi, Hiroshi; Hosono, Hideo

    2010-01-01

    To elucidate the thermoelectric properties at high temperatures, perovskite-type La-doped BaSnO 3 ceramics were fabricated by a polymerized complex (PC) method and subsequent spark plasma sintering (SPS) technique. Fine powders of Ba 1-x La x SnO 3 (x = 0.00-0.07) were prepared by the PC method using citrate complexes, and SPS treatment converted the powders into dense ceramics with relative densities of 93-97%. The La content dependence of the lattice parameter suggested that the solubility of La for Ba sites was approximately x = 0.03. The temperature dependence of the electrical conductivity σ and Seebeck coefficient S showed that each La-doped ceramic was an n-type degenerate semiconductor in the measured temperature range of 373-1073 K. The La content dependence of the S values indicated that the electron carrier concentration increased successively up to x = 0.03, which was the solubility limit of the La atoms. The thermoelectric power factors S 2 σ increased drastically with La doping, and reached a maximum for x = 0.01 with values of 0.8 x 10 -4 W m -1 K -2 at 373 K to 2.8 x 10 -4 W m -1 K -2 at 1073 K.

  16. Cooperative doping effects of Ti and nano-SiC on transport critical current density and grain connectivity of in situ MgB{sub 2} tapes

    Energy Technology Data Exchange (ETDEWEB)

    Pan, X.F., E-mail: PAN.Xifeng@nims.go.jp [National Institute for Materials Science, Superconducting Materials Research Center, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan)] [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Southwest Jiaotong University, Chengdu 610031 (China); Matsumoto, A.; Kumakura, H. [National Institute for Materials Science, Superconducting Materials Research Center, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Cheng, C.H.; Zhao, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Southwest Jiaotong University, Chengdu 610031 (China)] [School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia)

    2011-11-15

    We studied the cooperative doping effects of Ti and nano-SiC on transport J{sub c} and grain connectivity of MgB{sub 2} tape. Ti doping significantly weakens the current dependence of T{sub c} of MgB{sub 2} tapes at self-field, and does not change T{sub c} or slightly increases T{sub c}. Further Ti adding can enhance in-field J{sub c} performance of SiC doped MgB{sub 2} tapes by a factor of 50-100% at 4.2 K and 10 T. Ti addition improves the J{sub c} performance of undoped and SiC doped MgB{sub 2} by modifying their grains connection. By now, nano-SiC powder (20-30 nm) is still the most effective additive for improving upper critical field and critical current density of MgB{sub 2}-based superconducting materials. However, some decomposed carbon aggregates at grain boundaries and results in serious weak-links of MgB{sub 2} grains, and these weak-links limit the further improvement of critical current density, J{sub c} of MgB{sub 2}, especially at lower fields. Ti doping is reported to increase the compactness of MgB{sub 2}, and modify its intergranular coupling by forming ultrathin TiB{sub 2} layer at grain boundaries. In this work, we studied the cooperative doping effects of Ti and nano-SiC on transport J{sub c} and grain connectivity of MgB{sub 2} and the possibility to improve transport J{sub c} of SiC doped MgB{sub 2} by introducing Ti additive. The results suggest the Ti addition can obviously improve J{sub c} of MgB{sub 2} at lower fields and also enhance the J{sub c} of SiC doped MgB{sub 2} by improving their grain connectivity which shows serious intergranular weak-links.

  17. Lattice stability and formation energies of intrinsic defects in Mg2Si and Mg2Ge via first principles simulations

    International Nuclear Information System (INIS)

    Jund, Philippe; Viennois, Romain; Tédenac, Jean-Claude; Colinet, Catherine; Hug, Gilles; Fèvre, Mathieu

    2013-01-01

    We report an ab initio study of the semiconducting Mg 2 X (with X = Si, Ge) compounds and in particular we analyze the formation energies of the different point defects with the aim of understanding the intrinsic doping mechanisms. We find that the formation energy of Mg 2 Ge is 50% larger than that of Mg 2 Si, in agreement with the experimental tendency. From a study of the stability and the electronic properties of the most stable defects, taking into account the growth conditions, we show that the main cause of the n doping in these materials comes from interstitial magnesium defects. Conversely, since other defects acting like acceptors such as Mg vacancies or multivacancies are more stable in Mg 2 Ge than in Mg 2 Si, this explains why Mg 2 Ge can be of n or p type, in contrast to Mg 2 Si. The finding that the most stable defects are different in Mg 2 Si and Mg 2 Ge and depend on the growth conditions is important and must be taken into account in the search for the optimal doping to improve the thermoelectric properties of these materials.

  18. La5Zn2Sn

    Directory of Open Access Journals (Sweden)

    Igor Oshchapovsky

    2011-11-01

    Full Text Available A single crystal of pentalanthanum dizinc stannide, La5Zn2Sn, was obtained from the elements in a resistance furnace. It belongs to the Mo5SiB2 structure type, which is a ternary ordered variant of the Cr5B3 structure type. The space is filled by bicapped tetragonal antiprisms from lanthanum atoms around tin atoms sharing their vertices. Zinc atoms fill voids between these bicapped tetragonal antiprisms. All four atoms in the asymmetric unit reside on special positions with the following site symmetries: La1 (..m; La2 (4/m..; Zn (m.2m; Sn (422.

  19. Age hardening of a sintered Al-Cu-Mg-Si-(Sn) alloy

    International Nuclear Information System (INIS)

    Kent, D.; Schaffer, G.B.; Drennan, J.

    2005-01-01

    The age hardening response of a sintered Al-3.8 wt% Cu-1.0 wt% Mg-0.70 wt% Si alloy with and without 0.1 wt% Sn was investigated. The sequence of precipitation was characterised using transmission electron microscopy. The ageing response of the sintered Al-Cu-Mg-Si-(Sn) alloy is similar to that of cognate wrought 2xxx series alloys. Peak hardness was associated with a fine, uniform dispersion of lath shaped precipitates, believed to be either the β'or Q' phase, oriented along α directions and θ' plates lying on {0 0 1} α planes. Natural ageing also resulted in comparable behaviour to that observed in wrought alloys. Porosity in the powder metallurgy alloys did not significantly affect the kinetics of precipitation during artificial ageing. Trace levels of tin, used to aid sintering, slightly reduced the hardening response of the alloy. However, this was compensated for by significant improvements in density and hardness

  20. Mg2BIV: Narrow Bandgap Thermoelectric Semiconductors

    Science.gov (United States)

    Kim, Il-Ho

    2018-05-01

    : intrinsic Mg2Si, doped Mg2Si:Dm (D = Al, In, Bi, Sb, Te or Se), and solid solutions of intrinsic/doped Mg2Si1 - x Sn x :D m and Mg2Si1 - x Ge x :D m .

  1. Composition and local bonding in RE-Si-M-O-N (M=Mg, Al ; RE=La, Lu) glasses

    Energy Technology Data Exchange (ETDEWEB)

    Fouquet-Parry, V. [Service de Physique et de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Paumier, F. [Laboratoire de Metallurgie Physique - UMR 6630 CNRS, Department of Materials Sciences, University of Poitiers (France); Guittet, M.J. [Service de Physique et de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Gautier-Soyer, M. [Service de Physique et de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France)], E-mail: mgautiersoyer@cea.fr; Satet, R.; Hoffmann, M.J. [Institut fuer Keramik im Maschinenbau, Universitaet Karlsruhe (Thailand), Haid-und-Neu-Strasse 7, D 76131 Karlsruhe (Germany); Becher, P.F.; Painter, G.S. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2008-05-30

    Two series of oxynitride glasses, RE-Si-Mg-O-N (M=Mg, Al ; RE=La, Lu), have been studied by X-Ray photoelectron spectroscopy (XPS). The oxygen 1s photoelectron lineshape reveals a striking difference depending on the rare earth, both in the Mg series and in the Al series. Specifically, the oxygen 1s photoelectron lines of the La doped glasses are broader than the ones of the Lu doped glasses. This result is an experimental evidence that Lu has a larger affinity for oxygen versus nitrogen than La, as theoretically predicted by the first-principles calculations by Painter et al.

  2. Discharge characteristics of plasma display panels with Si-doped MgO protective layers

    Energy Technology Data Exchange (ETDEWEB)

    Ram, Sanjay K., E-mail: sanjayk.ram@gmail.co [Laboratoire de Physique des Interfaces et des Couches Minces (UMR 7647 du CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex (France); Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 (India); Barik, U K [Samtel Color Limited, Ghaziabad-201009 (India); Sarkar, Surajit; Biswas, Paramananda [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 (India); Singh, Vandana [Laboratoire de Physique des Interfaces et des Couches Minces (UMR 7647 du CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex (France); Dwivedi, H K [Samtel Color Limited, Ghaziabad-201009 (India); Kumar, Satyendra [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 (India)

    2009-10-01

    We report on our study of the influence of varying concentrations of Si doping on the secondary electron emission (SEE) yield of MgO thin films prepared by electron beam evaporation technique. The series of Si-doped MgO films were microstructurally characterized with various tools like X-ray diffraction, scanning electron microscopy and atomic force microscopy. The optimization of the concentration of Si doping is seen to enhance the SEE yield. We discuss the correlation of SEE yield in the context of different deposition and measurement conditions and crystalline orientation.

  3. Thin films of thermoelectric compound Mg2Sn deposited by co-sputtering assisted by multi-dipolar microwave plasma

    International Nuclear Information System (INIS)

    Le-Quoc, H.; Lacoste, A.; Hlil, E.K.; Bes, A.; Vinh, T. Tan; Fruchart, D.; Skryabina, N.

    2011-01-01

    Highlights: → Mg 2 Sn thin films deposited by plasma co-sputtering, on silicon and glass substrates. → Formation of nano-grained polycrystalline films on substrates at room temperature. → Structural properties vary with target biasing and target-substrate distance. → Formation of the hexagonal phase of Mg 2 Sn in certain deposition conditions. → Power factor ∼5.0 x 10 -3 W K -2 m -1 for stoichiometric Mg 2 Sn films doped with ∼1 at.% Ag. - Abstract: Magnesium stannide (Mg 2 Sn) thin films doped with Ag intended for thermoelectric applications are deposited on both silicon and glass substrates at room temperature by plasma assisted co-sputtering. Characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction confirms the formation of fine-grained polycrystalline thin films with thickness of 1-3 μm. Stoichiometry, microstructure and crystal structure of thin films are found to vary with target biasing and the distance from targets to substrate. Measurements of electrical resistivity and Seebeck coefficient at room temperature show the maximum power factor of ∼5.0 x 10 -3 W K -2 m -1 for stoichiometric Mg 2 Sn thin films doped with ∼1 at.% Ag.

  4. First-principles investigation of Fe-doped MgSiO3-ilmenite

    International Nuclear Information System (INIS)

    Stashans, Arvids; Rivera, Krupskaya; Pinto, Henry P.

    2012-01-01

    First principles density functional theory and generalised gradient approximation (GGA) have been exploited to investigate Fe-doped ilmenite-type MgSiO 3 mineral. Strong electron correlation effects not included in a density-functional formalism are described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach). Microstructure of equilibrium geometries, electronic band structures as well as magnetic properties are computed and discussed in detail. Hartree-Fock methodology is used as an extra tool to study optical properties of the same system. For equilibrium state of the doped mineral we find zigzag-type atomic rearrangements around the Fe impurity. The inclusion of correlation effects leads to an improved description of the electronic properties. In particular, it is discovered that Fe incorporation produces local energy levels within the band-gap of the material. Using ΔSCF method optical absorption energies are found to be equal to 2.2 and 2.6 eV leading to light absorption at longer wavelengths compared to the undoped MgSiO 3 . Our results provide evidence on the occurrence of local magnetic moment in the region surrounding iron dopant. According to the outcomes, the Fe⇒Mg reaction can be described as substitutionally labile with Fe 2+ complex being found in the high-spin state at low pressure MgSiO 3 -ilmenite conditions.

  5. A computational study on the electronic and field emission properties of Mg and Si doped AlN nanocones

    Science.gov (United States)

    Saedi, Leila; Soleymanabadi, Hamed; Panahyab, Ataollah

    2018-05-01

    Following an experimental work, we explored the effect of replacing an Al atom of an AlN nanocone by Si or Mg atom on its electronic and field emission properties using density functional theory calculations. We found that both Si-doping and Mg-doping increase the electrical conductivity of AlN nanocone, but their influences on the filed emission properties are significantly different. The Si-doping increases the electron concentration of AlN nanocone and results in a large electron mobility and a low work function, whereas Mg-doping leads to a high hole concentration below the conduction level and increases the work function in agreement with the experimental results. It is predicted that Si-doped AlN nanocones show excellent filed emission performance with higher emitted electron current density compared to the pristine AlN nanocone. But the Mg-doping meaningfully decreases the emitted electron current density from the surface of AlN nanocone. The Mg-doping can increase the work function about 41.9% and the Si-doping can decrease it about 6.3%. The Mg-doping and Si-doping convert the AlN nanocone to a p-type and n-type semiconductors, respectively. Our results explain in a molecular level what observed in the experiment.

  6. First-principles investigation of Fe-doped MgSiO{sub 3}-ilmenite

    Energy Technology Data Exchange (ETDEWEB)

    Stashans, Arvids, E-mail: arvids@utpl.edu.ec [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Rivera, Krupskaya [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Escuela de Geologia y Minas, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Pinto, Henry P. [Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217-0510 (United States)

    2012-06-15

    First principles density functional theory and generalised gradient approximation (GGA) have been exploited to investigate Fe-doped ilmenite-type MgSiO{sub 3} mineral. Strong electron correlation effects not included in a density-functional formalism are described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach). Microstructure of equilibrium geometries, electronic band structures as well as magnetic properties are computed and discussed in detail. Hartree-Fock methodology is used as an extra tool to study optical properties of the same system. For equilibrium state of the doped mineral we find zigzag-type atomic rearrangements around the Fe impurity. The inclusion of correlation effects leads to an improved description of the electronic properties. In particular, it is discovered that Fe incorporation produces local energy levels within the band-gap of the material. Using {Delta}SCF method optical absorption energies are found to be equal to 2.2 and 2.6 eV leading to light absorption at longer wavelengths compared to the undoped MgSiO{sub 3}. Our results provide evidence on the occurrence of local magnetic moment in the region surrounding iron dopant. According to the outcomes, the Fe Rightwards-Double-Arrow Mg reaction can be described as substitutionally labile with Fe{sup 2+} complex being found in the high-spin state at low pressure MgSiO{sub 3}-ilmenite conditions.

  7. Synthesis, Characterization, and Photocatalytic Activity of Zn-Doped SnO2/Zn2SnO4 Coupled Nanocomposites

    Directory of Open Access Journals (Sweden)

    Tiekun Jia

    2014-01-01

    Full Text Available Zn-doped SnO2/Zn2SnO4 nanocomposites were prepared via a two-step hydrothermal synthesis method. The as-prepared samples were characterized by X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM, UV-vis diffuse reflection spectroscopy, and adsorption-desorption isotherms. The results of FESEM and TEM showed that the as-prepared Zn-doped SnO2/Zn2SnO4 nanocomposites are composed of numerous nanoparticles with the size ranging from 20 nm to 50 nm. The specific surface area of the as-prepared Zn-doped SnO2/Zn2SnO4 nanocomposites is estimated to be 71.53 m2/g by the Brunauer-Emmett-Teller (BET method. The photocatalytic activity was evaluated by the degradation of methylene blue (MB, and the resulting showed that Zn-doped SnO2/Zn2SnO4 nanocomposites exhibited excellent photocatalytic activity due to their higher specific surface area and surface charge carrier transfer.

  8. Ionic conductivity and fuel cell properties of apatite-type lanthanum silicates doped with Mg and containing excess oxide ions

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Hideki [Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira-cho, Suma-ku, Kobe 654-0037 (Japan); Nojiri, Yoshihiro [Kyushu University, Department of Mechanical Engineering Science, Faculty of Engineering, Motooka 744, Nishi-ku, Fukuoka 819-0935 (Japan); Tanase, Shigeo [National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

    2008-11-30

    Enhancement of the ionic conductivity of lanthanum silicate-based apatites is examined with emphasis on optimizing the La composition and the Mg doping level at the same time. La{sub 10}Si{sub 5.8}Mg{sub 0.2}O{sub 26.8} and La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} show the highest level of the ionic conductivities among apatite silicates, 8.8 and 7.4 x 10{sup -} {sup 2} S cm{sup -} {sup 1} at 800 C, respectively, with a very low level of activation energy (0.42-0.43 eV). Their conductivities are higher than yttria stabilized zirconia (YSZ) below 900 C and even comparable to Sr and Mg doped lanthanum gallate (LSGM) below 550 C. A solid oxide fuel cell using La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} as an electrolyte with Ni-ceria cermet anode and Sr doped lanthanum cobaltite cathode exhibits a remarkable improvement in power generation compared to previous data using Pt electrodes. Structural investigation by the Rietveld analysis on the powder X-ray diffraction pattern shows significant enlargement of the bottleneck triangle sizes of the conduction channel with the Mg doping. (author)

  9. New members of the A2 M ‧ M2″ structure family (A=Ca, Sr, Yb, La; M ‧ = In , Sn , Pb; M ″ = Si , Ge)

    Science.gov (United States)

    Jehle, Michael; Dürr, Ines; Fink, Saskia; Lang, Britta; Langenmaier, Michael; Steckhan, Julia; Röhr, Caroline

    2015-01-01

    The new mixed tetrelides Sr2PbGe2 and Yb2SnGe2, several mixed Ca/Sr (AII) germanides A2II (Sn, Pb)Ge2 and two polymorphs of La2 InSi2 represent new members of the general structure family of ternary alkaline-earth/lanthanoid main group silicides/germanides A2 M ‧ M2″ (M ‧ = In , Sn , Pb ; M ″ = Si , Ge). All compounds were synthesized from melts of the elements and their crystal structures have been determined by means of single crystal X-ray diffraction. Sr2PbGe2 (Cmmm, a=402.36(11), b=1542.3(4), c=463.27(10) pm) crystallizes with the Mn2AlB2 -type structure. In exhibiting infinite planar Ge zig-zag chains, it represents one border of the compound series. The other borderline case, where only [Ge2 ] dumbbells are left as Ge building units, is represented by the Ca/Yb tin germanides Ca2SnGe2 and Yb2SnGe2 (Mo2FeB2 -type; P4/mbm, a=748.58(13)/740.27(7), c=445.59(8)/435.26(5) pm). In between these two border structures compounds with variable Si/Ge chain lengths could be obtained by varying the averaged size of the AII cations: Ca0.45Sr1.55PbGe2 (new structure type; Pbam, a=791.64(5), b=2311.2(2), c=458.53(3) pm) contains planar six-membered chain segments [Ge6 ]. Tetrameric pieces [Ge4 ] are the conspicuous structure elements in Ca1.16Sr0.84SnGe2 and La2 InSi2 (La2InNi2 -type; Pbam, a=781.01(2)/762.01(13), b=1477.95(3)/1494.38(6), c=457.004(9)/442.1(3) pm). The tetragonal form of 'La2 In Si2‧ (exact composition: La2In1.07Si1.93, P4/mbm, a=1309.11(12), c=443.32(4) pm) also crystallizes in a new structure type, containing only [Si3 ] trimers as cutouts of the planar chains. In all structures the Si/Ge zig-zag chains/chain segments are connected by In/Sn/Pb atoms to form planar M layers, which are separated by pure A layers. Band structure calculations within the FP-LAPW DFT approach together with the Zintl formalism, extended by the presence of hypervalent bonding of the heavier M ‧ elements, give insight into the chemical bonding of this series of p

  10. Electronic structure and magnetic properties of Ni-doped SnO2 thin films

    Science.gov (United States)

    Sharma, Mayuri; Kumar, Shalendra; Alvi, P. A.

    2018-05-01

    This paper reports the electronic structure and magnetic properties of Ni-doped SnO2 thin film which were grown on Si (100) substrate by PLD (pulse laser deposition) technique under oxygen partial pressure (PO2). For getting electronic structure and magnetic behavior, the films were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and DC magnetization measurements. The NEXAFS study at Ni L3,2 edge has been done to understand the local environment of Ni and Sn ions within SnO2 lattice. DC magnetization measurement shows that the saturation magnetization increases with the increase in substitution of Ni2+ ions in the system.

  11. Atomic and electronic structure of doped Si (111 ) (2 √{3 }×2 √{3 }) R 30∘ -Sn interfaces

    Science.gov (United States)

    Yi, Seho; Ming, Fangfei; Huang, Ying-Tzu; Smith, Tyler S.; Peng, Xiyou; Tu, Weisong; Mulugeta, Daniel; Diehl, Renee D.; Snijders, Paul C.; Cho, Jun-Hyung; Weitering, Hanno H.

    2018-05-01

    The hole-doped Si (111 ) (2 √ 3 ×2 √ 3 ) R 30∘ -Sn interface exhibits a symmetry-breaking insulator-insulator transition below 100 K that appears to be triggered by electron tunneling into the empty surface-state bands. No such transition is seen in electron-doped systems. To elucidate the nature and driving force of this phenomenon, the structure of the interface must be resolved. Here we report on an extensive experimental and theoretical study, including scanning tunneling microscopy and spectroscopy (STM/STS), dynamical low-energy electron diffraction (LEED) analysis, and density functional theory (DFT) calculations, to elucidate the structure of this interface. We consider six different structure models, three of which have been proposed before, and conclude that only two of them can account for the majority of experimental data. One of them is the model according to Törnevik et al. [C. Törnevik et al., Phys. Rev. B 44, 13144 (1991), 10.1103/PhysRevB.44.13144] with a total Sn coverage of 14/12 monolayers (ML). The other is the "revised trimer model" with a total Sn coverage of 13/12 ML, introduced in this work. These two models are very difficult to discriminate on the basis of DFT or LEED alone, but STS data clearly point toward the Törnevik model as the most viable candidate among the models considered here. The STS data also provide additional insights regarding the electron-injection-driven phase transformation. Similar processes may occur at other metal/semiconductor interfaces, provided they are nonmetallic and can be doped. This could open up a new pathway toward the creation of novel surface phases with potentially very interesting and desirable electronic properties.

  12. Solid phase epitaxial growth of high mobility La:BaSnO_3 thin films co-doped with interstitial hydrogen

    International Nuclear Information System (INIS)

    Niedermeier, Christian A.; Rhode, Sneha; Fearn, Sarah; Moram, Michelle A.; Ide, Keisuke; Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio

    2016-01-01

    This work presents the solid phase epitaxial growth of high mobility La:BaSnO_3 thin films on SrTiO_3 single crystal substrates by crystallization through thermal annealing of nanocrystalline thin films prepared by pulsed laser deposition at room temperature. The La:BaSnO_3 thin films show high epitaxial quality and Hall mobilities up to 26 ± 1 cm"2/Vs. Secondary ion mass spectroscopy is used to determine the La concentration profile in the La:BaSnO_3 thin films, and a 9%–16% La doping activation efficiency is obtained. An investigation of H doping to BaSnO_3 thin films is presented employing H plasma treatment at room temperature. Carrier concentrations in previously insulating BaSnO_3 thin films were increased to 3 × 10"1"9" cm"−"3 and in La:BaSnO_3 thin films from 6 × 10"1"9" cm"−"3 to 1.5 × 10"2"0" cm"−"3, supporting a theoretical prediction that interstitial H serves as an excellent n-type dopant. An analysis of the free electron absorption by infrared spectroscopy yields a small (H,La):BaSnO_3 electron effective mass of 0.27 ± 0.05 m_0 and an optical mobility of 26 ± 7 cm"2/Vs. As compared to La:BaSnO_3 single crystals, the smaller electron mobility in epitaxial thin films grown on SrTiO_3 substrates is ascribed to threading dislocations as observed in high resolution transmission electron micrographs.

  13. Investigation of pentacene growth on SiO2 gate insulator after photolithography for nitrogen-doped LaB6 bottom-contact electrode formation

    Science.gov (United States)

    Maeda, Yasutaka; Hiroki, Mizuha; Ohmi, Shun-ichiro

    2018-04-01

    Nitrogen-doped (N-doped) LaB6 is a candidate material for the bottom-contact electrode of n-type organic field-effect transistors (OFETs). However, the formation of a N-doped LaB6 electrode affects the surface morphology of a pentacene film. In this study, the effects of surface treatments and a N-doped LaB6 interfacial layer (IL) were investigated to improve the pentacene film quality after N-doped LaB6 electrode patterning with diluted HNO3, followed by resist stripping with acetone and methanol. It was found that the sputtering damage during N-doped LaB6 deposition on a SiO2 gate insulator degraded the crystallinity of pentacene. The H2SO4 and H2O2 (SPM) and diluted HF treatments removed the damaged layer on the SiO2 gate insulator surface. Furthermore, the N-doped LaB6 IL improved the crystallinity of pentacene and realized dendritic grain growth. Owing to these surface treatments, the hole mobility improved from 2.8 × 10-3 to 0.11 cm2/(V·s), and a steep subthreshold swing of 78 mV/dec for the OFET with top-contact configuration was realized in air even after bottom-contact electrode patterning.

  14. Application of Al-2La-1B Grain Refiner to Al-10Si-0.3Mg Casting Alloy

    Science.gov (United States)

    Jing, Lijun; Pan, Ye; Lu, Tao; Li, Chenlin; Pi, Jinhong; Sheng, Ningyue

    2018-05-01

    This paper reports the application and microstructure refining effect of an Al-2La-1B grain refiner in Al-10Si-0.3Mg casting alloy. Compared with the traditional Al-5Ti-1B refiner, Al-2La-1B refiner shows better performances on the grain refinement of Al-10Si-0.3Mg alloy. Transmission electron microscopy analysis suggests that the crystallite structure features of LaB6 are beneficial to the heterogeneous nucleation of α-Al grains. Regarding the mechanical performances, tensile properties of Al-10Si-0.3Mg casting alloy are prominently improved, due to the refined microstructures.

  15. Cellular Response to Doping of High Porosity Foamed Alumina with Ca, P, Mg, and Si

    Directory of Open Access Journals (Sweden)

    Edwin Soh

    2015-03-01

    Full Text Available Foamed alumina was previously synthesised by direct foaming of sulphate salt blends varying ammonium mole fraction (AMF, foaming heating rate and sintering temperature. The optimal product was produced with 0.33AMF, foaming at 100 °C/h and sintering at 1600 °C. This product attained high porosity of 94.39%, large average pore size of 300 µm and the highest compressive strength of 384 kPa. To improve bioactivity, doping of porous alumina by soaking in dilute or saturated solutions of Ca, P, Mg, CaP or CaP + Mg was done. Saturated solutions of Ca, P, Mg, CaP and CaP + Mg were made with excess salt in distilled water and decanted. Dilute solutions were made by diluting the 100% solution to 10% concentration. Doping with Si was done using the sol gel method at 100% concentration only. Cell culture was carried out with MG63 osteosarcoma cells. Cellular response to the Si and P doped samples was positive with high cell populations and cell layer formation. The impact of doping with phosphate produced a result not previously reported. The cellular response showed that both Si and P doping improved the biocompatibility of the foamed alumina.

  16. Selectivity enhancement of indium-doped SnO2 gas sensors

    International Nuclear Information System (INIS)

    Salehi, A.

    2002-01-01

    Indium doping was used to enhance the selectivity of SnO 2 gas sensor. Both indium-doped and undoped SnO 2 gas sensors fabricated with different deposition techniques were investigated. The changes in the sensitivity of the sensors caused by selective gases (hydrogen and wood smoke) ranging from 500 to 3000 ppm were measured at different temperatures from 50 to 300 deg. C. The sensitivity peaks of the samples exhibit different values for selective gases with a response time of approximately 0.5 s. Thermally evaporated indium-doped SnO 2 gas sensor shows a considerable increase in the sensitivity peak of 27% in response to wood smoke, whereas it shows a sensitivity peak of 7% to hydrogen. This is in contrast to the sputter deposited indium-doped SnO 2 gas sensor, which exhibits a much lower sensitivity peak of approximately 2% to hydrogen and wood smoke compared to undoped SnO 2 gas sensors fabricated by chemical vapor deposition and spray pyrolysis. Scanning electron microscopy shows that different deposition techniques result in different porosity of the films. It is observed that the thermally evaporated indium-doped SnO 2 gas sensor shows high porosity, while the sputtered sample exhibits almost no porosity

  17. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO2 fiber

    International Nuclear Information System (INIS)

    Katsumata, Toru; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-01-01

    Visible light thermal radiation from SiO 2 glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO 2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO 2 fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO 2 fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO 2 fibers are smaller than those from SiO 2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO 2 are potentially applicable for the fiber-optic thermometry above 900 K

  18. Incorporation of sol-gel SnO2:Sb into nanoporous SiO2

    International Nuclear Information System (INIS)

    Canut, B.; Blanchin, M.G.; Ramos-Canut, S.; Teodorescu, V.; Toulemonde, M.

    2006-01-01

    Silicon oxide films thermally grown on Si(1 0 0) wafers were irradiated with 200 MeV 197 Au ions in the 10 9 -10 1 cm -2 fluence range. The targets were then etched at room temperature in aqueous HF solution (1 vol.%) for various durations. Atomic force microscopy (AFM) in the tapping mode was used to probe the processed surfaces. Conical holes with a low size dispersion were evidenced. Their surface diameter varies between 20 and 70 nm, depending on the etching time. Sol-gel dip coating technique, associated with a further annealing treatment performed at 500 o C for 15 min, was used to fill the nanopores created in SiO 2 with a transparent conductive oxide (SnO 2 doped with antimony). Transmission electron microscopy (TEM) performed on cross-sectional specimen showed that SnO 2 :Sb crystallites of ∼5 nm mean size are trapped in the holes without degrading their geometry

  19. Quantification of MgO surface excess on the SnO2 nanoparticles and relationship with nanostability and growth

    International Nuclear Information System (INIS)

    Gouvea, Douglas; Pereira, Gilberto J.; Gengembre, Leon; Steil, Marlu C.; Roussel, Pascal; Rubbens, Annick; Hidalgo, Pilar; Castro, Ricardo H.R.

    2011-01-01

    In this work, we experimentally showed that the spontaneous segregation of MgO as surface excess in MgO doped SnO 2 nanoparticles plays an important role in the system's energetics and stability. Using X-ray fluorescence in specially treated samples, we quantitatively determined the fraction of MgO forming surface excess when doping SnO 2 with several different concentrations and established a relationship between this amount and the surface energy of the nanoparticles using the Gibbs approach. We concluded that the amount of Mg ions on the surface was directly related to the nanoparticles total free energy, in a sense that the dopant will always spontaneously distribute itself to minimize it if enough diffusion is provided. Because we were dealing with nanosized particles, the effect of MgO on the surface was particularly important and has a direct effect on the equilibrium particle size (nanoparticle stability), such that the lower the surface energy is, the smaller the particle sizes are, evidencing and quantifying the thermodynamic basis of using additives to control SnO 2 nanoparticles stability.

  20. Ab initio study of thermoelectric properties of doped SnO_2 superlattices

    International Nuclear Information System (INIS)

    Borges, P.D.; Silva, D.E.S.; Castro, N.S.; Ferreira, C.R.; Pinto, F.G.; Tronto, J.; Scolfaro, L.

    2015-01-01

    Transparent conductive oxides, such as tin dioxide (SnO_2), have recently shown to be promising materials for thermoelectric applications. In this work we studied the thermoelectric properties of Fe-, Sb- and Zn-uniformly doping and co-doping SnO_2, as well as of Sb and Zn planar (or delta)-doped layers in SnO_2 forming oxide superlattices (SLs). Based on the semiclassical Boltzmann transport equations (BTE) in conjunction with ab initio electronic structure calculations, the Seebeck coefficient (S) and figure of merit (ZT) are obtained for these systems, and are compared with available experimental data. The delta doping approach introduces a remarkable modification in the electronic structure of tin dioxide, when compared with the uniform doping, and colossal values for ZT are predicted for the delta-doped oxide SLs. This result is a consequence of the two-dimensional electronic confinement and the strong anisotropy introduced by the doped planes. In comparison with the uniformly doped systems, our predictions reveal a promising use of delta-doped SnO_2 SLs for enhanced S and ZT, which emerge as potential candidates for thermoelectric applications. - Graphical abstract: Band structure and Figure of merit for SnO2:Sb superlattice along Z direction, P. D. Borges, D. E. S. Silva, N. S. Castro, C. R. Ferreira, F. G. Pinto, J. Tronto and L. Scolfaro, Ab initio study of thermoelectric properties of doped SnO2 superlattices. - Highlights: • Thermoelectric properties of SnO_2-based alloys and superlattices. • High figure of merit is predicted for planar-doped SnO_2 superlattices. • Nanotechnology has an important role for the development of thermoelectric devices.

  1. Photoionization behavior of Eu2+-doped BaMgSiO4 long-persisting phosphor upon UV irradiation

    International Nuclear Information System (INIS)

    Li, Y.; Wang, Y.; Gong, Y.; Xu, X.; Zhang, F.

    2011-01-01

    Highlights: → Photoionization behavior of BaMgSiO 4 :Eu 2+ long persistent phosphor upon UV irradiation. → Green phosphorescence was obtained from BaMgSiO 4 :Eu 2+ . → The ionization of Eu 2+ to Eu 3+ was observed in BaMgSiO 4 :Eu 2+ . → The photogenerated Eu 3+ cannot change back to its divalent state at room temperature. → The phosphorescence is associated with the formation forming Eu 3+ -e - pairs. - Abstract: The fluorescence, phosphorescence and thermoluminescence properties of Eu-doped BaMgSiO 4 phosphors sintered in air and in a reducing atmosphere were investigated. Phosphorescence of phosphor sintered in a reducing atmosphere can last for 1.5 h at a recognizable intensity level, whereas phosphorescence of air-sintered phosphor can only persist for 6 min. In addition, a distinction between the shape of the fluorescence spectrum and its corresponding phosphorescence spectrum is observed in the former case. Ionization of Eu 2+ to Eu 3+ upon UV irradiation is observed in the phosphor prepared in a reducing atmosphere, but there is no indication that the photogenerated Eu 3+ cannot change back to its divalent state at room temperature after the excitation source is switched off. In addition, phosphor sintered in a reducing atmosphere shows photochromism upon UV irradiation. No such photoionization and photochromism behavior is observed for the air-sintered phosphor. A possible Eu 2+ photoionization mechanism is constructed on the basis of these experimental observations. The photoionization mechanism presented can also successfully explain the fluorescence and phosphorescence behavior of Eu in BaMgSiO 4 .

  2. Dielectric and magnetic properties of (Zn, Co) co-doped SnO2 nanoparticles

    International Nuclear Information System (INIS)

    Rajwali, Khan; Fang Ming-Hu

    2015-01-01

    Polycrystalline samples of (Zn, Co) co-doped SnO 2 nanoparticles were prepared using a co-precipitation method. The influence of (Zn, Co) co-doping on electrical, dielectric, and magnetic properties was studied. All of the (Zn, Co) co-doped SnO 2 powder samples have the same tetragonal structure of SnO 2 . A decrease in the dielectric constant was observed with the increase of Co doping concentration. It was found that the dielectric constant and dielectric loss values decrease, while AC electrical conductivity increases with doping concentration and frequency. Magnetization measurements revealed that the Co doping SnO 2 samples exhibits room temperature ferromagnetism. Our results illustrate that (Zn, Co) co-doped SnO 2 nanoparticles have an excellent dielectric, magnetic properties, and high electrical conductivity than those reported previously, indicating that these (Zn, Co) co-doped SnO 2 materials can be used in the field of the ultrahigh dielectric material, high frequency device, and spintronics. (paper)

  3. Photoluminescence of Er-doped Si-SiO2 and Al-Si-SiO2 sputtered thin films

    International Nuclear Information System (INIS)

    Rozo, C.; Fonseca, L.F.; Jaque, D.; Sole, J.Garcia

    2008-01-01

    Er-doped Si-SiO 2 and Al-Si-SiO 2 films have been deposited by rf-sputtering being annealed afterwards. Annealing behavior of the Er 3+ : 4 I 13/2 → 4 I 15/2 emission of Er-doped Si-SiO 2 yields a maximum intensity for annealing at 700-800 deg. C. 4 I 13/2 → 4 I 15/2 peak emission for Er-doped Al-Si-SiO 2 at 1525 nm is shifted from that for Er-doped Si-SiO 2 at 1530 nm and the bandwidth increases from 29 to 42 nm. 4 I 13/2 → 4 I 15/2 emission decays present a fast decaying component related to Er ions coupled to Si nanoparticles, defects, or other ions, and a slow decaying component related to isolated Er ions. Excitation wavelength dependence and excitation power dependence for the 4 I 13/2 → 4 I 15/2 emission correspond with energy transfer from Si nanoparticles. Populating of the 4 I 11/2 level in Er-doped Si-SiO 2 involves branching and energy transfer upconversion involving two or more Er ions. Addition of Al reduces the populating of this level to an energy transfer upconversion involving two ions

  4. Phase constitution in Sr and Mg doped LaGaO3 system

    International Nuclear Information System (INIS)

    Zheng Feng; Bordia, Rajendra K.; Pederson, Larry R.

    2004-01-01

    Sr and Mg doped lanthanum gallate perovskites (La 1-x Sr x Ga 1-y Mg y O 3-δ , shortened as LSGM-XY where X and Y are the doping levels in mole percentage (mol%) at the La- or A-site and the Ga- or B-site, respectively) are promising electrolyte materials for intermediate temperature solid oxide fuel cells (SOFCs). In this study, we have investigated the primary perovskites as well as the secondary phases formed in terms of doping content changes and A/B ratio variations in these materials. Fifteen powder compositions (three doping levels, X=Y=0, 0.1, and 0.2 mol; and five A/B ratios 0.95, 0.98, 1.00, 1.02, and 1.05) were synthesized by the glycine-nitrate combustion process (GNP). These powders were equilibrated by calcining at 1500 deg. C for 9 h prior to crystalline phase characterization by X-ray powder diffraction (XRD). From the results of this study and the available phase diagrams in the literature on constituent binary oxide systems, we propose a crystalline phase diagram of the La 2 O 3 -SrO-Ga 2 O 3 -MgO quaternary system at elevated temperature (1500 deg. C)

  5. MgO Nanoparticle Modified Anode for Highly Efficient SnO2-Based Planar Perovskite Solar Cells.

    Science.gov (United States)

    Ma, Junjie; Yang, Guang; Qin, Minchao; Zheng, Xiaolu; Lei, Hongwei; Chen, Cong; Chen, Zhiliang; Guo, Yaxiong; Han, Hongwei; Zhao, Xingzhong; Fang, Guojia

    2017-09-01

    Reducing the energy loss and retarding the carrier recombination at the interface are crucial to improve the performance of the perovskite solar cell (PSCs). However, little is known about the recombination mechanism at the interface of anode and SnO 2 electron transfer layer (ETL). In this work, an ultrathin wide bandgap dielectric MgO nanolayer is incorporated between SnO 2 :F (FTO) electrode and SnO 2 ETL of planar PSCs, realizing enhanced electron transporting and hole blocking properties. With the use of this electrode modifier, a power conversion efficiency of 18.23% is demonstrated, an 11% increment compared with that without MgO modifier. These improvements are attributed to the better properties of MgO-modified FTO/SnO 2 as compared to FTO/SnO 2 , such as smoother surface, less FTO surface defects due to MgO passivation, and suppressed electron-hole recombinations. Also, MgO nanolayer with lower valance band minimum level played a better role in hole blocking. When FTO is replaced with Sn-doped In 2 O 3 (ITO), a higher power conversion efficiency of 18.82% is demonstrated. As a result, the device with the MgO hole-blocking layer exhibits a remarkable improvement of all J-V parameters. This work presents a new direction to improve the performance of the PSCs based on SnO 2 ETL by transparent conductive electrode surface modification.

  6. Microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yih-Chien; Chen, Kuei-Chien; Hsu, Wei-Yu [Department of Electrical Engineering, Lunghwa University of Science and Technology, Gueishan Shiang, Taoyuan County (China)

    2010-11-15

    This study examined the potential applications of microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics in rectenna. The La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics were prepared by the conventional solid-state method with various sintering temperatures. An apparent density of 6.62 g/cm{sup 3}, a dielectric constant of 20.3, a quality factor of 51,700 GHz, and a temperature coefficient of resonant frequency of -78.2 ppm/K were obtained for La{sub 2.98/3}Ba{sub 0.01}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics that were sintered at 1550 C for 4 h. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Highly efficient electrochemical degradation of perfluorooctanoic acid (PFOA) by F-doped Ti/SnO{sub 2} electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bo, E-mail: boyang@szu.edu.cn [Department of Environmental Engineering, College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060 (China); School of Environment, POPs Research Center, Tsinghua University, Beijing 100084 (China); Jiang, Chaojin [Department of Environmental Engineering, College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060 (China); Yu, Gang, E-mail: yg-den@tsinghua.edu.cn [School of Environment, POPs Research Center, Tsinghua University, Beijing 100084 (China); Zhuo, Qiongfang [South China Institute of Environmental Sciences, The Ministry of Environment Protection, Guangzhou 510655 (China); Deng, Shubo [School of Environment, POPs Research Center, Tsinghua University, Beijing 100084 (China); Wu, Jinhua [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); Zhang, Hong [Department of Environmental Engineering, College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060 (China)

    2015-12-15

    Highlights: • A novel SnO{sub 2} electrode is prepared by F doping instead of the traditional Sb doping. • SnF{sub 4} as single-source precursor is used to fabricate the long-life Ti/SnO{sub 2}–F anode. • F-doped Ti/SnO{sub 2} anode possesses high OEP and decomposition ability for PFOA. • Further mechanistic detail of PFOA degradation on Ti/SnO{sub 2}–F electrode is proposed. - Abstract: The novel F-doped Ti/SnO{sub 2} electrode prepared by SnF{sub 4} as the single-source precursor was used for electrochemical degradation of aqueous perfluorooctanoic acid (PFOA). Higher oxidation reactivity and significantly longer service life were achieved for Ti/SnO{sub 2}–F electrode than Ti/SnO{sub 2}–X (X = Cl, Br, I, or Sb) electrode, which could decomposed over 99% of PFOA (50 mL of 100 mg L{sup −1}) within 30-min electrolysis. The property of Ti/SnO{sub 2}–F electrode and its electrooxidation mechanism were investigated by XRD, SEM–EDX, EIS, LSV, and interfacial resistance measurements. We propose that the similar ionic radii of F and O as well as strong electronegativity of F caused its electrochemical stability with high oxygen evolution potential (OEP) and smooth surface to generate weakly adsorbed ·OH. The preparation conditions of electrode were also optimized including F doping amount, calcination temperature, and dip coating times, which revealed the formation process of electrode. Additionally, the major mineralization product, F{sup −}, and low concentration of shorter chain perfluorocarboxylic acids (PFCAs) were detected in solution. So the reaction pathway of PFOA electrooxidation was proposed by intermediate analysis. These results demonstrate that Ti/SnO{sub 2}–F electrode is promising for highly efficient treatment of PFOA in wastewater.

  8. Effect of Magnesium Content and Processing Conditions on Phase Formation and Stability in Mg2+ δ Si0.3Sn0.7

    Science.gov (United States)

    Goyal, Gagan K.; Dasgupta, T.

    2018-03-01

    Mg2+ δ Si0.3Sn0.7 compositions with nominal Mg content of δ = 0, 0.2 are synthesized using a single-step quartz tube reaction method with different heating rates and holding times. The resulting powders are sintered using a uniaxial induction hot press under similar conditions to produce near-dense compacts. The effect of Mg content and processing conditions on the phase formation and its stability are studied using x-ray diffraction measurements, scanning electron microscopy (SEM) with elemental mapping and compositional analysis using energy dispersive spectroscopy (EDS). Results indicate that with sufficient Mg content and shorter synthesis time, the powder remains single phasic; however, prolonged heat treatment during synthesis results in Mg loss and causes the system to become biphasic. Compaction results in single-phase formation in all the specimens. This is attributed to the removal of the low-melting secondary Sn-rich phases present in the system. The decomposition of the specimens depends on the Mg content after the compaction step with a δ around - 0.15 necessary to preserve the single phase. The decomposition also results in Mg enrichment of the matrix (due to formation of elemental Sn), thereby acting as a self-healing mechanism. Annealing the dense products at 773 K for 24 h in static vacuum is carried out. Progressive Mg loss is observed resulting in degradation of the specimen.

  9. Applications of thermodynamic calculations to Mg alloy design: Mg-Sn based alloy development

    International Nuclear Information System (INIS)

    Jung, In-Ho; Park, Woo-Jin; Ahn, Sang Ho; Kang, Dae Hoon; Kim, Nack J.

    2007-01-01

    Recently an Mg-Sn based alloy system has been investigated actively in order to develop new magnesium alloys which have a stable structure and good mechanical properties at high temperatures. Thermodynamic modeling of the Mg-Al-Mn-Sb-Si-Sn-Zn system was performed based on available thermodynamic, phase equilibria and phase diagram data. Using the optimized database, the phase relationships of the Mg-Sn-Al-Zn alloys with additions of Si and Sb were calculated and compared with their experimental microstructures. It is shown that the calculated results are in good agreement with experimental microstructures, which proves the applicability of thermodynamic calculations for new Mg alloy design. All calculations were performed using FactSage thermochemical software. (orig.)

  10. Preparation and spectral analysis of a new Tb3+-doped CaO-MgO-SiO2 glass ceramics

    International Nuclear Information System (INIS)

    Cheng Jinshu; Tian Peijing; Zheng Weihong; Xie Jun; Chen Zhenxia

    2009-01-01

    Tb 3+ -doped CaO-MgO-SiO 2 glass ceramics have been prepared and characterized. The structure and optical properties of the glass ceramics were studied by XRD, SEM, Raman, and fluorescence spectra. The precipitated crystalline phase in the glass ceramics was columnar CaMgSi 2 O 6 . Raman spectra showed the introduction of rare earth nearly had no influence on the sample structure. Fluorescence measurements showed that Tb 3+ ions entered into the diopside crystalline phase and induced a much stronger emission in the glass ceramics than that in the corresponding glass. With increase of Tb 3+ content and the introduction of Gd 3+ , the fluorescence intensity of the luminescent glass ceramic increased

  11. Ab initio study of thermoelectric properties of doped SnO{sub 2} superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Borges, P.D., E-mail: pdborges@gmail.com [Instituto de Ciências Exatas e Tecnológicas, Universidade Federal de Viçosa, 38810-000 Rio Paranaíba, MG (Brazil); Silva, D.E.S.; Castro, N.S.; Ferreira, C.R.; Pinto, F.G.; Tronto, J. [Instituto de Ciências Exatas e Tecnológicas, Universidade Federal de Viçosa, 38810-000 Rio Paranaíba, MG (Brazil); Scolfaro, L. [Department of Physics, Texas State University, 78666 San Marcos, TX (United States)

    2015-11-15

    Transparent conductive oxides, such as tin dioxide (SnO{sub 2}), have recently shown to be promising materials for thermoelectric applications. In this work we studied the thermoelectric properties of Fe-, Sb- and Zn-uniformly doping and co-doping SnO{sub 2}, as well as of Sb and Zn planar (or delta)-doped layers in SnO{sub 2} forming oxide superlattices (SLs). Based on the semiclassical Boltzmann transport equations (BTE) in conjunction with ab initio electronic structure calculations, the Seebeck coefficient (S) and figure of merit (ZT) are obtained for these systems, and are compared with available experimental data. The delta doping approach introduces a remarkable modification in the electronic structure of tin dioxide, when compared with the uniform doping, and colossal values for ZT are predicted for the delta-doped oxide SLs. This result is a consequence of the two-dimensional electronic confinement and the strong anisotropy introduced by the doped planes. In comparison with the uniformly doped systems, our predictions reveal a promising use of delta-doped SnO{sub 2} SLs for enhanced S and ZT, which emerge as potential candidates for thermoelectric applications. - Graphical abstract: Band structure and Figure of merit for SnO2:Sb superlattice along Z direction, P. D. Borges, D. E. S. Silva, N. S. Castro, C. R. Ferreira, F. G. Pinto, J. Tronto and L. Scolfaro, Ab initio study of thermoelectric properties of doped SnO2 superlattices. - Highlights: • Thermoelectric properties of SnO{sub 2}-based alloys and superlattices. • High figure of merit is predicted for planar-doped SnO{sub 2} superlattices. • Nanotechnology has an important role for the development of thermoelectric devices.

  12. Synthesis and pressure effects on the La doped CaFe{sub 2}As{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Soo Hyun; Park, Tuson [Dept. of physics, Sungkyunkwan University, Suwon (Korea, Republic of); Shang, T.; Yuan, H. Q. [Dept. of physics, Zhejiang University, Hangzhou (China)

    2014-09-15

    We have synthesized La doped CaFe2As{sub 2} single crystals with Sn flux in an evacuated quartz ampule. Doping and pressure effects on the magnetic and superconducting properties of the under-doped Ca{sub 1-x}La{sub x}Fe{sub 2}As{sub 2} (x=0.08, 0.1) were studied by measuring electrical resistivity under quasi-hydrostatic pressure up to 21 kbar. Magnetic transition temperatures for all studied concentrations were sharply suppressed with slight amplitude of pressure, less than 3 kbar, while superconducting transition temperatures were robust against pressure. In this communication, we report temperature-pressure phase diagram for the La-doped CaFe{sub 2}As{sub 2} single crystals.

  13. Flux pinning properties of impurity doped MgB2 bulks synthesized by diffusion method

    International Nuclear Information System (INIS)

    Ueda, Shinya; Shimoyama, Jun-ichi; Yamamoto, Akiyasu; Katsura, Yukari; Iwayama, Isao; Horii, Shigeru; Kishio, Kohji

    2005-01-01

    Doping effects of carbon-containing impurities on the critical current properties and microstructure were systematically studied for highly dense MgB 2 bulks prepared by the diffusion method starting from magnesium and boron which are separately packed in sealed stainless tubes. Obtained samples exhibited improved critical current density, J c , simply by an increase of effective current pass. A non-doped MgB 2 recorded almost double high J c at 20 K compared with those of the conventional porous MgB 2 bulks having ∼50% of the theoretical density, while irreversibility field, H irr , did not largely change. J c under high magnetic fields were enhanced by doping of carbon-containing impurities, such as SiC and B 4 C. Optimal doping levels of SiC and B 4 C for high critical current properties at 20 K are found to be ∼2% and 5%, respectively, as nominal carbon concentration at boron site. Difference in the optimal doping levels is originated from the difference in their reactivity

  14. Local moments, exchange interactions, and magnetic order in Mn-doped LaFe2Si2 alloys

    International Nuclear Information System (INIS)

    Turek, I.; Divis, M.; Niznansky, D.; Vejpravova, J.

    2007-01-01

    Formation of local magnetic moments in the intermetallic compound LaFe 2 Si 2 due to doping by a few at% of Mn has been investigated by theoretical and experimental tools. While a number of low-temperature experiments prove appearance of non-zero magnetic moments due to the Mn doping, the measured 57 Fe Moessbauer spectra rule out sizable local moments of Fe atoms. This conclusion is in agreement with results of first-principles electronic structure calculations that yield non-vanishing moments only on Mn atoms. The calculated Mn-Mn exchange interactions are of both signs which indicate a magnetically frustrated ground state, probably with a spin-glass-like arrangement of the Mn moments

  15. Quantification of MgO surface excess on the SnO{sub 2} nanoparticles and relationship with nanostability and growth

    Energy Technology Data Exchange (ETDEWEB)

    Gouvea, Douglas, E-mail: dgouvea@usp.br [Departamento de Engenharia Metalurgica e de Materiais, Escola Politecnica, University of Sao Paulo, Av. Prof. Melo Moraes, 2463, Sao Paulo, CEP 05508-930, SP (Brazil); Pereira, Gilberto J. [Department of Materials Engineering, FEI University Center, Sao Bernardo do Campo, SP 09850-901 (Brazil); Gengembre, Leon [University Lille Nord de France, F-59000 Lille, 2USTL, Unite de Catalyse et de Chimie du Solide F-59652 Villeneuve d' Ascq, CNRS, UMR8181, ENSCL, UCCS F-59655 Villeneuve d' Ascq (France); Steil, Marlu C. [Laboratoire d' Electrochimie et de Physico-chimie des Materiaux et des Interfaces (LEPMI), CNRS, UJF, Grenoble-INP, 1130 Rue de la Piscine, B.P. 75, 38402 Saint Martin d' Heres Cedex (France); Roussel, Pascal; Rubbens, Annick [University Lille Nord de France, F-59000 Lille, 2USTL, Unite de Catalyse et de Chimie du Solide F-59652 Villeneuve d' Ascq, CNRS, UMR8181, ENSCL, UCCS F-59655 Villeneuve d' Ascq (France); Hidalgo, Pilar [Departamento de Engenharia Metalurgica e de Materiais, Escola Politecnica, University of Sao Paulo, Av. Prof. Melo Moraes, 2463, Sao Paulo, CEP 05508-930, SP (Brazil); Castro, Ricardo H.R. [Chemical Engineering and Materials Science Department and NEAT ORU, UC Davis, CA 95616 (United States)

    2011-02-15

    In this work, we experimentally showed that the spontaneous segregation of MgO as surface excess in MgO doped SnO{sub 2} nanoparticles plays an important role in the system's energetics and stability. Using X-ray fluorescence in specially treated samples, we quantitatively determined the fraction of MgO forming surface excess when doping SnO{sub 2} with several different concentrations and established a relationship between this amount and the surface energy of the nanoparticles using the Gibbs approach. We concluded that the amount of Mg ions on the surface was directly related to the nanoparticles total free energy, in a sense that the dopant will always spontaneously distribute itself to minimize it if enough diffusion is provided. Because we were dealing with nanosized particles, the effect of MgO on the surface was particularly important and has a direct effect on the equilibrium particle size (nanoparticle stability), such that the lower the surface energy is, the smaller the particle sizes are, evidencing and quantifying the thermodynamic basis of using additives to control SnO{sub 2} nanoparticles stability.

  16. Incorporation of sol-gel SnO{sub 2}:Sb into nanoporous SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Canut, B. [Laboratoire de Physique de la Matiere Condensee et Nanostructures, Universite ClaudeBernard Lyon I, UMR CNRS 5586, Dept. de Physique des Materiaux, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France)]. E-mail: bruno.canut@lpmcn.univ-lyon1.fr; Blanchin, M.G. [Laboratoire de Physique de la Matiere Condensee et Nanostructures, Universite ClaudeBernard Lyon I, UMR CNRS 5586, Dept. de Physique des Materiaux, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Ramos-Canut, S. [Laboratoire de Physique de la Matiere Condensee et Nanostructures, Universite ClaudeBernard Lyon I, UMR CNRS 5586, Dept. de Physique des Materiaux, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Teodorescu, V. [National Institute for Physics of Materials, Magurele, R-76900 Bucharest (Romania); Toulemonde, M. [Centre Interdisciplinaire de Recherche Ions Laser, CIRIL-GANIL, rue Claude Bloch, BP 5133, 14070 Caen Cedex 5 (France)

    2006-04-15

    Silicon oxide films thermally grown on Si(1 0 0) wafers were irradiated with 200 MeV {sup 197}Au ions in the 10{sup 9}-10{sup 1} cm{sup -2} fluence range. The targets were then etched at room temperature in aqueous HF solution (1 vol.%) for various durations. Atomic force microscopy (AFM) in the tapping mode was used to probe the processed surfaces. Conical holes with a low size dispersion were evidenced. Their surface diameter varies between 20 and 70 nm, depending on the etching time. Sol-gel dip coating technique, associated with a further annealing treatment performed at 500 {sup o}C for 15 min, was used to fill the nanopores created in SiO{sub 2} with a transparent conductive oxide (SnO{sub 2} doped with antimony). Transmission electron microscopy (TEM) performed on cross-sectional specimen showed that SnO{sub 2}:Sb crystallites of {approx}5 nm mean size are trapped in the holes without degrading their geometry.

  17. ZnO doped SnO2 nanoparticles heterojunction photo-catalyst for environmental remediation

    International Nuclear Information System (INIS)

    Lamba, Randeep; Umar, Ahmad; Mehta, S.K.; Kansal, Sushil Kumar

    2015-01-01

    ZnO doped SnO 2 nanoparticles were synthesized by facile and simple hydrothermal technique and used as an effective photocatalyst for the photocatalytic degradation of harmful and toxic organic dye. The prepared nanoparticles were characterized in detail using different techniques for morphological, structural and optical properties. The characterization results revealed that the synthesized nanoparticles possess both crystal phases of tetragonal rutile phase of pure SnO 2 and wurtzite hexagonal phase of ZnO. In addition, the nanoparticles were synthesized in very high quantity with good crystallinity. The photocatalytic activity of prepared nanoparticles was evaluated by the photocatalytic degradation of methylene blue (MB) dye. Detailed photocatalytic experiments based on the effects of irradiation time, catalyst dose and pH were performed and presented in this paper. The detailed photocatalytic experiments revealed that the synthesized ZnO doped SnO 2 nanoparticles heterojunction photocatalyst exhibit best photocatalytic performance when the catalyst dose was 0.25 g/L and pH = 10. ZnO doped SnO 2 nanoparticles heterojunction photocatalyst was also compared with commercially available TiO 2 (PC-50), TiO 2 (PC-500) and SnO 2 and interestingly ZnO doped SnO 2 nanoparticles exhibited superior photocatalytic performance. The presented work demonstrates that the prepared ZnO doped SnO 2 nanoparticles are promising material for the photocatalytic degradation of organic dyes and toxic chemicals. - Highlights: • Synthesis of well-crystalline ZnO-doped SnO 2 nanoparticles. • Excellent morphological, crystalline and photoluminescent properties. • Efficient environmental remediation using ZnO-doped SnO 2 nanoparticles.

  18. Variation of equation of state parameters in the Mg2(Si 1-xSnx) alloys

    KAUST Repository

    Pulikkotil, Jiji Thomas Joseph

    2010-08-03

    Thermoelectric performance peaks up for intermediate Mg2(Si 1-x:Snx) alloys, but not for isomorphic and isoelectronic Mg2(Si1-xGex) alloys. A comparative study of the equation of state parameters is performed using density functional theory, Green\\'s function technique, and the coherent potential approximation. Anomalous variation of the bulk modulus is found in Mg2(Si1-xSn x) but not in the Mg2(Si1-xGex) analogs. Assuming a Debye model, linear variations of the unit cell volume and pressure derivative of the bulk modulus suggest that lattice effects are important for the thermoelectric response. From the electronic structure perspective, Mg2(Si1-xSnx) is distinguished by a strong renormalization of the anion-anion hybridization. © 2010 IOP Publishing Ltd.

  19. Sol–gel glass-ceramics comprising rare-earth doped SnO2 and LaF3 nanocrystals: an efficient simultaneous UV and IR to visible converter

    International Nuclear Information System (INIS)

    Yanes, A. C.; Castillo, J. del; Méndez-Ramos, J.; Rodríguez, V. D.

    2011-01-01

    We report a novel class of nanostructured glass-ceramics comprising two co-existing rare-earth doped nanocrystalline phases, SnO 2 semiconductor nanocrystal (quantum dot), and LaF 3 , presenting sizes at around 4.6 and 9.8 nm, respectively, embedded into a silica glass matrix for an efficient simultaneous UV and IR to visible photon conversion. On one hand, the wide and strong UV absorption by SnO 2 quantum dot and subsequent efficient energy transfer to Eu 3+ and, on the other hand, the also very efficient IR to visible up-conversion with the pair Yb 3+ –Er 3+ partitioned into low phonon LaF 3 nanocrystalline environment, yield to visible emissions with application in improving the spectral response of photovoltaic solar cells.Graphical AbstractWe report a novel class of nanostructured glass-ceramics comprising two co-existing rare-earth doped nanocrystalline phases, SnO 2 semiconductor nanocrystal (quantum dot) and LaF 3 , presenting sizes at around 4.6 and 9.8 nm, respectively, embedded into a silica glass matrix for an efficient simultaneous UV and IR to visible photon conversion. On one hand, the wide and strong UV absorption by SnO 2 quantum dot and subsequent efficient energy transfer to Eu 3+ and, on the other hand, the also very efficient IR to visible up-conversion with the pair Yb 3+ –Er 3+ partitioned into low phonon LaF 3 nanocrystalline environment, yield to visible emissions with application in improving the spectral response of photovoltaic solar cells.

  20. In situ 119Sn Moessbauer spectroscopy used to study lithium insertion in c-Mg2Sn

    International Nuclear Information System (INIS)

    Aldon, L.; Ionica, C. M.; Lippens, P. E.; Larcher, D.; Tarascon, J.-M.; Olivier-Fourcade, J.; Jumas, J.-C.

    2006-01-01

    The electrochemical reactions of Li with c-Mg 2 Sn have been investigated by in situ Moessbauer spectroscopy of 119 Sn and X-ray diffraction. The lithiation transforms initially c-Mg 2 Sn part into Li x Mg 2 Sn alloy (x 2 MgSn ternary alloy. In situ Moessbauer spectroscopy provides valuable information on local environment of tin and swelling behavior and cracking of the particles during discharge and charge processes.

  1. Ultrahigh broadband photoresponse of SnO2 nanoparticle thin film/SiO2/p-Si heterojunction.

    Science.gov (United States)

    Ling, Cuicui; Guo, Tianchao; Lu, Wenbo; Xiong, Ya; Zhu, Lei; Xue, Qingzhong

    2017-06-29

    The SnO 2 /Si heterojunction possesses a large band offset and it is easy to control the transportation of carriers in the SnO 2 /Si heterojunction to realize high-response broadband detection. Therefore, we investigated the potential of the SnO 2 nanoparticle thin film/SiO 2 /p-Si heterojunction for photodetectors. It is demonstrated that this heterojunction shows a stable, repeatable and broadband photoresponse from 365 nm to 980 nm. Meanwhile, the responsivity of the device approaches a high value in the range of 0.285-0.355 A W -1 with the outstanding detectivity of ∼2.66 × 10 12 cm H 1/2 W -1 and excellent sensitivity of ∼1.8 × 10 6 cm 2 W -1 , and its response and recovery times are extremely short (oxide or oxide/Si based photodetectors. In fact, the photosensitivity and detectivity of this heterojunction are an order of magnitude higher than that of 2D material based heterojunctions such as (Bi 2 Te 3 )/Si and MoS 2 /graphene (photosensitivity of 7.5 × 10 5 cm 2 W -1 and detectivity of ∼2.5 × 10 11 cm H 1/2 W -1 ). The excellent device performance is attributed to the large Fermi energy difference between the SnO 2 nanoparticle thin film and Si, SnO 2 nanostructure, oxygen vacancy defects and thin SiO 2 layer. Consequently, practical highly-responsive broadband PDs may be actualized in the future.

  2. Improved flux pinning behaviour in bulk MgB2 achieved by nano-SiO2 addition

    International Nuclear Information System (INIS)

    Rui, X F; Zhao, Y; Xu, Y Y; Zhang, L; Sun, X F; Wang, Y Z; Zhang, H

    2004-01-01

    Bulk MgB 2 with SiO 2 nanoparticles added has been synthesized using a simple solid-state reaction route. The lattice constant in the c direction increases with additive content due to a small amount of Si being doped into the lattice of the MgB 2 ; however, T c is almost fixed at 37.2 K. The addition of SiO 2 nanoparticles also improves the J c -H and H irr -T characteristics of MgB 2 when the additive content is lower than 7%. At 20 K and 1 T, J c for the sample with 7% additive content reaches 2.5 x 10 5 A cm -2 . Microstructural analysis reveals that a high density of MgSi 2 nanoparticles (10-50 nm) exists inside the MgB 2 grains, leading to the formation of a nanocomposite superconductor

  3. Synthesis of ceramic powders of La9,56 (SiO4)6O2,34 and La9,8Si5,7MgO,3O26,4 by modified sol-gel process

    International Nuclear Information System (INIS)

    Lira, Sabrina Lopes; Paiva, Mayara Rafaela Soares; Misso, Agatha Matos; Elias, Daniel Ricco; Yamagata, Chieko

    2012-01-01

    Lanthanum silicate oxyapatite materials are promising for application as electrolyte in solid oxide fuel cells because of high ionic conductivity at temperatures between 600 deg C and 800 deg C. In this work, oxyapatites with the composition La 9,56 (SiO 4 ) 6 O 2,34 , and La 9,8 Si 5,7 Mg 0,3 O 26,4 were synthesized by using the sol-gel method, followed by precipitation. Initially, the gel of silica was synthesized from sodium silicate solution, by acid catalysis using lanthanum and magnesium chloride solution. Then, the La and Mg hydroxides were precipitated with NaOH in the gel. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and measurements of specific surface area. The crystalline oxyapatite phase of La 9,56 (SiO 4 ) 6 O 2,34 , and was La 9,8 Si 5,7 Mg 0,3 O 26,4 obtained by calcination at 900 deg C for 2 and 1h respectively (author)

  4. Pseudomorphic GeSiSn, SiSn and Ge layers in strained heterostructures

    Science.gov (United States)

    Timofeev, V. A.; Nikiforov, A. I.; Tuktamyshev, A. R.; Mashanov, V. I.; Loshkarev, I. D.; Bloshkin, A. A.; Gutakovskii, A. K.

    2018-04-01

    The GeSiSn, SiSn layer growth mechanisms on Si(100) were investigated and the kinetic diagrams of the morphological GeSiSn, SiSn film states in the temperature range of 150 °C-450 °C at the tin content from 0% to 35% were built. The phase diagram of the superstructural change on the surface of Sn grown on Si(100) in the annealing temperature range of 0 °C-850 °C was established. The specular beam oscillations were first obtained during the SiSn film growth from 150 °C to 300 °C at the Sn content up to 35%. The transmission electron microscopy and x-ray diffractometry data confirm the crystal perfection and the pseudomorphic GeSiSn, SiSn film state, and also the presence of smooth heterointerfaces between GeSiSn or SiSn and Si. The photoluminescence for the multilayer periodic GeSiSn/Si structures in the range of 0.6-0.8 eV was detected. The blue shift with the excitation power increase is observed suggesting the presence of a type II heterostructure. The creation of tensile strained Ge films, which are pseudomorphic to the underlying GeSn layer, is confirmed by the results of the formation and analysis of the reciprocal space map in the x-ray diffractometry. The tensile strain in the Ge films reached the value in the range of 0.86%-1.5%. The GeSn buffer layer growth in the Sn content range from 8% to 12% was studied. The band structure of heterosystems based on pseudomorphic GeSiSn, SiSn and Ge layers was calculated and the valence and conduction band subband position dependences on the Sn content were built. Based on the calculation, the Sn content range in the GeSiSn, SiSn, and GeSn layers, which corresponds to the direct bandgap GeSiSn, SiSn, and Ge material, was obtained.

  5. Enhancement of the mechanoluminescence properties on Ca2MgSi2O7:Dy3+ phosphor by co-doping of charge compensator ions

    Science.gov (United States)

    Sahu, Ishwar Prasad

    2016-08-01

    In the present article, effect of charge compensator ions (R+ = Li+, Na+ and K+) on dysprosium-doped di-calcium magnesium di-silicate (Ca2MgSi2O7:Dy3+) phosphors were investigated. The Ca2MgSi2O7:Dy3+ and Ca2MgSi2O7:Dy3+, R+ phosphors, were prepared by solid-state reaction method. The crystal structures of sintered phosphors were an akermanite-type structure which belongs to the tetragonal crystallography. The peaks of mechanoluminescence (ML) intensity were increased linearly with increasing impact velocity of the moving piston. Thus, present investigation indicates that the piezoelectricity was responsible to produce ML in prepared phosphors. The time of the peak ML intensity and the decay rate did not change significantly with respect to increasing impact velocity. Addition of charge compensator ions enhances the luminescence intensity of prepared Ca2MgSi2O7:Dy3+ phosphors, because they neutralize the charge generated by Dy3+ substitution for Ca2+ ions. The role of Li+ ions among all charge compensator ions (Na+ or K+) used was found to be most effective for enhanced Dy3+ ion emission. These ML materials can be used in the devices such as stress sensor, fracture sensor, impact sensor, damage sensors, safety management monitoring system and fuse system for army warheads.

  6. Computational assessment of promising mid-infrared nonlinear optical materials Mg–IV–V2 (IV = Si, Ge, Sn; V = P, As): a first-principles study

    Science.gov (United States)

    Xiao, Jianping; Zhu, Shifu; Zhao, Beijun; Chen, Baojun; Liu, Hui; He, Zhiyu

    2018-03-01

    The mid-infrared (mid-IR) nonlinear optical (NLO) capabilities of Mg–IV–V2 (IV = Si, Ge, Sn; V = P, As) are systematically assessed by the first-principles calculation. The results show that the compounds in this group except MgSiP2 and MgSnP2 have moderate birefringence values to fulfill the phase-matching conditions. In particular, MgGeP2 and MgSiAs2 possess relatively large band gaps and almost three to four times larger static SHG coefficients than the benchmark material AgGaSe2, exhibiting good potential for mid-IR NLO application. According to the detailed analysis of the electronic structures, it is found that the dominant SHG contributions are from the orbitals of the asymmetry anionic unit [IV–V2]2‑. Moreover, the further evaluation reveals that MgSiAs2, MgGeAs2, MgSnP2 and MgSnAs2 are not thermodynamically stable and the new synthesis strategy (i.e. synthesis under non-equilibrium conditions) should be considered.

  7. Luminescence characteristics of Mg2SiO4:Nd

    International Nuclear Information System (INIS)

    Indira, P.; Subrahmanyam, R.V.; Murthy, K.V.R.

    2011-01-01

    Thermoluminescence (TL) properties of Magnesium Ortho silicate (2:1) Mg 2 SiO 4 doped with various concentrations of rare earth (Nd) have been studied. The phosphor material were prepared using standard solid state reaction technique and heated specimens at 1100 ± 20 deg C for two hours. 4% Ammonium chloride was used as flux. The received material was grinded in an agate mortar and pestle. The TL exhibited by the Mg 2 SiO 4 with varying concentration of Nd is interesting in nature. It is interesting to note but as the concentration of Nd increases the peak around 125 deg C TL peak intensity increases. But the hump around 200 deg C resolved as TL peak at 253 deg C with high intensity. (author)

  8. Performance of Ce-doped (La, Gd).sub.2./sub.Si.sub.2./sub.O.sub.7./sub. scintillator with an avalanche photodiode

    Czech Academy of Sciences Publication Activity Database

    Kurosawa, S.; Shishido, T.; Suzuki, A.; Pejchal, Jan; Yokota, Y.; Yoshikawa, A.

    2014-01-01

    Roč. 744, Apr (2014), 30-34 ISSN 0168-9002 Institutional support: RVO:68378271 Keywords : scintillator * Ce-doped (La, Gd) 2 Si 2 O 7 * temperature dependence * APD Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.216, year: 2014

  9. Influences of the quantity of Mg2Sn phase on the corrosion behavior of Mg-7Sn magnesium alloy

    International Nuclear Information System (INIS)

    Liu Xianbin; Shan Dayong; Song Yingwei; Chen Rongshi; Han Enhou

    2011-01-01

    The influence of the quantity of the Mg 2 Sn phase on the corrosion behavior of different solution temperature treated Mg-7Sn magnesium alloy has been investigated by electrochemical measurements, scanning electron microscope (SEM) observation, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. With the increase of solution temperature, the quantity of Mg 2 Sn phase decreased and the tin concentration of matrix increased. The dissolved tin in Mg matrix took part in the film formation and the constituent of film was magnesium oxide and stannic oxide. The corrosion mode and corrosion rate were associated with the quantity of Mg 2 Sn phases and tin concentration of the matrix. If most of tin was present as Mg 2 Sn, the corrosion mode was pitting corrosion and it accelerated the corrosion rate. If most of tin was dissolved in matrix, the corrosion mode was filiform corrosion and it decreased the corrosion rate. The experiment evidences demonstrated that the corrosion resistance can be improved by increasing the tin concentration of matrix and the lowest corrosion rate was observed for sample solution treated at 540 o C.

  10. Magnetic exchange interactions in Mn doped ZnSnAs{sub 2} chalcopyrite

    Energy Technology Data Exchange (ETDEWEB)

    Bouhani-Benziane, H.; Sahnoun, O. [Laboratoire de Physique Quantique de la Matière et Modélisation Mathématique (LPQ3M), University of Mascara (Algeria); Sahnoun, M., E-mail: sahnoun_cum@yahoo.fr [Laboratoire de Physique Quantique de la Matière et Modélisation Mathématique (LPQ3M), University of Mascara (Algeria); Department of Chemistry, University of Fribourg (Switzerland); Driz, M. [Laboratoire de Sciences des Matériaux (LSM), University of Sidi Bel Abbes (Algeria); Daul, C. [Department of Chemistry, University of Fribourg (Switzerland)

    2015-12-15

    Accurate ab initio full-potential augmented plane wave (FP-LAPW) electronic calculations within generalized gradient approximation have been performed for Mn doped ZnSnAs{sub 2} chalcopyrites, focusing on their electronic and magnetic properties as a function of the geometry related to low Mn-impurity concentration and the spin magnetic alignment (i.e., ferromagnetic vs antiferromagnetic). As expected, Mn is found to be a source of holes and localized magnetic moments of about 4 µ{sub B} per Mn atom are calculated which are sufficiently large. The defect calculations are firstly performed by replacing a single cation (namely Zn and Sn) with a single Mn atom in the pure chalcopyrite ZnSnAs{sub 2} supercell, and their corresponding formation energies show that the substitution of a Sn atom (rather than Zn) by Mn is strongly favored. Thereafter, a comparison of total energy differences between ferromagnetic (FM) and antiferromagnetic (AFM) are given. Surprisingly, the exchange interaction between a Mn pairs is found to oscillate with the distance between them. Consequently, the AFM alignment is energetically favored in Mn-doped ZnSnAs{sub 2} compounds, except for low impurity concentration associated with lower distances between neighboring Mn impurities, in this case the stabilization of FM increases. Moreover, the ferromagnetic alignment in the Mn-doped ZnSnAs{sub 2} systems behaves half-metallic; the valence band for majority spin orientation is partially filled while there is a gap in the density of states for the minority spin orientation. This semiconducting gap of ~1 eV opened up in the minority channel and is due to the large bonding–antibonding splitting from the p–d hybridization. Our findings suggest that the Mn-doped ZnSnAs{sub 2} chalcopyrites could be a different class of ferromagnetic semiconductors. - Highlights: • ab initio calculations were performed on Mn doped ZnSnAs{sub 2} chalcopyrite. • Substitution of a Sn atom (rather than Zn) by Mn

  11. Nano SiO2 and MgO Improve the Properties of Porous β-TCP Scaffolds via Advanced Manufacturing Technology

    Directory of Open Access Journals (Sweden)

    Chengde Gao

    2015-03-01

    Full Text Available Nano SiO2 and MgO particles were incorporated into β-tricalcium phosphate (β-TCP scaffolds to improve the mechanical and biological properties. The porous cylindrical β-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped β-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from β-TCP to α-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 ± 0.36 MPa (β-TCP to 5.74 ± 0.62 MPa (β-TCP/SiO2, 9.02 ± 0.55 MPa (β-TCP/MgO and 10.43 ± 0.28 MPa (β-TCP/SiO2/MgO, respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of β-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of β-TCP scaffold.

  12. Ni doping effect on the electronic and sensing properties of 2D SnO2

    Science.gov (United States)

    Patel, Anjali; Roondhe, Basant; Jha, Prafulla K.

    2018-05-01

    In the present work using state of art first principles calculations under the frame work of density functional theory the effect of Nickel (Ni) doping on electronic as well as sensing properties of most stable two dimensional (2D) T-SnO2 phase towards ethanol (C2H5OH) has been observed. It has been found that Ni atom when dope on T-SnO2 causes prominent decrement in the band gap from 2.26 eV to 1.48 eV and improves the sensing phenomena of pristine T-SnO2 towards C2H5OH by increasing the binding energy from -0.18eV to -0.93eV. The comparative analysis of binding energy shows that Ni improves the binding of C2H5OH by 5.16 times the values for pristine T-SnO2. The doping of Ni into 2D T-SnO2 reduces the band gap through lowering of the conduction band minimum, thereby increasing the electron affinity which increases the sensing performance of T-SnO2. The variation in the electronic properties after and before the exposure of ethanol reinforced to use Ni:SnO2 nano structure for sensing applications. The results indicate that the Ni doped T-SnO2 can be utilized in improved optoelectronic as well as sensor devices in the future.

  13. Energetic prediction on the stability of A2Mg12Si7, A2Mg4Si3, and AMgSi in the A2Si–Mg2Si system (A = Ca, Sr and Ba) and their calculated electronic structures

    International Nuclear Information System (INIS)

    Imai, Yoji; Mori, Yoshihisa; Nakamura, Shigeyuki; Takarabe, Ken-ichi

    2014-01-01

    Highlights: • Formation energies of A 2 Mg 4 Si 3 , A 2 Mg 12 Si 7 , and AMgSi (A = Ca,Sr,Ba) were calculated. • All AMgSi are quite stable compared to mixture of A 2 Si and Mg 2 Si. • Ba 2 Mg 4 Si 3 and Sr 2 Mg 4 Si 3 are predicted to be stable, but Ca 2 Mg 4 Si 3 is not. • Ca 2 Mg 12 Si 7 and Sr 2 Mg 12 Si 7 are energetically unstable. • Stability of Ba 2 Mg 12 Si 7 is a tender subject. -- Abstract: In order to evaluate the relative stability of A 2 Mg 4 Si 3 , A 2 Mg 12 Si 7 , and AMgSi (A = Ca, Sr, and Ba) in the A 2 Si–Mg 2 Si system, electronic energy changes in the formation of these compounds were calculated using a density-functional theory with the Perdew–Wang generalized gradient approximations. It was found that (1) AMgSi’s are quite stable compared to equi-molar mixture of A 2 Si and Mg 2 Si, (2) Ba 2 Mg 4 Si 3 and Sr 2 Mg 4 Si 3 are also stable, (3) Ca 2 Mg 4 Si 3 and Ca 2 Mg 12 Si 7 are less stable than the mixture of CaMgSi and Mg 2 Si, and (4) Stability of Ba 2 Mg 12 Si 7 is a tender subject and Sr 2 Mg 12 Si 7 is energetically unstable compared to the mixture of Sr 2 Mg 4 Si 3 (or, SrMgSi) and Mg 2 Si. The presence of Sr 2 Mg 12 Si 7 may be due to the vibrational and/or configurational entropy, which are not treated in the present study. From the calculated electronic densities of state, complex compounds of SrMgSi and Mg 2 Si have both p-type and n-type character, depending on the ratio of SrMgSi and Mg 2 Si in that compound

  14. Effect of SnO2/SiO2 nano particle dispersant on the performance characteristic of complex multi-doped composite coating produced through electrodeposition on oil and gas storage tap

    Directory of Open Access Journals (Sweden)

    P.A.L. Anawe

    2018-06-01

    Full Text Available The effect of SnO2/SiO2 nano particle dispersant on the performance characteristic of complex zinc multi-doped composite coating produced through electrodeposition is studied. The degradation behaviour in term of wear and chemical corrosion activities were considered as a major factor in service. The wear mass loss was carried out with the help of reciprocating tester. The electrochemical corrosion characteristics were investigated using linear polarization technique in 3.5% simulated sodium chloride media. The outcome of the analysis shows that the developed coating was seen to provide a sound anti wear characteristics in its multidoped state. The corrosion resistance properties were observed to be massive compared to the binary based sample. It is expected that this characteristic will impact on the performance life span of storage tap in oil and gas. Keywords: Zn-SnO2-SiO2, Nanocomposite, Electrodeposition, Coatings and corrosion resistance

  15. Scintillation and optical properties of Sn-doped Ga2O3 single crystals

    Science.gov (United States)

    Usui, Yuki; Nakauchi, Daisuke; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2018-06-01

    Sn-doped Ga2O3 single crystals were synthesized by the Floating Zone (FZ) method. In photoluminescence (PL) under the excitation wavelength of 280 nm, we observed two types of luminescence: (1) defect luminescence due to recombination of the donor/acceptor pairs which appears at 430 nm and (2) the nsnp-ns2 transitions of Sn2+ which appear at 530 nm. The PL and scintillation decay time curves of the Sn-doped samples were approximated by a sum of exponential decay functions. The faster two components were ascribed to the defect luminescence, and the slowest component was owing to the nsnp-ns2 transitions. In the pulse height spectrum measurements under 241Am α-rays irradiation, all the Sn-doped Ga2O3 samples were confirmed to show a full energy absorption peak but the undoped one. Among the present samples, the 1% Sn-doped sample exhibited the highest scintillation light yield (1,500 ± 150 ph/5.5 MeV-α).

  16. The RMgSn{sub 2} series of compounds (R = rare earth metal). Synthesis, crystal structure, and magnetic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Solokha, Pavlo; Minetti, Riccardo; De Negri, Serena; Saccone, Adriana [Dipartimento di Chimica e Chimica Industriale, Universita di Genova (Italy); Pereira, Laura Cristina J.; Goncalves, Antonio P. [Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, EN 10, Universidade de Lisboa, Bobadela (Portugal)

    2017-06-30

    The novel isostructural series of phases RMgSn{sub 2} (R = Y, La-Nd, Sm, Gd-Tm, Lu) is presented. They were prepared by direct synthesis in an induction furnace and subsequently annealed at 500 C. Their crystal structures were determined through single-crystal X-ray diffraction analysis of the Ce representative [I anti 42m, tI32-LaMgSn{sub 2}, Z = 8, a = 0.82863(3) nm, c = 1.23129(5) nm] and confirmed by powder X-ray diffraction analysis of the other members of the series. Rietveld refinements were also performed on the homologues with R = Pr, Tm, and Y. The title phases show a unique space distribution of atoms, characterized by the presence of a Sn-Sn dumbbell distanced at around 0.29 nm. Their structures are related to those of a few binary AeTt{sub 3} (Ae = alkaline earth; Tt = Si, Ge; I4/mmm, tI32-YbSi{sub 3}) compounds that are stable at high pressure, characterized by a more complex 3D covalently bonded Tt network. Compounds CeMgSn{sub 2} and TbMgSn{sub 2} were magnetically characterized; they show paramagnetic behavior with the presence of ferromagnetic interactions, more pronounced in the case of TbMgSn{sub 2}, as suggested by the Curie-Weiss temperatures, determined in the high-temperature range, of 0.96 and 27.6 K for CeMgSn{sub 2} and TbMgSn{sub 2}, respectively. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Synthesis and Luminescence Properties of Novel Ce(3+)- and Eu(2+)-Doped Lanthanum Bromothiosilicate La3Br(SiS4)2 Phosphors for White LEDs.

    Science.gov (United States)

    Lee, Szu-Ping; Liu, Shuang-De; Chan, Ting-Shan; Chen, Teng-Ming

    2016-04-13

    Novel Ce(3+)- and Eu(2+)-doped lanthanum bromothiosilicate La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors were prepared by solid-state reaction in an evacuated and sealed quartz glass ampule. The La3Br(SiS4)2:Ce(3+) phosphor generates a cyan emission upon excitation at 375 nm, whereas the La3Br(SiS4)2:Eu(2+) phosphor could be excited with extremely broad range from UV to blue region (300 to 600 nm) and generates a reddish-orange broadband emission centered at 640 nm. In addition, thermal luminescence properties of La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors from 20 to 200 °C were investigated. The combination of a 450 nm blue InGaN-based LED chip with the red-emitting La3Br(SiS4)2:Eu(2+) phosphor, and green-emitting BOSE:Eu(2+) commercial phosphor produced a warm-white light with the CRI value of ∼95 and the CCT of 5,120 K. Overall, these results show that the prepared phosphors may have potential applications in pc-WLED.

  18. Fabrication of p-type conductivity in SnO{sub 2} thin films through Ga doping

    Energy Technology Data Exchange (ETDEWEB)

    Tsay, Chien-Yie, E-mail: cytsay@fcu.edu.tw; Liang, Shan-Chien

    2015-02-15

    Highlights: • P-type Ga-doped SnO{sub 2} semiconductor films were prepared by sol-gel spin coating. • Optical bandgaps of the SnO{sub 2}:Ga films are narrower than that of the SnO{sub 2} film. • SnO{sub 2}:Ga films exhibited p-type conductivity as Ga doping content higher than 10%. • A p-n heterojunction composed of p-type SnO{sub 2}:Ga and n-type ZnO:Al was fabricated. - Abstract: P-type transparent tin oxide (SnO{sub 2}) based semiconductor thin films were deposited onto alkali-free glass substrates by a sol-gel spin-coating method using gallium (Ga) as acceptor dopant. In this study, we investigated the influence of Ga doping concentration ([Ga]/[Sn] + [Ga] = 0%, 5%, 10%, 15%, and 20%) on the structural, optical and electrical properties of SnO{sub 2} thin films. XRD analysis results showed that dried Ga-doped SnO{sub 2} (SnO{sub 2}:Ga) sol-gel films annealed in oxygen ambient at 520 °C for 1 h exhibited only the tetragonal rutile phase. The average optical transmittance of as-prepared thin film samples was higher than 87.0% in the visible light region; the optical band gap energy slightly decreased from 3.92 eV to 3.83 eV with increases in Ga doping content. Hall effect measurement showed that the nature of conductivity of SnO{sub 2}:Ga thin films changed from n-type to p-type when the Ga doping level was 10%, and when it was at 15%, Ga-doped SnO{sub 2} thin films exhibited the highest mean hole concentration of 1.70 × 10{sup 18} cm{sup -3}. Furthermore, a transparent p-SnO{sub 2}:Ga (Ga doping level of 15%)/n-ZnO:Al (Al doping level of 2%) heterojunction was fabricated on alkali-free glass. The I-V curve measurement for the p-n heterojunction diode showed a typical rectifying characteristic with a forward turn-on voltage of 0.65 V.

  19. Adsorption-controlled growth of La-doped BaSnO3 by molecular-beam epitaxy

    Directory of Open Access Journals (Sweden)

    Hanjong Paik

    2017-11-01

    Full Text Available Epitaxial La-doped BaSnO3 films were grown in an adsorption-controlled regime by molecular-beam epitaxy, where the excess volatile SnOx desorbs from the film surface. A film grown on a (001 DyScO3 substrate exhibited a mobility of 183 cm2 V−1 s−1 at room temperature and 400 cm2 V−1 s−1 at 10 K despite the high concentration (1.2 × 1011 cm−2 of threading dislocations present. In comparison to other reports, we observe a much lower concentration of (BaO2 Ruddlesden-Popper crystallographic shear faults. This suggests that in addition to threading dislocations, other defects—possibly (BaO2 crystallographic shear defects or point defects—significantly reduce the electron mobility.

  20. Studies on the structural and electrical properties of F-doped SnO{sub 2} film prepared by APCVD

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jingkai; Liu Wenchang; Dong Lizhong; Li Yuanxun; Li Chuan [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Zhao Hongli, E-mail: zhaohongli@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2011-10-01

    Fluorine-doped tin oxide films (SnO{sub 2}:F, FTO) were deposited by atmosphere pressure chemical vapor deposition (APCVD) on Na-Ca-Si glass coated with a diffusion barrier layer of SiO{sub x}C{sub y}. The effects of post-heating time at 700 deg. C on the structural and electrical properties of SnO{sub 2}:F films were investigated. The results showed that SnO{sub 2}:F films were polycrystalline with tetragonal SnO{sub 2} structure, SnO phase was present in SnO{sub 2} film, and abnormal grain growth was observed. The element distribution in the film depth was measured with X-ray photoelectron spectroscopy (XPS) and revealed that when the heating time increased from 202 s to 262 s, the oxygen content in the surface increased from 78.63% to 83.38%. The resistivity increased from 3.13 x 10{sup -4} for as-deposited films to 4.73 x 10{sup -4} {Omega} cm when post-heated for 262 s. Hall mobility is limited by the ionized impurity scattering rather than the grain boundary scattering.

  1. CoO-doped MgO-Al2O3-SiO2-colored transparent glass-ceramics with high crystallinity

    Science.gov (United States)

    Tang, Wufu; Zhang, Qian; Luo, Zhiwei; Yu, Jingbo; Gao, Xianglong; Li, Yunxing; Lu, Anxian

    2018-02-01

    To obtain CoO-doped MgO-Al2O3-SiO2 (MAS)-colored transparent glass-ceramics with high crystallinity, the glass with the composition 21MgO-21Al2O3-54SiO2-4B2O3-0.2CoO (in mol %) was prepared by conventional melt quenching technique and subsequently thermal treated at several temperatures. The crystallization behavior of the glass, the precipitated crystalline phases and crystallinity were analyzed by X-ray diffraction (XRD). The microstructure of the glass-ceramics was characterized by field emission scanning electron microscopy (FSEM). The transmittance of glass-ceramic was measured by UV spectrophotometer. The results show that a large amount of α-cordierite (indianite) with nano-size was precipitated from the glass matrix after treatment at 1020 °C for 3 h. The crystallinity of the transparent glass-ceramic reached up to 97%. Meanwhile, the transmittance of the glass-ceramic was 74% at 400 nm with a complex absorption band from 450 nm to 700 nm. In addition, this colored transparent glass-ceramic possessed lower density (2.469 g/cm3), lower thermal expansion coefficient (1.822 × 10-6 /℃), higher Vickers hardness (9.1 GPa) and higher bending strength (198 MPa) than parent glass.

  2. Properties of Sn-doped TiO2 nanotubes fabricated by anodization of co-sputtered Ti–Sn thin films

    International Nuclear Information System (INIS)

    Kyeremateng, Nana Amponsah; Hornebecq, Virginie; Knauth, Philippe; Djenizian, Thierry

    2012-01-01

    Self-organized Sn-doped TiO 2 nanotubes (nts) were fabricated for the first time, by anodization of co-sputtered Ti and Sn thin films. This nanostructured material was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, UV–vis spectroscopy and transmission electron microscopy. Due to their remarkable properties, Sn-doped TiO 2 nts can find potential applications in Li-ion microbatteries, photovoltaics, and catalysis. Particularly, the electrochemical performance as an anode material for Li-ion microbatteries was evaluated in Li test cells. With current density of 70 μA cm −2 (1 C) and cut-off potential of 1 V, Sn-doped TiO 2 nts showed improved performance compared to simple TiO 2 nts, and differential capacity plots revealed that the material undergoes full electrochemical reaction as a Rutile-type TiO 2 .

  3. Theoretical perspective on the electronic, magnetic and optical properties of Zn-doped monolayer SnS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Lili; Zhou, Wei; Liu, Yanyu; Yu, Dandan [Department of Applied Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China); Liang, Yinghua [College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009 (China); Wu, Ping, E-mail: pingwu@tju.edu.cn [Department of Applied Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China)

    2016-12-15

    Highlights: • The Zn doping in monolayer SnS{sub 2} is energetically favored under S-rich condition. • The room temperature ferromagnetism can be realized in Zn-doped monolayer SnS{sub 2}. • The Zn doping enhances the effective utilization in the near-infrared light region. • The Zn doping could lead to the red shift of absorption edge in monolayer SnS{sub 2}. • The Zn-doped monolayer SnS{sub 2} is active for both the oxygen and hydrogen evolution. - Abstract: The electronic, magnetic and optical properties of Zn-doped monolayer SnS{sub 2} have been theoretically investigated with the density functional theory. Numerical results reveal that monolayer SnS{sub 2} can be easily synthesized by cleaving its bulk crystal. Besides, the Zn doping in monolayer SnS{sub 2} is energetically favored under the S-rich with respect to the Sn-rich condition. The doped system exhibits the magnetic ground states due to the formation of defect states above the Fermi level, which are introduced by the hybridization between S-3p states and a small amount of Sn-4d states. The room temperature ferromagnetism can also be realized in Zn-doped monolayer SnS{sub 2}. The injection of Zn can enhance the absorption efficiency of solar spectrum, especially in the near-infrared light region. Moreover, the Zn doping can enhance the photocatalytic activity for both the oxygen and hydrogen evolution reactions in the monolayer SnS{sub 2}.

  4. Investigation of superior electro-optical properties of SnO{sub 2}/SiO{sub 2} nanocomposite over its individual counterpart SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Naveen Kumar, P.; Sahaya Selva Mary, J.; Chandrakala, V.; Jothi Jeyarani, W.; Merline Shyla, J., E-mail: jmshyla@gmail.com

    2017-06-01

    A comparative investigation of SnO{sub 2}/SiO{sub 2} nanocomposite with SnO{sub 2} nanoparticles has been conducted in the present study with the intent of learning the probable enhancement of the properties of the nanocomposite over those of the bare nanoparticles which has not been widely reported before. SnO{sub 2} nanoparticles and SnO{sub 2}/SiO{sub 2} nanocomposite have been synthesized via the facile and versatile sol-gel method. The samples were characterized with X-Ray Diffraction (XRD), High Resolution Scanning Electron Microscopy (HRSEM), Brunauer Emmett Teller (BET) studies, Fourier Transform Infra-Red spectroscopy (FT-IR), UV–Visible (UV–Vis) spectroscopy and Field-dependent photo conductivity technique for the evaluation of their crystallite size, structure & morphology, surface, chemical, optical and electrical properties respectively. Scherrer’s equation was used to determine the crystallite size of the as-synthesized samples from the XRD data. The particle size of SnO{sub 2}/SiO{sub 2} nanocomposite as observed through HRSEM was found to be reduced when compared with the bare SnO{sub 2} nanoparticles suggesting a possible increase in the optical band gap of the former which has been further confirmed in the optical studies. The surface area of SnO{sub 2}/SiO{sub 2} nanocomposite revealed a remarkable enrichment by approximately 5 folds in comparison with that of SnO{sub 2} nanoparticles which suggests an enhancement in its corresponding optical and electrical properties. The SnO{sub 2}/SiO{sub 2} nanocomposite recorded appreciated values of field-dependent photo and dark currents with several folds of augmentation thereby qualifying as an efficient photoconducting material. Attributed with an improved surface area and increased photoconducting nature, the SnO{sub 2}/SiO{sub 2} nanocomposite could be presented as an excellent photoanode material for nanomaterials based Dye Sensitized Solar Cells (DSSCs). - Highlights: • SnO{sub 2}/SiO{sub 2

  5. Long afterglow property of Er"3"+ doped Ca_2SnO_4 phosphor

    International Nuclear Information System (INIS)

    Zhang, Dongyun; Shi, Mingming; Sun, Yiwen; Guo, Yunyun; Chang, Chengkang

    2016-01-01

    A novel green emitting long afterglow phosphor, Er"3"+ -doped Ca_2SnO_4 (Ca_2SnO_4:Er"3"+), was prepared successfully via a traditional high temperature solid–state reaction method. Its properties have been characterized and analyzed by utilizing x-ray diffraction (XRD), photoluminescence spectroscope (PLS), afterglow decay curve (ADC) and thermal luminescence spectroscope (TLS). Three main emission peaks of PLS locate at 524, 550 and 668 nm, corresponding to CIE chromaticity coordinates of x = 0.326, y = 0.6592. An optimal doping concentration of Er"3"+ of 2% was determined. The Ca_2SnO_4:Er"3"+ phosphors showed a typical triple-exponential afterglow decay behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Ca_2SnO_4:2 mol% Er"3"+ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the Ca_2SnO_4 host with rare-earth ions (Er"3"+). - Highlights: • A novel green emitting long afterglow phosphor, Ca_2SnO_4:Er"3"+, was prepared. • An optimal doping concentration of Er"3"+ of 2% was determined. • After the UV source was turned off, the Ca_2SnO_4:Er"3"+ showed a typical triple-exponential afterglow decay behavior. • CIE chromaticity coordinates results confirmed a green light emitting of the Ca_2SnO_4:Er"3"+. • The persistent afterglow of the Ca_2SnO_4:Er"3"+ was attributed to suitable electron or hole traps.

  6. Synthesis, structural and paramagnetic properties of SnO{sub 2} doped NiO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Islam, I., E-mail: ishtihadahislam@gmail.com; Dwivedi, Sonam; Dar, Hilal A.; Dar, M. A.; Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India)

    2016-05-06

    In this work, Sn doped NiO nanoparticles were synthesized by co-precipitation route to explore the impact of doping on lattice structure, dielectric constant and magnetization. X-ray diffraction analysis confirmed cubic (Fd-3m) structure of Sn doped NiO. Average crystallite size decreases from 78.2 nm (Ni{sub 0.95}Sn{sub 0.05}O) to 64.23 nm (Ni{sub 0.8}Sn{sub 0.2}O). Scanning electron microscopy images confirm that nanocrystals have agglomerated spherical morphology. The Raman spectrum exhibits a strong, broad peak at 410 cm{sup -1} and is attributed to the Ni-O stretching mode and doped samples show a blue shift. The dielectric constants at about 1 Hz are measured to be about 1.795, 1.030, 0.442, and 0.302 × 10{sup 3} Ni{sub 1-x}Sn{sub x}O (x = 0.05, 0.1, 0.15, 0.2), respectively. The dielectric constant in nanoparticles of doped Ni{sub 1-x}Sn{sub x}O is three orders of magnitude higher as compared to pure NiO ceramics. The nature of magnetization - applied field (M-H) infers paramagnetic behaviour for Sn doped NiO nanoparticles.

  7. Magnetotransport properties of c-axis oriented La0.7Sr0.3MnO3 thin films on MgO-buffered SiO2/Si substrates

    International Nuclear Information System (INIS)

    Kang, Young-Min; Ulyanov, Alexander N.; Shin, Geo-Myung; Lee, Sung-Yun; Yoo, Dae-Gil; Yoo, Sang-Im

    2009-01-01

    c-axis oriented La 0.7 Sr 0.3 MnO 3 (LSMO) films on MgO-buffered SiO 2 /Si substrates were prepared, and their texture, microstructure, and magnetotransport properties were studied and compared to epitaxial LSMO/MgO (001) and polycrystalline LSMO/SiO 2 /Si films. c-axis oriented MgO buffer layers were obtained on amorphous SiO 2 layer through rf sputter deposition at low substrate temperature and consequent postannealing processes. In situ pulsed laser deposition-grown LSMO films, deposited on the MgO layer, show strong c-axis texture, but no in-plane texture. The c-axis oriented LSMO films which are magnetically softer than LSMO/SiO 2 /Si films exhibit relatively large low field magnetoresistance (LFMR) and sharper MR drop at lower field. The large LFMR is attributed to a spin-dependent scattering of transport current at the grain boundaries

  8. Investigation on structural, surface morphological and dielectric properties of Zn-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sagadevan, Suresh [Department of Physics, AMET University, Chennai (India); Podder, Jiban, E-mail: sureshsagadevan@gmail.com [Department of Chemical and Biological Engineering, University of Saskatchewan (Canada)

    2016-03-15

    Zinc doped Tin oxide (SnO{sub 2}) nanoparticles were prepared by co-precipitation method. The average crystallite size of pure and Zn-doped SnO{sub 2} nanoparticles was calculated from the X-ray diffraction (XRD) pattern. The FT-IR spectrum indicated the strong presence of SnO{sub 2} nanoparticles. The morphology and the particle size were studied using the scanning electron microscope (SEM) and transmission electron microscope (TEM). The particle size of the Zn-doped SnO{sub 2} nanoparticles was also analyzed, using the Dynamic Light Scattering (DLS) experiment. The optical properties were studied by the UV-Visible absorption spectrum. The dielectric properties of Zn-doped SnO{sub 2} nanoparticles were studied at different frequencies and temperatures. The ac conductivity of Zn-doped SnO{sub 2} nanoparticles was also studied. (author)

  9. Synthesis of Ce-doped SnO{sub 2} nanoparticles and their acetone gas sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Xiaoxue, E-mail: lianxiaoxues@163.com; Li, Yan; Tong, Xiaoqiang; Zou, Yunling; Liu, Xiulin; An, Dongmin; Wang, Qiong

    2017-06-15

    Highlights: • The Ce-doped SnO{sub 2} nanoparticles were fabricated via a simple hydrothermal method. • Ce ions were successfully doped into the SnO{sub 2} lattice, and 5 wt% SnO{sub 2}:Ce had a higher specific surface area. • The Ce-doped SnO{sub 2} nanoparticles exhibited the highest response values and a well selectivity to acetone. - Abstract: Hydrothermal method was generally used to synthesis nanoparticles, which was used to fabricate pure and Ce-doped (3 wt%, 5 wt%, 7 wt%) SnO{sub 2} nanoparticles in this experiment. The as-prepared products were characterized by X-ray diffraction (XRD), energy dispersive spectrum (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET). The results clearly indicated that the nanoparticles were composed of SnO{sub 2} nanoparticles and Ce ions were successfully doped into the SnO{sub 2} lattice, and 5 wt% SnO{sub 2}:Ce has a higher specific surface area (173.53 m{sup 2}/g). Importantly, SnO{sub 2}:Ce sensor had obviously improved performance compared to pure SnO{sub 2} and exhibited the highest response values (50.5 for 50 ppm) and a well selectivity to acetone at 270 °C. It could detect acetone gas in a wide concentration range with very high response, good long-term stability and repeatability of response. The possible sensing mechanism was discussed in this paper.

  10. Effect of Si, Mn, Sn on Tensile and Corrosion Properties of Mg-4Zn-0.5Ca Alloys for Biodegradable Implant Materials

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Dae Hyun; Nam, Ji Hoon; Lee, Byeong Woo; Park, Ji Yong; Shin, Hyun Jung; Park, Ik Min [Pusan National University, Busan (Korea, Republic of)

    2015-03-15

    Effect of elements Si, Mn, Sn on tensile and corrosion properties of Mg-4Zn-0.5Ca alloys were investigated. The results of tensile properties show that the yield strength, ultimate tensile strength and elongation of Mg-4Zn-0.5Ca alloy increased significantly with the addition of 0.6 wt% Mn. This is considered the grain refinement effect due to addition of Mn. However addition of 0.6 wt% Si decreased yield strength, ultimate tensile strength and elongation. The bio-corrosion behavior of Mg-4Zn-0.5Ca-X alloys were investigated using immersion tests and potentiodynamic polarization test in Hank's solution. Immersion test showed that corrosion rate of Mg-4Zn-0.5Ca-0.6Mn alloy was the lowest rate and addition of 1.0 wt% Sn accelerated corrosion rate due to micro-galvanic effect in α-Mg/CaMgSn phases interface. And corrosion potential (E{sub c}orr) of Mg-4Zn-0.5Ca-0.6Mn alloy was the most noble among Mg-4Zn-0.5Ca-X alloys.

  11. Solvothermal synthesis of Mg-doped Li2FeSiO4/C nanocomposite cathode materials for lithium-ion batteries

    Science.gov (United States)

    Kumar, Ajay; Jayakumar, O. D.; Naik, V. M.; Nazri, G. A.; Naik, R.

    Lithium transition metal orthosilicates, such as Li2FeSiO4 and Li2MnSiO4, as cathode material have attracted much attention lately due to their high theoretical capacity ( 330 mAh/g), low cost, and environmental friendliness. However, they suffer from poor electronic conductivity and slow lithium ion diffusion in the solid phase. Several cation-doped orthosilicates have been studied to improve their electrochemical performance. We have synthesized partially Mg-substituted Li2Mgx Fe1-x SiO4-C, (x = 0.0, 0.01, 0.02, and 0.04) nano-composites by solvothermal method followed by annealing at 600oC in argon flow. The structure and morphology of the composites were characterized by XRD, SEM and TEM. The surface area and pore size distribution were measured by using N2 adsorption/desorption curves. The electrochemical performance of the Li2MgxFe1-x SiO4-C composites was evaluated by Galvanostatic cycling against metallic lithium anode, electrochemical impedance spectroscopy, and cyclic voltammetry. Li2Mg0.01Fe0.99SiO4-C sample shows a capacity of 278 mAh/g (at C/30 rate in the 1.5-4.6 V voltage window) with an excellent rate capability and stability, compared to the other samples. We attribute this observation to its higher surface area, enhanced electronic conductivity and higher lithium ion diffusion coefficient.

  12. Correlation between SnO{sub 2} nanocrystals and optical properties of Eu{sup 3+} ions in SiO{sub 2} matrix: Relation of crystallinity, composition, and photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Thanh, Bui Quang [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc, E-mail: hann@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); Khiem, Tran Ngoc, E-mail: khiem@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); Chien, Nguyen Duc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); School of Engineering Physics (SEP), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam)

    2015-07-15

    We report characteristics and optical properties of Eu{sup 3+}-doped SnO{sub 2} nanocrystals dispersed in SiO{sub 2} matrix. Samples are prepared by the sol–gel method. Crystallinity of SnO{sub 2} nanocrystals is examined by X-ray diffraction experiments. At annealing temperatures from 900 to 1200 °C, we observe the formation of single tetragonal rutile structure of SnO{sub 2} nanocrystals. Average sizes of SnO{sub 2} nanocrystals within 3–7 nm are estimated by Debye–Scherrer equation. Intense photoluminescent spectra of Eu{sup 3+} ions consist of a series of resolved emission bands within 570–645 nm, which are varied with different sample-preparation conditions. We show the efficient excitation process of Eu{sup 3+} ions through SnO{sub 2} nanocrystals in the materials. Microscopic structure of SnO{sub 2} nanoparticles and optical properties of Eu{sup 3+} ions are also presented and discussed. - Highlights: • Thin layers of Eu{sup 3+} doped SnO{sub 2} nanocrystals dispersed in SiO{sub 2} were prepared by sol-gel method and spin-coating process. • Formation of single-phase tetragonal rutile structure of SnO{sub 2} nanocrystals and highly efficient optical excitation of the Eu{sup 3+} dopants were exhibited. • Relations of the crystallinity and composition of SnO{sub 2} and optical properties of Eu{sup 3+} dopants were comprehensively investigated and presented. • Allocations of major optically-active Eu{sup 3+} ions in the materials were deduced from their emission bands.

  13. Flux pinning and inhomogeneity in magnetic nanoparticle doped MgB2/Fe wires

    Science.gov (United States)

    Novosel, Nikolina; Pajić, Damir; Mustapić, Mislav; Babić, Emil; Shcherbakov, Andrey; Horvat, Joseph; Skoko, Željko; Zadro, Krešo

    2010-06-01

    The effects of magnetic nanoparticle doping on superconductivity of MgB2/Fe wires have been investigated. Fe2B and SiO2-coated Fe2B particles with average diameters 80 and 150 nm, respectively, were used as dopands. MgB2 wires with different nanoparticle contents (0, 3, 7.5, 12 wt.%) were sintered at temperature 750°C. The magnetoresistivity and critical current density Jc of wires were measured in the temperature range 2-40 K in magnetic field B doped wires decreases quite rapidly with doping level (~ 0.5 K per wt.%). This results in the reduction of the irreversibility fields Birr(T) and critical current densities Jc(B,T) in doped samples (both at low (5 K) and high temperatures (20 K)). Common scaling of Jc(B,T) curves for doped and undoped wires indicates that the main mechanism of flux pinning is the same in both types of samples. Rather curved Kramer's plots for Jc of doped wires imply considerable inhomogeneity.

  14. Corrosion behavior of die-cast Mg-4Al-2Sn-xCa alloy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyung Chul; Kim, Byeong Ho; Kim, Kyung Ro [Defence Agency for Technology and Quality, Jinju (Korea, Republic of); Cho, Dae Hyun; Park, Ik Min [Pusan National University, Busan (Korea, Republic of)

    2016-05-15

    In the present work, the effect of Ca additions on microstructure and corrosion characteristics of high pressure die-cast Mg-4Al-2Sn alloy has been investigated. Mg-4Al-2Sn-xCa (x= 0, 0.3 and 0.7wt.%) alloy was prepared by using a high pressure die-casting method. Results indicated that the microstructure of Mg-4Al-2Sn alloy consisted of α-Mg, Mg{sub 17}Al{sub 12} and Mg{sub 2}Sn phase. With increase of Ca additions, CaMgSn phase was newly formed and grain size was sharply decreased. From the test results, the corrosion resistance of die-cast Mg-4Al-2Sn alloy was significantly improved by Ca addition. It is considered that stabilization of Mg(OH){sub 2} layer and refinements of microstructure with increase of Ca additions.

  15. Synthesis and characterization of vanadium doped SnO2 diluted magnetic semiconductor nanoparticles with enhanced photocatalytic activities

    International Nuclear Information System (INIS)

    Mazloom, J.; Ghodsi, F.E.; Golmojdeh, H.

    2015-01-01

    Highlights: • Pure and V-doped SnO 2 nanoparticles were synthesized using a facile sol–gel route. • The V 4+ ions were incorporated into the SnO 2 lattice and located at the Sn 4+ sites. • TEM images reveled that by increasing the doping content, average grain size decreased. • We show that the V-doped SnO 2 is more photoactive than undoped SnO 2 . • The V-doped SnO 2 nanoparticles exhibited ferromagnetism at room temperature. - Abstract: Vanadium doped SnO 2 nanoparticles were synthesized by a facile sol–gel method. Different analytical techniques including TG/DTG, XRD, XPS, VSM and PL were used to investigate the influence of dopant concentration on structural, morphological, compositional, magnetic and optical properties of prepared nanoparticles. The XRD study showed a dominant tetragonal structure. The X-ray photoelectron spectroscopy proved the presence of vanadium as V 4+ species. TEM image revealed that particle size decrease by doping. It was found that room temperature ferromagnetic (RTFM) behavior is strongly dependent on vanadium dopant content and the magnetic saturation dropped rapidly with increasing V content, which can be explained reasonably through bound magnetic polaron (BMP) model. A quenching in green luminescence intensity was observed in V-doped SnO 2 compared to undoped sample. The 5% V-doped SnO 2 sample showed better photocatalytic activity than undoped one in decomposing methylene blue and rhodamine B

  16. Sn-doped β-Ga2O3 nanowires deposited by radio frequency powder sputtering

    Science.gov (United States)

    Lee, Su Yong; Kang, Hyon Chol

    2018-01-01

    We report the synthesis and characterization of Sn-doped β-Ga2O3 nanowires (NWs) deposited using radio frequency powder sputtering. The growth sequence of Sn-doped β-Ga2O3 NWs is similar to that of the undoped β-Ga2O3 NWs. Self-assembled Ga clusters act as seeds for initiating the growth of Sn-doped β-Ga2O3 NWs through a vapor-liquid-solid process, while Sn atoms are incorporated into the trunk of NWs uniformly. Different from the straight shape of undoped NWs, the conical shape of NWs is observed, which is attributed to the change in supersaturation conditions and the diffusion of the catalyst tip and reaction species.

  17. Terbium doped SnO2 nanoparticles as white emitters and SnO2:5Tb/Fe3O4 magnetic luminescent nanohybrids for hyperthermia application and biocompatibility with HeLa cancer cells.

    Science.gov (United States)

    Singh, Laishram Priyobarta; Singh, Ningthoujam Premananda; Srivastava, Sri Krishna

    2015-04-14

    SnO2:5Tb (SnO2 doped with 5 at% Tb(3+)) nanoparticles were synthesised by a polyol method and their luminescence properties at different annealing temperatures were studied. Characterization of nanomaterials was done by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). XRD studies indicate that the prepared nanoparticles were of tetragonal structures. Upon Tb(3+) ion incorporation into SnO2, Sn(4+) changes to Sn(2+) and, on annealing again at higher temperature, Sn(2+) changes to Sn(4+). The prepared nanoparticles were spherical in shape. Sn-O vibrations were found from the FTIR studies. In photoluminescence studies, the intensity of the emission peaks of Tb(3+) ions increases with the increase of annealing temperature, and emission spectra lie in the region of white emission in the CIE diagram. CCT calculations show that the SnO2:5Tb emission lies in cold white emission. Quantum yields up to 38% can be obtained for 900 °C annealed samples. SnO2:5Tb nanoparticles were well incorporated into the PVA polymer and such a material incorporated into the polymer can be used for display devices. The SnO2:5Tb/Fe3O4 nanohybrid was prepared and investigated for hyperthermia applications at different concentrations of the nanohybrid. This achieves a hyperthermia temperature (42 °C) under an AC magnetic field. The hybrid nanomaterial SnO2:5Tb/Fe3O4 was found to exhibit biocompatibility with HeLa cells (human cervical cancer cells) at concentrations up to 74% for 100 μg L(-1). Also, this nanohybrid shows green emission and thus it will be helpful in tracing magnetic nanoparticles through optical imaging in vivo and in vitro application.

  18. Characteristics of nano Ti-doped SnO2 powders prepared by sol-gel method

    International Nuclear Information System (INIS)

    Liu, X.M.; Wu, S.L.; Chu, Paul K.; Zheng, J.; Li, S.L.

    2006-01-01

    Ti 4+ -doped SnO 2 nano-powders were prepared by the sol-gel process using tin tetrachloride and titanium tetrachloride as the starting materials. The crystallinity and purity of the powders were analyzed by X-ray diffraction (XRD) and the size and distribution of Ti 4+ -doped SnO 2 grains were studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that Ti 4+ has been successfully incorporated into the SnO 2 crystal lattice and the electrical conductivity of the doped materials improves significantly

  19. Centrifugally cast Zn-27Al-xMg-ySi alloys and their in situ (Mg2Si + Si)/ZA27 composites

    International Nuclear Information System (INIS)

    Wang Qudong; Chen Yongjun; Chen Wenzhou; Wei Yinhong; Zhai Chunquan; Ding Wenjiang

    2005-01-01

    Effects of composition, mold temperature, rotating rate and modification on microstructure of centrifugally cast Zn-27Al-xMg-ySi alloys have been investigated. In situ composites of Zn-27Al-6.3Mg-3.7Si and Zn-27Al-9.8Mg-5.2Si alloys were fabricated by centrifugal casting using heated permanent mold. These composites consist of three layers: inner layer segregates lots of blocky primary Mg 2 Si and a litter blocky primary Si, middle layer contains without primary Mg 2 Si and primary Si, outer layer contains primary Mg 2 Si and primary Si. The position, quantity and distribution of primary Mg 2 Si and primary Si in the composites are determined jointly by alloy composition, solidification velocity under the effect of centrifugal force and their floating velocity inward. Na salt modifier can refine grain and primary Mg 2 Si and make primary Mg 2 Si distribute more evenly and make primary Si nodular. For centrifugally cast Zn-27Al-3.2Mg-1.8Si alloy, the microstructures of inner layer, middle layer and outer layer are almost similar, single layer materials without primary Mg 2 Si and primary Si are obtained, and their grain sizes increased with the mold temperature increasing

  20. Electronic and magnetic properties of SnS2 monolayer doped with non-magnetic elements

    Science.gov (United States)

    Xiao, Wen-Zhi; Xiao, Gang; Rong, Qing-Yan; Wang, Ling-Ling

    2018-05-01

    We performed a systematic study of the electronic structures and magnetic properties of SnS2 monolayer doped with non-magnetic elements in groups IA, IIA and IIIA based on the first-principles methods. The doped systems exhibit half-metallic and metallic natures depending on the doping elements. The formation of magnetic moment is attributable to the cooperative effect of the Hund's rule coupling and hole concentration. The spin polarization can be stabilized and enhanced through confining the delocalized impurity states by biaxial tensile strain in hole-doped SnS2 monolayer. Both the double-exchange and p-p exchange mechanisms are simultaneously responsible for the ferromagnetic ground state in those hole-doped materials. Our results demonstrate that spin polarization can be induced and controlled in SnS2 monolayers by non-magnetic doping and tensile strain.

  1. Effect of co-doped SnO{sub 2} nanoparticles on photoluminescence of cu-doped potassium lithium borate glass

    Energy Technology Data Exchange (ETDEWEB)

    Namma, Haydar Aboud; Wagiran, H.; Hussin, R.; Ariwahjoedi, B. [Department of Physics, Universiti Teknologi Malaysia, Skudai 81310, Malaysia and Baghdad College of Economic Sciences University (Iraq); Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, 31750 Tronoh (Malaysia)

    2012-09-26

    The SnO{sub 2} co-doped lithium potassium borate glasses doped with 0.05, 0.10, 0.25 and 0.50 mol% of Cu were synthesized by the melt quenching technique. The SnO{sub 2} co-dope was added to the compounds in the amounts of 0.05, 0.10, and 0.20 mol%. The photoluminescent spectrum for different concentrations of copper was studied. It was observed that the intensity of blue emission (450, 490 nm) varies with concentration mol%. In addition, with different concentration of SnO{sub 2} to 0.10 mol% Cu, the influence of the luminescence has been observed to enhance intensity and shifted to blue and red (490, 535 nm) emissions.

  2. Fabrication and characterization of Er+3 doped SiO2/SnO2 glass-ceramic thin films for planar waveguide applications

    Science.gov (United States)

    Guddala, S.; Chiappini, A.; Armellini, C.; Turell, S.; Righini, G. C.; Ferrari, M.; Narayana Rao, D.

    2015-02-01

    Glass-ceramics are a kind of two-phase materials constituted by nanocrystals embedded in a glass matrix and the respective volume fractions of crystalline and amorphous phase determine the properties of the glass-ceramics. Among these properties transparency is crucial in particular when confined structures, such as, dielectric optical waveguides, are considered. Moreover, the segregation of dopant rare-earth ions, like erbium, in low phonon energy crystalline medium makes these structures more promising in the development of waveguide amplifiers. Here we are proposing a new class of low phonon energy tin oxide semiconductor medium doped silicate based planar waveguides. Er3+ doped (100-x) SiO2-xSnO2 (x= 10, 20, 25 and 30mol%), glass-ceramic planar waveguide thin films were fabricated by a simple sol-gel processing and dip coating technique. XRD and HRTEM studies indicates the glass-ceramic phase of the film and the dispersion of ~4nm diameter of tin oxide nanocrystals in the amorphous phase of silica. The spectroscopic assessment indicates the distribution of the dopant erbium ions in the crystalline medium of tin oxide. The observed low losses, 0.5±0.2 dB/cm, at 1.54 μm communication wavelength makes them a quite promising material for the development of high gain integrated optical amplifiers.

  3. Synthesis of pure and Sr-doped LaGaO3, LaFeO3 and LaCoO3 and Sr,Mg-doped LaGaO3 for ITSOFC application using different wet chemical routes

    International Nuclear Information System (INIS)

    Kumar, M.; Srikanth, S.; Ravikumar, B.; Alex, T.C.; Das, S.K.

    2009-01-01

    Pure and Sr-doped LaGaO 3 , LaFeO 3 and LaCoO 3 and Sr,Mg-doped LaGaO 3 were synthesized by various wet chemical routes, namely combustion, co-precipitation and citrate-gel methods. The effect of the various process parameters on the phase purity, particle size and surface area and morphology of the synthesized powders were determined by XRD, simultaneous TG-DTA, laser light scattering, BET and scanning electron microscopy. The stability of the synthesized pure phases in oxidizing and reducing atmosphere was also studied by thermogravimetry. It was observed that pure and Sr-doped single perovskite phases of lanthanum ferrite, cobaltite and gallate and Sr,Mg-doped lanthanum gallate could be synthesized by combustion and citrate-gel methods under suitable process conditions. Synthesis using the co-precipitation method yielded incomplete reaction irrespective of the calcination temperature adopted. The citrate-gel method yielded better powder properties in terms of particle size and morphology and surface area compared to combustion synthesis. It was found that pure and Sr-doped lanthanum ferrite, lanthanum cobaltite, lanthanum gallate and Sr,Mg-doped lanthanum gallate were stable in the oxidizing atmosphere. In the reducing atmosphere, pure and Sr-doped lanthanum ferrite and Sr,Mg-doped lanthanum gallate was found to be stable at least during the timeframe of the thermogravimetric experiment whereas pure and Sr-doped lanthanum cobaltite was partially reduced in hydrogen atmosphere

  4. Forging of cast Mg-3Sn-2Ca-0.4Al-0.4Si magnesium alloy using processing map

    International Nuclear Information System (INIS)

    Rao, K. P.; Suresh, K.; Prasad, Y. V. R. K.; Hort, N.; Kainer, K. U.

    2016-01-01

    Mg-3Sn-2Ca (TX32) alloy has good creep resistance but limited workability. Minor amounts of Al and Si have been added to TX32 for improving its hot workability. The processing map for the TX32-0.4Al-0.4Si alloy exhibited two workability domains in the temperature and strain rate ranges: (1) 310-415.deg.C/0.0003-0.003 s-1 and (2) 430-500.deg.C/0.003-3 s-1. The alloy exhibited flow instability at temperatures < 350.deg.C at strain rates > 0.01 s-1. The alloy has been forged to produce a cup shape component to validate these findings of processing map. Finite-element (FE) simulation has been performed for obtaining the local variations of strain and strain rate within the forging. The microstructures of the forged components under the optimal domain conditions revealed dynamically recrystallized grains, and those forged in the flow instability regime have fractured and exhibited flow localization bands and cracks. The experimental load stroke curves correlated well with those obtained by FE simulation.

  5. Forging of cast Mg-3Sn-2Ca-0.4Al-0.4Si magnesium alloy using processing map

    Energy Technology Data Exchange (ETDEWEB)

    Rao, K. P.; Suresh, K.; Prasad, Y. V. R. K. [University of Hong Kong, Hong Kong (China); Hort, N.; Kainer, K. U. [Magnesium Innovation Centre, Geesthacht (Germany)

    2016-06-15

    Mg-3Sn-2Ca (TX32) alloy has good creep resistance but limited workability. Minor amounts of Al and Si have been added to TX32 for improving its hot workability. The processing map for the TX32-0.4Al-0.4Si alloy exhibited two workability domains in the temperature and strain rate ranges: (1) 310-415.deg.C/0.0003-0.003 s-1 and (2) 430-500.deg.C/0.003-3 s-1. The alloy exhibited flow instability at temperatures < 350.deg.C at strain rates > 0.01 s-1. The alloy has been forged to produce a cup shape component to validate these findings of processing map. Finite-element (FE) simulation has been performed for obtaining the local variations of strain and strain rate within the forging. The microstructures of the forged components under the optimal domain conditions revealed dynamically recrystallized grains, and those forged in the flow instability regime have fractured and exhibited flow localization bands and cracks. The experimental load stroke curves correlated well with those obtained by FE simulation.

  6. Synthesis of ceramic powders of La{sub 9,56} (SiO{sub 4}){sub 6}O{sub 2,34} and La{sub 9,8}Si{sub 5,7}Mg{sub O,3}O{sub 26,}4 by modified sol-gel process; Sintese de pos ceramicos de La{sub 9,56} (SiO{sub 4}){sub 6}O{sub 2,34} e La{sub 9,8}Si{sub 5,7}Mg{sub O,3}O{sub 26,}4 por processo sol-gel modificado

    Energy Technology Data Exchange (ETDEWEB)

    Lira, Sabrina Lopes; Paiva, Mayara Rafaela Soares; Misso, Agatha Matos; Elias, Daniel Ricco; Yamagata, Chieko, E-mail: yamagata@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

    2012-07-01

    Lanthanum silicate oxyapatite materials are promising for application as electrolyte in solid oxide fuel cells because of high ionic conductivity at temperatures between 600 deg C and 800 deg C. In this work, oxyapatites with the composition La{sub 9,56}(SiO{sub 4}){sub 6}O{sub 2,34}, and La{sub 9,8}Si{sub 5,7}Mg{sub 0,3}O{sub 26,4} were synthesized by using the sol-gel method, followed by precipitation. Initially, the gel of silica was synthesized from sodium silicate solution, by acid catalysis using lanthanum and magnesium chloride solution. Then, the La and Mg hydroxides were precipitated with NaOH in the gel. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and measurements of specific surface area. The crystalline oxyapatite phase of La{sub 9,56}(SiO{sub 4}){sub 6}O{sub 2,34}, and was La{sub 9,8}Si{sub 5,7}Mg{sub 0,3}O{sub 26,4} obtained by calcination at 900 deg C for 2 and 1h respectively (author)

  7. Synthesis and Characterization of Highly Sensitive Hydrogen (H2 Sensing Device Based on Ag Doped SnO2 Nanospheres

    Directory of Open Access Journals (Sweden)

    Zhaorui Lu

    2018-03-01

    Full Text Available In this paper, pure and Ag-doped SnO2 nanospheres were synthesized by hydrothermal method and characterized via X-ray powder diffraction (XRD, field emission scanning electron microscopy (FESEM, energy dispersive spectroscopy (EDS, and X-ray photoelectron spectra (XPS, respectively. The gas sensing performance of the pure, 1 at.%, 3 at.%, and 5 at.% Ag-doped SnO2 sensing devices toward hydrogen (H2 were systematically evaluated. The results indicated that compared with pure SnO2 nanospheres, Ag-doped SnO2 nanospheres could not only decrease the optimum working temperature but also significantly improve H2 sensing such as higher gas response and faster response-recovery. Among all the samples, the 3 at.% Ag-doped SnO2 showed the highest response 39 to 100 μL/L H2 at 300 °C. Moreover, its gas sensing mechanism was discussed, and the results will provide reference and theoretical guidance for the development of high-performance SnO2-based H2 sensing devices.

  8. Photoluminescence properties and energy transfer in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8) phosphors for potential application in ultraviolet white light-emitting diodes.

    Science.gov (United States)

    Yu, Hong; Zi, Wenwen; Lan, Shi; Gan, Shucai; Zou, Haifeng; Xu, Xuechun; Hong, Guangyan

    2013-01-01

    Sr(3) MgSi(2) O(8) :Ce(3+) , Dy(3+) phosphors were prepared by a solid-state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce(3+) ions (403 nm) but also as a band due to Dy(3+) ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8)phosphors, and the co-doping of Ce(3+) could enhance the emission intensity of Dy(3+) to a certain extent by transferring its energy to Dy(3+) . The Ce(3+) /Dy(3+) energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr2.94 MgSi2 O8 :0.01Ce(3+) , 0.05Dy(3+) phosphors, the fluorescence lifetime of Dy(3+) (from 3.35 to 27.59 ns) is increased whereas that of Ce(3+) is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce(3+) to Dy(3+) energy transfer. The varied emitted color of Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) phosphors from blue to white were achieved by altering the concentration ratio of Ce(3+) and Dy(3+) . These results indicate Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) may be as a candidate phosphor for white light-emitting diodes. Copyright © 2012 John Wiley & Sons, Ltd.

  9. Enhanced J c property in nano-SiC doped thin MgB2/Fe wires by a modified in situ PIT process

    International Nuclear Information System (INIS)

    Jiang, C.H.; Nakane, T.; Hatakeyama, H.; Kumakura, H.

    2005-01-01

    A modified in situ PIT process, which included a short time pre-annealing and intermediate drawing step in the conventional in situ PIT process, was employed to fabricate thin round MgB 2 /Fe wires from MgH 2 and B powders. The pores and cracks resulted from the MgH 2 decomposition during the pre-annealing were effectively eliminated by the intermediate drawing step, which subsequently increased the core density and J c property of final heat treated wires. A higher reduction rate after the pre-annealing led to a larger enhancement in J c within this study. The reproducibility of our new process on the J c improvement in MgB 2 wires was confirmed in two series of wires doped with 5 mol% or 10 mol% nano-SiC particles separately

  10. Tunable graphene doping by modulating the nanopore geometry on a SiO2/Si substrate

    KAUST Repository

    Lim, Namsoo

    2018-02-28

    A tunable graphene doping method utilizing a SiO2/Si substrate with nanopores (NP) was introduced. Laser interference lithography (LIL) using a He–Cd laser (λ = 325 nm) was used to prepare pore size- and pitch-controllable NP SiO2/Si substrates. Then, bottom-contact graphene field effect transistors (G-FETs) were fabricated on the NP SiO2/Si substrate to measure the transfer curves. The graphene transferred onto the NP SiO2/Si substrate showed relatively n-doped behavior compared to the graphene transferred onto a flat SiO2/Si substrate, as evidenced by the blue-shift of the 2D peak position (∼2700 cm−1) in the Raman spectra due to contact doping. As the porosity increased within the substrate, the Dirac voltage shifted to a more positive or negative value, depending on the initial doping type (p- or n-type, respectively) of the contact doping. The Dirac voltage shifts with porosity were ascribed mainly to the compensation for the reduced capacitance owing to the SiO2–air hetero-structured dielectric layer within the periodically aligned nanopores capped by the suspended graphene (electrostatic doping). The hysteresis (Dirac voltage difference during the forward and backward scans) was reduced when utilizing an NP SiO2/Si substrate with smaller pores and/or a low porosity because fewer H2O or O2 molecules could be trapped inside the smaller pores.

  11. Enhanced B doping in CVD-grown GeSn:B using B δ-doping layers

    Science.gov (United States)

    Kohen, David; Vohra, Anurag; Loo, Roger; Vandervorst, Wilfried; Bhargava, Nupur; Margetis, Joe; Tolle, John

    2018-02-01

    Highly doped GeSn material is interesting for both electronic and optical applications. GeSn:B is a candidate for source-drain material in future Ge pMOS device because Sn adds compressive strain with respect to pure Ge, and therefore can boost the Ge channel performances. A high B concentration is required to obtain low contact resistivity between the source-drain material and the metal contact. To achieve high performance, it is therefore highly desirable to maximize both the Sn content and the B concentration. However, it has been shown than CVD-grown GeSn:B shows a trade-off between the Sn incorporation and the B concentration (increasing B doping reduces Sn incorporation). Furthermore, the highest B concentration of CVD-grown GeSn:B process reported in the literature has been limited to below 1 × 1020 cm-3. Here, we demonstrate a CVD process where B δ-doping layers are inserted in the GeSn layer. We studied the influence of the thickness between each δ-doping layers and the δ-doping layers process conditions on the crystalline quality and the doping density of the GeSn:B layers. For the same Sn content, the δ-doping process results in a 4-times higher B doping than the co-flow process. In addition, a B doping concentration of 2 × 1021 cm-3 with an active concentration of 5 × 1020 cm-3 is achieved.

  12. Electronic structures and Eu3+ photoluminescence behaviors in Y2Si2O7 and La2Si2O7

    International Nuclear Information System (INIS)

    Zhang Zhiya; Wang Yuhua; Zhang Feng; Cao Haining

    2011-01-01

    Research highlights: → Host excitation near the band gap of Y 2 Si 2 O 7 and La 2 Si 2 O 7 is analyzed. → The calculated result well explains Eu 3+ PL behaviors in Y 2 Si 2 O 7 and La 2 Si 2 O 7 . → The electronic structure and Eu 3+ VUV PL in La 2 Si 2 O 7 are first estimated. - Abstract: The electronic structures and linear optical properties of Y 2 Si 2 O 7 (YSO) and La 2 Si 2 O 7 (LSO) are calculated by LDA method based on the theory of DFT. Both YSO and LSO are direct-gap materials with the direct band gap of 5.89 and 6.06 eV, respectively. The calculated total and partial density of states indicate that in both YSO and LSO the valence band (VB) is mainly constructed from O 2p and the conduction band (CB) is mostly formed from Y 4d or La 5d. Both the calculated VB and CB of YSO exhibit relatively wider dispersion than that of LSO. In addition, the CB of YSO presents more electronic states. Meanwhile, the VB of LSO shows narrower energy distribution with higher electronic states density. The theoretical absorption of YSO shows larger bandwidth and higher intensity than that of LSO. The results are compared with the experimental host excitations and impurity photoluminescence in Eu 3+ -doped YSO and LSO.

  13. Enhanced separation efficiency of photoinduced charges for antimony-doped tin oxide (Sb-SnO{sub 2})/TiO{sub 2} heterojunction semiconductors with varied Sb doping concentration

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhen-Long [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Ma, Wen-Hai [School of Physical Education, Henan University, Kaifeng 475004 (China); Mao, Yan-Li, E-mail: ylmao1@163.com [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Institute for Computational Materials Science, Henan University, Kaifeng 475004 (China)

    2014-09-07

    In this paper, antimony-doped tin oxide (Sb-SnO{sub 2}) nanoparticles were synthesized with varied Sb doping concentration, and the Sb-SnO{sub 2}/TiO{sub 2} heterojunction semiconductors were prepared with Sb-SnO{sub 2} and TiO{sub 2}. The separation efficiency of photoinduced charges was characterized with surface photovoltage (SPV) technique. Compared with Sb-SnO{sub 2} and TiO{sub 2}, Sb-SnO{sub 2}/TiO{sub 2} presents an enhanced separation efficiency of photoinduced charges, and the SPV enhancements were estimated to be 1.40, 1.43, and 1.99 for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. To understand the enhancement, the band structure of Sb-SnO{sub 2} and TiO{sub 2} in the heterojunction semiconductor was determined, and the conduction band offsets (CBO) between Sb-SnO{sub 2} and TiO{sub 2} were estimated to be 0.56, 0.64, and 0.98 eV for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. These results indicate that the separation efficiency enhancement is resulting from the energy level matching, and the increase of enhancement is due to the rising of CBO.

  14. Carbon-doped SnS2 nanostructure as a high-efficiency solar fuel catalyst under visible light.

    Science.gov (United States)

    Shown, Indrajit; Samireddi, Satyanarayana; Chang, Yu-Chung; Putikam, Raghunath; Chang, Po-Han; Sabbah, Amr; Fu, Fang-Yu; Chen, Wei-Fu; Wu, Chih-I; Yu, Tsyr-Yan; Chung, Po-Wen; Lin, M C; Chen, Li-Chyong; Chen, Kuei-Hsien

    2018-01-12

    Photocatalytic formation of hydrocarbons using solar energy via artificial photosynthesis is a highly desirable renewable-energy source for replacing conventional fossil fuels. Using an L-cysteine-based hydrothermal process, here we synthesize a carbon-doped SnS 2 (SnS 2 -C) metal dichalcogenide nanostructure, which exhibits a highly active and selective photocatalytic conversion of CO 2 to hydrocarbons under visible-light. The interstitial carbon doping induced microstrain in the SnS 2 lattice, resulting in different photophysical properties as compared with undoped SnS 2 . This SnS 2 -C photocatalyst significantly enhances the CO 2 reduction activity under visible light, attaining a photochemical quantum efficiency of above 0.7%. The SnS 2 -C photocatalyst represents an important contribution towards high quantum efficiency artificial photosynthesis based on gas phase photocatalytic CO 2 reduction under visible light, where the in situ carbon-doped SnS 2 nanostructure improves the stability and the light harvesting and charge separation efficiency, and significantly enhances the photocatalytic activity.

  15. Evaluation of carbon incorporation and strain of doped MgB2 superconductor by Raman spectroscopy

    International Nuclear Information System (INIS)

    Yeoh, W.K.; Zheng, R.K.; Ringer, S.P.; Li, W.X.; Xu, X.; Dou, S.X.; Chen, S.K.; MacManus-Driscoll, J.L.

    2011-01-01

    Raman spectroscopy is employed to study both the strain and the carbon substitution level in SiC-doped MgB 2 bulk samples. Raman spectroscopy was demonstrated to be a better method to distinguish the individual influences of strain and carbon than standard X-ray diffraction. It is found that the lattice parameter correlation method for C content determination is invalid for highly strained samples. Our result also provides an alternative explanation for lattice variation in non-carbon-doped MgB 2 , which is basically due to lattice strain.

  16. Electrolytically exfoliated graphene-loaded flame-made Ni-doped SnO2 composite film for acetone sensing.

    Science.gov (United States)

    Singkammo, Suparat; Wisitsoraat, Anurat; Sriprachuabwong, Chakrit; Tuantranont, Adisorn; Phanichphant, Sukon; Liewhiran, Chaikarn

    2015-02-11

    In this work, flame-spray-made SnO2 nanoparticles are systematically studied by doping with 0.1-2 wt % nickel (Ni) and loading with 0.1-5 wt % electrolytically exfoliated graphene for acetone-sensing applications. The sensing films (∼12-18 μm in thickness) were prepared by a spin-coating technique on Au/Al2O3 substrates and evaluated for acetone-sensing performances at operating temperatures ranging from 150 to 350 °C in dry air. Characterizations by X-ray diffraction, transmission/scanning electron microscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy and Raman spectroscopy demonstrated that Ni-doped SnO2 nanostructures had a spheriodal morphology with a polycrystalline tetragonal SnO2 phase, and Ni was confirmed to form a solid solution with SnO2 lattice while graphene in the sensing film after annealing and testing still retained its high-quality nonoxidized form. Gas-sensing results showed that SnO2 sensing film with 0.1 wt % Ni-doping concentration exhibited an optimal response of 54.2 and a short response time of ∼13 s toward 200 ppm acetone at an optimal operating temperature of 350 °C. The additional loading of graphene at 5 wt % into 0.1 wt % Ni-doped SnO2 led to a drastic response enhancement to 169.7 with a very short response time of ∼5.4 s at 200 ppm acetone and 350 °C. The superior gas sensing performances of Ni-doped SnO2 nanoparticles loaded with graphene may be attributed to the large specific surface area of the composite structure, specifically the high interaction rate between acetone vapor and graphene-Ni-doped SnO2 nanoparticles interfaces and high electronic conductivity of graphene. Therefore, the 5 wt % graphene loaded 0.1 wt % Ni-doped SnO2 sensor is a promising candidate for fast, sensitive and selective detection of acetone.

  17. Thermoelectric Properties of SnO2 Ceramics Doped with Sb and Zn

    DEFF Research Database (Denmark)

    Yanagiya, S.; Van Nong, Ngo; Xu, Jianxiao Jackie

    2011-01-01

    Polycrystalline SnO2-based samples (Sn0.97−x Sb0.03Zn x O2, x = 0, 0.01, 0.03) were prepared by solid-state reactions. The thermoelectric properties of SnO2 doped with Sb and Zn were investigated from 300 K to 1100 K. X-ray diffraction (XRD) analysis revealed all XRD peaks of all the samples...

  18. Single-Crystal Growth of Cl-Doped n-Type SnS Using SnCl2 Self-Flux.

    Science.gov (United States)

    Iguchi, Yuki; Inoue, Kazutoshi; Sugiyama, Taiki; Yanagi, Hiroshi

    2018-06-05

    SnS is a promising photovoltaic semiconductor owing to its suitable band gap energy and high optical absorption coefficient for highly efficient thin film solar cells. The most significant carnage is demonstration of n-type SnS. In this study, Cl-doped n-type single crystals were grown using SnCl 2 self-flux method. The obtained crystal was lamellar, with length and width of a few millimeters and thickness ranging between 28 and 39 μm. X-ray diffraction measurements revealed the single crystals had an orthorhombic unit cell. Since the ionic radii of S 2- and Cl - are similar, Cl doping did not result in substantial change in lattice parameter. All the elements were homogeneously distributed on a cleaved surface; the Sn/(S + Cl) ratio was 1.00. The crystal was an n-type degenerate semiconductor with a carrier concentration of ∼3 × 10 17 cm -3 . Hall mobility at 300 K was 252 cm 2 V -1 s -1 and reached 363 cm 2 V -1 s -1 at 142 K.

  19. A Fast Humidity Sensor Based on Li+-Doped SnO2 One-Dimensional Porous Nanofibers

    Directory of Open Access Journals (Sweden)

    Min Yin

    2017-05-01

    Full Text Available One-dimensional SnO2- and Li+-doped SnO2 porous nanofibers were easily fabricated via electrospinning and a subsequent calcination procedure for ultrafast humidity sensing. Different Li dopant concentrations were introduced to investigate the dopant’s role in sensing performance. The response properties were studied under different relative humidity levels by both statistic and dynamic tests. The best response was obtained with respect to the optimal doping of Li+ into SnO2 porous nanofibers with a maximum 15 times higher response than that of pristine SnO2 porous nanofibers, at a relative humidity level of 85%. Most importantly, the ultrafast response and recovery time within 1 s was also obtained with the 1.0 wt % doping of Li+ into SnO2 porous nanofibers at 5 V and at room temperature, benefiting from the co-contributions of Li-doping and the one-dimensional porous structure. This work provides an effective method of developing ultrafast sensors for practical applications—especially fast breathing sensors.

  20. Influence of the cooling rate on the main factors affecting current-carrying ability in pure and SiC-doped MgB2 superconductors

    International Nuclear Information System (INIS)

    Shcherbakova, O V; Pan, A V; Soltanian, S; Dou, S X; Wexler, D

    2007-01-01

    We have systematically studied and compared the effect of cooling rate on microstructure, critical current density, upper critical field and irreversibility field in pure and 10 wt% SiC-added MgB 2 superconductors. The sintering process was carried out on the samples at a temperature of 750 deg. C for 1 h followed by quenching or cooling to room temperature in 0.3 h (2433 deg. C h -1 ), 14 h (52 deg. C h -1 ) and 25 h (30 deg. C h -1 ). Changes in the microstructure due to variations in cooling rate have been studied with the help of scanning and transmission electron microscopy. Correlations between microstructure and superconducting properties have been observed, identified and explained for both pure and SiC-added MgB 2 samples. Modifications to the pinning environment and grain boundary transparency are considered to be responsible for variations in the current-carrying ability. The dominant pinning on grain boundaries in the pure MgB 2 samples and on nano-inclusions (inducing accompanying defects) in the SiC-doped samples is clearly distinguished. On the basis of our experimental results, we have concluded that the cooling rate can be an important parameter influencing the superconducting properties of MgB 2 samples

  1. Conduction band edge effective mass of La-doped BaSnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    James Allen, S., E-mail: allen@itst.ucsb.edu; Law, Ka-Ming [Physics Department, University of California, Santa Barbara, California 93106-5100 (United States); Raghavan, Santosh; Schumann, Timo; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2016-06-20

    BaSnO{sub 3} has attracted attention as a promising material for applications requiring wide band gap, high electron mobility semiconductors, and moreover possesses the same perovskite crystal structure as many functional oxides. A key parameter for these applications and for the interpretation of its properties is the conduction band effective mass. We measure the plasma frequency of La-doped BaSnO{sub 3} thin films by glancing incidence, parallel-polarized resonant reflectivity. Using the known optical dielectric constant and measured electron density, the resonant frequency determines the band edge electron mass to be 0.19 ± 0.01. The results allow for testing band structure calculations and transport models.

  2. Substrate and Mg doping effects in GaAs nanowires

    Directory of Open Access Journals (Sweden)

    Perumal Kannappan

    2017-10-01

    Full Text Available Mg doping of GaAs nanowires has been established as a viable alternative to Be doping in order to achieve p-type electrical conductivity. Although reports on the optical properties are available, few reports exist about the physical properties of intermediate-to-high Mg doping in GaAs nanowires grown by molecular beam epitaxy (MBE on GaAs(111B and Si(111 substrates. In this work, we address this topic and present further understanding on the fundamental aspects. As the Mg doping was increased, structural and optical investigations revealed: i a lower influence of the polytypic nature of the GaAs nanowires on their electronic structure; ii a considerable reduction of the density of vertical nanowires, which is almost null for growth on Si(111; iii the occurrence of a higher WZ phase fraction, in particular for growth on Si(111; iv an increase of the activation energy to release the less bound carrier in the radiative state from nanowires grown on GaAs(111B; and v a higher influence of defects on the activation of nonradiative de-excitation channels in the case of nanowires only grown on Si(111. Back-gate field effect transistors were fabricated with individual nanowires and the p-type electrical conductivity was measured with free hole concentration ranging from 2.7 × 1016 cm−3 to 1.4 × 1017 cm−3. The estimated electrical mobility was in the range ≈0.3–39 cm2/Vs and the dominant scattering mechanism is ascribed to the WZ/ZB interfaces. Electrical and optical measurements showed a lower influence of the polytypic structure of the nanowires on their electronic structure. The involvement of Mg in one of the radiative transitions observed for growth on the Si(111 substrate is suggested.

  3. All-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayers fabricated by Sn-induced low-temperature epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, M.; Ikawa, M.; Arima, K.; Yamada, S.; Kanashima, T.; Hamaya, K., E-mail: hamaya@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531 (Japan)

    2016-01-28

    We demonstrate low-temperature growth of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures by developing Sn-induced surfactant-mediated molecular beam epitaxy (SMBE) of Ge on Co{sub 2}FeSi. Despite the growth of a semiconductor on a metal, we verify that the inserted Sn monolayers between Ge and Co{sub 2}FeSi enable to promote the 2D epitaxial growth of Ge up to 5 nm at a T{sub G} of 250 °C. An understanding of the mechanism of the Sn-induced SMBE leads to the achievement of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures with spin-valve-like magnetization reversals. This study will open a way for vertical-type and high-performance Ge-based spintronics devices.

  4. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    International Nuclear Information System (INIS)

    Yu, Zhongwei; Lu, Jiawen; Qian, Shengyi; Xu, Jun; Xu, Ling; Wang, Junzhuan; Shi, Yi; Chen, Kunji; Misra, Soumyadeep; Roca i Cabarrocas, Pere; Yu, Linwei

    2015-01-01

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs

  5. Wavelength-tuned light emission via modifying the band edge symmetry: Doped SnO2 as an example

    KAUST Repository

    Zhou, Hang

    2014-03-27

    We report the observation of ultraviolet photoluminescence and electroluminescence in indium-doped SnO2 thin films with modified "forbidden" bandgap. With increasing indium concentration in SnO 2, dominant visible light emission evolves into the ultraviolet regime in photoluminescence. Hybrid functional first-principles calculations demonstrate that the complex of indium dopant and oxygen vacancy breaks "forbidden" band gap to form allowed transition states. Furthermore, undoped and 10% indium-doped SnO2 layers are synthesized on p-type GaN substrates to obtain SnO2-based heterojunction light-emitting diodes. A dominant visible emission band is observed in the undoped SnO 2-based heterojunction, whereas strong near-ultraviolet emission peak at 398 nm is observed in the indium-doped SnO2-based heterojunction. Our results demonstrate an unprecedented doping-based approach toward tailoring the symmetry of band edge states and recovering ultraviolet light emission in wide-bandgap oxides. © 2014 American Chemical Society.

  6. Fabrication of hydrogen peroxide biosensor based on Ni doped SnO2 nanoparticles.

    Science.gov (United States)

    Lavanya, N; Radhakrishnan, S; Sekar, C

    2012-01-01

    Ni doped SnO(2) nanoparticles (0-5 wt%) have been prepared by a simple microwave irradiation (2.45 GHz) method. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirmed the formation of rutile structure with space group (P(42)/mnm) and nanocrystalline nature of the products with spherical morphology. Direct electrochemistry of horseradish peroxidase (HRP)/nano-SnO(2) composite has been studied. The immobilized enzyme retained its bioactivity, exhibited a surface confined, reversible one-proton and one-electron transfer reaction, and had good stability, activity and a fast heterogeneous electron transfer rate. A significant enzyme loading (3.374×10(-10) mol cm(-2)) has been obtained on nano-Ni doped SnO(2) as compared to the bare glassy carbon (GC) and nano-SnO(2) modified surfaces. This HRP/nano-Ni-SnO(2) film has been used for sensitive detection of H(2)O(2) by differential pulse voltammetry (DPV), which exhibited a wider linearity range from 1.0×10(-7) to 3.0×10(-4)M (R=0.9897) with a detection limit of 43 nM. The apparent Michaelis-Menten constant (K(M)(app)) of HRP on the nano-Ni-SnO(2) was estimated as 0.221 mM. This excellent performance of the fabricated biosensor is attributed to large surface-to-volume ratio and Ni doping into SnO(2) which facilitate the direct electron transfer between the redox enzyme and the surface of electrode. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Compensation and persistent photocapacitance in homoepitaxial Sn-doped β-Ga2O3

    Science.gov (United States)

    Polyakov, A. Y.; Smirnov, N. B.; Shchemerov, I. V.; Gogova, D.; Tarelkin, S. A.; Pearton, S. J.

    2018-03-01

    The electrical properties of epitaxial β-Ga2O3 doped with Sn (1016-9 × 1018 cm-3) and grown by metalorganic chemical vapor deposition on semi-insulating β-Ga2O3 substrates are reported. Shallow donors attributable to Sn were observed only in a narrow region near the film/substrate interface and with a much lower concentration than the total Sn density. For heavily Sn doped films (Sn concentration, 9 × 1018 cm-3), the electrical properties in the top portion of the layer were determined by deep centers with a level at Ec-0.21 eV not described previously. In more lightly doped layers, the Ec-0.21 eV centers and deeper traps at Ec-0.8 eV were present, with the latter pinning the Fermi level. Low temperature photocapacitance and capacitance voltage measurements of illuminated samples indicated the presence of high densities (1017-1018 cm-3) of deep acceptors with an optical ionization threshold of 2.3 eV. Optical deep level transient spectroscopy (ODLTS) and photoinduced current transient spectroscopy (PICTS) detected electron traps at Ec-0.8 eV and Ec-1.1 eV. For lightly doped layers, the compensation of film conductivity was mostly provided by the Ec-2.3 eV acceptors. For heavily Sn doped films, deep acceptor centers possibly related to Ga vacancies were significant. The photocapacitance and the photocurrent caused by illumination at low temperatures were persistent, with an optical threshold of 1.9 eV and vanished only at temperatures of ˜400 K. The capture barrier for electrons causing the persistent photocapacitance effect was estimated from ODLTS and PICTS to be 0.25-0.35 eV.

  8. Reduced graphene oxide decorated with Fe doped SnO{sub 2} nanoparticles for humidity sensor

    Energy Technology Data Exchange (ETDEWEB)

    Toloman, D. [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca (Romania); Popa, A., E-mail: popa@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca (Romania); Stan, M.; Socaci, C.; Biris, A.R. [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca (Romania); Katona, G. [Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, 400028 Cluj-Napoca (Romania); Tudorache, F. [Interdisciplinary Research Department – Field Science & RAMTECH, Al. I. Cuza University, 11 Carol I Blvd., 7000506 Iasi (Romania); Petrila, I. [Interdisciplinary Research Department – Field Science & RAMTECH, Al. I. Cuza University, 11 Carol I Blvd., 7000506 Iasi (Romania); Faculty of Automatic Control and Computer Engineering, Gheorghe Asachi Technical University, 27 Dimitrie Mangeron Street, 700050 Iasi (Romania); Iacomi, F. [Faculty of Physics, Al. I. Cuza University, 11 Carol I Blvd., 7000506 Iasi (Romania)

    2017-04-30

    Highlights: • Reduced graphene oxide decorated with Fe doped SnO{sub 2} nanoparticles were synthesized. • The decoration of rGO layers with SnO{sub 2}:Fe nanoparticles was highlited by TEM. • The reduction of graphene oxide was evidenced using XRD and FT-IR. • Sensitivity tests for relative humidity (RH) were carried out. • The composite sensor exhibited enhanced sensing response as compared with Fe:SnO{sub 2}. - Abstract: Reduced graphene oxide (rGO) decorated with Fe doped SnO{sub 2} nanoparticles were fabricated via the electrostatic interaction between positively charged modified Fe-doped SnO{sub 2} oxide and negatively charged graphene oxide (GO) in the presence of poly(allylamine) hydrochloride (PAH). The decoration of rGO layers with SnO{sub 2}:Fe nanoparticles was highlited by TEM microsopy. For composite sample the diffraction patterns coincide well with those of SnO{sub 2}:Fe nanoparticles. The reduction of graphene oxide was evidenced using XRD and FT-IR spectroscopy. The formation of SnO{sub 2}:Fe-PAH-graphene composites was confirmed by FT-IR, Raman and EPR spectroscopy. Sensitivity tests for relative humidity (RH) measurements were carried out at five different concentrations of humid air at room temperature. The prepared composite sensor exhibited a higher sensing response as compared with Fe:SnO{sub 2} nanoparticles.

  9. Investigation of TL, OSL and PTTL properties of Mg2SiO4:Tb dosimeters

    International Nuclear Information System (INIS)

    Oguz, K. F.; Goekce, M.; Karali, T.; Harmansah, C.

    2010-01-01

    In this study thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of Mg 2 SiO 4 :Tb in the form of sintered pellets were investigated. Mg 2 SiO 4 :Tb is a recently developed dosimetric material which offers high sensitivity for TL and OSL in dosimetric applications. Thermoluminescence glow curve of Tb doped Mg 2 SiO 4 samples show a glow peak at about 200 degree Celsius with two small peaks at about 275 and 330 degree Celsius, respectively. OSL experiments showed that blue light (470 nm) is six times more efficient than green light (532 nm) to stimulate the OSL emission. The aim of this study was to determine the TL and OSL fading properties of Mg 2 SiO 4 : Tb using OSL and TL methods. In addition, PTTL properties of the Mg 2 SiO 4 : Tb was investigated by using blue LEDs, UV lamp and blue laser. Investigations on the fading properties also showed that the TL signal fades % 10 in a period of 1 month and OSL signal fades % 10 in a period of 3 month, which then the signal remains relatively stable for longer periods.

  10. Photoelectrochemical Characterization of Sprayed alpha-Fe2O3 Thin Films : Influence of Si Doping and SnO2 Interfacial Layer

    NARCIS (Netherlands)

    Liang, Y.; Enache, C.S.; Van De Krol, R.

    2008-01-01

    a-Fe2O3 thin film photoanodes for solar water splitting were prepared by spray pyrolysis of Fe(AcAc)3. The donor density in the Fe2O3 films could be tuned between 10171020cm-3 by doping with silicon. By depositing a 5 nm SnO2 interfacial layer between the Fe2O3 films and the transparent conducting

  11. Structural, optical and magnetic properties of Cr doped SnO2 nanoparticles stabilized with polyethylene glycol

    International Nuclear Information System (INIS)

    Subramanyam, K.; Sreelekha, N.; Murali, G.; Reddy, D. Amaranatha; Vijayalakshmi, R.P.

    2014-01-01

    Pure and Cr (1, 3, 5 and 7 at%) doped SnO 2 nanoparticles were synthesized in aqueous solution by a simple chemical co-precipitation method using polyethylene glycol (PEG) as a stabilizing agent. The effect of Cr doping on the structural, optical and magnetic properties of SnO 2 nanoparticles was investigated. EDAX spectra confirmed the presence of Sn, O and Cr in near stoichiometry. XRD patterns revealed that particles of all samples were crystallized in single phase rutile type tetragonal crystal structure (P4 2 /mnm) of SnO 2 . The peak positions with Cr concentration shifted to higher 2θ values. Lattice parameters were also decreased with increasing Cr concentration. TEM studies indicated that the particle size is in the range of 8–10 nm. The optical absorption studies indicated that the absorption edge shifted towards lower wavelengths with inclusion of Cr content. FTIR spectrum displays various bands that are due to fundamental overtones of PEG and O–Sn–O entities. Further it revealed that the undoped and as well as Cr doped SnO 2 nanoparticles were capped by PEG. Magnetization measurements at room temperature revealed that all the doped samples were ferromagnetic in nature. Well defined strong room temperature ferromagnetic hysteresis loop was observed for 1% Cr doped SnO 2 nanoparticles

  12. Selective growth of Ge1- x Sn x epitaxial layer on patterned SiO2/Si substrate by metal-organic chemical vapor deposition

    Science.gov (United States)

    Takeuchi, Wakana; Washizu, Tomoya; Ike, Shinichi; Nakatsuka, Osamu; Zaima, Shigeaki

    2018-01-01

    We have investigated the selective growth of a Ge1- x Sn x epitaxial layer on a line/space-patterned SiO2/Si substrate by metal-organic chemical vapor deposition. We examined the behavior of a Sn precursor of tributyl(vinyl)tin (TBVSn) during the growth on Si and SiO2 substrates and investigated the effect of the Sn precursor on the selective growth. The selective growth of the Ge1- x Sn x epitaxial layer was performed under various total pressures and growth temperatures of 300 and 350 °C. The selective growth of the Ge1- x Sn x epitaxial layer on the patterned Si region is achieved at a low total pressure without Ge1- x Sn x growth on the SiO2 region. In addition, we found that the Sn content in the Ge1- x Sn x epitaxial layer increases with width of the SiO2 region for a fixed Si width even with low total pressure. To control the Sn content in the selective growth of the Ge1- x Sn x epitaxial layer, it is important to suppress the decomposition and migration of Sn and Ge precursors.

  13. Effect of indium and antimony doping in SnS single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chaki, Sunil H., E-mail: sunilchaki@yahoo.co.in; Chaudhary, Mahesh D.; Deshpande, M.P.

    2015-03-15

    Highlights: • Single crystals growth of pure SnS, indium doped SnS and antimony doped SnS by direct vapour transport (DVT) technique. • Doping of In and Sb occurred in SnS single crystals by cation replacement. • The replacement mechanism ascertained by EDAX, XRD and substantiated by Raman spectra analysis. • Dopants concentration affects the optical energy bandgap. • Doping influences electrical transport properties. - Abstract: Single crystals of pure SnS, indium (In) doped SnS and antimony (Sb) doped SnS were grown by direct vapour transport (DVT) technique. Two doping concentrations of 5% and 15% each were employed for both In and Sb dopants. Thus in total five samples were studied viz., pure SnS (S1), 5% In doped SnS (S2), 15% In doped SnS (S3), 5% Sb doped SnS (S4) and 15% Sb doped SnS (S5). The grown single crystal samples were characterized by evaluating their surface microstructure, stoichiometric composition, crystal structure, Raman spectroscopy, optical and electrical transport properties using appropriate techniques. The d.c. electrical resistivity and thermoelectric power variations with temperature showed semiconducting and p-type nature of the as-grown single crystal samples. The room temperature Hall Effect measurements further substantiated the semiconducting and p-type nature of the as-grown single crystal samples. The obtained results are deliberated in detail.

  14. Moessbauer effect in pure and impurity doped FeSi2

    International Nuclear Information System (INIS)

    Blaauw, C.; Hanson, H.; Woude, F. van der

    1975-01-01

    Numerical values of the calculated and experimentally determined Moessbauer parameters for pure β-FeSi 2 and α-FeSi 2 are given. Temperature dependence of isomer shift and quadrupole splitting for the two Fe positions in β-FeSi 2 is presented. For α-FeSi 2 only average values are given. Spectra of Co- and Al-doped FeSi 2 recorded at 80, 293, 557 and 788 K were analyzed in the same manner as those of undoped FeSi 2 . The average values of isomer shift and quadrupole splitting in Co- and Al-doped β-FeSi 2 (α-Fesi 2 ) were compared to those found in undoped β-FeSi 2 (α-FeSi 2 ). All data were based on the room temperature spectra. Changes in Moessbauer parameters of doped samples relative to undoped ones were generally small, being of the order of hundredths of mm/sec. (Z.S.)

  15. Luminescent and scintillation properties of Sc3+and La3+doped Y2SiO5 powders and single crystalline films

    International Nuclear Information System (INIS)

    Zorenko, Yu.; Gorbenko, V.; Zorenko, T.; Voznyak, T.; Voloshynovskii, A.; Vistovskiy, V.; Paprocki, K.; Mosińska, L.; Bilski, P.; Twardak, A.; Fedorov, A.; Nikl, M.; Mares, J.A.

    2016-01-01

    The paper is dedicated to the investigation of the luminescence of Sc 3+ and La 3+ isoelectronic impurities in Y 2 SiO 5 (YSO) single crystalline films (SCF), grown by the liquid phase epitaxy (LPE) method, and in the powder analogs of these compounds prepared using the ceramic technology. The Sc 3+ and La 3+ dopants replacing the Y 3+ cations in Y1and Y2 positions of YSO host introduce the strong complex emission bands in the UV range peaked at 330 and 345 nm, respectively. The Sc 3+ and La 3+ dopant in YSO matrix yields also the strong TSL peaks at 400 and 405 K related to the ScY and ScLa centers formation, respectively. The luminescence and scintillation properties of YSO SCFs doped with Sc 3+ and La 3+ ions and co-doped with Ce 3+ ions on the trace impurity level have been also studied in our work. We have found that the light yield (LY) of these YSO:Sc and YSO:La SCFs can reach 50–65% of LY in reference YSO:Ce SCF due to strong quenching influence of Pb 2+ ions. Finally, the potential of Sc 3+ and La 3+ doped SCF of orthosilicates for creation of heavy scintillation screens, emitting in the UV range, is discussed.

  16. A quantum chemical analysis of Zn and Sb doping and co-doping in SnO2

    Directory of Open Access Journals (Sweden)

    Luis Villamagua

    2017-10-01

    Full Text Available This work presents a quantum chemical study of Zn and Sb doping and co-doping in SnO2 carried out by a DFT+U method. The analysis has been developed by introducing three different modifications in the otherwise pure SnO2 system. In the first place, an oxygen vacancy was introduced within the crystal. Following, such a system was doped (separately by Zn or Sb impurities. Finally, the best energetic positions for both Zn and Sb atoms were simultaneously introduced within the lattice. Results of the simulations show that the confined charge that appeared due to the introduction of the oxygen vacancy interacts with the dopants atoms, being this interaction mostly responsible of the observed effects, i.e., EG shrinkage, F-centers formations, and magnetic momentum rise.

  17. Al-doped SnO2 nanocrystals from hydrothermal systems

    International Nuclear Information System (INIS)

    Jin Haiying; Xu Yaohua; Pang Guangsheng; Dong Wenjun; Wan Qiang; Sun Yan; Feng Shouhua

    2004-01-01

    Nanoparticles of Al-doped SnO 2 have been hydrothermally synthesized. The influences of the hydrothermal reaction time, the molar ratio of Sn/Al as well as the pH value of the solution have been studied. During the hydrothermal synthesis, the particle's core is rich in Sn and the surface is rich in Al. The Al-rich surface prevents the particles from further growing up either in the hydrothermal condition or during the calcination at 600 deg. C for a short period of time. The optimal hydrothermal synthesis condition of the nanoparticles is pH 5, Sn/Al=4:1 and 12 h at 160 deg. C. The products have been studied by XRD, TEM and 27 Al solid-state NMR

  18. Electrical and optical properties of Si-doped Ga2O3

    Science.gov (United States)

    Li, Yin; Yang, Chuanghua; Wu, Liyuan; Zhang, Ru

    2017-05-01

    The charge densities, band structure, density of states, dielectric functions of Si-doped β-Ga2O3 have been investigated based on the density functional theory (DFT) within the hybrid functional HSE06. The heavy doping makes conduction band split out more bands and further influences the band structure. It decreases the band gap and changes from a direct gap to an indirect gap. After doping, the top of the valence bands is mainly composed by the O-2p states, Si-3p states and Ga-4p states and the bottom of the conduction bands is almost formed by the Si-3s, Si-3p and Ga-4s orbits. The anisotropic optical properties have been investigated by means of the complex dielectric function. After the heavy Si doping, the position of absorption band edges did not change much. The slope of the absorption curve descends and indicates that the absorption became more slow for Si-doped β-Ga2O3 than undoped one due to the indirect gap of Si-doped β-Ga2O3.

  19. Magnetoresistance and phase composition of La-Sn-Mn-O systems

    DEFF Research Database (Denmark)

    Li, Z.W.; Morrish, A.H.; Jiang, Jianzhong

    1999-01-01

    The transport properties of the manganites La1 - xSnxMnO3 + delta with x = 0.1-0.5 and of Fe-doped samples have been comprehensively studied using magnetoresistance measurements, Fe-57 and Sn-119 Mossbauer spectroscopy, and x-ray diffraction. At the Sn concentration x = 0.5, La0.5Sn0.5MnO3 + delta...

  20. Itinerant magnetism in doped semiconducting β-FeSi2 and CrSi2

    Science.gov (United States)

    Singh, David J.; Parker, David

    2013-01-01

    Novel or unusual magnetism is a subject of considerable interest, particularly in metals and degenerate semiconductors. In such materials the interplay of magnetism, transport and other Fermi liquid properties can lead to fascinating physical behavior. One example is in magnetic semiconductors, where spin polarized currents may be controlled and used. We report density functional calculations predicting magnetism in doped semiconducting β-FeSi2 and CrSi2 at relatively low doping levels particularly for n-type. In this case, there is a rapid cross-over to a half-metallic state as a function of doping level. The results are discussed in relation to the electronic structure and other properties of these compounds. PMID:24343332

  1. SnO2 COMO CATALIZADOR Y SOPORTE DE Ni Y Sn EN LA ALCOHOLISIS DEL ACEITE DE PALMA

    Directory of Open Access Journals (Sweden)

    CARLOS E. ARARAT

    2011-01-01

    Full Text Available El óxido de estaño en forma de SnO2 (casiterita ha sido usado como catalizador en diferentes procesos de interés de la industria química, tales como la de deshidrogenación, cracking, isomerización y oxidación de hidrocarburos. En este trabajo se estudió la aplicación de SnO2 como catalizador y como soporte de especies de níquel y estaño, en la alcohólisis del aceite de palma. La obtención del SnO2 se realizó por el método de precipitación y la incorporación de níquel y estaño, al soporte, por el método de impregnación. Se determinó que el SnO2 presentaba una mayor actividad frente a la reacción de alcohólisis en comparación con otros óxidos, tal como el MgO, y que esta actividad era afectada por la adición de níquel y estaño en su superficie. Se utilizó cromatografía de gases CG para el seguimiento de las reacciones, así como la espectroscopia FTIR para realizar el análisis de los productos obtenidos después del proceso. Los catalizadores fueron analizados por DRX para la determinación de las fases cristalinas presentes y del análisis de área superficial, volumen y tamaño de poro, para determinar las propiedades texturales de los catalizadores.

  2. Micro structural and magnetic characterization of Gd doped SnO2 nanoparticles

    International Nuclear Information System (INIS)

    Adhikari, R.; Das, A.K.; Karmakar, D.; Chandrasekhar Rao, T.V.; Ghatak, J.

    2008-01-01

    Gd doped SnO 2 nanoparticles were prepared by a chemical co-precipitation method. The prepared samples were calcined at 600 deg C. The annealed samples were characterized using XRD, TEM and SQUID magnetometry. The structural characterizations showed formation of particles in the nanometer regime. The M(T) and M(H) studies indicated an antiferromagnetic (AFM) interaction in 3 and 6% (at. wt.) Gd doped SnO 2 nanoparticles. The M(H) plot of both samples indicate a super paramagnetic (SPM) behavior at 7K as against the perfect AFM nature at 300K. The samples exhibit an insulating DMS nature, but we do not observe any ferromagnetism as was observed for other Gd doped systems like GaN and ZnO. (author)

  3. Effect of Indium Doping on the Sensitivity of SnO2 Gas Sensor

    International Nuclear Information System (INIS)

    Suharni; Sayono

    2009-01-01

    The dependence of sensitivity f SnO 2 gas sensors on indium concentration has been studied. Undoped and indium-doped SnO 2 gas sensors have been prepared by DC sputtering technique with following parameters i.e : electrode voltage of 3 kV, current 20 mA, vacuum pressure 1.8 × 10 -1 torr, deposition time 60 minutes and temperature of 200℃. The effect of weight variations of indium in order of 0.0370; 0.0485 and 0.0702 grams into SnO 2 thin film gas sensor for optimum result were investigated. The measurement of resistance, sensitivity and response time for various temperature for detecting of carbon monoxide (CO), Ammonia (NH 3 ) and acetone (CH 3 COCH 3 ) gas for indium doped has been done. From the analysis result shows that for indium doped 0.0702 g on the SnO 2 the resistance can be decreased from 832.0 kΩ to 3.9 kΩ and the operating temperature from 200℃ to 90℃ and improving the sensitivity from 15.92% to 40.09% and a response time from 30 seconds to 10 seconds for CO. (author)

  4. Synthesis of pure and Sr-doped LaGaO{sub 3}, LaFeO{sub 3} and LaCoO{sub 3} and Sr,Mg-doped LaGaO{sub 3} for ITSOFC application using different wet chemical routes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M. [National Metallurgical Laboratory-Madras Center, CSIR Madras Complex, Chennai 600113 (India); Srikanth, S. [National Metallurgical Laboratory-Madras Center, CSIR Madras Complex, Chennai 600113 (India)], E-mail: s_srikanth_99@yahoo.com; Ravikumar, B.; Alex, T.C.; Das, S.K. [National Metallurgical Laboratory, Jamshedpur 831007 (India)

    2009-02-15

    Pure and Sr-doped LaGaO{sub 3}, LaFeO{sub 3} and LaCoO{sub 3} and Sr,Mg-doped LaGaO{sub 3} were synthesized by various wet chemical routes, namely combustion, co-precipitation and citrate-gel methods. The effect of the various process parameters on the phase purity, particle size and surface area and morphology of the synthesized powders were determined by XRD, simultaneous TG-DTA, laser light scattering, BET and scanning electron microscopy. The stability of the synthesized pure phases in oxidizing and reducing atmosphere was also studied by thermogravimetry. It was observed that pure and Sr-doped single perovskite phases of lanthanum ferrite, cobaltite and gallate and Sr,Mg-doped lanthanum gallate could be synthesized by combustion and citrate-gel methods under suitable process conditions. Synthesis using the co-precipitation method yielded incomplete reaction irrespective of the calcination temperature adopted. The citrate-gel method yielded better powder properties in terms of particle size and morphology and surface area compared to combustion synthesis. It was found that pure and Sr-doped lanthanum ferrite, lanthanum cobaltite, lanthanum gallate and Sr,Mg-doped lanthanum gallate were stable in the oxidizing atmosphere. In the reducing atmosphere, pure and Sr-doped lanthanum ferrite and Sr,Mg-doped lanthanum gallate was found to be stable at least during the timeframe of the thermogravimetric experiment whereas pure and Sr-doped lanthanum cobaltite was partially reduced in hydrogen atmosphere.

  5. The effect of electron and hole doping on the thermoelectric properties of shandite-type Co3Sn2S2

    OpenAIRE

    Mangelis, Panagiotis; Vaqueiro, Paz; Jumas, Jean-Claude; da Silva, Ivan; Smith, Ronald I; Powell, Anthony V

    2017-01-01

    Electron and hole doping in Co3Sn2S2, through chemical substitution of cobalt by the neighbouring elements, nickel and iron, affects both the structure and thermoelectric properties. Electron doping to form Co3-xNixSn2S2 (0 ≤ x ≤ 3) results in an expansion of the kagome layer and materials become increasingly metallic as cobalt is substituted. Conversely, hole doping in Co3-xFexSn2S2 (0 ≤ x ≤ 0.6) leads to a transition from metallic to n-type semiconducting behaviour at x = 0.5. Iron substitu...

  6. Synthesis and electrochemical properties of tin-doped MoS{sub 2} (Sn/MoS{sub 2}) composites for lithium ion battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Lin; Min, Feixia; Luo, Zhaohui; Wang, Shiquan, E-mail: wsqhao@126.com [Hubei University, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules (China); Teng, Fei [Nanjing University of Information Science and Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), School of Environmental Sciences and Engineering (China); Li, Guohua [Zhejiang University of Technology, School of Chemical Engineering and Materials Science (China); Feng, Chuanqi [Hubei University, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules (China)

    2016-12-15

    SnO{sub 2}-MoO{sub 3} composites were synthesized by using (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}·4H{sub 2}O and SnCl{sub 22H{sub 2}O as raw materials through a simple solvothermal method followed by pyrolysis. Tin-doped MoS{sub 2} (Sn/MoS{sub 2}) flowers have been synthesized by a solvothermal method followed with annealing in Ar(H{sub 2}) atmosphere, with SnO{sub 2}-MoO{sub 3}, thioacetamide (TAA), and urea as starting materials. The doping and the content of Sn-doping play crucial roles in the morphology and electrochemical performance of the MoS{sub 2}. As anode materials for lithium ion battery (LIB), all Sn/MoS{sub 2} composites exhibit both higher reversible capacity and better cycling performance at current density of 200 mA g{sup −1}, compared with MoS{sub 2} without Sn doping. The achieved discharge capacity for Sn/MoS{sub 2} composites is above 1000 mAh g{sup −1} after 100 cycles with nearly 100% coulombic efficiency. The doping of metal Sn in MoS{sub 2} can improve the conductivity of MoS{sub 2} and significantly enhance its electrochemical properties. The good electrochemical performance suggests that the Sn/MoS{sub 2} composite could be a promising candidate as a novel anode material for LIB application. Our present work provides a new approach to the fabrication of anode materials for LIB applications.

  7. A low temperature situ precipitation route to designing Zn-doped SnO2 photocatalyst with enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Jia, Xiaohua; Liu, Yingying; Wu, Xiangyang; Zhang, Zhen

    2014-01-01

    Highlights: • A new Zn doped SnO 2 photocatalyst was successfully achieved and characterized. • The Zn doped SnO 2 photocatalyst exhibited excellent photocatalytic activity and stability for the photodegradation RhB. • Photocatalytic mechanisms both under visible and UV–vis light irradiation were proposed. - Abstract: Zn doped SnO 2 nanoparticles have been fabricated through the low temperature situ precipitation technique. The morphology, structure and chemical composition of the nanoparticles are characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), Thermogravimetric-differential scanning calorimetry (TG–DSC) and UV–vis absorption spectroscopy. The products were also characterized by X-ray diffraction (XRD) and X-photoelectron spectrum (XPS), and the results indicated that Sn 4+ ions were successfully substituted by Zn 2+ . Their photocatalytic activities were evaluated using rhodamine B (RhB) as a decomposition objective. The results show that the Zn doped SnO 2 display higher photocatalytic activities in the degradation of RhB than pure ZnO products by exposure to UV irradiation. A possible reason of the increased photocatalytic activity of Zn doped SnO 2 is attributed to intrinsic oxygen vacancies in nanoparticles and extrinsic defect due to Zn hole doping

  8. Preparation and characterisation of Os doped MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Grivel, J.-C., E-mail: jean@dtu.dk; Namazkar, S.; Alexiou, A.; Holte, O.J.

    2014-12-15

    Highlights: • Polycrystalline osmium doped MgB{sub 2} samples were prepared by solid state route. • Up to 1 at.% Mg can be replaced by Os in the MgB{sub 2} lattice. • T{sub c} decreases at a rate of 2.1 K/at.% Os upon doping. - Abstract: Polycrystalline samples with Mg{sub 1−x}Os{sub x}B{sub 2.04} nominal stoichiometry were made by reacting elemental powders at 800 °C under argon atmosphere. Based on XRD diffraction patterns, EDS analysis and magnetisation measurements, it is found that Os can replace up to about 1 at.% Mg in the MgB{sub 2} lattice. Beyond this doping level, unreacted Os and Mg-rich Mg–Os impurity phases are formed. The a-axis parameter contracts upon doping while the superconducting transition temperature decreases at a rate of 2.1 K/at.% Os substitution. At 10 K, Os doping induces an improvement of the normalised critical current density under applied magnetic fields in excess of 0.5 T, indicating a modest enhancement of flux pinning in this range.

  9. Supraconductivity of TR-Ru3Si2 compounds (TR = La, Ce)

    International Nuclear Information System (INIS)

    Godart, C.; Gupta, L.C.; Parks, R.D.; Rauschwalbe, U.; Alheim, U.; Gottwick, U.; Lieke, W.; Steglich, F.

    1984-01-01

    A new family of superconducting ternary silicides MRu 3 Si 2 with M = La (Tsub(s) approximately 7 K), Y and Th was discovered by Barz and Vandenberg. Same compounds with M from Nd to Tm are magnetic and not superconductors. We studied superconductivity in the solid solution Cesub(1-x)Lasub(x)Ru 3 Si 2 of hexagonal structure from x = 0 to 1. CeRu 3 Si 2 is type II superconductor (Tsub(s) approximately 1 K), like LaRu 3 Si 2 , and is mixed valent (M.V.). Spin fluctuations temperature (Tsub(sf) approximately 440 K) is between these of non superconducting M.V. like CeSn 3 (Tsub(sf) approximately 270) and these of superconducting M.V. like CeRu 2 (Tsub(sf) approximately 770 K). Cesub(1-x)Lasub(x)Ru 3 Si 2 is the first M.V. system of Ce which is superconductor from x = 0 to 1 [fr

  10. Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

    Science.gov (United States)

    Fang, Gu; Chen, Chih-chi

    2015-07-01

    Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.

  11. A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

    Science.gov (United States)

    Le, Tran; Phuc Dang, Huu; Luc, Quang Ho; Hieu Le, Van

    2017-04-01

    This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19  ×  1018 cm-3, and 3.95 cm2 V-1 s-1, respectively. Besides, the average transmission of films was  >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current-voltage (I-V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

  12. Vertically aligned nitrogen doped (Sn,Nb)O_2 nanotubes – Robust photoanodes for hydrogen generation by photoelectrochemical water splitting

    International Nuclear Information System (INIS)

    Patel, Prasad Prakash; Hanumantha, Prashanth Jampani; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Gattu, Bharat; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

    2016-01-01

    Graphical abstract: - Highlights: • Nb and N co-doping provides excellent optoelectronic properties for SnO_2 NTs. • The optoelectronic properties of doped SnO_2 are studied by first principles study. • (Sn_0_._9_5Nb_0_._0_5)O_2:N-600 NTs exhibits superior ABPE (4.1%) to date. • Excellent photoelectrochemical stability of (Sn_0_._9_5Nb_0_._0_5)O_2:N-600 NTs. - Abstract: Hydrogen generation from photoelectrochemical (PEC) water splitting is on the forefront of clean energy generation landscape. The efficiency of PEC system is dependent on the engineering of semiconductors with tailored narrow band gap coupled with superior photoelectrochemical activity and desired stability vital for the commercialization of PEC water splitting cells. We report herein the study of vertically aligned Nb and N doped SnO_2 nanotubes (NTs), i.e., (Sn_0_._9_5Nb_0_._0_5)O_2:N NTs for PEC water splitting. (Sn_0_._9_5Nb_0_._0_5)O_2 NTs was selected for co-doping with nitrogen by systematic analysis of applied bias photon-to-current efficiency of various Nb doped SnO_2 (x = 0–0.1) compositions. Consequently, excellent photoelectrochemical stability and the highest efficiency of 4.1% is obtained for (Sn_0_._9_5Nb_0_._0_5)O_2:N-600 NTs never observed for other known TiO_2, ZnO, and Fe_2O_3 systems to date. Additionally, theoretical first principles study provides understanding of Nb and N co-doping on the electronic structure and band gap of SnO_2 semiconductor, further corroborating results of the experimental study.

  13. Magnetic and optical properties of electrospun hollow nanofibers of SnO{sub 2} doped with Ce-ion

    Energy Technology Data Exchange (ETDEWEB)

    Mohanapriya, P.; Victor Jaya, N. [Department of Physics, Anna University, Chennai 600 025 (India); Pradeepkumar, R. [Centre for Nanoscience and Technology, Anna University, Chennai 600 025 (India); Natarajan, T. S., E-mail: tsn@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India)

    2014-07-14

    Cerium doped SnO{sub 2} hollow nanofibers were synthesized by electrospinning. High resolution scanning electron microscope (HRSEM) and transmission electron microscopy (TEM) analysis showed hollow nanofibers with diameters around ∼200 nm. The optimized substitution of Ce ion into SnO{sub 2} lattices happened above 6 mol. % doping as confirmed by Powder X-ray diffraction (XRD) studies. Optical band gap was decreased by the doping confirming the direct energy transfer between f-electrons of rare earth ion and the SnO{sub 2} conduction or valence band. The compound also exhibited room temperature ferromagnetism with the saturation magnetization of 19 × 10{sup −5} emu/g at 6 mol. %. This study demonstrates the Ce doped SnO{sub 2} hollow nanofibers for applications in magneto-optoelectronic devices.

  14. Photo-Induced conductivity of heterojunction GaAs/Rare-Earth doped SnO2

    Directory of Open Access Journals (Sweden)

    Cristina de Freitas Bueno

    2013-01-01

    Full Text Available Rare-earth doped (Eu3+ or Ce3+ thin layers of tin dioxide (SnO2 are deposited by the sol-gel-dip-coating technique, along with gallium arsenide (GaAs films, deposited by the resistive evaporation technique. The as-built heterojunction has potential application in optoelectronic devices, because it may combine the emission from the rare-earth-doped transparent oxide, with a high mobility semiconductor. Trivalent rare-earth-doped SnO2 presents very efficient emission in a wide wavelength range, including red (in the case of Eu3+ or blue (Ce3+. The advantage of this structure is the possibility of separation of the rare-earth emission centers, from the electron scattering, leading to an indicated combination for electroluminescence. Electrical characterization of the heterojunction SnO2:Eu/GaAs shows a significant conductivity increase when compared to the conductivity of the individual films. Monochromatic light excitation shows up the role of the most external layer, which may act as a shield (top GaAs, or an ultraviolet light absorber sink (top RE-doped SnO2. The observed improvement on the electrical transport properties is probably related to the formation of short conduction channels in the semiconductors junction with two-dimensional electron gas (2DEG behavior, which are evaluated by excitation with distinct monochromatic light sources, where the samples are deposited by varying the order of layer deposition.

  15. Decrease in electrical contact resistance of Sb-doped n+-BaSi2 layers and spectral response of an Sb-doped n+-BaSi2/undoped BaSi2 structure for solar cells

    Science.gov (United States)

    Kodama, Komomo; Takabe, Ryota; Yachi, Suguru; Toko, Kaoru; Suemasu, Takashi

    2018-03-01

    We investigated how the electron concentration n in a 300-nm-thick Sb-doped n+-BaSi2 layer grown by molecular beam epitaxy affected the contact resistance R C to surface electrodes (Al, indium-tin-oxide). As the n of n-BaSi2 increased, R C decreased and reached a minimum of 0.019 Ω cm2 at n = 2.4 × 1018 cm-3 for the Al electrodes. This value was more than 1 order of magnitude smaller than that obtained for Al/B-doped p-BaSi2. We believe that this significant decrease in R C came from Sb segregation. Furthermore, the internal quantum efficiency (IQE) spectrum was evaluated for an Sb-doped n+-BaSi2 (20 nm)/undoped BaSi2 (500 nm)/n+-Si(111) structure. Its IQE reached as high as ˜50% over a wide wavelength range under a small bias voltage of 0.1 V applied between the top and bottom electrodes.

  16. Structural, optical and magnetic properties of Cr doped SnO{sub 2} nanoparticles stabilized with polyethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Subramanyam, K.; Sreelekha, N. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Murali, G. [Department of BIN Fusion Technology and Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk (Korea, Republic of); Reddy, D. Amaranatha [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609-735 (Korea, Republic of); Vijayalakshmi, R.P., E-mail: vijayaraguru@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2014-12-01

    Pure and Cr (1, 3, 5 and 7 at%) doped SnO{sub 2} nanoparticles were synthesized in aqueous solution by a simple chemical co-precipitation method using polyethylene glycol (PEG) as a stabilizing agent. The effect of Cr doping on the structural, optical and magnetic properties of SnO{sub 2} nanoparticles was investigated. EDAX spectra confirmed the presence of Sn, O and Cr in near stoichiometry. XRD patterns revealed that particles of all samples were crystallized in single phase rutile type tetragonal crystal structure (P4{sub 2}/mnm) of SnO{sub 2}. The peak positions with Cr concentration shifted to higher 2θ values. Lattice parameters were also decreased with increasing Cr concentration. TEM studies indicated that the particle size is in the range of 8–10 nm. The optical absorption studies indicated that the absorption edge shifted towards lower wavelengths with inclusion of Cr content. FTIR spectrum displays various bands that are due to fundamental overtones of PEG and O–Sn–O entities. Further it revealed that the undoped and as well as Cr doped SnO{sub 2} nanoparticles were capped by PEG. Magnetization measurements at room temperature revealed that all the doped samples were ferromagnetic in nature. Well defined strong room temperature ferromagnetic hysteresis loop was observed for 1% Cr doped SnO{sub 2} nanoparticles.

  17. Long afterglow property of Er{sup 3+} doped Ca{sub 2}SnO{sub 4} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongyun, E-mail: dyz@sit.edu.cn; Shi, Mingming; Sun, Yiwen; Guo, Yunyun; Chang, Chengkang

    2016-05-15

    A novel green emitting long afterglow phosphor, Er{sup 3+} -doped Ca{sub 2}SnO{sub 4} (Ca{sub 2}SnO{sub 4}:Er{sup 3+}), was prepared successfully via a traditional high temperature solid–state reaction method. Its properties have been characterized and analyzed by utilizing x-ray diffraction (XRD), photoluminescence spectroscope (PLS), afterglow decay curve (ADC) and thermal luminescence spectroscope (TLS). Three main emission peaks of PLS locate at 524, 550 and 668 nm, corresponding to CIE chromaticity coordinates of x = 0.326, y = 0.6592. An optimal doping concentration of Er{sup 3+} of 2% was determined. The Ca{sub 2}SnO{sub 4}:Er{sup 3+} phosphors showed a typical triple-exponential afterglow decay behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Ca{sub 2}SnO{sub 4}:2 mol% Er{sup 3+} phosphors was generated by the suitable electron or hole traps which were resulted from the doping the Ca{sub 2}SnO{sub 4} host with rare-earth ions (Er{sup 3+}). - Highlights: • A novel green emitting long afterglow phosphor, Ca{sub 2}SnO{sub 4}:Er{sup 3+}, was prepared. • An optimal doping concentration of Er{sup 3+} of 2% was determined. • After the UV source was turned off, the Ca{sub 2}SnO{sub 4}:Er{sup 3+} showed a typical triple-exponential afterglow decay behavior. • CIE chromaticity coordinates results confirmed a green light emitting of the Ca{sub 2}SnO{sub 4}:Er{sup 3+}. • The persistent afterglow of the Ca{sub 2}SnO{sub 4}:Er{sup 3+} was attributed to suitable electron or hole traps.

  18. Boron-doped, carbon-coated SnO2/graphene nanosheets for enhanced lithium storage.

    Science.gov (United States)

    Liu, Yuxin; Liu, Ping; Wu, Dongqing; Huang, Yanshan; Tang, Yanping; Su, Yuezeng; Zhang, Fan; Feng, Xinliang

    2015-03-27

    Heteroatom doping is an effective method to adjust the electrochemical behavior of carbonaceous materials. In this work, boron-doped, carbon-coated SnO2 /graphene hybrids (BCTGs) were fabricated by hydrothermal carbonization of sucrose in the presence of SnO2/graphene nanosheets and phenylboronic acid or boric acid as dopant source and subsequent thermal treatment. Owing to their unique 2D core-shell architecture and B-doped carbon shells, BCTGs have enhanced conductivity and extra active sites for lithium storage. With phenylboronic acid as B source, the resulting hybrid shows outstanding electrochemical performance as the anode in lithium-ion batteries with a highly stable capacity of 1165 mA h g(-1) at 0.1 A g(-1) after 360 cycles and an excellent rate capability of 600 mA h g(-1) at 3.2 A g(-1), and thus outperforms most of the previously reported SnO2-based anode materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Structural and fluorescence properties of Ni:MgO-SiO2 particles synthesized by flame spray pyrolysis

    International Nuclear Information System (INIS)

    Suzuki, Takenobu; Ohishi, Yasutake; Tani, Takao

    2006-01-01

    Structural and fluorescence properties of flame spray-synthesized Ni 1 mol%-doped MgO-SiO 2 nano-particles (MgO:SiO 2 = 100:0, 50:50, 25:75 and 0:100 in mol%) were investigated as a first step to prepare transparent materials containing Ni:MgO for optical gain media. Polyhedral aggregates of primary particles with diameters of 8-19 nm were obtained for all compositions. The 100MgO particles were single crystalline and showed the fluorescences (centered at 1260 and 1320 nm) and lifetime (3.8 ms) similar to those of solid state-synthesized Ni:MgO polycrystalline powder under laser excitation at 976 nm, suggesting Ni ions incorporated in MgO

  20. Enhanced thermoelectric property of oxygen deficient nickel doped SnO2 for high temperature application

    Science.gov (United States)

    Paulson, Anju; Sabeer, N. A. Muhammad; Pradyumnan, P. P.

    2018-04-01

    Motivated by the detailed investigation on the thermoelectric performance of oxide materials our work concentrated on the influence of acceptor dopants and defect density in the lattice plane for the enhancement of thermoelectric power. The series of Sn1‑x Nix O2 (0.01 ≤ x ≤ 0.05) compositions were prepared by solid state reaction mechanism and found that 3 atomic percentage Ni doped SnO2 can be considered as a good candidate due to its promising electrical and transport properties. Defect lattices were introduced in the sample and the deviation from oxygen stochiometry was ensured using photoluminescence measurement. High power factor was obtained for the 3 atomic percentage nickel doped SnO2 due to the effective number of charge carrier concentration and the depletion of oxygen rich layers. Defect centered and acceptor doped SnO2 lattice opens a new door for energy harvesting at higher temperatures.

  1. Fabrication of folic acid sensor based on the Cu doped SnO2 nanoparticles modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Lavanya, N; Radhakrishnan, S; Sudhan, N; Sekar, C; Leonardi, S G; Neri, G; Cannilla, C

    2014-01-01

    A novel folic acid biosensor has been fabricated using Cu doped SnO 2 nanoparticles (NPs) synthesized by a simple microwave irradiation method. Powder XRD and TEM studies confirmed that both the pure and Cu doped SnO 2 (Cu: 0, 10, 20wt%) crystallized in tetragonal rutile-type structure with spherical morphology. The average crystallite size of pure SnO 2 was estimated to be around 16 nm. Upon doping, the crystallite sizes decreased to 9 nm and 5 nm for 10 and 20wt% Cu doped SnO 2 respectively. XPS studies confirmed the electronic state of Sn and Cu to be 4+ and 2+ respectively. Cu (20wt%) doped SnO 2 NPs are proved to be a good sensing element for the determination of folic acid (FA). Cu-SnO 2 NPs (20wt%) modified glassy carbon electrode (GCE) exhibited the lowest detection limit of 0.024 nM over a wide folic acid concentration range of 1.0 × 10 −10 to 6.7 × 10 −5 M at physiological pH of 7.0. The fabricated sensor is highly selective towards the determination of FA even in the presence of a 100 fold excess of common interferent ascorbic acid. The sensor proved to be useful for the estimation of FA content in pharmaceutical sample with satisfactory recovery. (paper)

  2. Zr-doped SnO2 thin films synthesized by spray pyrolysis technique for barrier layers in solar cells

    Science.gov (United States)

    Reddy, N. Nanda Kumar; Akkera, Harish Sharma; Sekhar, M. Chandra; Park, Si-Hyun

    2017-12-01

    In the present work, we investigated the effect of Zr doping (0-6 at%) on the structural, electrical, and optical properties of tin oxide (SnO2) thin films deposited onto glass substrates using a spray pyrolysis technique. The room-temperature X-ray diffraction pattern shows that all deposited films exhibit polycrystalline tetragonal structure. The pure SnO2 film is grown along a preferred (200) direction, whereas Zr-doped SnO2 (Zr:SnO2) films started growing along the (220) orientation along with a high intensity peak of (200). Scanning electron microscope (SEM) and atomic force microscope (AFM) images showed that the grains of the films are spherical in structure, and the grain size decreased with increasing of Zr concentration. The optical transmission spectra of deposited films as a function of wavelength confirm that the average optical transmittance is > 85% for Zr:SnO2 films. The value of the optical bandgap is significantly decreased from 3.94 to 3.68 eV with increasing Zr concentration. Furthermore, the electrical measurements found that the sheet resistance ( R sh) and resistivity ( ρ) values are decreased with increasing of Zr doping. The lowest values of R sh = 6.82 Ω and ρ = 0.4 × 10- 3 Ω cm are found in 6-at% Zr-doped SnO2 film. In addition, a good efficiency value of the figure of merit ( ɸ = 3.35 × 10- 3 Ω-1) is observed in 6-at% Zr-doped SnO2 film. These outstanding properties of Zr-doped SnO2 films make them useful for several optoelectronic device applications.

  3. Photoluminescence of Mg_2Si films fabricated by magnetron sputtering

    International Nuclear Information System (INIS)

    Liao, Yang-Fang; Xie, Quan; Xiao, Qing-Quan; Chen, Qian; Fan, Meng-Hui; Xie, Jing; Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di

    2017-01-01

    Highlights: • High quality Mg_2Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg_2Si films was reported. • The Mg_2Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg_2Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg_2Si-based light-emitting devices, Mg_2Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg_2Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg_2Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg_2Si film on Si (111) displays polycrystalline structure, whereas Mg_2Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg_2Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg_2Si films was observed for the first time. The PL emission wavelengths of Mg_2Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg_2Si films on glass substrate is much larger than that of Mg_2Si film on Si (111) substrate. The activation energy of 18 meV is

  4. Doping effects on the structural, magnetic, and hyperfine properties of Gd-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Coelho-Júnior, H.; Aquino, J. C. R.; Aragón, F. H. [Universidade de Brasília, Núcleo de Física Aplicada, Instituto de Física (Brazil); Hidalgo, P. [Universidade de Brasília, Faculdade Gama-FGA, Setor Central Gama (Brazil); Cohen, R.; Nagamine, L. C. C. M. [Universidade de São Paulo, Instituto de Física (Brazil); Coaquira, J. A. H., E-mail: coaquira@unb.br; Silva, S. W. da [Universidade de Brasília, Núcleo de Física Aplicada, Instituto de Física (Brazil); Brito, H. F. [Universidade de São Paulo, Instituto de Química (Brazil)

    2014-12-15

    In this work we present the study of the structural, magnetic, and hyperfine properties of Gd-doped SnO{sub 2} nanoparticles synthesized by a polymer precursor method. The X-ray diffraction data analysis shows the formation of the rutile-type structure in all samples with Gd content from 1.0 to 10.0 mol%. The mean crystallite size is ∼11 nm for the 1.0 mol% Gd-doped samples and it shows a decreasing tendency as the Gd content is increased. The analysis of magnetic measurements indicates the coexistence of ferromagnetic and paramagnetic phases for the 1.0 mol% Gd-doped sample; however, above that content, only a paramagnetic phase is observed. The ferromagnetic phase observed in the 1.0 mol% Gd-doped sample has been assigned to the presence of bound magnetic polarons which overlap to create a spin-split impurity band. Room-temperature {sup 119}Sn Mössbauer measurements reveal the occurrence of strong electric quadrupole interactions. It has been determined that the absence of magnetic interactions even for 1.0 mol% Gd-doped sample has been related to the weak magnetic field associated to the exchange interaction between magnetic ions and the donor impurity band. The broad distribution of electric quadrupole interactions are attributed to the several non-equivalent surroundings of Sn{sup 4+} ions provoked by the entrance of Gd{sup 3+} ions and to the likely presence of Sn{sup 2+} ions. The isomer shift seems to be nearly independent of the Gd content for samples with Gd content below 7.5 mol%.

  5. Precipitation kinetics of Al-1.12 Mg{sub 2}Si-0.35 Si and Al-1.07 Mg{sub 2}Si-0.33 Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gaber, A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Gaffar, M.A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)]. E-mail: mgaafar@aucegypt.edu; Mostafa, M.S. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Zeid, E.F. Abo [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

    2007-02-21

    The kinetics of hardening precipitates of Al-1.12 wt.% Mg{sub 2}Si-0.35 wt.% Si (excess Si) and Al-1.07 wt.% Mg{sub 2}Si-0.33 wt.% Cu (balanced + Cu) alloys have been investigated by means of differential scanning calorimetry and hardness measurements. The excess Si enhances the precipitation kinetics and improves the strength of the material. On the other hand, however addition of Cu assist formation of the Q' phase which positively changed the alloy strength. The high binding energy between vacancies and solute atoms (Si and Mg) enhances the combination of Si, Mg and vacancies to form Si-Mg-vacancy clusters. These clusters act as nucleation sites for GP-zones. The coexistence of the {beta}'- and Q'-precipitates in the balanced + Cu alloy results in a higher peak age hardening compared to the alloy with Si in excess.

  6. Effect of Si/Fe ratio on the boron and phosphorus doping efficiency of β-FeSi2 by magnetron sputtering

    International Nuclear Information System (INIS)

    Xu Jiaxiong; Yao Ruohe

    2011-01-01

    Boron-doped or phosphorus-doped β-FeSi 2 thin films have been prepared on silicon substrate by magnetron sputtering. Effects of Si/Fe ratio on the boron and phosphorus doping efficiencies have been studied from the resistivities of doped β-FeSi 2 thin films and current-voltage characteristics of doped β-FeSi 2 /Si heterojunctions. The experimental results reveal that the carrier concentration and doping efficiency of boron or phosphorus dopants at the Fe-rich side are higher than that at the Si-rich side. The effect of Si/Fe ratio can be deduced from the comparison of the formation energies under two extreme conditions. At the Fe-rich limit condition, the formation energy of boron or phosphorous doping is lower than that at the Si-rich condition. Therefore, the activation of impurities is more effective at the Fe-rich side. These results demonstrate that the boron-doped and phosphorous-doped β-FeSi 2 thin films should be kept at the Fe-rich side to avoid the unexpected doping sites and low doping efficiency.

  7. Nonlinear I–V characteristics study of doped SnO2

    Indian Academy of Sciences (India)

    Unknown

    type semiconductor with many interesting electronic pro- perties. Tin oxide ... The current–voltage curves were plotted on log–log scale from which the ... 4. Conclusion. A new varistor system based on doped SnO2 system is prepared and it ...

  8. Structural, Optical and Ethanol Sensing Properties of Dy-Doped SnO2 Nanoparticles

    Science.gov (United States)

    Shaikh, F. I.; Chikhale, L. P.; Nadargi, D. Y.; Mulla, I. S.; Suryavanshi, S. S.

    2018-04-01

    We report a facile co-precipitation synthesis of dysprosium (Dy3+) doped tin oxide (SnO2) thick films and their use as gas sensors. The doping percentage (Dy3+) was varied from 1 mol.% to 4 mol.% with the step of 1 mol.%. As-produced material with varying doping levels were sintered in air; and by using a screen printing technique, their thick films were developed. Prior to sensing performance investigations, the films were examined for structural, morphological and compositional properties using x-ray diffraction, a field emission scanning electron microscope, a transmission electron microscope, selected area electron diffraction, energy dispersive analysis by x-rays, Fourier transform infrared spectroscopy and Raman spectroscopic techniques. The structural analyses revealed formation of single phase nanocrystalline material with tetragonal rutile structure of SnO2. The morphological analyses confirmed the nanocrystalline porous morphology of as-developed material. Elemental analysis defined the composition of material in accordance with the doping concentration. The produced sensor material exhibited good response towards different reducing gases (acetone, ethanol, LPG, and ammonia) at different operating temperatures. The present study confirms that the Dy3+ doping in SnO2 enhances the response towards ethanol with reduction in operating temperature. Particularly, 3 mol.% Dy3+ doped sensor exhibited the highest response (˜ 92%) at an operating temperature of 300°C with better selectivity, fast response (˜ 13 s) and recovery (˜ 22 s) towards ethanol.

  9. Fermi surfaces of YRu2Si2 and LaRu2Si2

    International Nuclear Information System (INIS)

    Settai, R.; Ikezawa, H.; Toshima, H.; Takashita, M.; Ebihara, T.; Sugawara, H.; Kimura, T.; Motoki, K.; Onuki, Y.

    1995-01-01

    We have measured the de Haas-van Alphen effect of YRu 2 Si 2 and LaRu 2 Si 2 to clarify the Fermi surfaces and cyclotron masses. Main hole-Fermi surfaces of both compounds with a distorted ellipsoid shape are similar, occupying about half of the Brillouin zone. The small hole-Fermi surfaces with the shape of a rugby ball are three in number for LaRu 2 Si 2 , and one for YRu 2 Si 2 . An electron-Fermi surface consists of a doughnut like shape for LaRu 2 Si 2 , while a cylinder along the [001] direction and a multiply-connected shape exist for YRu 2 Si 2 . The cyclotron masses of YRu 2 Si 2 are a little larger than those of LaRu 2 Si 2 . ((orig.))

  10. Defect phase diagram for doping of Ga2O3

    Science.gov (United States)

    Lany, Stephan

    2018-04-01

    For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association of dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO2) conditions. Considering further the stability constraints due to sublimation of molecular Ga2O, specific predictions of optimized pO2 and Si dopant concentrations are given. The incomplete passivation of dopant-defect complexes in β-Ga2O3 suggests a design rule for metastable doping above the solubility limit.

  11. Electronic structure and p-type doping of ZnSnN2

    Science.gov (United States)

    Wang, Tianshi; Janotti, Anderson; Ni, Chaoying

    ZnSnN2 is a promising solar-cell absorber material composed of earth abundant elements. Little is known about doping, defects, and how the valence and conduction bands in this material align with the bands in other semiconductors. Using density functional theory with the the Heyd-Scuseria-Ernzerhof hybrid functional (HSE06), we investigate the electronic structure of ZnSnN2, its band alignment to other semiconductors, such as GaN and ZnO, the possibility of p-type doping, and the possible causes of the observed unintentional n-type conductivity. We find that the position of the valence-band maximum of ZnSnN2 is 0.55 eV higher than that of GaN, yet the conduction-band minimum is close to that in ZnO. As possible p-type dopants, we explore Li, Na, and K substituting on the Zn site. Finally, we discuss the cause of unintentional n-type conductivity by analyzing the position of the conduction-band minimum with respect to that of GaN and ZnO.

  12. Vacancy-induced brittle to ductile transition of W-M co-doped Al3Ti (M=Si, Ge, Sn and Pb).

    Science.gov (United States)

    Zhu, Mingke; Wu, Ping; Li, Qiulin; Xu, Ben

    2017-10-25

    We investigated the effect of vacancy formation on brittle (D0 22 ) to ductile (L1 2 -like) transition in Al 3 Ti using DFT calculations. The well-known pseudogap on the density of states of Al 3 Ti migrates towards its Fermi level from far above, via a W - M co-doping strategy, where M is Si, Ge, Sn or Pb respectively. In particular, by a W - M co-doping the underline electronic structure of the pseudogap approaches an octahedral (L1 2 : t 2g , e g ) from the tetragonal (D0 22 : e g , b 2g , a 1g , b 1g ) crystal field. Our calculations demonstrated that (1) a W-doping is responsible for the close up of the energy gap between a 1g and b 1g so that they tend to merge into an e g symmetry, and (2) all M-doping lead to a narrower gap between e g and b 2g (moving towards a t 2g symmetry). Thus, a brittle to ductile transition in Al 3 Ti is possible by adopting this W - M co-doping strategy. We further recommend the use of W-Pb co-doped Al 3 Ti to replace the less anodic Al electrode in Al-battery, due to its improved ductility and high Al diffusivity. Finally this study opens a new field in physics to tailor mechanical properties by manipulating electron energy level(s) towards higher symmetry via vacancy optimization.

  13. Optical Properties of Malachite Green Dye Doped SiO2 Glasses: Effect of Transition Metal (Fe-I Used as a Codopant

    Directory of Open Access Journals (Sweden)

    Dulen Bora

    2014-01-01

    Full Text Available Enhanced luminescence properties of Malachite Green (MG (oxalate in Fe-MG codoped SiO2 glasses compared to its values in MG doped SiO2 glasses are reported here. The enhancement is chiefly attributed to a resonance nonradiative energy transfer between Fe and MG. The quantum yield of Malachite Green (MG, in presence of Iron, trapped in sol-gel derived SiO2 glass increases by an order of ~103 compared to that in low viscous solvent while a lifetime of 3.29 ns is reported.

  14. A comparative investigation on the effects of nitrogen-doping into graphene on enhancing the electrochemical performance of SnO2/graphene for sodium-ion batteries.

    Science.gov (United States)

    Xie, Xiuqiang; Su, Dawei; Zhang, Jinqiang; Chen, Shuangqiang; Mondal, Anjon Kumar; Wang, Guoxiu

    2015-02-21

    SnO2/nitrogen-doped graphene nanohybrids have been synthesized by an in situ hydrothermal method, during which the formation of SnO2 nanocrystals and nitrogen doping of graphene occur simultaneously. The as-prepared SnO2/nitrogen-doped graphene nanohybrids exhibit enhanced electrochemical performance for sodium-ion batteries compared to SnO2/graphene nanocomposites. A systematic comparison between SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart as anode materials for sodium-ion batteries has been conducted. The comparison is in a reasonable framework, where SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart have the same SnO2 ratio, similar SnO2 crystallinity and particle size, close surface area and pore size. The results clearly manifest that the improved electron transfer efficiency of SnO2/nitrogen-doped graphene due to nitrogen-doping plays a more important role than the increased electro-active sites within graphene network in enhancing the electro-activity of SnO2/nitrogen-doped graphene nanohybrids compared to the SnO2/graphene counterpart. In contrast to the previous reports which often ascribe the enhanced electro-activity of nitrogen-doped graphene based composites to two nitrogen-doping effects (improving the electron transfer efficiency and increasing electro-active sites within graphene networks) in one single declaration, this work is expected to provide more specific information for understanding the effects of nitrogen-doping into graphene on improving the electrochemical performance of graphene based composites.

  15. Hydrothermal Synthesis of Pt-, Fe-, and Zn-doped SnO2 Nanospheres and Carbon Monoxide Sensing Properties

    Directory of Open Access Journals (Sweden)

    Weigen Chen

    2013-01-01

    Full Text Available Pure and M-doped (M = Pt, Fe, and Zn SnO2 nanospheres were successfully synthesized via a simple and facile hydrothermal method and characterized by X-ray powder diffraction, field-emission scanning electron microscopy, and energy dispersive spectroscopy. Chemical gas sensors were fabricated based on the as-synthesized nanostructures, and carbon monoxide sensing properties were systematically measured. Compared to pure, Fe-, and Zn-doped SnO2 nanospheres, the Pt-doped SnO2 nanospheres sensor exhibits higher sensitivity, lower operating temperature, more rapid response and recovery, better stability, and excellent selectivity. In addition, a theoretical study based on the first principles calculation was conducted. All results demonstrate the potential of Pt dopant for improving the gas sensing properties of SnO2-based sensors to carbon monoxide.

  16. Blue and red dual emission nanophosphor CaMgSi2O6:Eun+; crystal structure and electronic configuration

    International Nuclear Information System (INIS)

    Pawar, A.U.; Jadhav, Abhijit P.; Pal, U.; Kim, Byung Kyu; Kang, Young Soo

    2012-01-01

    Well dispersed Eu doped CaMgSi 2 O 6 (CMS) nanoparticles of 12–19 nm average sizes were synthesized by the co-precipitation method using different ratios of water and ethanol mixture as a solvent and subsequent air annealing. While ethanol as solvent produced pure CMS in monoclinic phase, pure water produced Ca 2 MgSi 2 O 7 (C2MS) and CMS in the mixed phase. Apart from the composition of CMS and C2MS, concentration and ionization state of the activator depended strongly on the composition (effective dielectric constant) of the solvent. Both the blue and red emission bands could be revealed for the europium activated CMS nanoparticles using single europium precursor. Efficiency of blue and red emissions in the nanophosphors, controlled by the relative abundance of europium in Eu 2+ and Eu 3+ oxidation states, could be controlled by adjusting the water content in the solvent. The relative intensity of the red emission (615 nm) decreased with the increase of water content in the solvent. - Highlights: ► We have synthesized Eu doped CaMgSi 2 O 6 using different volume ratios of water and ethanol solvent. ► We observed Ca 2 MgSi 2 O 7 phase increases with increasing amount of water in solvent. ► Dual emission was observed using single europium precursor. ► As synthesized material can be used for wavelength conversion application.

  17. Improvement of the electrochemical performance of nanosized α-MnO2 used as cathode material for Li-batteries by Sn-doping

    International Nuclear Information System (INIS)

    Hashem, A.M.; Abdel-Latif, A.M.; Abuzeid, H.M.; Abbas, H.M.; Ehrenberg, H.; Farag, R.S.; Mauger, A.; Julien, C.M.

    2011-01-01

    Highlights: → Doping MnO 2 with Sn improved properties of α-MnO 2 . → Thermal stabilization and electrochemical performances were improved. → Doping affected also the morphology feature of α-MnO 2 . - Abstract: Sn-doped MnO 2 was prepared by hydrothermal reaction between KMnO 4 as oxidant, fumaric acid C 4 H 4 O 4 as reductant and SnCl 2 as doping agent. XRD analysis indicates the cryptomelane α-MnO 2 crystal structure for pure and doped samples. Thermal stabilization was observed for both oxides as detected from thermogravimetric analysis. SEM and TEM images show changes in the morphology of the materials from spherical-like particles for pristine P-MnO 2 to rod-like structure for Sn-MnO 2 . Electrochemical properties of the electrode materials have been tested in lithium cells. Improvement in capacity retention and cycling ability is observed for doped oxide at the expense of initial capacity. After 35 cycles, the Li//Sn doped MnO 2 cell display lower capacity loss.

  18. Combined addition of nano diamond and nano SiO2, an effective method to improve the in-field critical current density of MgB2 superconductor

    International Nuclear Information System (INIS)

    Rahul, S.; Varghese, Neson; Vinod, K.; Devadas, K.M.; Thomas, Syju; Anees, P.; Chattopadhyay, M.K.; Roy, S.B.; Syamaprasad, U.

    2011-01-01

    Highlights: → Both nano diamond and nano SiO 2 caused significant modifications in the structural properties of pure MgB 2 sample. → Reduction in T C for the best codoped sample was approximately 2 K. → The best codoped sample yielded a J C , an order of magnitude more than the undoped one at 5 K and 8 T. → The enhanced flux pinning capability provided by the additives is responsible for the improved in-field J C . -- Abstract: MgB 2 bulk samples added with nano SiO 2 and/or nano diamond were prepared by powder-in-sealed-tube (PIST) method and the effects of addition on structural and superconducting properties were studied. X-ray diffraction (XRD) analysis revealed that the addition caused systematic reduction in 'a' lattice parameter due to the substitution of C atoms at B sites and the strain caused by reacted intragrain nano particles of Mg 2 Si as evinced by transmission electron microscope image. Scanning electron microscopy images showed distinct microstructural variations with SiO 2 /diamond addition. It was evident from DC magnetization measurements that the in-field critical current density [J C (H)] of doped samples did not fall drastically like the undoped sample. Among the doped samples the J C (H) of co-doped samples were significantly higher and the best co-doped sample yielded a J C , an order of magnitude more than the undoped one at 5 K and 8 T.

  19. Effects of Sn doping on the morphology, structure, and electrical property of In{sub 2}O{sub 3} nanofiber networks

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xu; Wang, Yihua [Zhejiang Sci-Tech University, College of Materials and Textiles, Hangzhou (China); Yang, Bin [Zhejiang Sci-Tech University, Ministry of Education, Key Laboratory of Advanced Textile Materials and Manufacturing Technology, College of Materials and Textiles, Hangzhou (China); Zhejiang Sci-Tech University, College of Materials and Textiles, Hangzhou (China)

    2014-11-15

    This paper studies the effect of Sn doping on the morphological, structural, and electrical properties of the Sn-doping In{sub 2}O{sub 3} nanofiber networks. In{sub 2}O{sub 3}-based nanofibers with various relative concentration of Sn precursor (0-20 mol%) were fabricated through the electrospinning method. Scanning electron microscopy observations show that, depending on the relative concentration of SnCl{sub 4} in the starting materials, the doped nanofibers with different morphologies, from smooth to corn-like and then to accidented, are fabricated. Transmission electron microscopy and X-ray diffraction analyses reveal that the Sn dopants influence the growth direction of seeds, resulting in doped nanoparticles having diverse shapes and sizes, which are critical for the formation of doped nanofiber with different morphology. From these nanofiber networks, we fabricated several thin sheets to characterize the effect of Sn concentration on the electrical resistivity. The resistivity of thin sheets decreased significantly before the doping concentration up to 12.5 mol%, and then increased slightly at a larger addition. This work will assist further understanding the formation of Sn-doped In{sub 2}O{sub 3} nanofibers and is expected to be extended to other transparent conductive oxides. (orig.)

  20. Dopant activation in Sn-doped Ga{sub 2}O{sub 3} investigated by X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Siah, S. C., E-mail: sincheng@alum.mit.edu; Brandt, R. E.; Jaramillo, R.; Buonassisi, T., E-mail: buonassisi@mit.edu [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Lim, K. [SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Schelhas, L. T.; Toney, M. F. [SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025 (United States); Heinemann, M. D. [PVcomB, Helmholtz-Zentrum Berlin, 12489 Berlin (Germany); Chua, D.; Gordon, R. G. [Department of Chemistry Materials Science and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 (United States); Wright, J.; Segre, C. U. [Physics Department and CSRRI, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Perkins, J. D. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    2015-12-21

    Doping activity in both beta-phase (β-) and amorphous (a-) Sn-doped gallium oxide (Ga{sub 2}O{sub 3}:Sn) is investigated by X-ray absorption spectroscopy (XAS). A single crystal of β-Ga{sub 2}O{sub 3}:Sn grown using edge-defined film-fed growth at 1725 °C is compared with amorphous Ga{sub 2}O{sub 3}:Sn films deposited at low temperature (<300 °C). Our XAS analyses indicate that activated Sn dopant atoms in conductive single crystal β-Ga{sub 2}O{sub 3}:Sn are present as Sn{sup 4+}, preferentially substituting for Ga at the octahedral site, as predicted by theoretical calculations. In contrast, inactive Sn atoms in resistive a-Ga{sub 2}O{sub 3}:Sn are present in either +2 or +4 charge states depending on growth conditions. These observations suggest the importance of growing Ga{sub 2}O{sub 3}:Sn at high temperature to obtain a crystalline phase and controlling the oxidation state of Sn during growth to achieve dopant activation.

  1. A comparative study of the magnetization in transition metal ion doped CeO2, TiO2 and SnO2 nanoparticles

    Science.gov (United States)

    Apostolov, A. T.; Apostolova, I. N.; Wesselinowa, J. M.

    2018-05-01

    Using the microscopic s-d model taking into account anharmonic spin-phonon interactions we have studied the magnetic properties of Co and Cu ion doped CeO2 and TiO2 nanoparticles and compared them with those of SnO2. By Co-doping there is a maximum in the magnetization M(x) curve for all nanoparticles observed in the most transition metal doped ones. The s-d interaction plays an important role by the decrease of M at higher dopant concentration. We have discussed the magnetization in dependence of different model parameters. By small Cu-ion doping there are some differences. In CeO2M decreases with the Cu-concentration, whereas in TiO2 and SnO2M increases. For higher Cu dopant concentrations M(X) decreases in TiO2 nanoparticles. We obtain room temperature ferromagnetism also in Zn doped CeO2, TiO2 and SnO2 nanoparticles, i.e. in non-transition metal ion doped ones. The different behavior of M in Co and Cu doped nanoparticles is due to a combination effect of multivalent metal ions, oxygen vacancies, different radius of cation dopants, connection between lattice and magnetism, as well as competition between the s-d and d-d ferromagnetic or antiferromagnetic interactions.

  2. Synthesis and photoluminescence of Ca-(Sn,Ti)-Si-O compounds

    International Nuclear Information System (INIS)

    Abe, Shunsuke; Yamane, Hisanori; Yoshida, Hisashi

    2010-01-01

    The phase relation of the compounds prepared in the CaO-SnO 2 -SiO 2 system at 1673 K and in the CaO-TiO 2 -SiO 2 system at 1573 K was investigated in order to explore new Ti 4+ -activated stannate phosphors. Solid solutions of Ca(Sn 1-x Ti x )SiO 5 and Ca 3 (Sn 1-y Ti y )Si 2 O 9 were synthesized at x = 0-1.0 and y = 0-0.10, respectively, and their crystal structures were analyzed by powder X-ray diffraction. Photoluminescence of these solid solutions was observed in a broad range of a visible light wavelength region under ultraviolet (UV) light excitation. The peaks of the emission band of Ca(Sn 0.97 Ti 0.03 )SiO 5 and Ca 3 (Sn 0.925 Ti 0.075 )Si 2 O 9 were at 510 nm under excitation of 252 nm and at 534 nm under excitation of 258 nm, respectively. The absorption edges estimated by the diffuse reflectance spectra were at 300 nm (4.1 eV) for CaSnSiO 5 and at 270 nm (4.6 eV) for Ca 3 SnSi 2 O 9 , suggesting that the excitation levels in Ca(Sn 1-x Ti x )SiO 5 were above the band gap of the host, although the levels in Ca 3 (Sn 1-y Ti y )Si 2 O 9 were within the band gap and near the conduction band edge.

  3. SnO2 nanocrystals anchored on N-doped graphene for high-performance lithium storage.

    Science.gov (United States)

    Zhou, Wei; Wang, Jinxian; Zhang, Feifei; Liu, Shumin; Wang, Jianwei; Yin, Dongming; Wang, Limin

    2015-02-28

    A SnO2-N-doped graphene (SnO2-NG) composite is synthesized by a rapid, facile, one-step microwave-assisted solvothermal method. The composite exhibits excellent lithium storage capability and high durability, and is a promising anode material for lithium ion batteries.

  4. Electronic and magnetic properties of SnS2 monolayer doped with 4d transition metals

    Science.gov (United States)

    Xiao, Wen-Zhi; Xiao, Gang; Rong, Qing-Yan; Chen, Qiao; Wang, Ling-Ling

    2017-09-01

    We investigate the electronic structures and magnetic properties of SnS2 monolayers substitutionally doped with 4-d transition-metal through systematic first principles calculations. The doped complexes exhibit interesting electronic and magnetic behaviors, depending on the interplay between crystal field splitting, Hund's rule, and 4d levels. The system doped with Y is nonmagnetic metal. Both the Zr- and Pd-doped systems remain nonmagnetic semiconductors. Doping results in half-metallic states for Nb-, Ru-, Rh-, Ag, and Cd doped cases, and magnetic semiconductors for systems with Mo and Tc dopants. In particular, the Nb- and Mo-doped systems display long-ranged ferromagnetic ordering with Curie temperature above room temperature, which are primarily attributable to the double-exchange mechanism, and the p-d/p-p hybridizations, respectively. Moreover, The Mo-doped system has excellent energetic stability and flexible mechanical stability, and also possesses remarkable dynamic and thermal (500 K) stability. Our studies demonstrate that Nb- and Mo-doped SnS2 monolayers are promising candidates for preparing 2D diluted magnetic semiconductors, and hence will be a helpful clue for experimentalists.

  5. A novel type heterojunction photodiodes formed junctions of Au/LiZnSnO and LiZnSnO/p-Si in series

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, H. [Department of Metallurgical and Materials Science, Faculty of Engineering, Tunceli University, Tunceli (Turkey); Tataroğlu, A. [Department of Physics, Faculty of Science, Gazi University, Ankara (Turkey); Al-Ghamdi, Ahmed A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Yakuphanoglu, F., E-mail: fyhanoglu@firat.edu.tr [Department of Metallurgical and Materials Science, Faculty of Engineering, Tunceli University, Tunceli (Turkey); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); El-Tantawy, Farid [Department of Physics, Faculty of Science, Suez Canal University, Ismailia (Egypt); Farooq, W.A. [Physics and Astronomy Department, College of Science, King Saud University, Riyadh (Saudi Arabia)

    2015-03-15

    Highlights: • Lithium–zinc–tin–oxide thin films were prepared by sol gel method. • The Au/LiZnSnO/p-Si/Al photodiodes were fabricated using a LZTO layer grown on p-Si. • The photodiodes with Li-doped ZTO interfacial layer exhibited a better device performance. - Abstract: Lithium–zinc–tin–oxide thin films were prepared by sol gel method. The structural and optical properties of the films were investigated. The optical band gaps of the LiZnSnO films were found to be 3.78 eV for 0 at.% Li, 3.77 eV for 1 at.% Li, 3.87 eV for 3 at.% Li and 3.85 eV for 5 at.% Li, respectively. Au/LiZnSnO/p-Si/Al photodiodes were fabricated using a lithium–zinc–tin–oxide (LZTO, Li–Zn–Sn–O) layer grown on p-Si semiconductor. The electrical characteristics of the photodiodes were analyzed by current–voltage, capacitance–voltage and conductance–voltage measurements. The reverse current of the diodes increases with both the increasing illumination intensity and Li content. It was found that the Li-doped ZTO photodiodes exhibited a better device performance than those with an undoped ZTO.

  6. Synthesis and characterization of Sn doped TiO{sub 2} photocatalysts: Effect of Sn concentration on the textural properties and on the photocatalytic degradation of 2,4-dichlorophenoxyacetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Rangel-Vázquez, I.; Del Angel, G.; Bertin, V. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); González, F. [Departamento de Ingeniería de Procesos e Hidráulica, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); Vázquez-Zavala, A.; Arrieta, A. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); Padilla, J.M. [Universidad Tecnológica del Centro de Veracruz, Área de Tecnología, Av. Universidad Carretera Federal Cuitláhuac-La Tinaja No. 350, Cuitláhuac, Veracruz 94910 (Mexico); Barrera, A. [Universidad de Guadalajara, Centro Universitario de la Ciénega, Av. Universidad, Número 1115, Col. Linda Vista, Apdo. Postal 106, Ocotlán Jal. (Mexico); Ramos-Ramirez, E. [Departamento de Química, División de Ciencias Naturales y Exactas, Campus Guanajuato de la Universidad de Guanajuato Noria Alta S/N, Col. Noria Alta, Guanajuato, Gto. C.P. 36050 (Mexico)

    2015-09-15

    Abstract: TiO{sub 2} and Sn-doped TiO{sub 2} materials were prepared by sol–gel method using titanium and tin alkoxides at different Sn concentration (0.1 mol%, 0.5 mol%, 1 mol%, 3 mol% and 5 mol%). Samples were characterized by thermo gravimetric analyzer with differential scanning calorimeter (TGA–DSC), X-ray Rietveld refinement, N{sub 2} adsorption (BET), transmission electron microscopy (TEM), UV–vis spectroscopies technology and Raman spectroscopy. Only anatase phase was observed in pure TiO{sub 2}, whereas anatase and brookite were obtained in Sn-doped TiO{sub 2} samples. Sn dopant acts as a promoter in phase transformation of TiO{sub 2}. The Rietveld refinements method was used to determine the relative weight of anatase and brookite, and crystallite size as a function of Sn concentration after calcination of samples at 673 K. It was also demonstrated the incorporation of Sn{sup 4+} into the anatase TiO{sub 2} structure. Sn{sup 4+} inhibits the growth of TiO{sub 2} crystallite size, which leads to an increase of the specific surface area of TiO{sub 2}. From XRD analysis, the solid solution limit of Sn{sup 4+} into TiO{sub 2} is 5 mol% Sn. The photocatalytic activity on Sn{sup 4+} doped TiO{sub 2} was determined for the 2,4-dichlorophenoxyacetic acid reaction. The maximum in activity was attributed to the coexistence of anatase and brookite phases in the appropriate ratio and crystallite size.

  7. The effect of electron and hole doping on the thermoelectric properties of shandite-type Co3Sn2S2

    Science.gov (United States)

    Mangelis, Panagiotis; Vaqueiro, Paz; Jumas, Jean-Claude; da Silva, Ivan; Smith, Ronald I.; Powell, Anthony V.

    2017-07-01

    Electron and hole doping in Co3Sn2S2, through chemical substitution of cobalt by the neighbouring elements, nickel and iron, affects both the structure and thermoelectric properties. Electron doping to form Co3-xNixSn2S2 (0≤x≤3) results in an expansion of the kagome layer and materials become increasingly metallic as cobalt is substituted. Conversely, hole doping in Co3-xFexSn2S2 (0≤x≤0.6) leads to a transition from metallic to n-type semiconducting behaviour at x=0.5. Iron substitution induces a small increase in the separation between the kagome layers and improves the thermoelectric performance. Neutron diffraction data reveal that substitution occurs at the Co 9(d) site in a disordered fashion. Mössbauer spectroscopy reveals two iron environments with very different isomer shifts, which may be indicative of a mixed-valence state, while Sn exhibits an oxidation state close to zero in both series. Co2.6Fe0.4Sn2S2 exhibits a maximum figure-of-merit, ZT=0.2 at 523 K while Co2.4Fe0.6Sn2S2 reaches a power factor of 10.3 μW cm-1 K-2 close to room temperature.

  8. Influence of iridium doping in MgB2 superconducting wires

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2018-01-01

    MgB2 wires with iridium doping were manufactured using the in-situ technique in a composite Cu-Nb sheath. Reaction was performed at 700°C, 800°C or 900°C for 1h in argon atmosphere. A maximum of about 1.5 at.% Ir replaces Mg in MgB2. The superconducting transition temperature is slightly lowered...... by Ir doping. The formation of IrMg3 and IrMg4 secondary phase particles is evidenced, especially for a nominal stoichiometry with 2.0 at.% Ir doping. The critical current density and accommodation field of the wires are strongly dependent on the Ir content and are generally weakened in the presence...

  9. Alternative route for the preparation of CoSb3 and Mg2Si derivatives

    International Nuclear Information System (INIS)

    Godlewska, E.; Mars, K.; Zawadzka, K.

    2012-01-01

    An alternative manufacturing route has been developed for cobalt triantimonide and magnesium disilicide derivatives. Elemental powders were mixed in stoichiometric proportions, cold pressed into cylindrical preforms and heated in oxygen-free environment to initiate the exothermic reaction. According to DTA/TG measurements and observations under high-temperature microscope, the onset of reaction occurred at a temperature not exceeding the melting point of the more volatile component, i.e. antimony in the case of CoSb 3 and magnesium in the case of Mg 2 Si. The reaction products were additionally heat treated to secure homogenization. Dense sinters were obtained by hot uniaxial pressing of the obtained powders in moderate temperature-and-pressure conditions. Several advantages were identified in the proposed technology: absence of liquid phases, relatively short time of the synthesis, possibility of in-situ or ex-situ doping and grain size control. - Graphical abstract: (1) Manufacturing flow sheet for CoSb 3 (milling included) and Mg 2 Si (no milling). (2) Micrographs of CoSb 3 product. (3) Micrographs of Mg 2 Si product. Highlights: ► The combustion synthesis followed by HP was used for the manufacturing of CoSb 3 or Mg 2 Si. ► The time of reaction is shorter compared with many other synthesis methods. ► The process is scalable and practically wasteless.

  10. Application of hydrogen-doped In2O3 transparent conductive oxide to thin-film microcrystalline Si solar cells

    International Nuclear Information System (INIS)

    Koida, Takashi; Sai, Hitoshi; Kondo, Michio

    2010-01-01

    Hydrogen-doped In 2 O 3 (IO:H) films with high electron mobility and improved near-infrared (NIR) transparency have been applied as a transparent conducting oxide (TCO) electrode in substrate-type hydrogenated microcrystalline silicon (μc-Si:H) solar cells. The incorporation of IO:H, instead of conventional Sn-doped In 2 O 3 , improved the short-circuit current density (J sc ) and the resulting conversion efficiency. Optical analysis of the solar cells and TCO films revealed that the improvement in J sc is due to the improved spectral sensitivity in the visible and NIR wavelengths by reduction of absorption loss caused by free carriers in the TCO films.

  11. Refinement of Mg2Si reinforcement in a commercial Al–20%Mg2Si in-situ composite with bismuth, antimony and strontium

    International Nuclear Information System (INIS)

    Nordin, Nur Azmah; Farahany, Saeed; Ourdjini, Ali; Abu Bakar, Tuty Asma; Hamzah, Esah

    2013-01-01

    Refinement by addition elements of Al–Mg 2 Si alloys is known to result in a change of primary Mg 2 Si morphology. In this paper, the effects of Bi, Sb and Sr on the characteristic parameters of Al–20%Mg 2 Si in-situ composite have been investigated by computer aided cooling curve thermal analysis and microstructural inspection. Size, density and aspect ratio measurements showed that additions of 0.4 wt.% Bi, 0.8 wt.% Sb and 0.01 wt.% Sr refined the Mg 2 Si reinforcement. Exceeding these concentrations, however, resulted in coarsening of Mg 2 Si particles with no change in the morphology. The results also showed that addition elements caused a decrease in the nucleation and growth temperatures of Mg 2 Si particles. The refining effect of Bi, Sb and Sr is likely to be related to the effect of oxide bifilms suspended in the composite melt as favored nucleation substrates for Mg 2 Si particles. - Highlight: • 0.4 wt.%, 0.8 wt.% and 0.01 wt.% is the optimum content for Bi, Sb and Sr addition. • Exceeding optimum concentration resulted in the coarsening of reinforcements. • Nucleation and growth temperatures decrease with addition of Bi, Sb and Sr. • The refining effect of Bi, Sb and Sr is likely to be related to the oxide bifilms

  12. Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi2Te2Se

    International Nuclear Information System (INIS)

    Kushwaha, S. K.; Gibson, Q. D.; Cava, R. J.; Xiong, J.; Ong, N. P.; Pletikosic, I.; Weber, A. P.; Fedorov, A. V.; Valla, T.

    2014-01-01

    A comparative study of the properties of topological insulator Bi 2 Te 2 Se (BTS) crystals grown by the vertical Bridgeman method is described. Two defect mechanisms that create acceptor impurities to compensate for the native n-type carriers are compared: Bi excess, and light Sn doping. Both methods yield low carrier concentrations and an n-p crossover over the length of the grown crystal boules, but lower carrier concentrations and higher resistivities are obtained for the Sn-doped crystals, which reach carrier concentrations as low as 8 × 10 14  cm −3 . Further, the temperature dependent resistivities for the Sn-doped crystals display strongly activated behavior at high temperatures, with a characteristic energy of half the bulk band gap. The (001) cleaved Sn-doped BTS crystals display high quality Shubnikov de Haas (SdH) quantum oscillations due to the topological surface state electrons. Angle resolved photoelectron spectroscopy (ARPES) characterization shows that the Fermi energy (E F ) for the Sn-doped crystals falls cleanly in the surface states with no interference from the bulk bands, which the Dirac point for the surface states lies approximately 60 meV below the top of the bulk valence band maximum, and allows for a determination of the bulk and surface state carrier concentrations as a function of Energy near E F . Electronic structure calculations that compare Bi excess and Sn dopants in BTS demonstrate that Sn acts as a special impurity, with a localized impurity band that acts as a charge buffer occurring inside the bulk band gap. We propose that the special resonant level character of Sn in BTS gives rise to the exceptionally low carrier concentrations and activated resistivities observed

  13. Electrochemical capacitance of nanostructured ruthenium-doped tin oxide Sn1- x Ru x O2 by the microemulsion method

    Science.gov (United States)

    Saraswathy, Ramanathan

    2017-12-01

    Synthesis of nanostructured Ru-doped SnO2 was successfully carried out using the reverse microemulsion method. The phase purity and the crystallite size were analyzed by XRD. The surface morphology and the microstructure of synthesized nanoparticles were analyzed by SEM and TEM. The vibration mode of nanoparticles was investigated using FTIR and Raman studies. The electrochemical behavior of the Ru-doped SnO2 electrode was evaluated in a 0.1 mol/L Na2SO4 solution using cyclic voltammetry. The 5% Ru-doped SnO2 electrode exhibited a high specific capacitance of 535.6 F/g at a scan rate 20 mV/s, possessing good conductivity as well as the electrocycling stability. The Ru-doped SnO2 composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors.

  14. Synthesis, structural and luminescence properties of Bi3+ co-doped Y2Sn2O7:Tb nanoparticles

    International Nuclear Information System (INIS)

    Nigam, S.; Sudarsan, V.; Vatsa, R.K.

    2010-01-01

    Full text: In recent years, advanced materials derived from Pyrochlore-type oxides (A 2 B 2 O 7 ) have been of extensive scientific and technological interest. Chemical substitution of A or B sites of pyrochlore oxide by rare earth ions is a widely used approach to prepare thermally stable, lanthanide ion doped luminescent materials. Due to the higher symmetry around the A and B sites in the lattice lanthanide ions like Eu 3+ and Tb 3+ when incorporated at the A or B sites give very poor luminescence. This problem can be avoided by incorporating other ions like Bi 3+ in the lattice so that the lattice gets distorted and luminescent intensity from the lanthanide ions increases. The present study deals with the synthesis and characterization of Bi 3+ co-doped Y 2 Sn 2 O 7 :Tb nanoparticles. For the preparation of Tb 3+ and Bi 3+ doped Y 2 Sn 2 O 7 nano-materials, Sn metal, Bi(NO 3 ) 3 , Tb 4 O 7 , Y 2 CO 3 , were used as starting materials. The solution containing Y 3+ , Sn 4+ ,and Bi 3+ -Tb 3+ in ethylene glycol medium was slowly heated up to 120 deg C and then subjected to urea hydrolysis. The obtained precipitate after washing was heated to 700 deg C. As prepared samples are amorphous in nature and 700 deg C heated sample showed well crystalline pyrochlore structure as revealed by the XRD studies. Average particles size is calculated from the width of the X-ray diffraction peaks and found to be ∼ 5 nm. TEM images of the nanoparticles obtained at 700 deg C shows very fine spherical particles having a diameter in the range of 2-5 nm. Luminescence measurements were carried out for as prepared and 700 deg C heated samples of 2.5%Tb doped Y 2 Sn 2 O 7 nanoparticles. Green emission characteristic 5 D 4 7 F 5 transition of Tb 3+ has been observed from as prepared sample but on heating to 700 deg C the emission characteristic of Tb 3+ ions got completely removed . However, there is a significant improvement in Tb 3+ emission from 2.5% Bi 3+ co-doped Y 2 Sn 2 O 7 :Tb 3

  15. The effect of MgO doping on the structure, magnetic and magnetotransport properties of La0.8Sr0.2MnO3 composite

    International Nuclear Information System (INIS)

    Aezami, A.; Eshraghi, M.; Kameli, P.; Salamati, H.

    2007-01-01

    Full text: The recent observation of anomalously Colossal Magnetoresistance (CMR) in the La 1-x A x MnO 3 (A = Sr, Ca, Ba or vacancies) system, has spurred renewed interest in studying these doped perovskite manganites. The properties of these materials are explained by double exchange theory of Zener and electron lattice interaction. However, the intrinsic CMR effect in the perovskite manganites is found on a magnetic field scale of several teslas and a narrow temperature range. It was found that, the presence of grain boundaries in polycrystalline samples leads to a large Low Field Magnetoresistance (LFMR) effect over a wide temperature range below the Curie temperature Tc. To achieve LFMR, different properties are considered. One of them is mixing of these CMR materials with secondary insulator phases. In this work, La 0.8 Sr 0.2 MnO 3 (LSMO) was selected as matrix material and MgO as a dopant. The La 0.8 Sr 0.2 MnO 3/x MgO samples with x= 0, 1, 2, 3, 5 and 7.5 Wt.% were prepared by Solid State Reaction method. Studies show that most part of the MgO goes into the perovskite lattice and Mg substituted Mn in LSMO and remainder segregates as a separate phase at the grain boundaries. Results also show that the value of MR decreases for all the doping levels. It seems that, due to the almost same ionic radii of Mg2+ and Mn2+, and at the higher sintering temperature, Mg2+ mostly replaced Mn3+ and weakens double exchange interaction. This speculation has been confirmed by XRD, SEM, susceptibility, resistivity and magnetoresistance analysis and measurements. (authors)

  16. Phthalocyanine doping to improve critical current densities in MgB2 tapes

    International Nuclear Information System (INIS)

    Zhang Xianping; Ma Yanwei; Wang Dongliang; Gao Zhaoshun; Wang Lei; Qi Yanpeng; Awaji, Satoshi; Watanabe, Kazuo; Mossang, Eric

    2009-01-01

    Phthalocyanine-doped MgB 2 tapes were prepared by the in situ powder-in-tube method. The relationships between the critical current properties, crystallinity and microstructure were studied as a function of the phthalocyanine doping level. It is found that both H irr and H c2 were improved when MgB 2 samples were doped with phthalocyanine, which are mainly attributed to the effective carbon substitution and enhanced flux pinning strength caused by very fine grain sizes. Furthermore, compared to pure samples, the MgO content remained almost unchanged in all doped tapes, which is very beneficial to having better grain connectivity in MgB 2 . Significantly improved J c was obtained in the phthalocyanine-doped MgB 2 tapes, especially under high magnetic fields.

  17. Enhanced Photocatalytic Activity of ZrO2-SiO2 Nanoparticles by Platinum Doping

    Directory of Open Access Journals (Sweden)

    Mohammad W. Kadi

    2013-01-01

    Full Text Available ZrO2-SiO2 mixed oxides were prepared via the sol-gel method. Photo-assisted deposition was utilized for doping the prepared mixed oxide with 0.1, 0.2, 0.3, and 0.4 wt% of Pt. XRD spectra showed that doping did not result in the incorporation of Pt within the crystal structure of the material. UV-reflectance spectrometry showed that the band gap of ZrO2-SiO2 decreased from 3.04 eV to 2.48 eV with 0.4 wt% Pt doping. The results show a specific surface area increase of 20%. Enhanced photocatalysis of Pt/ZrO2-SiO2 was successfully tested on photo degradation of cyanide under illumination of visible light. 100% conversion was achieved within 20 min with 0.3 wt% of Pt doped ZrO2-SiO2.

  18. Luminescence studies on Sb3+ co-doped Y2Sn2O7: Tb nanoparticles

    International Nuclear Information System (INIS)

    Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2008-01-01

    Pyrochlore-type oxides (A 2 B 2 O 7 ) have emerged as important host matrices for lanthanide doped luminescent materials due to their good thermal stability. Due to the higher symmetry around the A and B cations in the lattice lanthanide ions like Eu 3+ and Tb 3+ when incorporated at the A or B sites give very poor luminescence. One way to circumvent this problem is to incorporate ions like Sb 3+ or Bi 3+ in the lattice so that the lattice get distorted and luminescent intensity from the lanthanide ions increases. The present study deals with the synthesis and characterisation of Sb 3+ co-doped Y 2 Sn 2 O 7 :Tb nanoparticles prepared by the hydrolysis of Y 3+ , Sn 4+ , Tb 3+ and Sb 3+ in ethylene glycol medium followed by heating at 700 deg C for 4 hours. From XRD studies it is confirmed that as prepared sample is amorphous and heat treatment at 700 deg C results in the formation of highly crystalline Y 2 Sn 2 O 7 phase having pyrochlore structure

  19. Improvement of the electrochemical performance of nanosized {alpha}-MnO{sub 2} used as cathode material for Li-batteries by Sn-doping

    Energy Technology Data Exchange (ETDEWEB)

    Hashem, A.M., E-mail: ahmedh242@yahoo.com [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Abdel-Latif, A.M.; Abuzeid, H.M. [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Abbas, H.M. [National Research Centre, Physical Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Ehrenberg, H. [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Farag, R.S. [Department of Chemistry, Faculty of Science, Al-Azhar University, Cairo (Egypt); Mauger, A. [Universite Pierre et Marie Curie, Institut de Mineralogie et Physique de la Matiere Condensee (IMPMC), 4 Place Jussieu, 75005 Paris (France); Julien, C.M. [Universite Pierre et Marie Curie, Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), 4 Place Jussieu, 75005 Paris (France)

    2011-10-06

    Highlights: > Doping MnO{sub 2} with Sn improved properties of {alpha}-MnO{sub 2}. > Thermal stabilization and electrochemical performances were improved. > Doping affected also the morphology feature of {alpha}-MnO{sub 2}. - Abstract: Sn-doped MnO{sub 2} was prepared by hydrothermal reaction between KMnO{sub 4} as oxidant, fumaric acid C{sub 4}H{sub 4}O{sub 4} as reductant and SnCl{sub 2} as doping agent. XRD analysis indicates the cryptomelane {alpha}-MnO{sub 2} crystal structure for pure and doped samples. Thermal stabilization was observed for both oxides as detected from thermogravimetric analysis. SEM and TEM images show changes in the morphology of the materials from spherical-like particles for pristine P-MnO{sub 2} to rod-like structure for Sn-MnO{sub 2}. Electrochemical properties of the electrode materials have been tested in lithium cells. Improvement in capacity retention and cycling ability is observed for doped oxide at the expense of initial capacity. After 35 cycles, the Li//Sn doped MnO{sub 2} cell display lower capacity loss.

  20. Cation vacancies and electrical compensation in Sb-doped thin-film SnO2 and ZnO

    International Nuclear Information System (INIS)

    Korhonen, E; Prozheeva, V; Tuomisto, F; Bierwagen, O; Speck, J S; White, M E; Galazka, Z; Liu, H; Izyumskaya, N; Avrutin, V; Özgür, Ü; Morkoç, H

    2015-01-01

    We present positron annihilation results on Sb-doped SnO 2 and ZnO thin films. The vacancy types and the effect of vacancies on the electrical properties of these intrinsically n-type transparent semiconducting oxides are studied. We find that in both materials low and moderate Sb-doping leads to formation of vacancy clusters of variable sizes. However, at high doping levels cation vacancy defects dominate the positron annihilation signal. These defects, when at sufficient concentrations, can efficiently compensate the n-type doping produced by Sb. This is the case in ZnO, but in SnO 2 the concentrations appear too low to cause significant compensation. (invited article)

  1. Cation vacancies and electrical compensation in Sb-doped thin-film SnO2 and ZnO

    Science.gov (United States)

    Korhonen, E.; Prozheeva, V.; Tuomisto, F.; Bierwagen, O.; Speck, J. S.; White, M. E.; Galazka, Z.; Liu, H.; Izyumskaya, N.; Avrutin, V.; Özgür, Ü.; Morkoç, H.

    2015-02-01

    We present positron annihilation results on Sb-doped SnO2 and ZnO thin films. The vacancy types and the effect of vacancies on the electrical properties of these intrinsically n-type transparent semiconducting oxides are studied. We find that in both materials low and moderate Sb-doping leads to formation of vacancy clusters of variable sizes. However, at high doping levels cation vacancy defects dominate the positron annihilation signal. These defects, when at sufficient concentrations, can efficiently compensate the n-type doping produced by Sb. This is the case in ZnO, but in SnO2 the concentrations appear too low to cause significant compensation.

  2. Lattice location of Mg in GaN: a fresh look at doping limitations

    CERN Document Server

    AUTHOR|(CDS)2069243; Augustyns, Valerie; Granadeiro Costa, Angelo Rafael; David Bosne, Eric; De Lemos Lima, Tiago Abel; Lippertz, Gertjan; Martins Correia, Joao; Castro Ribeiro Da Silva, Manuel; Kappers, Menno; Temst, Kristiaan; Vantomme, André; Da Costa Pereira, Lino Miguel

    2017-01-01

    Radioactive 27Mg (t1/2=9.5 min) was implanted into GaN of different doping types at CERN’s ISOLDE facility and its lattice site determined via beta− emission channeling. Following implantations between room temperature and 800°C, the majority of 27Mg occupies the substitutional Ga sites, however, below 350°C significant fractions were also found on interstitial positions ~0.6 Å from ideal octahedral sites. The interstitial fraction of Mg was correlated with the GaN doping character, being highest (up to 31%) in samples doped p-type with 2E19 cm−3 stable Mg during epilayer growth, and lowest in Si-doped n-GaN, thus giving direct evidence for the amphoteric character of Mg. Implanting above 350°C converts interstitial 27Mg to substitutional Ga sites, which allows estimating the activation energy for migration of interstitial Mg as between 1.3 and 2.0 eV.

  3. Exploring d{sup 0} magnetism in doped SnO{sub 2}–a first principles DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Brahmananda, E-mail: brahma@barc.gov.in; Ramaniah, Lavanya M.

    2015-07-01

    In search of d{sup 0} magnetism, the magnetic behavior of SnO{sub 2} with cation substitution from group1A (Li, Na, K) and group 2A (Be, Mg, Ca) elements has been systematically studied using Density Functional Theory (DFT). While an impurity from group 1A elements switches on ferromagnetism at a lower concentration itself, sufficient hole density is required for a group 2A impurity to create a spontaneous spin polarized ground state, a finding that has not been reported in earlier investigations. Our DFT results predict for the first time that impurities from group 2A (Mg, Ca) in SnO{sub 2} can promote room temperature ferromagnetism. Further, the emergence of ferromagnetism due to doping from group 1A elements, which injects three holes per defect, has been mapped successfully onto a modified Hubbard model from the literature. Doping of a single Na atom in the supercell (concentration 6.25 at%) makes the system ferromagnetic, with a magnetic moment close to 3.0 μ{sub B} per defect, and a Curie temperature of 815 K, obtained in the mean field approximation. This agrees closely with a model prediction of 750 K. Finally, the triggering of ferromagnetism by an impurity atom from group 2A, which adds two holes per defect in the system, implies that the prescription of three holes per defect given in the literature is not a necessary criterion for hole induced ferromagnetism. Rather, the analysis of the density of states and ferromagnetic coupling indicate that the system needs a critical hole concentration to activate ferromagnetism, by pushing the Fermi level inside the valence band in order to satisfy the Stoner criterion. - Graphical abstract: Spin density (Δρ=ρ↑−ρ↓) shown in yellow color mainly concentrated on the first shell O atoms around the impurity (a)Li, (b)Na, (c) K for isovalue 0.2e (d) K for isovalue 0.1. - Highlights: • Systematic study of d{sup 0} magnetism in SnO{sub 2} doped with group 1A (Li, Na, K) and group 2A (Be, Mg, Ca).

  4. Synthesis and photocatalytic properties of Sn-doped TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Tu Yafang; Huang Shengyou [Department of Physics, Wuhan University, Wuhan 430072 (China); Sang Jianping, E-mail: jpsang@acc-lab.whu.edu.c [Department of Physics, Wuhan University, Wuhan 430072 (China); Department of Physics, Jianghan University, Wuhan 430056 (China); Zou Xianwu [Department of Physics, Wuhan University, Wuhan 430072 (China)

    2009-08-12

    TiO{sub 2} nanotube arrays doped by Sn up to 12 at% have been prepared using template-based liquid phase deposition method. Their morphologies, structures and optical properties have been investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and photoluminescence spectroscopy. The photocatalytic properties of the samples were evaluated with the degradation of methylene blue under UV irradiation. The result shows that doping an appropriate amount of Sn can effectively improve the photocatalytic activity of TiO{sub 2} nanotube arrays, and the optimum dopant amount is found to be 5.6 at% in our experiments.

  5. Defect phase diagram for doping of Ga2O3

    Directory of Open Access Journals (Sweden)

    Stephan Lany

    2018-04-01

    Full Text Available For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn, a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T, O partial pressures (pO2, and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association of dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO2 conditions. Considering further the stability constraints due to sublimation of molecular Ga2O, specific predictions of optimized pO2 and Si dopant concentrations are given. The incomplete passivation of dopant-defect complexes in β-Ga2O3 suggests a design rule for metastable doping above the solubility limit.

  6. Effect of Pd ion doping in the band gap of SnO{sub 2} nanoparticles: structural and optical studies

    Energy Technology Data Exchange (ETDEWEB)

    Nandan, Brajesh; Venugopal, B. [Pondicherry University, Centre for Nanoscience and Technology (India); Amirthapandian, S.; Panigrahi, B. K. [Indira Gandhi Centre for Atomic Research, Ion Beam and Computer Simulation Section, Materials Science Group (India); Thangadurai, P., E-mail: thangadurai.p@gmail.com [Pondicherry University, Centre for Nanoscience and Technology (India)

    2013-10-15

    Pd ion doping has influenced the band gap of SnO{sub 2} nanoparticles. Undoped and Pd ion-doped SnO{sub 2} nanoparticles were synthesized by chemical co-precipitation method. A tetragonal phase of SnO{sub 2} with a grain size range of 7-13 nm was obtained (studied by X-ray diffraction and transmission electron microscopy). A decreasing trend in the particle size with increasing doping concentration was observed. The presence of Pd in doped SnO{sub 2} was confirmed by chemical analysis carried out by energy-dispersive spectroscopy in the transmission electron microscope. Diffuse reflectance spectra showed a blue shift in absorption with increasing palladium concentration. Band gap of SnO{sub 2} nanoparticles was estimated from the diffuse reflectance spectra using Kubelka-Munk function and it was increasing with the increase of Pd ion concentration from 3.73 to 4.21 eV. The variation in band gap is attributed predominantly to the lattice strain and particle size. All the samples showed a broad photoluminescence emission centered at 375 nm when excited at 270 nm. A systematic study on the structural and optical properties of SnO{sub 2} nanoparticles is presented.

  7. Magnetic phase change in Mn-doped ZnSnAs2 thin films depending on Mn concentration

    Science.gov (United States)

    Uchitomi, Naotaka; Hidaka, Shiro; Saito, Shin; Asubar, Joel T.; Toyota, Hideyuki

    2018-04-01

    The relationship between Mn concentration and Curie temperature (TC) is studied for Mn-doped ZnSnAs2 ferromagnetic semiconductors, epitaxially grown on InP substrates by molecular beam epitaxy. In the ferromagnetic phase, Mn distributions in a (Zn,Mn,Sn)As2 thin film with 7.2 cation percent (cat. %) Mn are investigated using three-dimensional atom probe tomography. The results indicate an inhomogeneous distribution which spreads to a relatively high Mn concentration of 9.0 at. % (at. %). In the paramagnetic phase, it is found that the paramagnetic to ferromagnetic transition takes place sharply with a TC of 334 K when the Mn doping concentration increases to about 4 cat. % Mn, which corresponds to a magnetic percolation threshold for ferromagnetism in (Zn,Mn,Sn)As2. An effective Curie temperature ⟨TC⟩ is considered to bridge the Curie temperatures obtained experimentally to those calculated theoretically in inhomogeneous magnetic semiconductors. The behavior of magnetism in Mn-doped ZnSnAs2 can be explained by three different phases within the present framework.

  8. Synthesis and fundamental properties of stable Ph(3)SnSiH(3) and Ph(3)SnGeH(3) hydrides: model compounds for the design of Si-Ge-Sn photonic alloys.

    Science.gov (United States)

    Tice, Jesse B; Chizmeshya, Andrew V G; Groy, Thomas L; Kouvetakis, John

    2009-07-06

    The compounds Ph(3)SnSiH(3) and Ph(3)SnGeH(3) (Ph = C(6)H(5)) have been synthesized as colorless solids containing Sn-MH(3) (M = Si, Ge) moieties that are stable in air despite the presence of multiple and highly reactive Si-H and Ge-H bonds. These molecules are of interest since they represent potential model compounds for the design of new classes of IR semiconductors in the Si-Ge-Sn system. Their unexpected stability and high solubility also makes them a safe, convenient, and potentially useful delivery source of -SiH(3) and -GeH(3) ligands in molecular synthesis. The structure and composition of both compounds has been determined by chemical analysis and a range of spectroscopic methods including multinuclear NMR. Single crystal X-ray structures were determined and indicated that both compounds condense in a Z = 2 triclinic (P1) space group with lattice parameters (a = 9.7754(4) A, b = 9.8008(4) A, c = 10.4093(5) A, alpha = 73.35(10)(o), beta = 65.39(10)(o), gamma = 73.18(10)(o)) for Ph(3)SnSiH(3) and (a = 9.7927(2) A, b = 9.8005(2) A, c = 10.4224(2) A, alpha = 74.01(3)(o), beta = 65.48(3)(o), gamma = 73.43(3)(o)) for Ph(3)SnGeH(3). First principles density functional theory simulations are used to corroborate the molecular structures of Ph(3)SnSiH(3) and Ph(3)SnGeH(3), gain valuable insight into the relative stability of the two compounds, and provide correlations between the Si-Sn and Ge-Sn bonds in the molecules and those in tetrahedral Si-Ge-Sn solids.

  9. Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

    International Nuclear Information System (INIS)

    Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

    2016-01-01

    Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO_2 anatase surface (101) is studied. • Effect of Mg defect to the TiO_2 anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO_2 anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO_2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO_2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J_S_C of the surface while slightly decreasing V_O_C compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

  10. Effect of Pre-Oxidation Treatment of Nano-SiC Particulates on Microstructure and Mechanical Properties of SiC/Mg-8Al-1Sn Composites Fabricated by Powder Metallurgy Combined with Hot Extrusion.

    Science.gov (United States)

    Li, Chuan-Peng; Wang, Zhi-Guo; Zha, Min; Wang, Cheng; Yu, Hong-Chen; Wang, Hui-Yuan; Jiang, Qi-Chuan

    2016-11-26

    Nano-SiC particulates (n-SiC p ) reinforced Mg-8Al-1Sn (AT81) composites with different pre-oxidation parameters were fabricated by powder metallurgy (P/M) process combined with hot extrusion. The effects of pre-oxidization treatment of n-SiC p on the microstructure and tensile properties of 0.5 vol % n-SiC p /AT81 composites were investigated accordingly. The distribution of n-SiC p with different pre-oxidation parameters was homogeneous in the composites. Moreover, it was found that a thin MgAl₂O₄ layer formed at the interface when the n-SiC p were pre-oxidized at 1073 K for 2 h, while the MgAl₂O₄ layer became much thicker with pre-oxidization temperature increasing to 1273 K for 2 h. After an appropriate pre-oxidization treatment of n-SiC p at 1073 K for 2 h, the as-extruded 0.5 vol % n-SiC p /AT81 composites exhibited an enhanced strength. It was found that the yield strength (YS) and ultimate tensile strength (UTS) increased from 168 MPa and 311 MPa to 255 MPa and 393 MPa compared with the as-extruded AT81 alloy, reflecting 51.8% and 26.4% increments, respectively. The improvement of mechanical properties should be mainly attributed to the grain refinement and homogeneous distribution of n-SiC p in the composites. Moreover, a well-bonded interface and the formation of an appropriate amount of interfacial product (MgAl₂O₄) benefited the material's mechanical properties.

  11. Facile synthesis of Zn-doped SnO{sub 2} dendrite-built hierarchical cube-like architectures and their application in lithium storage

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Tiekun, E-mail: tiekunjia@126.com [Department of Materials Science and Engineering, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Chen, Jian [Department of Materials Science and Engineering, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Deng, Zhao [State Key Lab of Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Fu, Fang; Zhao, Junwei; Wang, Xiaofeng [Department of Materials Science and Engineering, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Long, Fei [School of Materials Science and Engineering, Guilin University of Technology, Guilin 541004 (China)

    2014-11-15

    Highlights: • Novel Zn-doped SnO{sub 2} dendrite-built hierarchical cube-like architectures were synthesized via a facile hydrothermal approach without surfactant. • The Zn-doped SnO{sub 2} dendrite-built hierarchical cube-like architectures were assembled by pronounced needle-like nanorod truncks with highly ordered needle-like nanorod branches. • The as-obtained Zn-doped SnO{sub 2} sample exhibited good electrochemical property. - Abstract: Zn-doped SnO{sub 2} dendrite-built hierarchical cube-like architectures were successfully synthesized by a facile hydrothermal approach without the use of any surfactants or templates. The as-prepared samples were characterized by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The observation of FESEM and HRTEM showed that Zn-doped SnO{sub 2} hierarchical cube-like architectures were composed of numerous oriented dendrites. Each dendrite is assembled by a pronounced trunk with highly ordered branches distributing on the both sides. The as-prepared Zn-doped SnO{sub 2} dendrite-built hierarchical cube-like architectures were used as anode materials for Li-ion battery, and a stable capacity of 488.3 mA h g{sup −1} was achieved after 50 cycles. The results of electrochemical measurements indicated that the as-prepared Zn-doped SnO{sub 2} dendrite-built hierarchical cube-like architectures have potential application in Li-ion battery.

  12. Analyses of the As doping of SiO{sub 2}/Si/SiO{sub 2} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ruffino, Francesco; Miritello, Maria [CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Tomasello, Mario Vincenzo [Scuola Superiore di Catania, via San Nullo 5/i, 95123 Catania (Italy); De Bastiani, Riccardo; Grimaldi, Maria Grazia [Dipartimento di Fisica ed Astronomia, Universita di Catania, via S. Sofia 64, 95123 Catania (Italy); CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Nicotra, Giuseppe; Spinella, Corrado [Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM), VIII Strada 5, 95121 Catania (Italy)

    2011-03-15

    We illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO{sub 2}(70nm)/Si(30nm)/SiO{sub 2}(70nm) multilayer and its spatial redistribution when annealing processes are performed. By Rutherford backscattering spectrometry and Z-contrast transmission electron microscopy we found an As accumulation at the Si/SiO{sub 2} interfaces and at the Si grain boundaries with no segregation of the As in the Si layer. Such an effect is in agreement with a model that assumes a traps distribution in the Si in the first 2-3 nm above the SiO{sub 2}/Si interfaces and along the Si grain boundaries. The traps concentration at the Si/SiO{sub 2} interfaces was estimated in 10{sup 14} traps/cm{sup 2}. The outlined results can open perspectives on the doping properties of As in Si nanocrystals, whose applications in nanoelectronics and optoelectronics are widely investigated (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Continuous hydrogenation of ethyl levulinate to γ-valerolactone and 2-methyl tetrahydrofuran over alumina doped Cu/SiO2 catalyst: the potential of commercialization

    Science.gov (United States)

    Zheng, Junlin; Zhu, Junhua; Xu, Xuan; Wang, Wanmin; Li, Jiwen; Zhao, Yan; Tang, Kangjian; Song, Qi; Qi, Xiaolan; Kong, Dejin; Tang, Yi

    2016-01-01

    Hydrogenation of levulinic acid (LA) and its esters to produce γ-valerolactone (GVL) and 2-methyl tetrahydrofuran (2-MTHF) is a key step for the utilization of cellulose derived LA. Aiming to develop a commercially feasible base metal catalyst for the production of GVL from LA, with satisfactory activity, selectivity, and stability, Al2O3 doped Cu/SiO2 and Cu/SiO2 catalysts were fabricated by co-precipitation routes in parallel. The diverse physio-chemical properties of these two catalysts were characterized by XRD, TEM, dissociative N2O chemisorptions, and Py-IR methods. The catalytic properties of these two catalysts were systematically assessed in the continuous hydrogenation of ethyl levulinate (EL) in a fixed-bed reactor. The effect of acidic property of the SiO2 substrate on the catalytic properties was investigated. To justify the potential of its commercialization, significant attention was paid on the initial activity, proper operation window, by-products control, selectivity, and stability of the catalyst. The effect of reaction conditions, such as temperature and pressure, on the performance of the catalyst was also thoroughly studied. The development of alumina doped Cu/SiO2 catalyst strengthened the value-chain from cellulose to industrially important chemicals via LA and GVL. PMID:27377401

  14. Quasiparticle electronic and optical properties of the Si-Sn system

    International Nuclear Information System (INIS)

    Jensen, Rasmus V S; Pedersen, Thomas G; Larsen, Arne N

    2011-01-01

    The Si 1-x Sn x material system is an interesting candidate for an optically active material compatible with Si. Based on density functional theory with quasiparticle corrections we calculate the electronic band structure of zinc-blende SiSn under both compressive and tensile strain. At 2.2% tensile strain the band gap becomes direct with a magnitude of 0.85 eV. We develop an accurate tight-binding parameterization of the electronic structure and calculate the optical properties of SiSn. Furthermore, the silicide SiSn 2 is investigated and found to have metallic character. (paper)

  15. Photoluminescence of Mg{sub 2}Si films fabricated by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Yang-Fang [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Xie, Quan, E-mail: qxie@gzu.edu.cn [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xiao, Qing-Quan [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Engineering Center for Avionics Electrical and Information Network of Guizhou Provincial Colleges and Universities, Anshun 561000 (China); Chen, Qian; Fan, Meng-Hui [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xie, Jing [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China)

    2017-05-01

    Highlights: • High quality Mg{sub 2}Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg{sub 2}Si films was reported. • The Mg{sub 2}Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg{sub 2}Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg{sub 2}Si-based light-emitting devices, Mg{sub 2}Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg{sub 2}Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg{sub 2}Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg{sub 2}Si film on Si (111) displays polycrystalline structure, whereas Mg{sub 2}Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg{sub 2}Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg{sub 2}Si films was observed for the first time. The PL emission wavelengths of Mg{sub 2}Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg{sub 2}Si films on glass substrate is much larger than that of Mg

  16. Influence of Sn ion doping on the photocatalytic performance of V2O5 nanorods prepared by hydrothermal method

    Science.gov (United States)

    Rajeshwari, S.; Santhosh Kumar, J.; Rajendrakumar, R. T.; Ponpandian, N.; Thangadurai, P.

    2018-02-01

    Pure and different concentrations of Sn4+ doped V2O5 (Sn:V2O5) nanorods were synthesized by hydrothermal method. The Sn:V2O5 nanorods obtained were orthorhombic in structure. No secondary phase was observed up to 10% of Sn doping, but beyond that, there evolved a secondary phase of SnO2. Microstructural analysis revealed the morphology of V2O5 as nanorods and platelets like structure. Presence of V, O and Sn elements in the samples was confirmed by energy dispersive spectroscopy. The V2O5 nanorods have shown a strong absorption in the visible region and the band gap energy was obtained to be varying from 2.21 to 2.26 eV as a function of Sn ion doping. Photocatalytic studies on methylene blue (MB) under visible light irradiation showed that the 3% Sn:V2O5 had effectively degraded MB up to a maximum degradation of 96% and further increase in Sn content had decreased the photodegradation due to higher recombination rate of photogenerated electrons. The mechanism of photodegradation was completely understood and the OH· radicals have played a dominant role in the photodegradation of the organic dyes.

  17. Site selective, time and temperature dependent spectroscopy of Eu{sup 3+} doped apatites (Mg,Ca,Sr){sub 2}Y{sub 8}Si{sub 6}O{sub 26}

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, T., E-mail: t.jansen@fh-muenster.de [Münster University of Applied Sciences, Stegerwaldstrasse 39, 48565 Steinfurt (Germany); Jüstel, T. [Münster University of Applied Sciences, Stegerwaldstrasse 39, 48565 Steinfurt (Germany); Kirm, M.; Mägi, H.; Nagirnyi, V.; Tõldsepp, E.; Vielhauer, S. [Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu (Estonia); Khaidukov, N.M. [N. S. Kurnakov Institute of General and Inorganic Chemistry, 31 Leninskiy Prospekt, 119991 Moscow (Russian Federation); Makhov, V.N. [P.N. Lebedev Physical Institute, 53 Leninskiy Prospekt, 119991 Moscow (Russian Federation)

    2017-06-15

    This work concerns the optical properties of alkaline earth yttrium apatites according to the composition AE{sub 2}Y{sub 8}Si{sub 6}O{sub 26} (AE=Mg, Ca, Sr) doped with Eu{sup 3+}, which are materials of interest for LED applications. Using a multistep preparation route, which includes hydrothermal synthesis of precursors for solid state reaction, ceramic samples were prepared and their structural and optical properties characterised. More particularly, this work relates to site-selective spectroscopy, since the compounds comprise two distinguishable crystallographic sites within the host structure, where Eu{sup 3+} can be substituted. It also describes the temperature dependent photoluminescence, which thermal quenching temperature (T{sub 1/2}) for Sr{sub 2}Y{sub 8}Si{sub 6}O{sub 26}:Eu{sup 3+} and Ca{sub 2}Y{sub 8}Si{sub 6}O{sub 26}:Eu{sup 3+} is in the range of 561 K and 591 K respectively, whereas Mg{sub 2}Y{sub 8}Si{sub 6}O{sub 26}:Eu{sup 3+} shows bi-sigmoidal quenching behaviour in the range between 210 and 452 K.

  18. Density-functional study on the robust ferromagnetism in rare-earth element Yb-doped SnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai-Cheng, E-mail: kczhang@yeah.net [College of Mathematics and Physics, Bohai University, Jinzhou 121013 (China); Li, Yong-Feng [Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal ResourcesInner Mongolia University of Science and Technology, Baotou 014010 (China); School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Liu, Yong [State Key Laboratory of Metastable Materials Science and Technology and College of Science, Yanshan University, Qinhuangdao, Hebei 066004 (China); Chi, Feng [College of Engineering, Bohai University, Jinzhou 121013 (China)

    2014-06-01

    So far, little has been known about the ferromagnetism induced by p–f hybridization. We investigate the magnetic properties of Yb-doped SnO{sub 2} by first-principles calculations. We find that the doped system favors the ferromagnetic state and a room-temperature ferromagnetism can be expected in it. The origin of ferromagnetism can be attributed to the p–f hybridization between Yb impurity and its surrounding oxygen atoms. The formation energy of defect complex is calculated and the magnetic mediation of intrinsic vacancies is studied. Our results reveal that the formation energy of the defect complex with Sn vacancy is about 7.3 eV lower in energy than that with oxygen vacancy. This means Sn vacancy is much easier to form than oxygen vacancy in the presence of Yb substitution. The ferromagnetism of the doped system is greatly enhanced in the presence of Sn vacancies. - Highlights: • Room-temperature ferromagnetism can be expected in Yb-doped SnO{sub 2}. • The origin of ferromagnetism can be attributed to the p–f hybridization between Yb and O atoms. • Oxygen vacancies are much hard to form and contribute little to the ferromagnetism. • Sn vacancies are easy to form under oxygen-rich condition and stabilize the ferromagnetism effectively.

  19. Synthesis and optical properties of red/blue-emitting Sr2MgSi2O7:Eu3+/Eu2+ phosphors for white LED

    Directory of Open Access Journals (Sweden)

    Tong Thi Hao Tam

    2016-06-01

    Full Text Available Phosphor-converted white light emitting diodes (white LEDs have received great attention in recent years since they have several excellent features such as high lumen output, low power consumption, long lifetime and environmentally friendly. In this work, we report the co-precipitation synthesis of red/blue Sr2MgSi2O7:Eu3+/Eu2+ phosphors with various Eu doping concentration. The results show that the obtained Sr2MgSi2O7:Eu3+/Eu2+ phosphors have good crystallinity and emit strong red (Sr2MgSi2O7:Eu3+ and blue (Sr2MgSi2O7:Eu2+ emissions under near UV light excitation. The sharp emission peaks at 577, 590, 612, 653, and 701 nm corresponded to the typical 5D0 → 7Fj (j = 0,1,2,3,4 transitions of Eu3+, and the blue emission peaking at 460 nm is attributed to the typical 4f65d1-4f7 transition of Eu2+ in the same Sr2MgSi2O7 host lattice. Both phosphors can be well excited in the wavelength range of 260–400 nm where the near UV-LED is well matched. The above results suggest that the Sr2MgSi2O7:Eu3+/Eu2+ phosphors are promising red/blue-emitting phosphors for the application in near UV pumped phosphor-converted white LEDs.

  20. Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

    Energy Technology Data Exchange (ETDEWEB)

    Sasani, Alireza [Department of Science, Karaj Islamic Azad University, Karaj, Alborz, P.O. Box 31485-313 (Iran, Islamic Republic of); Baktash, Ardeshir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Mirabbaszadeh, Kavoos, E-mail: mirabbas@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, P. O. Box 15875-4413 (Iran, Islamic Republic of); Khoshnevisan, Bahram [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

    2016-10-30

    Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO{sub 2} anatase surface (101) is studied. • Effect of Mg defect to the TiO{sub 2} anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO{sub 2} anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO{sub 2} anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO{sub 2} surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J{sub SC} of the surface while slightly decreasing V{sub OC} compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

  1. Band gap narrowing and fluorescence properties of nickel doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Arham S; Shafeeq, M Muhamed [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z. H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202002 (India); Singla, M L [Central Scientific Instruments Organization (CSIO), Council of Scientific and Industrial Research (CSIR), Materials Research and Bio-Nanotechnology Division, Sector - 30/C, Chandigarh-160030 (India); Tabassum, Sartaj [Department of Chemistry, Aligarh Muslim University, Aligarh-202002 (India); Naqvi, Alim H [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z. H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202002 (India); Azam, Ameer [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z. H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202002 (India)

    2011-01-15

    Nickel-doped tin oxide nanoparticles (sub-5 nm size) with intense fluorescence emission behavior have been synthesized by sol-gel route. The structural and compositional analysis has been carried out by using XRD, TEM, FESEM and EDAX. The optical absorbance spectra indicate a band gap narrowing effect and it was found to increase with the increase in nickel concentration. The band gap narrowing at low dopant concentration (<5%) can be assigned to SnO{sub 2}-SnO{sub 2-x} alloying effect and for higher doping it may be due to the formation of defect sub-bands below the conduction band.

  2. Effect of SnO2/SiO2 nano particle dispersant on the performance characteristic of complex multi-doped composite coating produced through electrodeposition on oil and gas storage tap

    Science.gov (United States)

    Anawe, P. A. L.; Fayomi, O. S. I.; Ayoola, A. A.; Popoola, A. P. I.

    2018-06-01

    The effect of SnO2/SiO2 nano particle dispersant on the performance characteristic of complex zinc multi-doped composite coating produced through electrodeposition is studied. The degradation behaviour in term of wear and chemical corrosion activities were considered as a major factor in service. The wear mass loss was carried out with the help of reciprocating tester. The electrochemical corrosion characteristics were investigated using linear polarization technique in 3.5% simulated sodium chloride media. The outcome of the analysis shows that the developed coating was seen to provide a sound anti wear characteristics in its multidoped state. The corrosion resistance properties were observed to be massive compared to the binary based sample. It is expected that this characteristic will impact on the performance life span of storage tap in oil and gas.

  3. Synthesis of TiO2-doped SiO2 composite films and its applications

    Indian Academy of Sciences (India)

    Wintec

    structure of the titanium oxide species in the TiO2-doped SiO2 composite films and the photocatalytic reactiv- ity in order to ... gaku D-max γA diffractometer with graphite mono- chromized ... FT–IR absorption spectra of TiO2-doped SiO2 com-.

  4. THE THERMODYNAMIC PROPERTIES OF MELTS OF DOUBLE SYSTEM MgO – Al2O3, MgO – SiO2, MgO – CaF2, Al2O3 – SiO2, Al2O3 – CaF2, SiO2 – CaF2

    Directory of Open Access Journals (Sweden)

    В. Судавцова

    2012-04-01

    Full Text Available Methodology of prognostication of thermodynamics properties of melts is presented from the coordinatesof liquidus of diagram of the state in area of equilibria a hard component is solution, on which energies ofmixing of Gibbs are expected in the double border systems of MgO – Al2O3, MgO – SiO2, MgO – CaF2,Al2O3 – SiO2, Al2O3 - CaF2, SiO2 - CaF2. For the areas of equilibrium there is quasibinary connection(MgAl2O4, Mg2SiO4, Al6Si2O13 – a grout at calculations was used equalization of Hauffe-Wagner. Theobtained data comport with literary

  5. Local structure and thermoelectric properties of Mg{sub 2}Si{sub 0.977−x}Ge{sub x}Bi{sub 0.023} (0.1 ⩽ x ⩽ 0.4)

    Energy Technology Data Exchange (ETDEWEB)

    Farahi, Nader [Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Prabhudev, Sagar; Botton, Gianluigi A. [Materials Science and Engineering Department, McMaster University, Hamilton, ON L8S 4L8 (Canada); Zhao, Jianbao; Tse, John S. [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK S7N 5E2 (Canada); Liu, Zhenxian [Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015 (United States); Salvador, James R. [General Motors Research & Development Center, Warren, MI 48090 (United States); Kleinke, Holger, E-mail: kleinke@uwaterloo.ca [Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2015-09-25

    Highlights: • Incorporating Ge into Bi-doped Mg{sub 2}Si decreases the thermal conductivity and enhances the thermoelectric performance. • Ge-rich domains, identified via TEM, contribute to these changes. • Interstitial sites are in part filled with Mg atoms, as revealed via TEM. • Doping with Bi is advantageous over doping with Sb, resulting in an increase of 48% of the thermoelectric figure of merit. • The highest figure-of-merit of these materials is zT{sub max} = 0.7 at 773 K, realized for Mg{sub 2}Si{sub 0.677}Ge{sub 0.3}Bi{sub 0.023}. - Abstract: We investigated the effect of germanium substitution for silicon in bismuth doped Mg{sub 2}Si. This alloying reduces the thermal conductivity from above 7 W m{sup −1} K{sup −1} to 2.7 W m{sup −1} K{sup −1} at around 300 K in part due to the added mass contrast. High resolution transmission electron microscopy (HRTEM) revealed the presence of Ge-rich domains within the Mg{sub 2}(Si,Ge,Bi) particles, contributing to decreasing thermal conductivity with increasing Ge content up to 0.3 Ge per formula unit. The electrical conductivity also decreases with Ge alloying because of the increasing amount of scattering centers, while the Seebeck coefficient increased only very slightly. In total, the positive effect of Ge substitution on the thermoelectric properties of Bi doped Mg{sub 2}Si resulted in a figure of merit of 0.7 at 773 K for Mg{sub 2}Si{sub 0.677}Ge{sub 0.3}Bi{sub 0.023} sample. The optimum amount of Bi seems to be 0.023 per formula unit (0.77 at%), since lower Bi content resulted in electrical conductivity that is too low, and higher Bi content generated the Mg{sub 3}Bi{sub 2} intermetallic phase.

  6. Efficient photocatalytic activity with carbon-doped SiO2 nanoparticles

    KAUST Repository

    Zhang, Dongen

    2013-01-01

    Photocatalysis provides a \\'green\\' approach to completely eliminate various kinds of contaminants that are fatal for current environmental and energy issues. Semiconductors are one of the most frequently used photocatalysts as they can absorb light over a wide spectral range. However, it is also well known that naked SiO2 is not an efficient photocatalyst due to its relatively large band gap, which could only absorb shortwave ultraviolet light. In this report, nanoscale particles of carbon-doped silicon dioxide (C-doped SiO2) for use in photocatalysis were successfully prepared by a facile one-pot thermal process using tetraethylorthosilicate (TEOS) as the source of both silicon and carbon. These particles were subsequently characterized by thermogravimetric analysis, X-ray diffraction, standard and high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The C-doped SiO2 displayed outstanding photocatalytic properties, as evidenced by its catalysis of Rhodamine B degradation under near-UV irradiation. We propose that carbon doping of the SiO2 lattice creates new energy states between the bottom of the conduction band and the top of the valence band, which narrows the band gap of the material. As a result, the C-doped SiO2 nanoparticles exhibit excellent photocatalytic activities in a neutral environment. The novel synthesis reported herein for this material is both energy efficient and environmentally friendly and as such shows promise as a technique for low-cost, readily scalable industrial production. © 2013 The Royal Society of Chemistry.

  7. Mg doped Li2FeSiO4/C nanocomposites synthesized by the solvothermal method for lithium ion batteries.

    Science.gov (United States)

    Kumar, Ajay; Jayakumar, O D; Jagannath; Bashiri, Parisa; Nazri, G A; Naik, Vaman M; Naik, Ratna

    2017-10-14

    A series of porous Li 2 Fe 1-x Mg x SiO 4 /C (x = 0, 0.01, 0.02, 0.04) nanocomposites (LFS/C, 1Mg-LFS/C, 2Mg-LFS and 4Mg-LFS/C) have been synthesized via a solvo-thermal method using the Pluronic P123 polymer as an in situ carbon source. Rietveld refinement of the X-ray diffraction data of Li 2 Fe 1-x Mg x SiO 4 /C composites confirms the formation of the monoclinic P2 1 structure of Li 2 FeSiO 4 . The addition of Mg facilitates the growth of impurity-free Li 2 FeSiO 4 with increased crystallinity and particle size. Despite having the same percentage of carbon content (∼15 wt%) in all the samples, the 1Mg-LFS/C nanocomposite delivered the highest initial discharge capacity of 278 mA h g -1 (∼84% of the theoretical capacity) at the C/30 rate and also exhibited the best rate capability and cycle stability (94% retention after 100 charge-discharge cycles at 1C). This is attributed to its large surface area with a narrow pore size distribution and a lower charge transfer resistance with enhanced Li-ion diffusion coefficient compared to other nanocomposites.

  8. Ex situ n+ doping of GeSn alloys via non-equilibrium processing

    Science.gov (United States)

    Prucnal, S.; Berencén, Y.; Wang, M.; Rebohle, L.; Böttger, R.; Fischer, I. A.; Augel, L.; Oehme, M.; Schulze, J.; Voelskow, M.; Helm, M.; Skorupa, W.; Zhou, S.

    2018-06-01

    Full integration of Ge-based alloys like GeSn with complementary-metal-oxide-semiconductor technology would require the fabrication of p- and n-type doped regions for both planar and tri-dimensional device architectures which is challenging using in situ doping techniques. In this work, we report on the influence of ex situ doping on the structural, electrical and optical properties of GeSn alloys. n-type doping is realized by P implantation into GeSn alloy layers grown by molecular beam epitaxy (MBE) followed by flash lamp annealing. We show that effective carrier concentration of up to 1 × 1019 cm‑3 can be achieved without affecting the Sn distribution. Sn segregation at the surface accompanied with an Sn diffusion towards the crystalline/amorphous GeSn interface is found at P fluences higher than 3 × 1015 cm‑2 and electron concentration of about 4 × 1019 cm‑3. The optical and structural properties of ion-implanted GeSn layers are comparable with the in situ doped MBE grown layers.

  9. Aluminum-Doped SnO2 Hollow Microspheres as Photoanode Materials for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Binghua Xu

    2016-01-01

    Full Text Available Al doped SnO2 microspheres were prepared through hydrothermal method. As-prepared SnO2 microspheres were applied as photoanode materials in dye-sensitized solar cells (DSCs. The properties of the assembled DSCs were significantly improved, especially the open-circuit voltage. The reason for the enhancement was explored through the investigation of dark current curves and electrochemistry impedance spectra. These results showed that the Al doping significantly increased the reaction resistance of recombination reactions and restrained the dark current. The efficient lifetime of photoexcited electrons was also obviously lengthened.

  10. In Situ Synthesis of Tungsten-Doped SnO2 and Graphene Nanocomposites for High-Performance Anode Materials of Lithium-Ion Batteries.

    Science.gov (United States)

    Wang, Shuai; Shi, Liyi; Chen, Guorong; Ba, Chaoqun; Wang, Zhuyi; Zhu, Jiefang; Zhao, Yin; Zhang, Meihong; Yuan, Shuai

    2017-05-24

    The composite of tungsten-doped SnO 2 and reduced graphene oxide was synthesized through a simple one-pot hydrothermal method. According to the structural characterization of the composite, tungsten ions were doped in the unit cells of tin dioxide rather than simply attaching to the surface. Tungsten-doped SnO 2 was in situ grown on the surface of graphene sheet to form a three-dimensional conductive network that enhanced the electron transportation and lithium-ion diffusion effectively. The issues of SnO 2 agglomeration and volume expansion could be also avoided because the tungsten-doped SnO 2 nanoparticles were homogeneously distributed on a graphene sheet. As a result, the nanocomposite electrodes of tungsten-doped SnO 2 and reduced graphene oxide exhibited an excellent long-term cycling performance. The residual capacity was still as high as 1100 mA h g -1 at 0.1 A g -1 after 100 cycles. It still remained at 776 mA h g -1 after 2000 cycles at the current density of 1A g -1 .

  11. Structural, optical and gas sensing properties of screen-printed nanostructured Sr-doped SnO2 thick film sensor

    International Nuclear Information System (INIS)

    Shaikh, F.I.; Chikhale, L.P.; Patil, J.Y.; Rajgure, A.V.; Suryavanshi, S.S.; Mulla, I.S.

    2013-01-01

    The nanocrystalline materials of strontium doped tin oxide powders were synthesized by conventional co-precipitation method. Synthesized nanophase SnO 2 powders were used to fabricate thick films of pure and Sr-doped SnO 2 using screen-printing technology and investigated for their gas sensing properties towards LPG, ethanol, ammonia and acetone vapor. The crystal structure and phase of the sintered powders were characterized by X-ray diffractometer (XRD) and microstructure by scanning electron microscopy (SEM). All the doped and undoped SnO 2 compositions revealed single phase and solid solution formation. X-ray diffractometer (XRD) results indicated that well crystallized Sr-doped SnO 2 particles of size about 10 nm were obtained at sintering temperature 700℃. The optical properties viz. UV-Vis, FTIR and Raman were used to characterize various physico-chemical properties of samples. The reduction of grain size in metal oxide is a key factor to enhance the gas sensing properties. The doping of Sr in SnO 2 has reduced the grain size and improved the gas response. The results of gas sensing measurements showed that the thick films deposited on alumina substrates using screen-printing technique exhibited high gas response, quick response time and fast recovery time to acetone gas at a working temperature of 250℃. Further, the selectivity of sensor towards acetone with respect to other reducing gases (LPG, ethanol, ammonia) was studied. (author)

  12. Defect phase diagram for doping of Ga2O3

    OpenAIRE

    Stephan Lany

    2018-01-01

    For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have d...

  13. Electrochemical and optical properties of CeO2-SnO2 and CeO2-SnO2:X (X = Li, C, Si films

    Directory of Open Access Journals (Sweden)

    Berton Marcos A.C.

    2001-01-01

    Full Text Available Thin solid films of CeO2-SnO2 (17 mol% Sn and CeO2-SnO2:X (X = Li, C and Si were prepared by the sol-gel route, using an aqueous-based process. The addition of Li, C and Si to the precursor solution leads to films with different electrochemical performances. The films were deposited by the dip-coating technique on ITO coated glass (Donnelly Glass at a speed of 10 cm/min and submitted to a final thermal treatment at 450 °C during 10 min in air. The electrochemical and optical properties of the films were determined from the cyclic voltammetry and chronoamperometry measurements using 0.1 M LiOH as supporting electrolyte. The ion storage capacity of the films was investigated using in situ spectroelectrochemical method and during the insertion/extraction process the films remained transparent. The powders were characterized by thermal analysis (DSC/TGA and X-ray diffraction.

  14. Electronic structures and Eu{sup 3+} photoluminescence behaviors in Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiya, E-mail: zhangzhiya@lzu.edu.cn [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000 (China); Wang Yuhua [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000 (China); Zhang Feng [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Cao Haining [Computational Science Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of)

    2011-04-14

    Research highlights: > Host excitation near the band gap of Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7} is analyzed. > The calculated result well explains Eu{sup 3+} PL behaviors in Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7}. > The electronic structure and Eu{sup 3+} VUV PL in La{sub 2}Si{sub 2}O{sub 7} are first estimated. - Abstract: The electronic structures and linear optical properties of Y{sub 2}Si{sub 2}O{sub 7} (YSO) and La{sub 2}Si{sub 2}O{sub 7} (LSO) are calculated by LDA method based on the theory of DFT. Both YSO and LSO are direct-gap materials with the direct band gap of 5.89 and 6.06 eV, respectively. The calculated total and partial density of states indicate that in both YSO and LSO the valence band (VB) is mainly constructed from O 2p and the conduction band (CB) is mostly formed from Y 4d or La 5d. Both the calculated VB and CB of YSO exhibit relatively wider dispersion than that of LSO. In addition, the CB of YSO presents more electronic states. Meanwhile, the VB of LSO shows narrower energy distribution with higher electronic states density. The theoretical absorption of YSO shows larger bandwidth and higher intensity than that of LSO. The results are compared with the experimental host excitations and impurity photoluminescence in Eu{sup 3+}-doped YSO and LSO.

  15. Tunable graphene doping by modulating the nanopore geometry on a SiO2/Si substrate

    KAUST Repository

    Lim, Namsoo; Yoo, Tae Jin; Kim, Jin Tae; Pak, Yusin; Kumaresan, Yogeenth; Kim, Hyeonghun; Kim, Woochul; Lee, Byoung Hun; Jung, Gun Young

    2018-01-01

    A tunable graphene doping method utilizing a SiO2/Si substrate with nanopores (NP) was introduced. Laser interference lithography (LIL) using a He–Cd laser (λ = 325 nm) was used to prepare pore size- and pitch-controllable NP SiO2/Si substrates

  16. Refinement of Mg{sub 2}Si reinforcement in a commercial Al–20%Mg{sub 2}Si in-situ composite with bismuth, antimony and strontium

    Energy Technology Data Exchange (ETDEWEB)

    Nordin, Nur Azmah; Farahany, Saeed, E-mail: saeedfarahany@gmail.com; Ourdjini, Ali; Abu Bakar, Tuty Asma; Hamzah, Esah

    2013-12-15

    Refinement by addition elements of Al–Mg{sub 2}Si alloys is known to result in a change of primary Mg{sub 2}Si morphology. In this paper, the effects of Bi, Sb and Sr on the characteristic parameters of Al–20%Mg{sub 2}Si in-situ composite have been investigated by computer aided cooling curve thermal analysis and microstructural inspection. Size, density and aspect ratio measurements showed that additions of 0.4 wt.% Bi, 0.8 wt.% Sb and 0.01 wt.% Sr refined the Mg{sub 2}Si reinforcement. Exceeding these concentrations, however, resulted in coarsening of Mg{sub 2}Si particles with no change in the morphology. The results also showed that addition elements caused a decrease in the nucleation and growth temperatures of Mg{sub 2}Si particles. The refining effect of Bi, Sb and Sr is likely to be related to the effect of oxide bifilms suspended in the composite melt as favored nucleation substrates for Mg{sub 2}Si particles. - Highlight: • 0.4 wt.%, 0.8 wt.% and 0.01 wt.% is the optimum content for Bi, Sb and Sr addition. • Exceeding optimum concentration resulted in the coarsening of reinforcements. • Nucleation and growth temperatures decrease with addition of Bi, Sb and Sr. • The refining effect of Bi, Sb and Sr is likely to be related to the oxide bifilms.

  17. Combined addition of nano diamond and nano SiO{sub 2}, an effective method to improve the in-field critical current density of MgB{sub 2} superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Rahul, S.; Varghese, Neson; Vinod, K.; Devadas, K.M.; Thomas, Syju; Anees, P. [National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695019 (India); Chattopadhyay, M.K.; Roy, S.B. [Magnetic and Superconducting Materials Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Syamaprasad, U., E-mail: syamcsir@gmail.com [National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695019 (India)

    2011-11-15

    Highlights: {yields} Both nano diamond and nano SiO{sub 2} caused significant modifications in the structural properties of pure MgB{sub 2} sample. {yields} Reduction in T{sub C} for the best codoped sample was approximately 2 K. {yields} The best codoped sample yielded a J{sub C}, an order of magnitude more than the undoped one at 5 K and 8 T. {yields} The enhanced flux pinning capability provided by the additives is responsible for the improved in-field J{sub C}. -- Abstract: MgB{sub 2} bulk samples added with nano SiO{sub 2} and/or nano diamond were prepared by powder-in-sealed-tube (PIST) method and the effects of addition on structural and superconducting properties were studied. X-ray diffraction (XRD) analysis revealed that the addition caused systematic reduction in 'a' lattice parameter due to the substitution of C atoms at B sites and the strain caused by reacted intragrain nano particles of Mg{sub 2}Si as evinced by transmission electron microscope image. Scanning electron microscopy images showed distinct microstructural variations with SiO{sub 2}/diamond addition. It was evident from DC magnetization measurements that the in-field critical current density [J{sub C}(H)] of doped samples did not fall drastically like the undoped sample. Among the doped samples the J{sub C}(H) of co-doped samples were significantly higher and the best co-doped sample yielded a J{sub C}, an order of magnitude more than the undoped one at 5 K and 8 T.

  18. Synthesis and microwave absorption enhancement of Fe-doped NiO@SiO2@graphene nanocomposites

    International Nuclear Information System (INIS)

    Wang, Lei; Huang, Ying; Ding, Xiao; Liu, Panbo; Zong, Meng; Wang, Yan

    2013-01-01

    Highlights: • Fe-doped NiO@SiO 2 @graphene composites have excellent microwave performance. • The reflection loss of Fe doped NiO@SiO 2 @graphene was below −10 dB in 7–11 GHz. • The maximum absorption of Fe-doped NiO@SiO 2 @graphene was −51.2 dB at 8.6 GHz. -- Abstract: Fe-doped NiO@SiO 2 @graphene nanocomposites have been successfully fabricated for the first time, in which Fe-doped NiO nanoparticles are about 3 nm in diameter. In order to measure their electromagnetic properties, Fe-doped NiO@SiO 2 @graphene (25 wt%) wax composites were then prepared. The experimental results show that Fe-doped NiO@SiO 2 @graphene nanocomposites exhibit significantly enhanced microwave absorption performance in terms of both the maximum reflection loss value and the absorption bandwidth in comparison with NiO@SiO 2 @graphene. The maximum reflection loss of Fe-doped NiO@SiO 2 @graphene nanocomposites can reach −51.2 dB at 8.6 GHz with a thickness of 4 mm, and the absorption bandwidth with the reflection loss below −10 dB is 4 GHz (from 7 to 11 GHz). Therefore, this kind of nanocomposites may have the potential as high-efficient absorbers for microwave absorption applications

  19. Microstructural Analysis of AM50/Mg2Si Cast Magnesium Composites

    Directory of Open Access Journals (Sweden)

    Malik M.A.

    2012-12-01

    Full Text Available AM50/Mg2Si composites containing 5.7 wt. % and 9.9 wt. %. of Mg2Si reinforcing phase were prepared successfully by casting method. The microstructure of the cast AM50/Mg2Si magnesium matrix composites was investigated by light microscopy and X-ray diffractometry (XRD. The microstructure of these composites was characterized by the presence of α-phase (a solid solution of aluminium in magnesium, Mg17Al12 (γ-phase, Al8Mn5 and Mg2Si. It was demonstrated that the Mg2Si phase was formed mainly as primary dendrites and eutectic.

  20. Preparation of MnO2 electrodes coated by Sb-doped SnO2 and their effect on electrochemical performance for supercapacitor

    International Nuclear Information System (INIS)

    Zhang, Yuqing; Mo, Yan

    2014-01-01

    Highlights: • Sb-doped SnO 2 coated MnO 2 electrodes (SS-MnO 2 electrodes) are prepared. • The capacitive property and stability of SS-MnO 2 electrode is superior to uncoated MnO 2 electrode and SnO 2 coated MnO 2 electrode. • Sb-doped SnO 2 coating enhances electrochemical performance of MnO 2 effectively. • SS-MnO 2 electrodes are desirable to become a novel electrode material for supercapacitor. - Abstract: To enhance the specific capacity and cycling stability of manganese binoxide (MnO 2 ) for supercapacitor, antimony (Sb) doped tin dioxide (SnO 2 ) is coated on MnO 2 through a sol-gel method to prepare MnO 2 electrodes, enhancing the electrochemical performance of MnO 2 electrode in sodium sulfate electrolytes. The structure and composition of SS-MnO 2 electrode are characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-Ray diffraction spectroscopy (XRD). The electrochemical performances are evaluated and researched by galvanostatic charge-discharge test, cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). The results show that SS-MnO 2 electrodes hold porous structure, displaying superior cycling stability at large current work condition in charge-discharge tests and good capacity performance at high scanning rate in CV tests. The results of EIS show that SS-MnO 2 electrodes have small internal resistance. Therefore, the electrochemical performances of MnO 2 electrodes are enhanced effectively by Sb-doped SnO 2 coating

  1. Thermal expansion of lanthanum silicate oxyapatite (La9.33+2x(SiO4)6O2+3x), lanthanum oxyorthosilicate (La2SiO5) and lanthanum sorosilicate (La2Si2O7)

    International Nuclear Information System (INIS)

    Fukuda, Koichiro; Asaka, Toru; Uchida, Tomohiro

    2012-01-01

    Four types of powder specimens of La 9.33 (SiO 4 ) 6 O 2 (space group P6 3 /m and Z=1), La 9.33+2x (SiO 4 ) 6 O 2+3x with 0.06≤x≤0.13 (P6 3 /m and Z=1), La 2 SiO 5 (P2 1 /c and Z=4) and La 2 Si 2 O 7 (P2 1 /c and Z=4) were examined by high-temperature X-ray powder diffractometry to determine the changes in unit-cell dimensions up to 1473 K. The anisotropy of thermal expansion was demonstrated for the former two crystals to clarify the thermal behaviors of the highly c-axis-oriented polycrystals. With La 9.33 (SiO 4 ) 6 O 2 , the linear expansion coefficient of the a-axis (α a ) was 4.8×10 −6 K −1 and that of the c-axis (α c ) was 1.8×10 −6 K −1 in the temperature range from 298 to 1473 K. The α a - and α c -values of La 9.33+2x (SiO 4 ) 6 O 2+3x (0.06≤x≤0.13) were, respectively, 5.9×10 −6 K −1 and 2.3×10 −6 K −1 . The coefficients of mean linear thermal expansion were 4.9×10 −6 K −1 for La 2 SiO 5 and 6.0×10 −6 K −1 for La 2 Si 2 O 7 , which describe the thermal expansion behaviors of the randomly grain-oriented polycrystalline materials. - Graphical abstarct: Temperature dependence of the coefficients of thermal expansion (CTE). The linear CTE along the a-axes for La 9.33 (SiO 4 ) 6 O 2 and La 9.33+2x (SiO 4 ) 6 O 2+3x with 0.06≤x≤0.13. The mean linear CTE for La 2 SiO 5 and La 2 Si 2 O 7 . Highlights: ► We examined the thermal expansion of La 9.33+2x (SiO 4 ) 6 O 2+3x (x=0 and 0.06≤x≤0.13), La 2 SiO 5 and La 2 Si 2 O 7 ► Unit-cell dimensions were determined up to 1473 K by high-temperature X-ray diffraction ► Anisotropic expansion was clarified for La 9.33+2x (SiO 4 ) 6 O 2+3x (x=0 and 0.06≤x≤0.13) ► Mean linear thermal expansion was determined for La 2 SiO 5 and La 2 Si 2 O 7.

  2. Do SiO 2 and carbon-doped SiO 2 nanoparticles melt? Insights from QM/MD simulations and ramifications regarding carbon nanotube growth

    Science.gov (United States)

    Page, Alister J.; Chandrakumar, K. R. S.; Irle, Stephan; Morokuma, Keiji

    2011-05-01

    Quantum chemical molecular dynamics (QM/MD) simulations of pristine and carbon-doped SiO 2 nanoparticles have been performed between 1000 and 3000 K. At temperatures above 1600 K, pristine nanoparticle SiO 2 decomposes rapidly, primarily forming SiO. Similarly, carbon-doped nanoparticle SiO 2 decomposes at temperatures above 2000 K, primarily forming SiO and CO. Analysis of the physical states of these pristine and carbon-doped SiO 2 nanoparticles indicate that they remain in the solid phase throughout decomposition. This process is therefore one of sublimation, as the liquid phase is never entered. Ramifications of these observations with respect to presently debated mechanisms of carbon nanotube growth on SiO 2 nanoparticles will be discussed.

  3. Positron annihilation study of YBa2Cu3Oy superconductors doped with SnO2

    International Nuclear Information System (INIS)

    Chen, A.; Zhi, Y.; Li Biaorong; Wang Shaojie

    1992-01-01

    The positron annihilation lifetime spectra of YBa 2 Cu 3 O y superconductors doped with SnO 2 were measured. The results indicate that the tin element substitutes for Cu(1) sites. A brief discussion is given based on the experimental results. (orig.)

  4. Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi{sub 2}Te{sub 2}Se

    Energy Technology Data Exchange (ETDEWEB)

    Kushwaha, S. K., E-mail: kushwaha@princeton.edu; Gibson, Q. D.; Cava, R. J. [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States); Xiong, J.; Ong, N. P. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Pletikosic, I. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973 (United States); Weber, A. P. [National Synchrotron Light Source, Brookhaven National Lab, Upton, New York 11973 (United States); Fedorov, A. V. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Valla, T. [Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973 (United States)

    2014-04-14

    A comparative study of the properties of topological insulator Bi{sub 2}Te{sub 2}Se (BTS) crystals grown by the vertical Bridgeman method is described. Two defect mechanisms that create acceptor impurities to compensate for the native n-type carriers are compared: Bi excess, and light Sn doping. Both methods yield low carrier concentrations and an n-p crossover over the length of the grown crystal boules, but lower carrier concentrations and higher resistivities are obtained for the Sn-doped crystals, which reach carrier concentrations as low as 8 × 10{sup 14} cm{sup −3}. Further, the temperature dependent resistivities for the Sn-doped crystals display strongly activated behavior at high temperatures, with a characteristic energy of half the bulk band gap. The (001) cleaved Sn-doped BTS crystals display high quality Shubnikov de Haas (SdH) quantum oscillations due to the topological surface state electrons. Angle resolved photoelectron spectroscopy (ARPES) characterization shows that the Fermi energy (E{sub F}) for the Sn-doped crystals falls cleanly in the surface states with no interference from the bulk bands, which the Dirac point for the surface states lies approximately 60 meV below the top of the bulk valence band maximum, and allows for a determination of the bulk and surface state carrier concentrations as a function of Energy near E{sub F}. Electronic structure calculations that compare Bi excess and Sn dopants in BTS demonstrate that Sn acts as a special impurity, with a localized impurity band that acts as a charge buffer occurring inside the bulk band gap. We propose that the special resonant level character of Sn in BTS gives rise to the exceptionally low carrier concentrations and activated resistivities observed.

  5. Highly sensitive formaldehyde resistive sensor based on a single Er-doped SnO_2 nanobelt

    International Nuclear Information System (INIS)

    Li, Shuanghui; Liu, Yingkai; Wu, Yuemei; Chen, Weiwu; Qin, Zhaojun; Gong, Nailiang; Yu, Dapeng

    2016-01-01

    SnO_2 nanobelts (SnO_2 NBs) and Er"3"+-doped SnO_2 nanobelts (Er–SnO_2 NBs) were synthesized by thermal evaporation. The obtained samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersion spectrometer (EDS), and X-ray photoelectron spectrometer (XPS). It is found that Er–SnO_2 NBs have a good morphology with smooth surface and their thickness are about 30 nm, widths between 200 nm and 600 nm, and lengths 30–80 mm. The nanobelts with good morphology were taken to develop sensors based on a single Er–SnO_2 NB/SnO_2 NB for studying sensitive properties. The results reveal that the response of a single Er–SnO_2 nanobelt device is 9 to the formaldehyde gas with a shorter response (recovery time) of 17 (25) s.

  6. Flux pinning characteristics of Sn-doped YBCO film by the MOD process

    International Nuclear Information System (INIS)

    Choi, S.M.; Shin, G.M.; Yoo, S.I.

    2013-01-01

    Highlights: ► The pinning effects of undoped and Sn-doped YBCO films by MOD were characterized. ► Sn-containing nanoparticles were trapped in Sn-doped YBCO films by MOD. ► Sn-containing nanoparticles were identified as the YBa 2 SnO 5.5 (YBSO) phase by TEM. ► The YBSO nanoparticles are responsible for improved flux pinning effect. ► We report the orientation relationship between YBSO nanoparticles and YBCO matrix. -- Abstract: Compared with the undoped YBa 2 Cu 3 O 7−δ (YBCO) film, 10 mol% Sn-doped YBCO film exhibited significantly enhanced critical current densities (J c ) in magnetic fields up to 5 T at 65 and 77 K for H//c, indicating that the Sn-doped YBCO film possesses more effective flux pinning centers. Both samples were grown on the SrTiO 3 (STO) (1 0 0) single crystal substrates by the metal-organic deposition (MOD) process. Larger J c (77 K, 1 T) values of Sn-doped YBCO film are observed over a wide field-orientation angle (θ) except the field-orientations close to the ab-plane of YBCO (85° c values for 85° 2 SnO 5.5 (YBSO) phase by STEM (scanning transmission electron microscopy)-EDS (energy dispersive X-ray spectroscopy) analysis. Further analyses by HR-TEM (high resolution-transmission electron microscopy) revealed that YBSO nanoparticles completely surrounded by the YBCO matrix had random orientation with YBCO while those located at the interface of YBCO/STO substrate had epitaxial relationship with YBCO

  7. SnS2 nanosheets arrays sandwiched by N-doped carbon and TiO2 for high-performance Na-ion storage

    Directory of Open Access Journals (Sweden)

    Weina Ren

    2018-01-01

    Full Text Available In this paper, SnS2 nanosheets arrays sandwiched by porous N-doped carbon and TiO2 (TiO2@SnS2@N-C on flexible carbon cloth are prepared and tested as a free-standing anode for high-performance sodium ion batteries. The as-obtained TiO2@SnS2@N-C composite delivers a remarkable capacity performance (840 mA h g−1 at a current density of 200 mA g−1, excellent rate capability and long-cycling life stability (293 mA h g−1 at 1 A g−1 after 600 cycles. The excellent electrochemical performance can be attributed to the synergistic effect of each component of the unique hybrid structure, in which the SnS2 nanosheets with open framworks offer high capacity, while the porous N-doped carbon nanoplates arrays on flexible carbon cloth are able to improve the conductivity and the TiO2 passivation layer can keep the structure integrity of SnS2 nanosheets.

  8. Polarized micro-Raman scattering characterization of Mg2Si nanolayers in (001) Si matrix

    International Nuclear Information System (INIS)

    Zlateva, G; Atanassov, A; Baleva, M; Nikolova, L; Abrashev, M V

    2007-01-01

    An orientational growth of the Mg 2 Si lattice relative to the Si lattice is considered assuming minimum mismatch of their lattice parameters. The Raman scattering cross-sections are calculated for the four possible orientations of the Mg 2 Si lattice positioned in this way. The integral intensity ratios for the F 2g mode of Mg 2 Si in different polarization configurations, obtained from the experimental spectra, are compared with the calculated ratios. It is found that the Mg 2 Si nanolayer's morphology is sensitive to the implantation energy, which determines both the peak Mg concentration in the initial implantation profile and its position in the sample depth. At a peak concentration of the order of the stoichiometric concentration, the layers are highly oriented. When the peak concentration is higher and the peak is placed closer to the surface, the layers are polycrystalline

  9. Si and Mg pair-doped interlayers for improving performance of AlGaN/GaN heterostructure field effect transistors grown on Si substrate

    Science.gov (United States)

    Ni, Yi-Qiang; He, Zhi-Yuan; Yao, Yao; Yang, Fan; Zhou, De-Qiu; Zhou, Gui-Lin; Shen, Zhen; Zhong, Jian; Zheng, Yue; Zhang, Bai-Jun; Liu, Yang

    2015-05-01

    We report a novel structure of AlGaN/GaN heterostructure field effect transistors (HFETs) with a Si and Mg pair-doped interlayer grown on Si substrate. By optimizing the doping concentrations of the pair-doped interlayers, the mobility of 2DEG increases by twice for the conventional structure under 5 K due to the improved crystalline quality of the conduction channel. The proposed HFET shows a four orders lower off-state leakage current, resulting in a much higher on/off ratio (˜ 109). Further temperature-dependent performance of Schottky diodes revealed that the inhibition of shallow surface traps in proposed HFETs should be the main reason for the suppression of leakage current. Project supported by the National Natural Science Foundation of China (Grant Nos. 51177175 and 61274039), the National Basic Research Project of China (Grant Nos. 2010CB923200 and 2011CB301903), the Ph.D. Program Foundation of Ministry of Education of China (Grant No. 20110171110021), the International Sci. & Tech. Collaboration Program of China (Grant No. 2012DFG52260), the National High-tech R&D Program of China (Grant No. 2014AA032606), the Science and Technology Plan of Guangdong Province, China (Grant No. 2013B010401013), and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics (Grant No. IOSKL2014KF17).

  10. Metal-Organic Frameworks Derived Okra-like SnO2 Encapsulated in Nitrogen-Doped Graphene for Lithium Ion Battery.

    Science.gov (United States)

    Zhou, Xiangyang; Chen, Sanmei; Yang, Juan; Bai, Tao; Ren, Yongpeng; Tian, Hangyu

    2017-04-26

    A facile process is developed to prepare SnO 2 -based composites through using metal-organic frameworks (MOFs) as precursors. The nitrogen-doped graphene wrapped okra-like SnO 2 composites (SnO 2 @N-RGO) are successfully synthesized for the first time by using Sn-based metal-organic frameworks (Sn-MOF) as precursors. When utilized as an anode material for lithium-ion batteries, the SnO 2 @N-RGO composites possess a remarkably superior reversible capacity of 1041 mA h g -1 at a constant current of 200 mA g -1 after 180 charge-discharge processes and excellent rate capability. The excellent performance can be primarily ascribed to the unique structure of 1D okra-like SnO 2 in SnO 2 @N-RGO which are actually composed of a great number of SnO 2 primary crystallites and numerous well-defined internal voids, can effectively alleviate the huge volume change of SnO 2 , and facilitate the transport and storage of lithium ions. Besides, the structural stability acquires further improvement when the okra-like SnO 2 are wrapped by N-doped graphene. Similarly, this synthetic strategy can be employed to synthesize other high-capacity metal-oxide-based composites starting from various metal-organic frameworks, exhibiting promising application in novel electrode material field of lithium-ion batteries.

  11. Effects of graphite doping on critical current density and microstructure of MgB2 bulks by an improved Mg-diffusion method

    International Nuclear Information System (INIS)

    Pan, X.F.; Zhao, Y.; Feng, Y.; Yang, Y.; Cheng, C.H.

    2008-01-01

    abstract: A series of graphite-doped MgB 2 bulks with high density have been successfully prepared by an improved Mg-diffusion method in ambient pressure. The effects of graphite doping on lattice parameters, T c , J c and microstructure of MgB 2 have been investigated. The results show that compared to the nano-C-doped or CNTs-doped MgB 2 , C is not easy to substitute B in graphite-doped MgB 2 . However, at the same C content, the graphite-doped MgB 2 has a higher J c . At 10 K and self-field, the J c for MgB 1.985 C 0.015 reaches 0.58 MA/cm 2 . For the MgB 1.945 C 0.055 , at 5 K, 7 T and 10 K, 6 T the J c achieves 10,000 A/cm 2 which is two orders of magnitude higher than that for the undoped sample. In addition to improving electron scattering and intergranular connectivity, the unreacted graphite in the graphite-doped MgB 2 is proposed to be responsible to the excellent J c properties of MgB 2 in high fields, due to depressed grain growth and enhanced grain boundary flux pinning

  12. Modification of GaN(0001) growth kinetics by Mg doping

    International Nuclear Information System (INIS)

    Monroy, E.; Andreev, T.; Holliger, P.; Bellet-Amalric, E.; Shibata, T.; Tanaka, M.; Daudin, B.

    2004-01-01

    We have studied the effect of Mg doping on the surface kinetics of GaN during growth by plasma-assisted molecular-beam epitaxy. Mg tends to segregate on the surface of GaN, inhibiting the formation of the self-regulated Ga film which is used as a surfactant for the growth of undoped and Si-doped GaN. The growth window is hence significantly reduced. Higher growth temperatures lead to an enhancement of Mg segregation and an improvement of the surface morphology

  13. Thermoelectric study of Ag doped SnSe-Sb2Se3 based alloy

    Science.gov (United States)

    Das, Anish; Talukdar, M.; Kumar, Aparabal; Sarkar, Kalyan Jyoti; Dhama, P.; Banerji, P.

    2018-05-01

    In this article we have synthesized p-type alloy of SnSe and Sb2Se3 (10 atomic %) to study the thermoelectric transport properties. The alloy was prepared by melt grown technique followed by spark plasma sintering and latter doped with 2 atomic % Ag to compensate the carrier density in order to achieve higher electrical conductivity (σ). Out of these, the doped sample resulted in the maximum figure of merit, ZT˜0.7 at 773 K due to the existence of the secondary phase AgSbSe2 and reduced lattice thermal conductivity (0.61 W m-1 K-1 at 300 K). The fitted lattice thermal conductivity shows that point defect and Umklapp scattering are the primary process of phonon scattering for all the samples whereas the fitted mobility data confirms acoustic phonon scattering along with point defect and grain boundary scattering to be the main carrier scattering mechanism. More over room temperature carrier density and electrical conductivity are found to increase for the doped sample which further corroborate (90%)SnSe-(10%)Sb2Se3:2%Ag to be a potential candidate for highly efficient thermoelectric materials.

  14. VUV-UV–vis photoluminescence of Ce{sup 3+} and Ce{sup 3+}-Eu{sup 2+} energy transfer in Ba{sub 2}MgSi{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jing; Liu, Chunmeng; Zhou, Weijie [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275 (China); Huang, Yan; Tao, Ye [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Liang, Hongbin, E-mail: cesbin@mail.sysu.edu.cn [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275 (China)

    2017-05-15

    A series of Ce{sup 3+} doped and Ce{sup 3+}-Eu{sup 2+} co-doped Ba{sub 2}MgSi{sub 2}O{sub 7} phosphors was prepared via a high-temperature solid-state reaction technique. The photoluminescence properties, which include synchrotron radiation VUV-UV excitation spectra, emission spectra and concentration effect, thermal stability of Ce{sup 3+} are investigated. Hence the energies of the crystal field split 5d excited states of Ce{sup 3+} are determined. Due to spectral overlap, the energy transfer from sensitizer Ce{sup 3+} to activator Eu{sup 2+} in Ba{sub 2}MgSi{sub 2}O{sub 7}:Ce{sup 3+}, Eu{sup 2+} occurs, and the mechanism is demonstrated to be an electric dipole−dipole interaction. - Highlights: •The energies of five crystal field split 5d states of Ce{sup 3+} in Ba{sub 2}MgSi{sub 2}O{sub 7} were determined by synchrotron radiation VUV-UV excitation spectrum. •The concentration effect, thermal stability of Ce{sup 3+} were investigated. •The energy transfer from Ce{sup 3+} to Eu{sup 2+} and its influence on luminescence decays of Ce{sup 3+} and Eu{sup 2+} were studied.

  15. Evaluation of surface energy state distribution and bulk defect concentration in DSSC photoanodes based on Sn, Fe, and Cu doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ako, Rajour Tanyi [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Ekanayake, Piyaisiri, E-mail: piyasiri.ekanayake@ubd.edu.bn [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Young, David James [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research -A*STAR, 3 Research Link, 117602 (Singapore); Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland, 4558 (Australia); Hobley, Jonathan [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Chellappan, Vijila [Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research - A*STAR, 3 Research Link, 117602 (Singapore); Tan, Ai Ling [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Gorelik, Sergey; Subramanian, Gomathy Sandhya [Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research - A*STAR, 3 Research Link, 117602 (Singapore); Lim, Chee Ming [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam)

    2015-10-01

    Graphical abstract: - Highlights: • The structural, optical and optoelectronic properties of 1 mol.% Fe, Sn and Cu doped TiO{sub 2} have been compared. • Transient lifetimes for pure TiO{sub 2} and Sn doped TiO{sub 2} were considerably shorter than Fe and Cu doped TiO{sub 2}. • A good correlation between the bulk defects and transient decay for the doped TiO{sub 2} powders was observed. • Photon to current conversion efficiency of DSSC based on the metal doped TiO{sub 2} were in order Sn-TiO{sub 2} > Cu-TiO{sub 2} > Pure >> Fe-TiO{sub 2}. • DSSC based on Fe doped photoanodes is limited by a high concentration of surface free holes observed at 433 nm. - Abstract: Electron transfer dynamics in the oxide layers of the working electrodes in both dye-sensitized solar cells and photocatalysts greatly influences their performance. A proper understanding of the distribution of surface and bulk energy states on/in these oxide layers can provide insights into the associated electron transfer processes. Metal ions like Iron (Fe), Copper (Cu) and Tin (Sn) doped onto TiO{sub 2} have shown enhanced photoactivity in these processes. In this work, the structural, optical and transient properties of Fe, Cu and Sn doped TiO{sub 2} nanocrystalline powders have been investigated and compared using EDX, Raman spectroscopy, X-ray Photoelectron spectroscopy (XPS), and Transient Absorption spectroscopy (TAS). Surface free energy states distributions were probed using Electrochemical Impedance spectroscopy (EIS) on Dye Sensitized Solar Cells (DSSC) based on the doped TiO{sub 2} photoanodes. Raman and XPS Ti2p{sub 3/2} peak shifts and broadening showed that the concentration of defects were in the order: Cu doped TiO{sub 2} > Fe doped TiO{sub 2} > Sn doped TiO{sub 2} > pure TiO{sub 2}. Nanosecond laser flash photolysis of Fe and Cu doped TiO{sub 2} indicated slower transient decay kinetics than that of Sn doped TiO{sub 2} or pure TiO{sub 2}. A broad absorption peak and fast

  16. Flux pinning behaviors of Ti and C co-doped MgB2 superconductors

    International Nuclear Information System (INIS)

    Yang, Y.; Zhao, D.; Shen, T.M.; Li, G.; Zhang, Y.; Feng, Y.; Cheng, C.H.; Zhang, Y.P.; Zhao, Y.

    2008-01-01

    Flux pinning behavior of carbon and titanium concurrently doped MgB 2 alloys has been studied by ac susceptibility and dc magnetization measurements. It is found that critical current density and irreversibility field of MgB 2 have been significantly improved by doping C and Ti concurrently, sharply contrasted to the situation of C-only-doped or Ti-only-doped MgB 2 samples. AC susceptibility measurement reveals that the dependence of the pinning potential on the dc applied field of Mg 0.95 Ti 0.05 B 1.95 C 0.05 has been determined to be U(B dc )∝B dc -1 compared to that of MgB 2 U(B dc )∝B dc -1.5 . As to the U(J) behavior, a relationship of U(J) ∝ J -0.17 is found fitting well for Mg 0.95 Ti 0.05 B 1.95 C 0.05 with respect to U(J) ∝ J -0.21 for MgB 2 . All the results reveal a strong enhancement of the high field pinning potential in C and Ti co-doped MgB 2

  17. Lattice doped Zn–SnO{sub 2} nanospheres: A systematic exploration of dopant ion effects on structural, optical, and enhanced gas sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Baraneedharan, P. [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India); Alternative Energy and Nanotechnology Laboratory, Indian Institute of Technology Madras, Chennai 600036 (India); Imran Hussain, S. [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India); Department of Applied Science and Technology, Anna University, Chennai 600 025 (India); Dinesh, V.P. [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641004 (India); Siva, C. [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India); Department of Physics and Nanotechnology, SRM University, Kattankulathur 603 203 (India); Biji, P. [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641004 (India); Sivakumar, M., E-mail: muthusiva@gmail.com [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India)

    2015-12-01

    Graphical abstract: - Highlights: • A simple, novel and surfactant free hydrothermal route to prepare SnO{sub 2} nanospheres. • A systematic investigation of growth mechanism with the assist of time dependent HR-TEM images. • Incorporation of Zn ions into SnO{sub 2} lattices clearly elucidated with XRD and XPS spectrums. • Three fold time increased response in Zn–SnO{sub 2} nanospheres when compared to undoped SnO{sub 2}. - Abstract: A surfactant-free one step hydrothermal method is reported to synthesize zinc (Zn{sup 2+}) doped SnO{sub 2} nanospheres. The structural analysis of X-ray diffraction confirms the tetragonal crystal system of the material with superior crystalline nature. The shift in diffraction peak, variation in lattice constant and disparity in particle size confirm the incorporation of Zn{sup 2+} ions to the Sn host lattices. The lattice doped structure, the disparity in morphology, size and shape by the addition of Zn{sup 2+} ions are evident from X-ray photoelectron spectroscopic and electron microscopic analysis. Significant changes in the absorption edge and the band gap with increased doping concentration were observed in UV–vis absorption spectral analysis. The formation of acceptor energy levels with the incorporation of Zn{sup 2+} ions has a significant effect on the electrical conductivity of SnO{sub 2} nanospheres. Comparative tests for gas sensors based on Zn doped SnO{sub 2} nanospheres and SnO{sub 2} nanospheres clearly show that the former exhibited excellent NO{sub 2} sensing performance. The responses of Zn{sup 2+} ions incorporated SnO{sub 2} nanospheres sensor were increased 3 fold at trace level NO{sub 2} gas concentrations ranging from 1 to 5 ppm. The excellent sensitivity, selectivity and fast response make the Zn{sup 2+} doped SnO{sub 2} nanospheres ideal for NO{sub 2} sensing.

  18. Nanocrystalline Cobalt-doped SnO2 Thin Film: A Sensitive Cigarette Smoke Sensor

    Directory of Open Access Journals (Sweden)

    Patil Shriram B.

    2011-11-01

    Full Text Available This article discusses a sensitive cigarette smoke sensor based on Cobalt doped Tin oxide (Co-SnO2 thin films deposited on glass substrate by a conventional Spray Pyrolysis technique. The Co-SnO2 thin films have been characterized by X-ray Diffraction (XRD, Scanning Electron Microscopy (SEM and Energy Dispersive X-ray Spectroscopy (EDAX. The XRD spectrum shows polycrystalline nature of the film with a mixed phase comprising of SnO2 and Co3O4. The SEM image depicts uniform granular morphology covering total substrate surface. The compositional analysis derived using EDAX confirmed presence of Co in addition to Sn and O in the film. Cigarette smoke sensing characteristics of the Co-SnO2 thin film have been studied under atmospheric condition at different temperatures and smoke concentration levels. The sensing parameters such as sensitivity, response time and recovery time are observed to be temperature dependent, exhibiting better results at 330 oC.

  19. Hydrogen peroxide route to Sn-doped titania photocatalysts

    Directory of Open Access Journals (Sweden)

    Štengl Václav

    2012-10-01

    Full Text Available Abstract Background The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements Results The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Conclusions Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders.

  20. Semiconducting ZnSnN{sub 2} thin films for Si/ZnSnN{sub 2} p-n junctions

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Ruifeng [Hebei Engineering Laboratory of Photoelectronic Functional Crystals, Hebei University of Technology (HEBUT), Tianjin 300401 (China); Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, and Key Laboratory of Additive Manufacturing Materials of Zhejiang Province, Ningbo 315201 (China); Cao, Hongtao; Liang, Lingyan, E-mail: lly@nimte.ac.cn, E-mail: swz@hebut.edu.cn; Xie, Yufang; Zhuge, Fei; Zhang, Hongliang; Gao, Junhua; Javaid, Kashif [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, and Key Laboratory of Additive Manufacturing Materials of Zhejiang Province, Ningbo 315201 (China); Liu, Caichi; Sun, Weizhong, E-mail: lly@nimte.ac.cn, E-mail: swz@hebut.edu.cn [Hebei Engineering Laboratory of Photoelectronic Functional Crystals, Hebei University of Technology (HEBUT), Tianjin 300401 (China)

    2016-04-04

    ZnSnN{sub 2} is regarded as a promising photovoltaic absorber candidate due to earth-abundance, non-toxicity, and high absorption coefficient. However, it is still a great challenge to synthesize ZnSnN{sub 2} films with a low electron concentration, in order to promote the applications of ZnSnN{sub 2} as the core active layer in optoelectronic devices. In this work, polycrystalline and high resistance ZnSnN{sub 2} films were fabricated by magnetron sputtering technique, then semiconducting films were achieved after post-annealing, and finally Si/ZnSnN{sub 2} p-n junctions were constructed. The electron concentration and Hall mobility were enhanced from 2.77 × 10{sup 17} to 6.78 × 10{sup 17 }cm{sup −3} and from 0.37 to 2.07 cm{sup 2} V{sup −1} s{sup −1}, corresponding to the annealing temperature from 200 to 350 °C. After annealing at 300 °C, the p-n junction exhibited the optimum rectifying characteristics, with a forward-to-reverse ratio over 10{sup 3}. The achievement of this ZnSnN{sub 2}-based p-n junction makes an opening step forward to realize the practical application of the ZnSnN{sub 2} material. In addition, the nonideal behaviors of the p-n junctions under both positive and negative voltages are discussed, in hope of suggesting some ideas to further improve the rectifying characteristics.

  1. Rutile-type Co doped SnO{sub 2} diluted magnetic semiconductor nanoparticles: Structural, dielectric and ferromagnetic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Mehraj, Sumaira, E-mail: sumairamehraj07@gmail.com [Department of Applied Physics, Aligarh Muslim University, Aligarh-202002 (India); Shahnawaze Ansari, M. [Center of Nanotechnology, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Alimuddin [Department of Applied Physics, Aligarh Muslim University, Aligarh-202002 (India)

    2013-12-01

    Nanoparticles of basic composition Sn{sub 1−x}Co{sub x}O{sub 2} (x=0.00, 0.01, 0.03, 0.05 and 0.1) were synthesized through the citrate-gel method and were characterized for structural properties using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR). XRD analysis of the powder samples sintered at 500 °C for 12 h showed single phase rutile type tetragonal structure and the crystallite size decreased as the cobalt content was increased. FT-IR spectrum displayed various bands that came due to fundamental overtones and combination of O–H, Sn–O and Sn–O–Sn entities. The effect of Co doping on the electrical and magnetic properties was studied using dielectric spectroscopy and vibrating sample magnetometer (VSM) at room temperature. The dielectric parameters (ε, tan δ and σ{sub ac}) show their maximum value for 10% Co doping. The dielectric loss shows anomalous behavior with frequency where it exhibits the Debye relaxation. The variation of dielectric properties and ac conductivity with frequency reveals that the dispersion is due to the Maxwell–Wagner type of interfacial polarization in general and hopping of charge between Sn{sup 2+} and Sn{sup 4+} as well as between Co{sup 2+} and Co{sup 3+} ions. The complex impedance analysis was used to separate the grain and grain boundary contributions in the system which shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. Hysteresis loops were observed clearly in M–H curves from 0.01 to 0.1% Co doped SnO{sub 2} samples. The saturation magnetization of the doped samples increased slightly with increase of Co concentration. However pure SnO{sub 2} displayed paramagnetism which vanished at higher values of magnetic field.

  2. Synthesis of Doped and non-Doped Nano MgO Ceramic Membranes

    Directory of Open Access Journals (Sweden)

    Shiraz Labib

    2013-12-01

    Full Text Available Doped and non-doped MgO coated thin films on alumina substrates were prepared using a chelating sol-gel method under controlled conditions to prepare nanomaterials with unprecedented properties. The effect of doping of ZnO on thermal, surface and structural properties was investigated using DTA-TG, BET and XRD respectively. Also microstructural studies and coating thickness measurements of MgO thin film were conducted using SEM. An increase in the thermal stability of MgO with increasing ZnO doping percent was observed. The increase of ZnO doping percent showed a marked decrease in the average particle size of MgO powder as a result of the replacement of some Mg2+ by Zn2+ which has similar ionic radius as Mg2+. This decrease in particle size of MgO was also related to the decrease of the degree of MgO crystalinity. The increase of ZnO doping also showed a marked decrease in coating thickness values of the prepared membranes. This decrease was related to the  mechanism of ZnO doping into a MgO crystal lattice.

  3. Spheroidization of primary Mg{sub 2}Si in Al-20Mg{sub 2}Si-4.5Cu alloy modified with Ca and Sb during T6 heat treatment process

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hong-Chen; Wang, Hui-Yuan, E-mail: wanghuiyuan@jlu.edu.cn; Chen, Lei; Zha, Min, E-mail: minzha@jlu.edu.cn; Wang, Cheng; Li, Chao; Jiang, Qi-Chuan

    2017-02-08

    The morphology evolution of primary Mg{sub 2}Si particles in a Al-20Mg{sub 2}Si-4.5Cu alloy both unmodified and modified with 0.5 wt% Ca-Sb prepared by hot-extrusion followed by T6 heat treatment was investigated in the present study. Interestingly, we found that the combination of hot-extrusion and T6 heat treatment was efficient in transforming truncated octahedral primary Mg{sub 2}Si into sphere in the modified alloy. In contrast, the primary Mg{sub 2}Si particles still kept dentritic in the unmodified alloy. It suggested that the formation of truncated octahedral primary Mg{sub 2}Si particles in as-cast state, the fragmentation of particles by hot-extrusion and the enhanced solid-state diffusion of Si and/or Mg atoms during heat treatment were responsible for the spheroidization of primary Mg{sub 2}Si. Moreover, the existence of fine (~10–20 µm) spherical primary Mg{sub 2}Si played an important role in strengthening the alloy, i.e., the ultimate tensile strength (UTS) increased from ~227 MPa in the unmodified alloy to ~303 MPa in the modified one. It is because the fine spherical primary Mg{sub 2}Si particles can provide a higher fracture stress and strength of the matrix/particle interface. Our study offered a simple methodology to prepare spherical primary Mg{sub 2}Si in an Al-high Mg{sub 2}Si alloy, which is beneficial to design novel light-weight Al-Mg-Si alloys with improved mechanical properties.

  4. Concurrent doping effect of Ti and nano-diamond on flux pinning of MgB2

    International Nuclear Information System (INIS)

    Zhao, Y.; Ke, C.; Cheng, C.H.; Feng, Y.; Yang, Y.; Munroe, P.

    2010-01-01

    Nano-diamond and titanium concurrently doped MgB 2 nanocomposites have been prepared by solid state reaction method. The effects of carbon and Ti concurrent doping on J c -H behavior and pinning force scaling features of MgB 2 have been investigated. Although T c was slightly depressed, J c of MgB 2 have been significantly improved by the nano-diamond doping, especially in the high field region. In the mean time, the J c value in low field region is sustained though concurrent Ti doping. Microstructure analysis reveals that when nano-diamond was concurrently doped with titanium in MgB 2 , a unique nanocomposite in which TiB 2 forms a thin layer surrounding MgB 2 grains whereas nano-diamond particles were wrapped inside the MgB 2 grains. Besides, nano-diamond doping results in a high density stress field in the MgB 2 samples, which may take responsibility for the Δκ pinning behavior in the carbon-doped MgB 2 system.

  5. A detailed study on Sn4+ doped ZnO for enhanced photocatalytic degradation

    Science.gov (United States)

    Beura, Rosalin; Pachaiappan, R.; Thangadurai, P.

    2018-03-01

    The samples of Sn4+ doped (1, 5, 10, 15, 20 & 30%) ZnO nanostructures were synthesized by a low temperature hydrothermal method. Structural analysis by XRD and Raman spectroscopy showed the hexagonal wurtzite phase of ZnO and the formation of a secondary phase Zn2SnO4 beyond 10% doping of Sn4+. Microstructural analysis by TEM also confirmed the wurtzite ZnO with rod as well as particle like structure. Presence of various functional groups (sbnd OH, sbnd CH, Znsbnd O) were confirmed by FTIR. Optical properties were studied by UV-vis absorption, photoluminescence emission spectroscopies and lifetime measurement. Band gap of the undoped and Sn4+ doped ZnO were analyzed by Tauc plot and it was observed that the band gap of the materials had slightly decreased from 3.2 to 3.16 eV and again increased to 3.23 eV with respect to the increase in the doping concentration from 1 to 30%. A significant change was also noticed in the photoluminescence emission properties of ZnO i.e. increase in the intensity of NBE emission and decrease in DLE, on subject to Sn4+ doping. Average PL lifetime had increased from 29.45 ns for ZnO to 30.62 ns upon 1% Sn ion doping in ZnO. Electrical properties studied by solid state impedance spectroscopy showed that the conductivity had increased by one order of magnitude (from 7.48×10-8 to 2.21×10-7 S/cm) on Sn4+ doping. Photocatalytic experiments were performed on methyl orange (MO) as a model industrial dye under UV light irradiation for different irradiation times. The optimum Sn4+ content in order to achieve highest photocatalytic activity was found to be 1% Sn 4+ doping. The enhancement was achieved due to a decrease in the band gap favoring the generation of electron-hole pairs and the enhanced PL life time that delays the recombination of these charge carrier formation. The third reason was that the increased electrical conductivity that indicated the faster charge transfer in this material to enhance the photocatalytic activity. The Sn

  6. Preparation of Pr-doped SnO{sub 2} hollow nanofibers by electrospinning method and their gas sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, W.Q.; Ma, S.Y., E-mail: lwq19891013@126.com; Li, Y.F.; Li, X.B.; Wang, C.Y.; Yang, X.H.; Cheng, L.; Mao, Y.Z.; Luo, J.; Gengzang, D.J.; Wan, G.X.; Xu, X.L.

    2014-08-25

    Highlights: • Pr-doped SnO{sub 2} hollow nanofibers were fabricated by electrospinning. • The crystal structures, surface morphology, chemical state and gas sensing performance were investigated. • The Pr-doped SnO{sub 2} hollow structure exhibited good gas-sensing properties to ethanol at 300 °C. • The relationships between response time (recovery time) and temperature, response time (recovery time) and concentration were investigated. • A sensor mechanism of hollow nanofibers depend on temperature was discussed. - Abstract: Pure and Pr-doped SnO{sub 2} hollow nanofibers were fabricated through a facile single capillary electrospinning and followed by calcination. The properties of as-synthesized nanofibers were characterized by scanning electron microscopy, Brunauer–Emmett–Teller, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Compared with pure fibers, Pr-doped SnO{sub 2} nanofibers exhibited excellent ethanol sensing properties at the optimum temperature of 300 °C. Maximum sensing response to ethanol was received in the fibers with 0.6 wt% Pr. The relationships between response time (recovery time) and temperature, response time (recovery time) and concentration were investigated. The results demonstrated that the high response and relatively short response/recovery time were related to surface area, adsorbed oxygen species and oxygen vacancies.

  7. Lanthanide ions doped Y2Sn2O7 nano-particles: low temperature synthesis and photoluminescence study

    International Nuclear Information System (INIS)

    Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2008-01-01

    During the past decade, pyrochlore-type oxides (A 2 B 2 O 7 ) have emerged as important host matrices for lanthanide doped luminescent materials due to their higher thermal stability. Up to now, conventional solid-state reaction is the most commonly used synthetic method for preparation, of rare-earth pyrochlore oxides. This synthesis route employs a solid-state reaction of metal-oxide with appropriate rare-earth oxides at high temperature (>1200 deg C) for a long time (several days). However, in present work, Y 2 Sn 2 O 7 nanoparticles co-doped with lanthanide ions Tb 3+ and Ce 3+ were prepared based on the urea hydrolysis of Y 3+ , Sn 4+ , and Ln 3+ in ethylene glycol medium at 150 deg C followed by heating at 500, 700 and 900 deg C

  8. CO_2 capture in Mg oxides doped with Fe and Ni

    International Nuclear Information System (INIS)

    Sanchez S, I. F.

    2016-01-01

    In this work the CO_2 capture-desorption characteristics in Mg oxides doped with Fe and Ni obtained by the direct oxidation of Mg-Ni and Mg-Fe mixtures are presented. Mixtures of Mg-Ni and Mg-Fe in a different composition were obtained by mechanical milling in a Spex-type mill in a controlled atmosphere of ultra high purity argon at a weight / weight ratio of 4:1 powder using methanol as a lubricating agent, for 20 h. The powders obtained by mechanical milling showed as main phase, the Mg with nanocrystalline structure. Subsequently, the mixtures of Mg-Ni and Mg-Fe were oxidized within a muffle for 10 min at 600 degrees Celsius. By means of X-ray diffraction analysis, the Mg O with nano metric grain size was identified as the main phase, which was determined by the Scherrer equation. In the Mg O doped with Ni, was identified that as the Ni amount 1 to 5% by weight dispersed in the Mg O matrix was increased, the main peak intensity of the Ni phase increased, whereas in the Mg O doped with Fe was observed by XRD, that the Fe_2O_3 phase was present and by increasing the amount of Fe (1 to 5% by weight) dispersed in the crystalline phase of Mg O, the intensity of this impurity also increased. Sem-EDS analysis showed that the Ni and Fe particles are dispersed homogeneously in the Mg O matrix, and the particles are porous, forming agglomerates. Through energy dispersive spectroscopy analysis, the elemental chemical composition obtained is very close to the theoretical composition. The capture of CO_2 in the Mg O-1% Ni was carried out in a Parr reactor at different conditions of pressure, temperature and reaction time. Was determined that under the pressure of 0.2 MPa at 26 degrees Celsius for 1 h of reaction, the highest CO_2 capture of 7.04% by weight was obtained, while in Mg O-1% Fe the CO_2 capture was 6.32% by weight. The other magnesium oxides doped in 2.5 and 5% by weight Ni and Fe showed lower CO_2 capture. The different stages of mass loss and thermal

  9. Study of Si-Ge interdiffusion with phosphorus doping

    KAUST Repository

    Cai, Feiyang; Anjum, Dalaver H.; Zhang, Xixiang; Xia, Guangrui

    2016-01-01

    Si-Ge interdiffusion with phosphorus doping was investigated by both experiments and modeling. Ge/Si1-x Ge x/Ge multi-layer structures with 0.75doping, and a dislocation density of 108 to 109 cm−2 range were studied. The P-doped sample shows an accelerated Si-Ge interdiffusivity, which is 2–8 times of that of the undoped sample. The doping dependence of the Si-Ge interdiffusion was modelled by a Fermi-enhancement factor. The results show that the Si-Ge interdiffusion coefficient is proportional to n2/n2i for the conditions studied, which indicates that the interdiffusion in a high Ge fraction range with n-type doping is dominated by V2− defects. The Fermi-enhancement factor was shown to have a relatively weak dependence on the temperature and the Ge fraction. The results are relevant to the structure and thermal processing condition design of n-type doped Ge/Si and Ge/SiGe based devices such as Ge/Si lasers.

  10. Study of Si-Ge interdiffusion with phosphorus doping

    KAUST Repository

    Cai, Feiyang

    2016-10-28

    Si-Ge interdiffusion with phosphorus doping was investigated by both experiments and modeling. Ge/Si1-x Ge x/Ge multi-layer structures with 0.75doping, and a dislocation density of 108 to 109 cm−2 range were studied. The P-doped sample shows an accelerated Si-Ge interdiffusivity, which is 2–8 times of that of the undoped sample. The doping dependence of the Si-Ge interdiffusion was modelled by a Fermi-enhancement factor. The results show that the Si-Ge interdiffusion coefficient is proportional to n2/n2i for the conditions studied, which indicates that the interdiffusion in a high Ge fraction range with n-type doping is dominated by V2− defects. The Fermi-enhancement factor was shown to have a relatively weak dependence on the temperature and the Ge fraction. The results are relevant to the structure and thermal processing condition design of n-type doped Ge/Si and Ge/SiGe based devices such as Ge/Si lasers.

  11. Quaternary chalcogenides La{sub 3}Sn{sub 0.5}InS{sub 7} and La{sub 3}Sn{sub 0.5}InSe{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, Abishek K.; Lee, Emma J.; Bernard, Guy M.; Michaelis, Vladimir K.; Mar, Arthur [Department of Chemistry, University of Alberta, Edmonton, AB (Canada); Yin, Wenlong [Department of Chemistry, University of Alberta, Edmonton, AB (Canada); Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang (China)

    2017-12-13

    The quaternary chalcogenides La{sub 3}Sn{sub 0.5}InS{sub 7} and La{sub 3}Sn{sub 0.5}InSe{sub 7} were prepared by reactions of the elements at 1050 C and 950 C, respectively. They adopt noncentrosymmetric structures [hexagonal, space group P6{sub 3}, Z = 2; a = 10.2993(11) Aa, c = 6.0921(6) Aa for La{sub 3}Sn{sub 0.5}InS{sub 7}; a = 10.6533(7) Aa, c = 6.4245(4) Aa for La{sub 3}Sn{sub 0.5}InSe{sub 7}] in which the half-occupancy of Sn atoms within octahedral sites classifies them as belonging to the La{sub 3}Mn{sub 0.5}SiS{sub 7}-type branch of the large family of quaternary rare-earth chalcogenides RE{sub 3}M{sub 1-x}M{sup '}Ch{sub 7}. The site distribution in La{sub 3}Sn{sub 0.5}InCh{sub 7}, with higher-valent Sn atoms occupying octahedral instead of tetrahedral sites, is reversed from the typical situation observed in other RE{sub 3}M{sub 1-x}M{sup '}Ch{sub 7} compounds. The ordered distribution of Sn atoms in octahedral sites and In atoms in tetrahedral sites was evaluated by bond valence sum analyses. Moreover, {sup 119}Sn solid-state nuclear magnetic resonance (NMR) spectroscopy confirms the occupation of Sn{sup 4+} species exclusively within octahedral sites. An optical bandgap of 1.45 eV was found for La{sub 3}Sn{sub 0.5}InS{sub 7}. Band structure calculations on an ordered superstructure model of La{sub 3}Sn{sub 0.5}InS{sub 7} reveal that avoidance of strongly Sn-S antibonding levels is an important driving force for the Sn deficiency. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. In situ growth of SnO2 nanoparticles in heteroatoms doped cross-linked carbon frameworks for lithium ion batteries anodes

    International Nuclear Information System (INIS)

    Zhou, Xiangyang; Xi, Lihua; Chen, Feng; Bai, Tao; Wang, Biao; Yang, Juan

    2016-01-01

    Highlights: • A facile hydrothermal method is proposed to prepare cross-linked NSG/CNTs@SnO 2 . • The graphene/CNTs anchored with untrasmall SnO 2 nanoparticles can be obtained. • The N, S are successfully incorporated into the carbon matrix. • The NSG/CNTs@SnO 2 presents enhanced cycling stability and good high-rate capacity. - Abstract: SnO 2 -based nanostructures have attracted considerable interest as a promising high-capacity anode materials for lithium ion batteries. We present herein a facile one step hydrothermal approach for in situ growth of SnO 2 nanoparticles in heteroatoms doped cross-linked carbon framework (NSG/CNTs@SnO 2 ). Thiourea is employed as a single source of nitrogen and sulfur in the cross-linked carbon framework (NSG/CNTs). Characterization shows that the SnO 2 nanoparticles with an average size of 6–10 nm are uniformly anchored on NSG/CNTs matrix. When evaluated for the electrochemical properties in lithium ion batteries, the obtained NSG/CNTs@SnO 2 composite with ultrasmall SnO 2 particle size (6–10 nm) delivers a high reversible capacity of 999 mAh g −1 at 200 mA g −1 after 120 cycles and excellent rate performance. Such outstanding electrochemical performance of the peculiar cross-linked NSG/CNTs@SnO 2 composite can be primarily attributed to the synergistic effect of the ultrasmall anchored SnO 2 nanoparticles and the dual-doped NSG/CNTs matrix. The uniformly distributed SnO 2 nanoparticles can deliver large capacity and the robust dual-doped NSG/CNTs matrix can guarantee the good structural integrity and high electrical conductivity during cycling. Besides, the porous structure can provide free space for the volume expansion of SnO 2 and accommodate the strain formed during repeated lithiation/delithiation processes.

  13. Corrosion analysis of AlMg2 and AlMgSi using electrochemical method

    International Nuclear Information System (INIS)

    Dian A; Maman Kartaman; Rosika K; Yanlinastuti

    2014-01-01

    Corrosion test of cladding materials and structures of research reactor fuel, AlMgSi and AlMg2 have been performed in demineralized water of pH 2 and 6.7 using an electrochemical method. Corrosion phenomenon is affected by several factor such as composition and condition of solution. The purpose of this activity is to investigate the corrosion phenomena through the determination of the parameters of corrosion and polarization curve. The materials used are AlMg2 and AlMgSi alloy in circular dish shape with an area of 1 Cm"2. Preparation of the test sample is performed through several stages polishing, cleaning and drying procedures followed ASTM G3. The electrochemical method is done by measuring the open circuit potential (OCP), polarization resistance and potentiodynamic in demineralized water of pH 2 and pH 6.7 at temperature of 25°C. The results of the OCP is the corrosion potential (Ecorr) of AlMg2 and AlMgSi each of -906.1 mV and -619.8 mV at pH 2 and -868.6 and -756.7 mV at pH 6.7 mV. The results of measurements by polarization resistance technique showed that the corrosion rate of AlMg2 and AlMgSi in safe category (<2 mpy) at pH 6.7 and at pH 2 corrosion rate increased significantly, but still in the lightweight category (<20 mpy). Potentiodynamic curves showed that the passivation at pH 6.7 is very low while the passivation at pH 2 occurs within a relatively short range potential and followed events corroded. (author)

  14. Near-infrared light absorption by polycrystalline SiSn alloys grown on insulating layers

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, Masashi, E-mail: kurosawa@alice.xtal.nagoya-u.ac.jp [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); JSPS, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Kato, Motohiro; Yamaha, Takashi; Taoka, Noriyuki; Nakatsuka, Osamu [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Zaima, Shigeaki [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-04-27

    High-Sn-content SiSn alloys are strongly desired for the next-generation near-infrared optoelectronics. A polycrystalline growth study has been conducted on amorphous SiSn layers with a Sn-content of 2%–30% deposited on either a substrate of SiO{sub 2} or SiN. Incorporating 30% Sn into Si permits the crystallization of the amorphous layers at annealing temperatures below the melting point of Sn (231.9 °C). Composition analyses indicate that approximately 20% of the Sn atoms are substituted into the Si lattice after solid-phase crystallization at 150–220 °C for 5 h. Correspondingly, the optical absorption edge is red-shifted from 1.12 eV (Si) to 0.83 eV (Si{sub 1−x}Sn{sub x} (x ≈ 0.18 ± 0.04)), and the difference between the indirect and direct band gap is significantly reduced from 3.1 eV (Si) to 0.22 eV (Si{sub 1−x}Sn{sub x} (x ≈ 0.18 ± 0.04)). These results suggest that with higher substitutional Sn content the SiSn alloys could become a direct band-gap material, which would provide benefits for Si photonics.

  15. Effect of Mn doping on the structural, magnetic, optical and electrical properties of ZrO_2SnO_2 thin films prepared by sol–gel method

    International Nuclear Information System (INIS)

    Anitha, V.S.; Sujatha Lekshmy, S.; Joy, K.

    2016-01-01

    Manganese doped ZrO_2SnO_2 (ZrO_2SnO_2: Mn) nanocomposite thin films were prepared using sol – gel dip coating technique. The structural, morphological, magnetic, optical and electrical properties of the films were studied for undoped and different (15 mol %) manganese doping concentrations. X-ray diffraction pattern (XRD) of films showed the formation of tetragonal phase of SnO_2 and orthorhombic ZrSnO_4. Decrease in crystallinity with increase of Mn concentration was observed for the films. Scanning electron microscopy (SEM) showed the formation of grain growth with an increase in Mn concentration. X-ray photo electron spectroscopy (XPS) confirmed the presence of Zr"4"+, Sn"4"+ and Mn"2"+ ion in ZrO_2SnO_2: Mn films. Vibrating sample magnetometer (VSM) measurements reveal the presence of magnetic properties in Mn doped nanocomposite thin films. Antiferromagnetic interactions were observed for 5 mol % Mn doping. An average transmittance >80% (UV - Vis region) was observed for all the films. Band gap of the films decreased from 4.78 to 4.41 eV with increase in Mn concentration. Photoluminescence (PL) spectra of the films exhibited emission peaks in visible region of the electromagnetic spectra. Conductivity of the film increased up to 3 mol % Mn doping and then decreased. - Highlights: • ZrO_2SnO_2: Mn films were deposited onto quartz substrates by Sol –Gel dip coating. • Structural, magnetic, optical and electrical properties of the films were analyzed. • Optical band gap decreased with increase in manganese concentration. • Ferromagnetic behavior was observed for Mn doped films. • These ferromagnetic ZrO_2SnO_2: Mn films find application in spintronic devices.

  16. Epitaxial Sb-doped SnO_2 and Sn-doped In_2O_3 transparent conducting oxide contacts on GaN-based light emitting diodes

    International Nuclear Information System (INIS)

    Tsai, Min-Ying; Bierwagen, Oliver; Speck, James S.

    2016-01-01

    We demonstrate the growth of epitaxial (100)-oriented, rutile Sb-doped SnO_2 (ATO) and (111)-oriented, cubic Sn-doped In_2O_3 (ITO) transparent conducting oxide (TCO) contacts on top of an InGaN/GaN(0001) light emitting diode (LED) by plasma-assisted molecular beam epitaxy (PAMBE). Both oxides form rotational domains. The in-plane epitaxial alignment of the two ITO(111) rotational domains to the GaN(0001) was: GaN [21-10]|| ITO_D_o_m_a_i_n_1[‐ 211]|| ITO_D_o_m_a_i_n_2[‐ 1‐12]. A growth temperature as low as 600 °C was necessary to realize a low contact resistance between ATO and the top p-GaN layer of the LED but resulted in non-optimal resistivity (3.4 × 10"− "3 Ω cm) of the ATO. The current–voltage characteristics of a processed LED, however, were comparable to that of a reference LED with a standard electron-beam evaporated ITO top contact. At short wavelengths, the optical absorption of ATO was lower than that of ITO, which is beneficial even for blue LEDs. Higher PAMBE growth temperatures resulted in lower resistive ATO but higher contact resistance to the GaN, likely by the formation of an insulating Ga_2O_3 interface layer. The ITO contact grown by PAMBE at 600 °C showed extremely low resistivity (10"−"4 Ω cm) and high crystalline and morphological quality. These proof-of-principle results may lead to the development of epitaxial TCO contacts with low resistivity, well-defined interfaces to the p-GaN to help minimize contact losses, and enable further epitaxy on top of the TCO. - Highlights: • Plasma-assisted molecular beam epitaxy of SnO_2:Sb (ATO) and In_2O_3:Sn (ITO) contacts • Working light emitting diodes processed with the ATO contact on the top p-GaN layer • Low growth temperature ensures low contact resistance (limiting interface reaction). • ITO showed significantly better structural and transport properties than ATO. • ATO showed higher optical transmission at short wavelengths than ITO.

  17. Influence of film thickness on structural, optical, and electrical properties of spray deposited antimony doped SnO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Abhijit A., E-mail: aay_physics@yahoo.co.in

    2015-09-30

    Transparent conducting antimony doped SnO{sub 2} thin films with varying thickness were deposited by chemical spray pyrolysis technique from non-aqueous solvent Propan-2-ol. The effect of film thickness on the properties of antimony doped SnO{sub 2} thin films have been studied. X-ray diffraction measurements showed tetragonal crystal structure of as-deposited antimony doped SnO{sub 2} films irrespective of film thickness. The surface morphology of antimony doped SnO{sub 2} thin film is spherical with the continuous distribution of grains. Electrical and optical properties were investigated by Hall Effect and optical measurements. The average optical transmittance of films decreased from 89% to 73% within the visible range (350–850 nm) with increase in film thickness. The minimum value of sheet resistance observed is 4.81 Ω/cm{sup 2}. The lowest resistivity found is 3.76 × 10{sup −4} Ω cm at 660 nm film thickness. - Highlights: • Effect of film thickness on the properties of antimony doped SnO{sub 2} thin films • Crystalline size in the range of 34–37 nm • Average transmittance decreased from 89% to 73% in the visible region. • Minimum sheet resistance of 4.81 Ω/cm{sup 2} • Lowest resistivity is found to be 3.76 × 10{sup −4} Ω cm at 660 nm film thickness.

  18. Phase relationships in the quasi-ternary LaO1.5–SiO2MgO system at 1773 K

    Directory of Open Access Journals (Sweden)

    Kiyoshi Kobayashi and Yoshio Sakka

    2012-01-01

    Full Text Available Phase relationships in the LaO1.5–SiO2MgO quasi-ternary system at 1773 K were investigated by powder x-ray diffraction (XRD analysis applying single- and multiple-phase Rietveld methods. Most of the formed phases satisfied the Gibbs' phase rule, except for the samples containing LaO1.5 and a liquid phase at 1773 K. The detection of segregated MgO phases was difficult in the XRD profiles of the compositional samples around the oxyapatite single phase because the MgO peaks were weak and heavily overlapped by peaks from the oxyapatite and La(OH3 phases. The solid solubility limit of MgO in oxyapatite was determined not only from the chemical composition of the oxyapatite phase, which was confirmed by XRD, but also from several phase boundary compositions among the two-phase and three-phase regions based on the Gibbs' phase rule. Formation of a liquid phase at 1773 K was observed in a wide range of compositions and considered when constructing the phase diagram.

  19. SiO{sub 2}@SnO{sub 2}/graphene composite with a coating and hierarchical structure as high performance anode material for lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xingfa; Zhang, Haiyan, E-mail: hyzhang@gdut.edu.cn; Chen, Yiming; Li, Na; Li, Yunyong; Liu, Liying

    2016-08-25

    In order to ease the agglomeration and huge volume change of SnO{sub 2} particles, SnO{sub 2} nanoparticles were usually anchored on reduced graphene oxide (rGO) and used as anode materials for lithium ion batteries. Unfortunately, graphene sheets tended to overlap with adjacent ones and SnO{sub 2} nanoparticles still suffered from agglomeration and huge volume changes to some extent. In this paper, a composite SiO{sub 2}@SnO{sub 2}/rGO with coating and hierarchical structure was synthesized by a facile hydrothermal method. SnO{sub 2} nanoparticles mono-dispersed on the surface of rGO sheets and SiO{sub 2} spheres, while the SiO{sub 2}@SnO{sub 2} spheres were imbedded in the layers of rGO, which was in favor of alleviating the overlapping of graphene sheets and could make large spacious room to accommodate the huge volume changes of SnO{sub 2} nanoparticles. SiO{sub 2}@SnO{sub 2}/rGO composite also displayed good electrochemical performance. In the first charge/discharge cycle, the SiO{sub 2}@SnO{sub 2}/rGO electrode exhibited a large discharge capacity of 1548 mA h g{sup −1} at a current density of 100 mA g{sup −1} and it still retained a discharge capacity of about 600 mA h g{sup −1} after 100 cycles. - Highlights: • Anodes fabricated by using activated carbon have the highest fracture strength. • SnO{sub 2} nanoparticles are mono-dispersed on the surface of rGO sheets and SiO{sub 2} spheres. • The hierarchical structure SiO{sub 2}@SnO{sub 2}/rGO shows a good electrochemical performance.

  20. The Effect of Eu Doping on Microstructure, Morphology and Methanal-Sensing Performance of Highly Ordered SnO2 Nanorods Array

    Directory of Open Access Journals (Sweden)

    Yanping Zhao

    2017-11-01

    Full Text Available Layered Eu-doped SnO2 ordered nanoarrays constructed by nanorods with 10 nm diameters and several hundred nanometers length were synthesized by a substrate-free hydrothermal route using alcohol and water mixed solvent of sodium stannate and sodium hydroxide at 200 °C. The Eu dopant acted as a crystal growth inhibitor to prevent the SnO2 nanorods growth up, resulting in tenuous SnO2 nanorods ordered arrays. The X-ray diffraction (XRD revealed the tetragonal rutile-type structure with a systematic average size reduction and unit cell volume tumescence, while enhancing the residual strain as the Eu-doped content increases. The surface defects that were caused by the incorporation of Eu ions within the surface oxide matrix were observed by high-resolution transmission electron microscope (HRTEM. The results of the response properties of sensors based on the different levels of Eu-doped SnO2 layered nanoarrays demonstrated that the 0.5 at % Eu-doped SnO2 layered nanorods arrays exhibited an excellent sensing response to methanal at 278 °C. The reasons of the enhanced sensing performance were discussed from the complicated defect surface structure, the large specific surface area, and the excellent catalytic properties of Eu dopant.

  1. Coherent interface structures and intergrain Josephson coupling in dense MgO/Mg{sub 2}Si/MgB{sub 2} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Katsuya; Takahashi, Kazuyuki; Uchino, Takashi, E-mail: uchino@kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Nagashima, Yukihito [Nippon Sheet Glass Co., Ltd., Konoike, Itami 664-8520 (Japan); Seto, Yusuke [Department of Planetology, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Matsumoto, Megumi; Sakurai, Takahiro [Center for Support to Research and Education Activities, Kobe University, Nada, Kobe 657-8501 (Japan); Ohta, Hitoshi [Molecular Photoscience Research Center, Kobe University, Nada, Kobe 657-8501 (Japan)

    2016-07-07

    Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg{sub 2}Si)/superconductor(MgB{sub 2}) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg{sub 2}Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB{sub 2} nanograins surrounded by the MgO/Mg{sub 2}Si matrix. This transition is followed by the intergrain phase-lock transition at ∼24 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces, but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling.

  2. Synthesis, characterization and photoluminescence properties of Dy3+ -doped nano-crystalline SnO2.

    CSIR Research Space (South Africa)

    Pillai, SK

    2010-04-15

    Full Text Available the crystallite size. The experimental result on photoluminescence characteristics originating from Dy3+-doping in nanocrystalline SnO2 reveals the dependence of the luminescent intensity on dopant concentration....

  3. Al-doped MgB_2 materials studied using electron paramagnetic resonance and Raman spectroscopy

    International Nuclear Information System (INIS)

    Bateni, Ali; Somer, Mehmet; Erdem, Emre; Repp, Sergej; Weber, Stefan

    2016-01-01

    Undoped and aluminum (Al) doped magnesium diboride (MgB_2) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB_2 samples were systematically investigated using X-ray powder diffraction, Raman spectroscopy, and electron paramagnetic resonance. It was found that Mg-vacancies are responsible for defect-induced peculiarities in MgB_2. Above a certain level of Al doping, enhanced conductive properties of MgB_2 disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites.

  4. All-perovskite transparent high mobility field effect using epitaxial BaSnO3 and LaInO3

    Directory of Open Access Journals (Sweden)

    Useong Kim

    2015-03-01

    Full Text Available We demonstrate an all-perovskite transparent heterojunction field effect transistor made of two lattice-matched perovskite oxides: BaSnO3 and LaInO3. We have developed epitaxial LaInO3 as the gate oxide on top of BaSnO3, which were recently reported to possess high thermal stability and electron mobility when doped with La. We measured the dielectric properties of the epitaxial LaInO3 films, such as the band gap, dielectric constant, and the dielectric breakdown field. Using the LaInO3 as a gate dielectric and the La-doped BaSnO3 as a channel layer, we fabricated field effect device structure. The field effect mobility of such device was higher than 90 cm2 V−1 s−1, the on/off ratio was larger than 107, and the subthreshold swing was 0.65 V dec−1. We discuss the possible origins for such device performance and the future directions for further improvement.

  5. Binding SnO2 nanocrystals in nitrogen-doped graphene sheets as anode materials for lithium-ion batteries.

    Science.gov (United States)

    Zhou, Xiaosi; Wan, Li-Jun; Guo, Yu-Guo

    2013-04-18

    Hybrid anode materials for Li-ion batteries are fabricated by binding SnO2 nanocrystals (NCs) in nitrogen-doped reduced graphene oxide (N-RGO) sheets by means of an in situ hydrazine monohydrate vapor reduction method. The SnO2NCs in the obtained SnO2NC@N-RGO hybrid material exhibit exceptionally high specific capacity and high rate capability. Bonds formed between graphene and SnO2 nanocrystals limit the aggregation of in situ formed Sn nanoparticles, leading to a stable hybrid anode material with long cycle life. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. The effect of simultaneous substitution on the electronic band structure and thermoelectric properties of Se-doped Co3SnInS2 with the Kagome lattice

    Science.gov (United States)

    Fujioka, Masaya; Shibuya, Taizo; Nakai, Junya; Yoshiyasu, Keigo; Sakai, Yuki; Takano, Yoshihiko; Kamihara, Yoichi; Matoba, Masanori

    2014-12-01

    The thermoelectric properties and electronic band structures for Se-doped Co3SnInS2 were examined. The parent compound of this material (Co3Sn2S2) has two kinds of Sn sites (Sn1 and Sn2 sites). The density functional theory (DFT) calculations show that the indium substitution at the Sn2 site induces a metallic band structure, on the other hand, a semiconducting band structure is obtained from substitution at the Sn1 site. However, according to the previous reports, since the indium atom prefers to replace the tin atom at the Sn1 site rather than the Sn2 site, the resistivity of Co3SnInS2 shows semiconducting-like behavior. In this study we have demonstrated that metallic behavior and a decrease in resistivity for Se-doped Co3SnInS2 occurs without suppression of the Seebeck coefficient. From the DFT calculations, when the selenium content is above 0.5, the total crystallographic energy shows that a higher indium occupancy at Sn2 site is more stable. Therefore, it is suggested that the selenium doping suppress the site preference for indium substitution. This is one of the possible explanations for the metallic conductivity observed in Se-doped Co3SnInS2

  7. Structure and electrochemical properties of Mg2SnO4 nanoparticles synthesized by a facile co-precipitation method

    International Nuclear Information System (INIS)

    Tang, Hao; Cheng, Cuixia; Yu, Gaige; Liu, Haowen; Chen, Weiqing

    2015-01-01

    Nanosized Mg 2 SnO 4 has been synthesized by a facile co-precipitation method. The structure and morphology of the as-prepared samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), fourier Transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that Mg 2 SnO 4 sample is very sensitive to the aging time of the precursor. The single phase Mg 2 SnO 4 nanoparticles with ∼23 nm can be obtained at 900 °C using the aging 35 min percusor as source. The electrochemical properties of the powder obtained at 900 °C are investigated by galvanostatic discharge-charge tests and cyclic voltammograms (CVs). The initial specific discharge capacity reaches as high as 927.7 mAh g −1 at 0.2 mA cm −2 in 0.05–3.0 V, which indicates that Mg 2 SnO 4 nanoparticles could be a promising candidate of anode material for Li-ion batteries. - Highlights: • Nanosized Mg 2 SnO 4 has been synthesized by a facile co-precipitation method. • We find that Mg 2 SnO 4 sample is very sensitive to the ageing time of the precursor. • The single phase Mg 2 SnO 4 nanoparticles with about 23 nm can be obtained by calcining the ageing 35 min percusor at 900 °C. • The obtained powders show a better electrochemical performance

  8. SiFTO: An Empirical Method for Fitting SN Ia Light Curves

    Science.gov (United States)

    Conley, A.; Sullivan, M.; Hsiao, E. Y.; Guy, J.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Hardin, D.; Howell, D. A.; Hook, I. M.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.

    2008-07-01

    We present SiFTO, a new empirical method for modeling Type Ia supernova (SN Ia) light curves by manipulating a spectral template. We make use of high-redshift SN data when training the model, allowing us to extend it bluer than rest-frame U. This increases the utility of our high-redshift SN observations by allowing us to use more of the available data. We find that when the shape of the light curve is described using a stretch prescription, applying the same stretch at all wavelengths is not an adequate description. SiFTO therefore uses a generalization of stretch which applies different stretch factors as a function of both the wavelength of the observed filter and the stretch in the rest-frame B band. We compare SiFTO to other published light-curve models by applying them to the same set of SN photometry, and demonstrate that SiFTO and SALT2 perform better than the alternatives when judged by the scatter around the best-fit luminosity distance relationship. We further demonstrate that when SiFTO and SALT2 are trained on the same data set the cosmological results agree. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.

  9. The effect of doping on thermoelectric performance of p-type SnSe: Promising thermoelectric material

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Niraj Kumar; Bathula, Sivaiah; Gahtori, Bhasker [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Tyagi, Kriti [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Acdemy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (NPL) Campus, New Delhi (India); Haranath, D. [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Dhar, Ajay, E-mail: adhar@nplindia.org [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

    2016-05-25

    Tin selenide (SnSe) based thermoelectric materials are being explored for making inexpensive and efficient thermoelectric devices with improved thermoelectric efficiency. As both Sn and Se are earth abundant and relatively inexpensive and these alloys do not involve toxic materials, such as lead and expensive tellurium. Hence, in the present study, we have synthesized SnSe doped with 2 at% of aluminium (Al), lead (Pb), indium (In) and copper (Cu) individually, which is not reported in literature. Out of these, Cu doped SnSe resulted in enhancement of figure-of-merit (zT) of ∼0.7 ± 0.02 at 773 K, synthesized employing conventional fusion method followed by spark plasma sintering. This enhancement in zT is ∼16% over the existing state-of-the-art value for p-type SnSe alloy doped with expensive Ag. This enhancement in ZT is primarily due to the presence of Cu{sub 2}Se second phase associated with intrinsic nanostructure formation of SnSe. This enhancement has been corroborated with the microstructural characterization using field emission scanning electron microscopy and X-ray diffraction studies. Also, Cu doped SnSe exhibited a higher value of carrier concentration in comparison to other samples doped with Al, Pb and In. Further, the compatibility factor of Cu doped SnSe alloys exhibited value of 1.62 V{sup −1} at 773 K and it is suitable to segment with most of the novel TE materials for obtaining the higher thermoelectric efficiencies. - Highlights: • Tin selenide (SnSe) doped with non-toxic and inexpensive dopants. • Synthesized highly dense SnSe employing Spark plasma sintering. • Enhanced thermoelectric compatibility factor of SnSe. • Enhanced thermoelectric performance of SnSe doped with Copper.

  10. Sol–gel synthesis of SnO2MgO nanoparticles and their photocatalytic activity towards methylene blue degradation

    International Nuclear Information System (INIS)

    Bayal, Nisha; Jeevanandam, P.

    2013-01-01

    Graphical abstract: - Highlights: • A simple sol–gel method for the synthesis of SnO 2MgO nanoparticles is reported. • Band gap of SnO 2 can be tuned by varying the magnesium content in SnO 2MgO. • SnO 2MgO shows good photocatalytic activity towards degradation of methylene blue. - Abstract: SnO 2MgO mixed metal oxide nanoparticles were prepared by a simple sol–gel method. The nanoparticles were characterized by power X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The XRD results indicate the formation of mixed metal oxide nanoparticles and also a decrease of SnO 2 crystallite size in the mixed metal oxide nanoparticles with increasing magnesium oxide content. The reflectance spectroscopy results show a blue shift of the band gap of SnO 2 in the mixed metal oxide nanoparticles. The photocatalytic activity of the SnO 2MgO nanoparticles was tested using the photodegradation of aqueous methylene blue in the presence of sunlight. The results indicate that the mixed metal oxide nanoparticles possess higher efficiency for the photodegradation of methylene blue compared to pure SnO 2 nanoparticles

  11. Study on preparation of orange-emitting phosphor Y3Mg2AlSi2O12: Ce3+ for wLED

    Directory of Open Access Journals (Sweden)

    Yan Shirun

    2017-12-01

    Full Text Available Ce3+-doped garnet-structured orange-emitting phosphor Y3Mg2AlSi2O12:Ce3+ was prepared by sol-gel combustion using urea as a fuel.Effects of the reduction temperature,Ce3+ doping concentration on the structure,morphology,and photoluminescence property of the as-prepared phosphor were investigated by X-ray diffraction(XRD,scaning electron microscope(SEM,photoluminescence spectroscopy and UV-Vis reflection spectroscopy.The crystallinities,morphologies,and photoluminescence properties of the phosphors prepared by sol-gel combustion and solid-state reaction were compared.The reasons causing different performance of the phosphors were discussed.

  12. Doping effects on structural and magnetic properties of Heusler alloys Fe2Cr1-xCoxSi

    Science.gov (United States)

    Liu, Yifan; Ren, Lizhu; Zheng, Yuhong; He, Shikun; Liu, Yang; Yang, Ping; Yang, Hyunsoo; Teo, Kie Leong

    2018-05-01

    In this work, 30nm Fe2Cr1-xCoxSi (FCCS) magnetic films were deposited on Cr buffered MgO (100) substrates by sputtering. Fe2Cr0.5Co0.5Si exhibits the largest magnetization and optimal ordered L21 cubic structure at in-situ annealing temperature (Tia) of 450°C. The Co composition dependence of crystalline structures, surface morphology, defects, lattice distortions and their correlation with the magnetic properties are analyzed in detail. The Co-doped samples show in-plane M-H loops with magnetic squareness ratio of 1 and increasing anisotropy energy density with Co composition. Appropriate Co doping composition promotes L21 phase but higher Co composition converts L21 to B2 phase. Doping effect and lattice mismatch both are proved to increase the defect density. In addition, distortions of the FCCS lattice are found to be approximately linear with Co composition. The largest lattice distortion (c/a) is 0.969 for Fe2Cr0.25Co0.75Si and the smallest is 0.983 for Fe2CrSi. Our analyses suggest that these tetragonal distortions mainly induced by an elastic stress from Cr buffer account for the large in-plane anisotropy energy. This work paves the way for further tailoring the magnetic and structural properties of quaternary Heusler alloys.

  13. The effect of doping Mg2+ on structure and properties of Sr(1.992-x)MgxSiO4: 0.008Eu2+ blue phosphor synthesized by co-precipitation method

    Science.gov (United States)

    Yang, Lingxiang; Wang, Jin-shan; Zhu, Da-chuan; Pu, Yong; Zhao, Cong; Han, Tao

    2018-01-01

    In order to improve the luminescence property of silicate phosphors, a series of Sr(1.992-x)MgxSiO4: 0.008Eu2+(x = 0, 0.25, 0.50, 0.75) blue phosphors have been synthesized using one-step calcination of a precursor prepared by chemical co-precipitation. And then the crystal structure and luminescence properties of the phosphors are investigated by means of X-Ray Diffraction and spectrophotometer. The results show that β-phase existed in the mixed phases of Sr2SiO4 (β+α‧) would transform to α‧-phase with Mg2+ ions doping into the silicate host until it disappeared. On the other hand, the introduction of Mg2+ ions can enhance the intensity of the excitation spectrum and promote the excitation sensitivity of Sr(1.992-x)MgxSiO4: 0.008Eu2+ phosphors in NUV region. Under NUV excitation at 350 nm, all samples exhibit a broadband emission in range of 400-550 nm due to the 4f65d1→4f7(8S7/2) transition of Eu2+ ions. According to Multi-peak fitting to emission spectra by Gauss method, the broad emission band consists of two single bands with peaks Em1 and Em2 locating at 460 and 490 nm, which corresponds to Eu2+ ions occupying the ten-fold oxygen-coordinated Sr1 site and the nine-fold oxygen-coordinated Sr2 site, respectively. The luminescence intensity of Sr(1.992-x)MgxSiO4:0.008Eu2+(x = 0, 0.25, 0.50, 0.75) blue phosphors has been enhanced remarkably after Mg2+ ions are added. Meanwhile, the chromaticity coordinates change from the blue-green region to the blue region as x moves from 0 to 0.75. Moreover, the decay curves are measured and can be well fitted with double exponential decay equation. It shows that the average lifetime is extended with the concentration of Mg2+ ions increasing. These results indicate that Sr(1.992-x)MgxSiO4: 0.008Eu2+(x = 0, 0.25, 0.50, 0.75) can be used as a potential blue phosphor in near UV-excited white LEDs.

  14. Development and characterization of Mn2+-doped MgO nanoparticles by solution combustion synthesis

    Science.gov (United States)

    Basha, Md. Hussain; Gopal, N. O.; Rao, J. L.; Nagabhushana, H.; Nagabhushana, B. M.; Chakradhar, R. P. S.

    2015-06-01

    Mn doped MgO Nanoparticles have been prepared by Solution Combustion Synthesis. The synthesized sample is characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Paramagnetic Resonance (EPR). The prepared MgO:Mn (1 mol%) nano crystals appear to be of simple cubic crystalline phase with lattice parameters a = 4.218(2) Å and cell volume = 74.98 (7) Å3. SEM micrograph of powders show highly porous, many agglomerates with irregular morphology, large voids, cracks and pores. EPR spectrum of the sample at room temperature exhibit an isotropic sextet hyperfine pattern, centered at g=1.99, characteristic if Mn2+ ions with S=I=5/2.The observed g value and the hyperfine value reveal the ionic bonding between Mn2+ and its surroundings.

  15. Development and characterization of Mn2+-doped MgO nanoparticles by solution combustion synthesis

    International Nuclear Information System (INIS)

    Basha, Md. Hussain; Gopal, N. O.; Rao, J. L.; Nagabhushana, H.; Nagabhushana, B. M.; Chakradhar, R. P. S.

    2015-01-01

    Mn doped MgO Nanoparticles have been prepared by Solution Combustion Synthesis. The synthesized sample is characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Paramagnetic Resonance (EPR). The prepared MgO:Mn (1 mol%) nano crystals appear to be of simple cubic crystalline phase with lattice parameters a = 4.218(2) Å and cell volume = 74.98 (7) Å 3 . SEM micrograph of powders show highly porous, many agglomerates with irregular morphology, large voids, cracks and pores. EPR spectrum of the sample at room temperature exhibit an isotropic sextet hyperfine pattern, centered at g=1.99, characteristic if Mn 2+ ions with S=I=5/2.The observed g value and the hyperfine value reveal the ionic bonding between Mn 2+ and its surroundings

  16. Investigation of fluorine adsorption on nitrogen doped MgAl_2O_4 surface by first-principles

    International Nuclear Information System (INIS)

    Lv, Xiaojun; Xu, Zhenming; Li, Jie; Chen, Jiangan; Liu, Qingsheng

    2016-01-01

    Graphical abstract: First-principles calculations indicate that MgAl_2O_4 surface is fluorine-loving, but hydrophobic. N doped MgAl_2O_4 (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl_2O_4 (100) > Al_2O_3 (0001) > MgAl_2O_4 (100) > MgO (100). N doped MgAl_2O_4 is a promising candidate for fluorine removal. - Highlights: • MgAl_2O_4 surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl_2O_4 > Al_2O_3 > MgAl_2O_4 > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl_2O_4 is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl_2O_4 surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl_2O_4 surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl_2O_4 (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl_2O_4 (100) > Al_2O_3 (0001) > MgAl_2O_4 (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl_2O_4 attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these evidences demonstrate a fact nitrogen doped MgAl_2O_4 is a promising candidate for fluorine removal.

  17. Sn-doped polyhedral In2O3 particles: Synthesis, characterization, and origins of luminous emission in wide visible range

    International Nuclear Information System (INIS)

    Zhu Yunqing; Chen Yiqing

    2012-01-01

    Sn-doped octahedronal and tetrakaidecahedronal In 2 O 3 particles were successfully synthesized by simple thermal evaporation of indium grains using SnO as dopant. Structural characterization results demonstrated that the Sn-doped tetrakaidecahedronal In 2 O 3 particle had additional six {001} crystal surfaces compared with the octahedronal one. The luminous properties of both samples were characterized by photoluminescence (PL) and cathodoluminescence (CL) spectroscopy. A broad visible luminous emission around 570 nm was observed. Studies revealed that the emission consisted of three peaks of 511 nm, 564 nm, and 622 nm, which were attributed to radioactive recombination centers such as single ionized oxygen vacancy, indium interstitial, and antisite oxygen, respectively. We believe that the Sn donor level plays an important role in the visible luminous emission. - Graphical abstract: With more oxygen vacancies and tin doping. ITO particles can exhibit a better CL performance. Sn donor level near the conduction band edge plays an important role in luminous emission in wide visible range. Highlights: ► Polyhedral ITO particles synthesized by thermal evaporation using SnO as dopant. ► Broad visible luminous emission around 570 nm. ► Sn donor level plays an important role in the visible emission. ► ITO particles with more oxygen vacancies have better CL performance in visible range.

  18. Magnetic nanoparticles induced dielectric enhancement in (La, Gd)2O3: SiO2 composite systems

    Science.gov (United States)

    Kao, T. H.; Mukherjee, S.; Yang, H. D.

    2013-11-01

    Magnetic Gd2O3 and non-magnetic La2O3 nanoparticles (NPs) have been synthesized together with different doping concentrations in SiO2 matrix via sol-gel route calcination at 700 °C and above. Properly annealed NP-glass composite systems show enhancement of dielectric constant and magnetodielectric effect (MDE) near room temperature, depending on superparamagnetic NPs concentrations. From application point of view, the enhancement of dielectric constant along with MDE can be achieved by tuning the NPs size through varying calcination temperature and/or increasing the doping concentration of magnetic rare earth oxide.

  19. Microscopic unravelling of nano-carbon doping in MgB2 superconductors fabricated by diffusion method

    International Nuclear Information System (INIS)

    Wong, D.C.K.; Yeoh, W.K.; De Silva, K.S.B.; Kondyurin, A.; Bao, P.; Li, W.X.; Xu, X.; Peleckis, G.; Dou, S.X.; Ringer, S.P.; Zheng, R.K.

    2015-01-01

    Highlights: • First report on nano-carbon doped MgB 2 superconductors synthesized by diffusion method. • Microstructure and superconducting properties of the superconductors are discussed. • B 4 C region blocks the Mg from reacting with B in the 10% nano-carbon doped sample. • MgB 2 with 2.5% nano-carbon doped showed the highest J c , ≈10 4 A/cm 2 for 20 K at 4 T. - Abstract: We investigated the effects of nano-carbon doping as the intrinsic (B-site nano-carbon substitution) and extrinsic (nano-carbon derivatives) pinning by diffusion method. The contraction of the in-plane lattice confirmed the presence of disorder in boron sublattice caused by carbon substitution. The increasing value in full width half maximum (FWHM) in the X-ray diffraction (XRD) patterns with each increment in the doping level reveal smaller grains and imperfect MgB 2 crystalline. The strain increased across the doping level due to the carbon substitution in the MgB 2 matrix. The broadening of the T c curves from low to high doping showed suppression of the connectivity of the bulk samples with progressive dirtying. At high doping, the presence of B 4 C region blocked the Mg from reacting with crystalline B thus hampering the formation of MgB 2 . Furthermore, the unreacted Mg acted as a current blocking phase in lowering down the grain connectivity hence depressing the J c of the 10% nano-carbon doped MgB 2 bulk superconductor

  20. Effects of graphite doping on critical current density and microstructure of MgB{sub 2} bulks by an improved Mg-diffusion method

    Energy Technology Data Exchange (ETDEWEB)

    Pan, X.F. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia)], E-mail: yshao@home.swjtu.edu.cn; Feng, Y. [Northwest Institute for Nonferrous Metal Research, P.O. Box 51, Xi' an, Shaanxi 710016 (China); Western Superconductivity Technology Company, Xi' an (China); Yang, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia)

    2008-09-15

    abstract: A series of graphite-doped MgB{sub 2} bulks with high density have been successfully prepared by an improved Mg-diffusion method in ambient pressure. The effects of graphite doping on lattice parameters, T{sub c}, J{sub c} and microstructure of MgB{sub 2} have been investigated. The results show that compared to the nano-C-doped or CNTs-doped MgB{sub 2}, C is not easy to substitute B in graphite-doped MgB{sub 2}. However, at the same C content, the graphite-doped MgB{sub 2} has a higher J{sub c}. At 10 K and self-field, the J{sub c} for MgB{sub 1.985}C{sub 0.015} reaches 0.58 MA/cm{sup 2}. For the MgB{sub 1.945}C{sub 0.055}, at 5 K, 7 T and 10 K, 6 T the J{sub c} achieves 10,000 A/cm{sup 2} which is two orders of magnitude higher than that for the undoped sample. In addition to improving electron scattering and intergranular connectivity, the unreacted graphite in the graphite-doped MgB{sub 2} is proposed to be responsible to the excellent J{sub c} properties of MgB{sub 2} in high fields, due to depressed grain growth and enhanced grain boundary flux pinning.

  1. La5M3X (M=Sn, Bi; X=Cl, Br, I): exploring the limit of the Mn5Si3-type hosting lattice

    International Nuclear Information System (INIS)

    Zheng Chong; Mattausch, Hansjuergen; Simon, Arndt

    2002-01-01

    Three new compounds add to the family of the Mn 5 Si 3 type host-guest lattice. These are La 5 Sn 3 X (X=Cl, Br, I) synthesized from stoichiometric mixtures of La, LaX 3 and Sn heated under Ar atmosphere in sealed Ta ampoules at 850-990 deg. C for 13-62 days. La 5 Sn 3 X crystallize in the space group P6 3 /mcm (No. 193) with lattice parameters a=9.603(1) A, 9.637(1) A and 9.673(1) A; c=6.890(1) A, 6.931(1) A and 6.987(1) A, respectively, for X=Cl, Br and I. Computational analysis using both the extended Hueckel and the local density functional methods showed that the Sn and La site acts as electron reservoir, providing electrons to the interstitials as necessary. This gives rise to a metallic behavior. Susceptibility and conductivity measurements confirmed these predictions. The single crystal structure of La 5 Bi 3 Br is also reported

  2. Concurrent doping effect of Ti and nano-diamond on flux pinning of MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Y., E-mail: yzhao@swjtu.edu.c [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Ke, C. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Feng, Y. [Northwest Institute for Nonferrous Metal Research, P.O. Box 51, Xian, Shaanxi 710016 (China); Western Superconductivity Technology Company, Xian (China); Yang, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Munroe, P. [Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)

    2010-11-01

    Nano-diamond and titanium concurrently doped MgB{sub 2} nanocomposites have been prepared by solid state reaction method. The effects of carbon and Ti concurrent doping on J{sub c}-H behavior and pinning force scaling features of MgB{sub 2} have been investigated. Although T{sub c} was slightly depressed, J{sub c} of MgB{sub 2} have been significantly improved by the nano-diamond doping, especially in the high field region. In the mean time, the J{sub c} value in low field region is sustained though concurrent Ti doping. Microstructure analysis reveals that when nano-diamond was concurrently doped with titanium in MgB{sub 2}, a unique nanocomposite in which TiB{sub 2} forms a thin layer surrounding MgB{sub 2} grains whereas nano-diamond particles were wrapped inside the MgB{sub 2} grains. Besides, nano-diamond doping results in a high density stress field in the MgB{sub 2} samples, which may take responsibility for the {Delta}{kappa} pinning behavior in the carbon-doped MgB{sub 2} system.

  3. Preparation of p-type GaN-doped SnO2 thin films by e-beam evaporation and their applications in p-n junction

    Science.gov (United States)

    Lv, Shuliang; Zhou, Yawei; Xu, Wenwu; Mao, Wenfeng; Wang, Lingtao; Liu, Yong; He, Chunqing

    2018-01-01

    Various transparent GaN-doped SnO2 thin films were deposited on glass substrates by e-beam evaporation using GaN:SnO2 targets of different GaN weight ratios. It is interesting to find that carrier polarity of the thin films was converted from n-type to p-type with increasing GaN ratio higher than 15 wt.%. The n-p transition in GaN-doped SnO2 thin films was explained for the formation of GaSn and NO with increasing GaN doping level in the films, which was identified by Hall measurement and XPS analysis. A transparent thin film p-n junction was successfully fabricated by depositing p-type GaN:SnO2 thin film on SnO2 thin film, and a low leakage current (6.2 × 10-5 A at -4 V) and a low turn-on voltage of 1.69 V were obtained for the p-n junction.

  4. Polar catastrophe at the MgO(100)/SnO2(110) interface

    KAUST Repository

    Albar, Arwa

    2016-11-14

    First principles calculations, based on density functional theory, are used to investigate the structural and electronic properties of the epitaxial MgO(100)/SnO2(110) interface of wide band gap insulators. Depending on the interface termination, nonmagnetic metallic and half-metallic interface states are observed. The formation of these states is explained by a polar catastrophe model for nonpolar-polar interfaces. Strong lattice distortions and buckling develop in SnO2, which influence the interface properties as the charge discontinuity is partially screened. Already a single unit cell of SnO2 is sufficient to drive the polar catastrophe scenario. © 2016 The Royal Society of Chemistry.

  5. Luminescence properties of Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Lei Bingfu, E-mail: tleibf@jnu.edu.cn [Department of Physics, Jinan University, Guangzhou 510632 (China); Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Man Shiqing [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Department of Electronic Engineering, Jinan University, Guangzhou 510632 (China); Liu Yingliang [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Yue Song [Department of Physics, Jinan University, Guangzhou 510632 (China)

    2010-12-01

    We report on a luminescent phenomenon in Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} afterglow phosphor. XRD, photoluminescence, afterglow emission spectra and long-lasting phosphorescence decay curve are used to characterize this phosphor. After irradiation by a 267-nm UV light for 5 min, the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor emits intense reddish-orange emitting afterglow from the {sup 4}G{sub 5/2} to {sup 6}H{sub J} (J = 5/2, 7/2, 9/2) transitions, and its afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source. Photoluminescence spectra reveal that the reddish-orange light-emitting long-lasting phosphorescence originate from the mixture of Sm{sup 3+} characteristic transitions. The afterglow decay curve of the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor contains a fast decay component and another slow decay one. The possible mechanism of this reddish-orange light-emitting LLP phosphor is also discussed based on the experiment results.

  6. Growth of SnO2 Nanoflowers on N-doped Carbon Nanofibers as Anode for Li- and Na-ion Batteries

    Science.gov (United States)

    Liang, Jiaojiao; Yuan, Chaochun; Li, Huanhuan; Fan, Kai; Wei, Zengxi; Sun, Hanqi; Ma, Jianmin

    2018-06-01

    It is urgent to solve the problems of the dramatic volume expansion and pulverization of SnO2 anodes during cycling process in battery systems. To address this issue, we design a hybrid structure of N-doped carbon fibers@SnO2 nanoflowers (NC@SnO2) to overcome it in this work. The hybrid NC@SnO2 is synthesized through the hydrothermal growth of SnO2 nanoflowers on the surface of N-doped carbon fibers obtained by electrospinning. The NC is introduced not only to provide a support framework in guiding the growth of the SnO2 nanoflowers and prevent the flower-like structures from agglomeration, but also serve as a conductive network to accelerate electronic transmission along one-dimensional structure effectively. When the hybrid NC@SnO2 was served as anode, it exhibits a high discharge capacity of 750 mAh g-1 at 1 A g-1 after 100 cycles in Li-ion battery and 270 mAh g-1 at 100 mA g-1 for 100 cycles in Na-ion battery, respectively.[Figure not available: see fulltext.

  7. Surface passivation of n-type doped black silicon by atomic-layer-deposited SiO2/Al2O3 stacks

    Science.gov (United States)

    van de Loo, B. W. H.; Ingenito, A.; Verheijen, M. A.; Isabella, O.; Zeman, M.; Kessels, W. M. M.

    2017-06-01

    Black silicon (b-Si) nanotextures can significantly enhance the light absorption of crystalline silicon solar cells. Nevertheless, for a successful application of b-Si textures in industrially relevant solar cell architectures, it is imperative that charge-carrier recombination at particularly highly n-type doped black Si surfaces is further suppressed. In this work, this issue is addressed through systematically studying lowly and highly doped b-Si surfaces, which are passivated by atomic-layer-deposited Al2O3 films or SiO2/Al2O3 stacks. In lowly doped b-Si textures, a very low surface recombination prefactor of 16 fA/cm2 was found after surface passivation by Al2O3. The excellent passivation was achieved after a dedicated wet-chemical treatment prior to surface passivation, which removed structural defects which resided below the b-Si surface. On highly n-type doped b-Si, the SiO2/Al2O3 stacks result in a considerable improvement in surface passivation compared to the Al2O3 single layers. The atomic-layer-deposited SiO2/Al2O3 stacks therefore provide a low-temperature, industrially viable passivation method, enabling the application of highly n- type doped b-Si nanotextures in industrial silicon solar cells.

  8. Wavelength-tuned light emission via modifying the band edge symmetry: Doped SnO2 as an example

    KAUST Repository

    Zhou, Hang; Deng, Rui; Li, Yongfeng; Yao, Bin; Ding, Zhanhui; Wang, Qingxiao; Han, Yu; Wu, Tao; Liu, Lei

    2014-01-01

    at 398 nm is observed in the indium-doped SnO2-based heterojunction. Our results demonstrate an unprecedented doping-based approach toward tailoring the symmetry of band edge states and recovering ultraviolet light emission in wide-bandgap oxides. © 2014

  9. Effects of Ge- and Sb-doping and annealing on the tunable bandgaps of SnS films

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsuan-Tai; Chiang, Ming-Hung; Huang, Chen-Hao [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Wen-Tai, E-mail: wtlin@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Fu, Yaw-Shyan [Department of Greenergy, National University of Tainan, Tainan 700, Taiwan (China); Guo, Tzung-Fang [Department of Photonics, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2015-06-01

    SnS, Ge- and Sb-doped SnS films with single orthorhombic SnS phase were fabricated via solvothermal routes and subsequent spin-coating, respectively. The substitution solubilities of Ge and Sb in SnS are about 6 and 5 at.%, respectively. The bandgaps of Ge- and Sb-doped SnS films can be tuned in the ranges of 1.25–1.35 and 1.30–1.39 eV, respectively. The possible mechanisms for the tunable bandgaps of Ge- and Sb-doped SnS films are discussed. For the Ge- and Sb-doped SnS films subjected to annealing at 200–350 °C in N{sub 2}, the bandgaps of 200 °C-annealed films remain unchanged, while those of 300 °C- and 350 °C-annealed films decrease with the annealing temperature because of the evaporation of Ge and Sb respectively. - Highlights: • Ge- and Sb-doped SnS films were fabricated via spin-coating. • The solubilities of Ge and Sb in SnS are about 6 and 5 at.%, respectively. • The bandgaps of SnS films can be tuned by Ge and Sb doping respectively. • Annealing above 300 °C reduces the bandgaps of Ge- and Sb-doped SnS films.

  10. Band gap narrowing and fluorescence properties of nickel doped SnO2 nanoparticles

    International Nuclear Information System (INIS)

    Ahmed, Arham S.; Shafeeq, M. Muhamed; Singla, M.L.; Tabassum, Sartaj; Naqvi, Alim H.; Azam, Ameer

    2011-01-01

    Nickel-doped tin oxide nanoparticles (sub-5 nm size) with intense fluorescence emission behavior have been synthesized by sol-gel route. The structural and compositional analysis has been carried out by using XRD, TEM, FESEM and EDAX. The optical absorbance spectra indicate a band gap narrowing effect and it was found to increase with the increase in nickel concentration. The band gap narrowing at low dopant concentration ( 2 -SnO 2-x alloying effect and for higher doping it may be due to the formation of defect sub-bands below the conduction band.

  11. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn{sub 2}, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe); Moessbauerspektroskopische Untersuchung von Struktur und Magnetismus der austauschgekoppelten Schichtsysteme Fe/FeSn{sub 2} und Fe/FeSi/Si und des ionenimplantierten verduennten magnetischen Halbleiters SiC(Fe)

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, Frank

    2009-07-07

    In line with this work the structural and magnetic properties of the exchange coupled layered systems Fe/FeSn{sub 2} and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective {sup 57}Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the {sup 57}Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn{sub 2}(001) films and of the exchange-bias system Fe/FeSn{sub 2}(001) on InSb(001) were investigated. With the application of {sup 57}Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (B{sub hf}) of FeSn{sub 2} could be examined. The evaporation of Fe films on the FeSn{sub 2} films produced in the latter ones a high perpendicular spin component at the Fe/FeSn{sub 2} interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore {sup 57}Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn{sub 2}. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures T{sub B}{sup *}, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures T{sub B} of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of t{sub FeSi}=10-12 A of the

  12. La modified TiO{sub 2} photoanode and its effect on DSSC performance: A comparative study of doping and surface treatment on deep and surface charge trapping

    Energy Technology Data Exchange (ETDEWEB)

    Ako, Rajour Tanyi [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Ekanayake, Piyasiri, E-mail: piyasiri.ekanayake@ubd.edu.bn [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Centre for Advanced Material and Energy Sciences (CAMES), Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Tan, Ai Ling [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Young, David James [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, 4558 (Australia); Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research - A*STAR, #08-03, 2 Fusionopolis Way, Innovis, 138634 (Singapore)

    2016-04-01

    The effect of Lanthanum ions (La{sup 3+}) on charge trapping in dye-sensitized solar cell (DSSC) photoanodes has been investigated with doped and surface-treated TiO{sub 2} nanoparticles. Doped nanoparticles consisting of 0.5 mol.% Mg and La co-doped TiO{sub 2}, 0.5 mol.% Mg doped TiO{sub 2} and pure TiO{sub 2} were synthesized by the sol gel method. Surface-treated nanoparticles of Mg doped TiO{sub 2} and pure TiO{sub 2} were prepared by ball milling in 0.05 M aqueous La{sup 3+} solution. All materials were analyzed by XRD, XPS and UV–Vis DRS. Cell performance, surface free energy state changes and electron injection efficiency of DSSCs based on these nanoparticles were evaluated using current –voltage measurements, EIS and Incident photon to current conversion efficiency. Doped materials had La and Mg ions incorporated into the TiO{sub 2} lattice, while no lattice changes were observed for the surface-treated materials. Less visible light was absorbed by treated oxides compared with doped oxide samples. The overall power conversion efficiencies (PCE) of DSSC photoanodes based on doped materials were twice those of photoanodes fabricated from treated nanoparticles. Doping establishes deep traps that reduce the recombination of electron–hole (e–h) pairs. Conversely, the presence of absorbed oxygen in treated materials enhances e–h recombination with electrolyte at surface trap sites. - Highlights: • DSSC performance is investigated using photoanodes of doped and La{sup 3+} surface treated TiO{sub 2}. • TiO{sub 2} and Mg–TiO{sub 2} treated with La{sup 3+} absorbed less visible light. • A high concentration of absorbed oxygen on surface treated oxides reduced band bending. • Increased surface free energy in the modified DSSC anodes is caused more by Mg{sup 2+} at Ti{sup 4+} than by La{sup 3+} at the surfaces. • Near surface charge traps due to La{sup 3+} treatment promotes e–h recombination.

  13. H{sub 2}-Ar dilution for improved c-Si quantum dots in P-doped SiN{sub x}:H thin film matrix

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jia [Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); Zhang, Weijia, E-mail: zwjghx@126.com [Center of Condensed Matter and Material Physics, School of Physics and Nuclear Energy Engineering, Beihang University, Beijing, 100191 (China); Liu, Shengzhong, E-mail: szliu@dicp.ac.cn [Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); State key Laboratory of Catalysis, iChEM, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian 116023 (China)

    2017-02-28

    Highlights: • Phosphorous-doped SiN{sub x}:H thin films containing c-Si QDs were prepared by PECVD in H{sub 2}-Ar mixed dilution under low temperature. • QD density and QD size can be controlled by tuning H{sub 2}/Ar flow ratio. • The sample prepared at the H{sub 2}/Ar flow ratio of 100/100 possesses both wide band gap and excellent conductivity. • Detail discussion has been presented for illustrating the influence of H{sub 2}/Ar mixed dilution on the crystallization process and P-doping. - Abstract: Phosphorus-doped hydrogenated silicon nitride (SiN{sub x}:H) thin films containing crystalline silicon quantum dot (c-Si QD) was prepared by plasma enhanced chemical vapor deposition (PECVD) using hydrogen-argon mixed dilution. The effects of H{sub 2}/Ar flow ratio on the structural, electrical and optical characteristics of as-grown P-doped SiN{sub x}:H thin films were systematically investigated. Experimental results show that crystallization is promoted by increasing the H{sub 2}/Ar flow ratio in dilution, while the N/Si atomic ratio is higher for thin film deposited with argon-rich dilution. As the H{sub 2}/Ar flow ratio varies from 100/100 to 200/0, the samples exhibit excellent conductivity owing to the large volume fraction of c-Si QDs and effective P-doping. By adjusting the H{sub 2}/Ar ratio to 100/100, P-doped SiN{sub x}:H thin film containing tiny and densely distributed c-Si QDs can be obtained. It simultaneously possesses wide optical band gap and high dark conductivity. Finally, detailed discussion has been made to analyze the influence of H{sub 2}-Ar mixed dilution on the properties of P-doped SiN{sub x}:H thin films.

  14. Efficient photocatalytic degradation of phenol in aqueous solution by SnO2:Sb nanoparticles

    International Nuclear Information System (INIS)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika; Bora, Tanujjal; Dutta, Joydeep

    2016-01-01

    Highlights: • Sb doped SnO 2 nanoparticles were synthesized using sol–gel process. • Photocatalytic degradation of phenol were studies using SnO 2 :Sb nanoparticles. • Under solar light phenol was degraded within 2 h. • Phenol mineralization and intermediates were investigated by using HPLC. - Abstract: Photodegradation of phenol in the presence of tin dioxide (SnO 2 ) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO 2 . In this study antimony (Sb) doped tin dioxide (SnO 2 ) nanoparticles were prepared at a low temperature (80 °C) by a sol–gel method and studied for its photocatalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO 2 :Sb was found to be a maximum for 0.6 wt.% Sb doped SnO 2 nanoparticles with 10 mg L −1 phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.

  15. Structural and transport properties of Sn-Mg alloys

    International Nuclear Information System (INIS)

    Meydaneri, F.; Saatci, E.; Oezdemir, M.; Ari, M.; Durmus, S.

    2010-01-01

    The structural and temperature dependence transport of Sn-Mg alloys have been investigated for five different samples (Pure Sn, Sn-1.0 wt % Mg , Sn-2.0 wt % Mg , Sn-6.0 wt.% Mg and Pure Mg). Scanning Electron Microscopy (SEM), x-ray diffraction (XRD) and Energy Dispersive x-ray Analysis (EDX) measurements were carried out in order to clarify the structural properties of the samples. It has been found that, the samples have tetragonal crystal symmetry except the pure Mg which has hexagonal crystal symmetry. The cell parameters decrease slightly with addition of Mg element. The SEM micrographs of the samples show that, the samples have smooth surfaces with clear grain boundary. There is no crack, porosity or defects on the surfaces. The electrical resistivity of the samples increases almost linearly with the increasing temperature, which were measured by four-point probe technique. The thermal conductivity values are in between 0.60-1.00 W/Km, which are decrease slightly with temperature and increase with composition of Mg. The thermal conductivity values of the alloys are in between the values of the pure samples. Thermal conductivity results of the alloys have been compared with available other studies and a good agreement has been seen between the results. In addition, the temperature coefficients of electrical resistivity and thermal conductivity have been determined, which are independent with the compositions of alloying elements

  16. N2O + CO reaction over Si- and Se-doped graphenes: An ab initio DFT study

    International Nuclear Information System (INIS)

    Gholizadeh, Reza; Yu, Yang-Xin

    2015-01-01

    Graphical abstract: Si-doped graphene can be one of efficient green catalysts for conversion of the airborne pollutants. - Highlights: • N 2 O can be efficiently reduced by CO over Si-doped graphenes. • Enough charge transferred from Si to N 2 O makes the N 2 –O bond break easily. • Si-doped graphene is efficient green catalysts for conversion of the airborne pollutants. • vdW interaction and ZPE energy significantly influence the predictions of activation energies. - Abstract: Catalytic conversion of non-CO 2 green house gases and other harmful gases is a promising way to protect the atmospheric environment. Non-metal atom-doped graphene is attractive for use as a catalyst in the conversion due to its unique electronic properties, relatively low price and leaving no burden to the environment. To make an attempt on the development of green catalysts for the conversion, ab initio density functional theory is used to investigate the mechanisms of N 2 O reduction by CO on Si- and Se-doped graphenes. We have calculated the geometries and adsorption energies of reaction species (N 2 O, CO, N 2 and CO 2 ) as well as energy profiles along the reaction pathways. The activation energies of N 2 O decomposition and CO oxidation on both Si- and Se-doped graphenes have been obtained. Our calculated results indicate that the catalytic activity of Si-doped graphene is better than the Fe + in gas phase and comparable to the single Fe atom embedded on graphene. In the calculations, we found that van der Waals interactions and zero-point energy are two non-negligible factors for the predictions of the activation energies. Further discussion shows that Si-doped graphene can be one of efficient green catalysts for conversion of the airborne pollutants and Se-doped graphene can be a candidate for oxidizing CO by atomic oxygen.

  17. Synthesis and characterization of SnO2 doped with fluorine by the technique of polymeric precursors

    International Nuclear Information System (INIS)

    Pereira, Gilberto J.; Lopes, Rafael Ialago

    2016-01-01

    The present work deals with the synthesis of tin dioxide powders doped with fluorine and chlorine anions to evaluate the influence of these on the physico-chemical properties of SnO2, as well as to verify if the dopant does not make a solid solution with the material and its possible use as sintering additive. The samples were synthesized by Pechini method (polymer precursors) with tin oxalate as a source not contaminated with chlorine of this metal. Specific surface area characterization (BET method) and X-ray diffractometry (XRD) show that doping reduces the particle size of SnO2, being more effective at lower dopant levels. The dilatometry of the doped powders shows a reduction in the beginning and end temperatures of the sintering of the tin dioxide when compared with values in the literature

  18. Synthesis and photoluminescence of Eu3+ and Mn2+ doped double phosphates KMLa(PO4)2 (M = Zn, Mg)

    International Nuclear Information System (INIS)

    Pan Yuexiao; Zhang Qinyuan; Jiang Zhonghong

    2006-01-01

    Two compounds, KMgLa(PO 4 ) 2 and KZnLa(PO 4 ) 2 doped with Eu 3+ and Mn 2+ ions, have been synthesized by a conventional solid-state method at 850 deg. C. Structures of KMgLa(PO 4 ) 2 and KZnLa(PO 4 ) 2 have been investigated and confirmed by X-ray diffraction and photoluminescence spectra. The results indicate that the compounds have remained the monoclinic structure of LaPO 4 with space group of C s when (K + , Mg 2+ ) or (K + , Zn 2+ ) could substitute half of the La 3+ ions. Under an ultraviolet source, KMgLa(PO 4 ) 2 :Mn 2+ has shown a bright red phosphorescent color, while KZnLa(PO 4 ) 2 :Mn 2+ has shown an orange-red emission which is assigned to the electronic transition of 4 T 1 ( 4 G)- 6 A 1 ( 6 S) of Mn 2+ in strong crystal field

  19. Magnetocaloric effect in La(FexSi1-x)13 doped with hydrogen and under external pressure

    International Nuclear Information System (INIS)

    Medeiros, L.G. de; Oliveira, N.A. de

    2006-01-01

    In this paper, we calculate the magnetocaloric effect in the compounds La(Fe x Si 1-x ) 13 doped with hydrogen and subjected to external pressure. We use a microscopical model where the Coulomb interaction between itinerant electrons is treated in the mean field approach. The effect of hydrogen atoms is considered as a chemical pressure. We also include phenomenologically the magnetoelastic coupling via the renormalization of the electron dispersion relation and the Debye temperature. The calculated isothermal entropy changes upon magnetic field variations for the compound La(Fe 0.88 Si 0.12 ) 13 H y are in good agreement with the available experimental data

  20. Flux pinning behaviors of Ti and C co-doped MgB{sub 2} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.; Zhao, D.; Shen, T.M.; Li, G.; Zhang, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Feng, Y. [Northwest Institute for Nonferrous Metal Research, P.O. Box 51, Xian, Shaanxi 710016 (China); Western Superconductivity Technology Company, Xian (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia); Zhang, Y.P. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia)], E-mail: yzhao@swjtu.edu.cn

    2008-09-15

    Flux pinning behavior of carbon and titanium concurrently doped MgB{sub 2} alloys has been studied by ac susceptibility and dc magnetization measurements. It is found that critical current density and irreversibility field of MgB{sub 2} have been significantly improved by doping C and Ti concurrently, sharply contrasted to the situation of C-only-doped or Ti-only-doped MgB{sub 2} samples. AC susceptibility measurement reveals that the dependence of the pinning potential on the dc applied field of Mg{sub 0.95}Ti{sub 0.05}B{sub 1.95}C{sub 0.05} has been determined to be U(B{sub dc}){proportional_to}B{sub dc}{sup -1} compared to that of MgB{sub 2}U(B{sub dc}){proportional_to}B{sub dc}{sup -1.5}. As to the U(J) behavior, a relationship of U(J) {proportional_to} J{sup -0.17} is found fitting well for Mg{sub 0.95}Ti{sub 0.05}B{sub 1.95}C{sub 0.05} with respect to U(J) {proportional_to} J{sup -0.21} for MgB{sub 2}. All the results reveal a strong enhancement of the high field pinning potential in C and Ti co-doped MgB{sub 2}.

  1. Mg doping and its effect on the semipolar GaN(1122) growth kinetics

    International Nuclear Information System (INIS)

    Lahourcade, L.; Wirthmueller, A.; Monroy, E.; Pernot, J.; Chauvat, M. P.; Ruterana, P.; Laufer, A.; Eickhoff, M.

    2009-01-01

    We report the effect of Mg doping on the growth kinetics of semipolar GaN(1122) synthesized by plasma-assisted molecular-beam epitaxy. Mg tends to segregate on the surface, inhibiting the formation of the self-regulated Ga film which is used as a surfactant for the growth of undoped and Si-doped GaN(1122). We observe an enhancement of Mg incorporation in GaN(1122) compared to GaN(0001). Typical structural defects or polarity inversion domains found in Mg-doped GaN(0001) were not observed for the semipolar films investigated in the present study.

  2. EDX and ion beam treatment studies of filamentary in situ MgB2 wires with Ti barrier

    International Nuclear Information System (INIS)

    Rosova, A.; Kovac, P.; Husek, I.; Kopera, L.

    2011-01-01

    Highlights: → SiC-doped MgB 2 wires with Ti barrier showed good Jc in magnetic field. → Explanation why the Ti barrier fits to SiC-doped MgB 2 filaments. → Ti barrier getters Si from SiC-doped filaments and improve their properties. → Si accumulated in an inner layer of Ti barrier protects filaments from Cu diffusion. → Ion beam treatment helps to discover microstructure of complicated systems. - Abstract: In situ SiC-doped filamentary MgB 2 wires (with the diameter of 0.860 and 0.375 mm) with Cu stabilization separated by Ti barrier layers supported by outer SS sheath and annealed at 800 deg. C/0.5 h have been studied by combination of EDX analysis and ion beam selective etching. It was found that several Ti-Cu inter-metallic compounds were created by Cu-Ti interdiffusion and thus the barrier protection against Cu penetration into the superconducting filaments is limited. We showed an advantage of Ti use as the barrier material in our wires. Ti getters silicon out from the superconducting filament, what purges superconducting MgB 2 from Si and creates an additional Si-rich layer in inner part of Ti barrier which prevents Cu diffusion more effectively.

  3. Low-temperature thermoelectric properties of Pb doped Cu2SnSe3

    Science.gov (United States)

    Prasad K, Shyam; Rao, Ashok; Gahtori, Bhasker; Bathula, Sivaiah; Dhar, Ajay; Chang, Chia-Chi; Kuo, Yung-Kang

    2017-09-01

    A series of Cu2Sn1-xPbxSe3 (0 ≤ x ≤ 0.04) compounds was prepared by solid state synthesis technique. The electrical resistivity (ρ) decreased with increase in Pb content up to x = 0.01, thereafter it increased with further increase in x (till x = 0.03). However, the lowest value of electrical resistivity is observed for Cu2Sn0.96Pb0.04Se3. Analysis of electrical resistivity of all the samples suggests that small poloron hoping model is operative in the high temperature regime while variable range hopping is effective in the low temperature regime. The positive Seebeck coefficient (S) for pristine and doped samples in the entire temperature range indicates that the majority charge carriers are holes. The electronic thermal conductivity (κe) of the Cu2Sn1-xPbxSe3 compounds was estimated by the Wiedemann-Franz law and found that the contribution from κe is less than 1% of the total thermal conductivity (κ). The highest ZT 0.013 was achieved at 400 K for the sample Cu2Sn0.98Pb0.02Se3, about 30% enhancement as compared to the pristine sample.

  4. Al-doped MgB{sub 2} materials studied using electron paramagnetic resonance and Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bateni, Ali; Somer, Mehmet, E-mail: emre.erdem@physchem.uni-freiburg.de, E-mail: msomer@ku.edu.tr [Department of Chemistry, Koç University, Rumelifeneri Yolu, Sariyer, Istanbul (Turkey); Erdem, Emre, E-mail: emre.erdem@physchem.uni-freiburg.de, E-mail: msomer@ku.edu.tr; Repp, Sergej [Institut für Physikalische Chemie, Universität Freiburg, Albertstr. 21, Freiburg (Germany); Weber, Stefan [Institut für Physikalische Chemie, Universität Freiburg, Albertstr. 21, Freiburg (Germany); Freiburg Institute for Advanced Studies (FRIAS), Universität Freiburg, Albertstr. 19, Freiburg (Germany)

    2016-05-16

    Undoped and aluminum (Al) doped magnesium diboride (MgB{sub 2}) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB{sub 2} samples were systematically investigated using X-ray powder diffraction, Raman spectroscopy, and electron paramagnetic resonance. It was found that Mg-vacancies are responsible for defect-induced peculiarities in MgB{sub 2}. Above a certain level of Al doping, enhanced conductive properties of MgB{sub 2} disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites.

  5. Effect of polyethylene glycol in preparation of Eu3+ doped SnO2 nanoparticles using ethylene glycol and luminescence properties

    International Nuclear Information System (INIS)

    Singh, L.J.; Singh, R.K.H.; Ningthoujam, R.S.; Vatsa, R.K.

    2010-01-01

    Full text: Eu 3+ doped SnO 2 nanoparticles have been prepared by urea hydrolysis. The two different capping agents such as ethylene glycol (EG) and polyethylene glycol (PEG) are used. Particles prepared in EG shows the crystalline nature while in the presence of PEG, crystallinity decreases. In TEM study of 5 at.% Eu doped SnO 2 sample prepared in presence of EG and PEG, there is a particle size distribution from 2.5 to 5.5 nm and average particle size is found to be 4 nm. In order to see the particle morphology for small particles, HRTEM images are also recorded and average crystallite region is found to be 2.7 nm. From this, we can conclude that 4 nm smaller particle has crystallite region of 2.7 nm and surface region of 1.3 nm. Thus, with decrease of particle size, the contribution of surface to bulk increases. This reflects the broad peak in XRD pattern of samples prepared in EG-PEG. The excitation spectra of SnO 2 nanoparticles (prepared in EG-PEG) doped with 2, 5 and 10 at.% Eu 3+ monitoring emission at 614 nm is shown. The excitation peaks at 250, 325 and 395 nm are observed. The peak at 250 nm is due to Eu-O charge transfer. The broad peak centered at 325 nm is due to exciton formation from SnO 2 and the last peak at 395 nm due to Eu 3+ ( 7 F 0 → 5 L 6 ). The relative peak intensity of Eu 3+ (peak at 395 nm) with respect to SnO 2 (peak at 325 nm) decreases with increase of Eu 3+ content/dopant in SnO 2 . This suggests that energy transfer from SnO 2 to Eu 3+ increases with Eu 3+ content/dopant in SnO 2 . The emission spectra of SnO 2 nanoparticles doped with 5 at.% Eu 3+ (prepared in EG-PEG) after excitation at different wavelengths (250, 300, 320, 330, 340 and 395 nm) is also shown. The main emission peaks at 425 (broad), 578 (weak), 591 (sharp) and 614 nm (sharp) are observed

  6. All-perovskite transparent high mobility field effect using epitaxial BaSnO{sub 3} and LaInO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Useong; Park, Chulkwon; Kim, Young Mo; Ju, Chanjong; Park, Jisung; Char, Kookrin, E-mail: kchar@phya.snu.ac.kr [Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Ha, Taewoo; Kim, Jae Hoon [Department of Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Namwook; Yu, Jaejun [Center for Theoretical Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-03-01

    We demonstrate an all-perovskite transparent heterojunction field effect transistor made of two lattice-matched perovskite oxides: BaSnO{sub 3} and LaInO{sub 3}. We have developed epitaxial LaInO{sub 3} as the gate oxide on top of BaSnO{sub 3}, which were recently reported to possess high thermal stability and electron mobility when doped with La. We measured the dielectric properties of the epitaxial LaInO{sub 3} films, such as the band gap, dielectric constant, and the dielectric breakdown field. Using the LaInO{sub 3} as a gate dielectric and the La-doped BaSnO{sub 3} as a channel layer, we fabricated field effect device structure. The field effect mobility of such device was higher than 90 cm{sup 2} V{sup −1} s{sup −1}, the on/off ratio was larger than 10{sup 7}, and the subthreshold swing was 0.65 V dec{sup −1}. We discuss the possible origins for such device performance and the future directions for further improvement.

  7. Karakterisasi Paduan AlMgSi Untuk Kelongsong Bahan Bakar U3Si2/Al Dengan Densitas Uranium 5,2 gU/cm3

    Directory of Open Access Journals (Sweden)

    Aslina Br. Ginting

    2018-03-01

    Full Text Available Meningkatnya densitas uranium dari 2,96 gU/cm3 menjadi 5,2 gU/cm3 bahan bakar U3Si2/Al harus diikuti dengan penggunaan kelongsong yang kompatibel. Bahan bakar berdensitas tinggi mempunyai kekerasan yang tinggi, sehingga bila menggunakan paduan AlMg2 sebagai kelongsong dapat menyebabkan terjadi dogbone pada saat perolan. Selain fenomena dogbone, pada saat bahan bakar tersebut digunakan di reaktor dapat terjadi swelling karena meningkatnya hasil fisi maupun burn up. Oleh karena itu, perlu dicari pengganti bahan kelongsong untuk bahan bakar U3Si2/Al densitas tinggi. Pada penelitian ini telah dilakukan karakterisasi paduan AlMgSi sebagai kandidat pengganti kelongsong AlMg2. Karakterisasi yang dilakukan meliputi analisis termal, kekerasan, mikrostruktur dan laju korosi. Analisis termal dilakukan menggunakan DTA (Differential Thermal Analysis dan DSC (Differential Scanning Calorimetry. Analisis kekerasan menggunakan alat uji kekerasan mikro, mikrostruktur menggunakan SEM (Scanning Electron Microscope dan analisis laju korosi dilakukan dengan pemanasan pada temperatur 150 oC selama 77 jam di dalam autoclave. Hasil analisis menunjukkan bahwa kelongsong AlMgSi maupun AlMg2 mempunyai kompatibilitas panas dengan bahan bakar U3Si2/Al cukup stabil hingga temperatur 650 oC. Kelongsong AlMgSi mempunyai kekerasan sebesar 115 HVN dan kelongsong AlMg2 sebesar 70,1 HVN. Sementara itu, analisis mikrostruktur menunjukkan bahwa morfologi ikatan antarmuka (interface bonding kelongsong AlMgSi lebih baik dari kelongsong AlMg2, demikian halnya dengan laju korosi bahwa kelongsong AlMgSi mempunyai laju korosi lebih kecil dibanding kelongsong AlMg2. Hasil karakterisasi termal, kekerasan, mikrostruktur dan laju korosi menunjukkan bahwa PEB U3Si2/Al densitas 5,2 gU/cm3 menggunakan kelongsong AlMgSi lebih baik dibanding PEB U3Si2/Al  densitas 5,2 gU/cm3  menggunakan kelongsong AlMg2. Kata kunci: U3Si2/Al, densitas 5,2 gU/cm3, kelongsong AlMgSi dan AlMg2.

  8. The electrorheological properties of nano-sized SiO2 particle materials doped with rare earths

    International Nuclear Information System (INIS)

    Liu Yang; Liao Fuhui; Li Junran; Zhang Shaohua; Chen Shumei; Wei Chenguan; Gao Song

    2006-01-01

    Electrorheological (ER) materials of pure SiO 2 and SiO 2 doped with rare earths (RE = Ce, Gd, Y) (non-metallic glasses (silicates)) were prepared using Na 2 SiO 3 and RECl 3 as starting materials. The electrorheological properties are not enhanced by all rare earth additions. The material doped with Ce exhibits the best ER performance

  9. Doping effects of carbon and titanium on the critical current density of MgB2

    International Nuclear Information System (INIS)

    Shen, T M; Li, G; Cheng, C H; Zhao, Y

    2006-01-01

    MgB 2 bulks doped with Ti or/and C were prepared by an in situ solid state reaction method to determine the combined effect of C and Ti doping and to probe the detailed mechanism. The magnetization measurement shows that Mg 0.95 Ti 0.05 B 1.95 C 0.05 sample has significantly improved flux pinning compared to the MgB 1.95 C 0.05 sample at 20 K, indicating that C and Ti are largely cooperative in improving the J c (H) behaviour. No TiC phase was detected in the x-ray diffraction (XRD) patterns. Moreover, the overlap of the (100) peaks of MgB 1.95 C 0.05 and Mg 0.95 Ti 0.05 B 1.95 C 0.05 showed that Ti doping does not reduce the amount of C in MgB 2 . Microstructural analyses revealed that the addition of Ti eliminated the porosity present in the carbon-doped MgB 2 pellet, resulting in an improved intergrain connectivity and an increase of effective current pass. Further, MgB 2 doped with C and Ti, which mainly consists of spherical grains about 200-300 nm in size, shows an higher grain homogeneity than the C-doped sample, suggesting that the Ti doping in MgB 1-x C x has played an important role in obtaining uniform grains

  10. Electrical and optical properties of nitrogen doped SnO2 thin films deposited on flexible substrates by magnetron sputtering

    International Nuclear Information System (INIS)

    Fang, Feng; Zhang, Yeyu; Wu, Xiaoqin; Shao, Qiyue; Xie, Zonghan

    2015-01-01

    Graphical abstract: The best SnO 2 :N TCO film: about 80% transmittance and 9.1 × 10 −4 Ω cm. - Highlights: • Nitrogen-doped tin oxide film was deposited on PET by RF-magnetron sputtering. • Effects of oxygen partial pressure on the properties of thin films were investigated. • For SnO 2 :N film, visible light transmittance was 80% and electrical resistivity was 9.1 × 10 −4 Ω cm. - Abstract: Nitrogen-doped tin oxide (SnO 2 :N) thin films were deposited on flexible polyethylene terephthalate (PET) substrates at room temperature by RF-magnetron sputtering. Effects of oxygen partial pressure (0–4%) on electrical and optical properties of thin films were investigated. Experimental results showed that SnO 2 :N films were amorphous state, and O/Sn ratios of SnO 2 :N films were deviated from the standard stoichiometry 2:1. Optical band gap of SnO 2 :N films increased from approximately 3.10 eV to 3.42 eV as oxygen partial pressure increased from 0% to 4%. For SnO 2 :N thin films deposited on PET, transmittance was about 80% in the visible light region. The best transparent conductive oxide (TCO) deposited on flexible PET substrates was SnO 2 :N thin films preparing at 2% oxygen partial pressure, the transmittance was about 80% and electrical conductivity was about 9.1 × 10 −4 Ω cm

  11. Structural and critical current properties in Al-doped MgB2

    International Nuclear Information System (INIS)

    Zheng, D.N.; Xiang, J.Y.; Lang, P.L.; Li, J.Q.; Che, G.C.; Zhao, Z.W.; Wen, H.H.; Tian, H.Y.; Ni, Y.M.; Zhao, Z.X.

    2004-01-01

    A series of Al-doped Mg 1-x Al x B 2 samples have been fabricated and systematic study on structure and superconducting properties have been carried out for the samples. In addition to a structural transition observed by XRD, TEM micrographs showed the existence of a superstructure of double c-axis lattice constant along the direction perpendicular to the boron honeycomb sheet. In order to investigate the effect of Al doping on flux pinning and critical current properties in MgB 2 , measurements on the superconducting transition temperature T c , irreversible field B irr and critical current density J c were performed too, for the samples with the doping levels lower than 0.15 in particular. These experimental observations were discussed in terms of Al doping induced changes in carrier concentration

  12. Structural and critical current properties in Al-doped MgB 2

    Science.gov (United States)

    Zheng, D. N.; Xiang, J. Y.; Lang, P. L.; Li, J. Q.; Che, G. C.; Zhao, Z. W.; Wen, H. H.; Tian, H. Y.; Ni, Y. M.; Zhao, Z. X.

    2004-08-01

    A series of Al-doped Mg 1- xAl xB 2 samples have been fabricated and systematic study on structure and superconducting properties have been carried out for the samples. In addition to a structural transition observed by XRD, TEM micrographs showed the existence of a superstructure of double c-axis lattice constant along the direction perpendicular to the boron honeycomb sheet. In order to investigate the effect of Al doping on flux pinning and critical current properties in MgB 2, measurements on the superconducting transition temperature Tc, irreversible field Birr and critical current density Jc were performed too, for the samples with the doping levels lower than 0.15 in particular. These experimental observations were discussed in terms of Al doping induced changes in carrier concentration.

  13. Structural and physical properties of transparent conducting, amorphous Zn-doped SnO2 films

    Science.gov (United States)

    Zhu, Q.; Ma, Q.; Buchholz, D. B.; Chang, R. P. H.; Bedzyk, M. J.; Mason, T. O.

    2014-01-01

    The structural and physical properties of conducting amorphous Zn-doped SnO2 (a-ZTO) films, prepared by pulsed laser deposition, were investigated as functions of oxygen deposition pressure (pO2), composition, and thermal annealing. X-ray scattering and X-ray absorption spectroscopy measurements reveal that at higher pO2, the a-ZTO films are highly transparent and have a structural framework similar to that found in crystalline (c-), rutile SnO2 in which the Sn4+ ion is octahedrally coordinated by 6 O2- ions. The Sn4+ ion in these films however has a coordination number (CN) smaller by 2%-3% than that in c-SnO2, indicating the presence of oxygen vacancies, which are the likely source of charge carriers. At lower pO2, the a-ZTO films show a brownish tint and contain some 4-fold coordinated Sn2+ ions. Under no circumstances is the CN around the Zn2+ ion larger than 4, and the Zn-O bond is shorter than the Sn-O bond by 0.07 Å. The addition of Zn has no impact on the electroneutrality but improves significantly the thermal stability of the films. Structural changes due to pO2, composition, and thermal annealing account well for the changes in the physical properties of a-ZTO films.

  14. Development and characterization of Mn{sup 2+}-doped MgO nanoparticles by solution combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Basha, Md. Hussain; Gopal, N. O., E-mail: nogopal@yahoo.com [Department of Physics, Vikrama Simhapuri University Post Graduate Center, Kavali-524201 (India); Rao, J. L. [Department of physics, Sri Venkateswara University, Tirupati-517502 (India); Nagabhushana, H. [Prof. C.N.R. Rao Centre for Nano Research, Tumkur University, Tumkur-572103 (India); Nagabhushana, B. M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore - 560054 (India); Chakradhar, R. P. S. [CSIR- National Aerospace Laboratories, Bangalore -560017 (India)

    2015-06-24

    Mn doped MgO Nanoparticles have been prepared by Solution Combustion Synthesis. The synthesized sample is characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Paramagnetic Resonance (EPR). The prepared MgO:Mn (1 mol%) nano crystals appear to be of simple cubic crystalline phase with lattice parameters a = 4.218(2) Å and cell volume = 74.98 (7) Å{sup 3}. SEM micrograph of powders show highly porous, many agglomerates with irregular morphology, large voids, cracks and pores. EPR spectrum of the sample at room temperature exhibit an isotropic sextet hyperfine pattern, centered at g=1.99, characteristic if Mn{sup 2+} ions with S=I=5/2.The observed g value and the hyperfine value reveal the ionic bonding between Mn{sup 2+} and its surroundings.

  15. Synthesis, structural and luminescent aspect of Tb3+ doped Sr2SnO4 phosphor

    International Nuclear Information System (INIS)

    Taikar, Deepak R.

    2016-01-01

    A novel green emitting, Tb 3+ doped Sr 2 SnO 4 phosphor was synthesized by the co-precipitation method and its photoluminescence characterization was performed. Sr 2 SnO 4 has an ordered tetragonal K 2 NiF 4 -type structure with space group I4/mmm. The structure of Sr 2 SnO 4 consists of SnO 6 octahedra. From the structure of Sr 2 SnO 4 , it was observed that the sites of Sn 4+ ions have inverse symmetry while the Sr 2+ ions have the low symmetry. X-ray powder diffraction (XRD) analysis confirmed the formation of Sr 2 SnO 4 :Tb 3+ . Photoluminescence measurements showed that the phosphor exhibited bright green emission at about 543 nm attributed to 5 D 4 à 7 F 5 transition of Tb 3+ ion under UV excitation. The emission spectra did not exhibit conventional blue emission peaks of Tb 3+ ions due to 5 D 3 → 7 F J transitions in the spectral region 350-470 nm. The excitation spectra indicate that this compound may be useful as a lamp phosphor. (author)

  16. Microscopic unravelling of nano-carbon doping in MgB{sub 2} superconductors fabricated by diffusion method

    Energy Technology Data Exchange (ETDEWEB)

    Wong, D.C.K. [School of Physics, The University of Sydney, New South Wales 2006 (Australia); Yeoh, W.K. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia); Australian Centre for Microscopy & Microanalysis, The University of Sydney, New South Wales 2006 (Australia); De Silva, K.S.B. [Institute for Superconducting & Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Institute for Nanoscale Technology, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007 (Australia); Kondyurin, A.; Bao, P. [School of Physics, The University of Sydney, New South Wales 2006 (Australia); Li, W.X. [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Xu, X.; Peleckis, G.; Dou, S.X. [Institute for Superconducting & Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Ringer, S.P. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia); Australian Centre for Microscopy & Microanalysis, The University of Sydney, New South Wales 2006 (Australia); Zheng, R.K., E-mail: rongkun.zheng@sydney.edu.au [School of Physics, The University of Sydney, New South Wales 2006 (Australia)

    2015-09-25

    Highlights: • First report on nano-carbon doped MgB{sub 2} superconductors synthesized by diffusion method. • Microstructure and superconducting properties of the superconductors are discussed. • B{sub 4}C region blocks the Mg from reacting with B in the 10% nano-carbon doped sample. • MgB{sub 2} with 2.5% nano-carbon doped showed the highest J{sub c}, ≈10{sup 4} A/cm{sup 2} for 20 K at 4 T. - Abstract: We investigated the effects of nano-carbon doping as the intrinsic (B-site nano-carbon substitution) and extrinsic (nano-carbon derivatives) pinning by diffusion method. The contraction of the in-plane lattice confirmed the presence of disorder in boron sublattice caused by carbon substitution. The increasing value in full width half maximum (FWHM) in the X-ray diffraction (XRD) patterns with each increment in the doping level reveal smaller grains and imperfect MgB{sub 2} crystalline. The strain increased across the doping level due to the carbon substitution in the MgB{sub 2} matrix. The broadening of the T{sub c} curves from low to high doping showed suppression of the connectivity of the bulk samples with progressive dirtying. At high doping, the presence of B{sub 4}C region blocked the Mg from reacting with crystalline B thus hampering the formation of MgB{sub 2}. Furthermore, the unreacted Mg acted as a current blocking phase in lowering down the grain connectivity hence depressing the J{sub c} of the 10% nano-carbon doped MgB{sub 2} bulk superconductor.

  17. Ultrasonic synthesis of In-doped SnS nanoparticles and their physical properties

    Science.gov (United States)

    Jamali-Sheini, Farid; Cheraghizade, Mohsen; Yousefi, Ramin

    2018-05-01

    Indium (In)-doped Tin (II) Sulfide (SnS) nanoparticles (NPs) were synthesized by an ultra-sonication method and their optical, electrical, dielectric and photocatalytic properties were investigated. XRD patterns of the obtained NPs indicated formation of orthorhombic polycrystalline SnS. Field emission scanning electron microscopy exhibited flower-like NPs with particle sizes below 100 nm for both SnS and In-doped SnS samples. Optical analysis showed a decrease in energy band gap of SnS NPs upon In doping. In addition, electrical results demonstrated p-type nature of the synthesized SnS NPs and enhanced electrical conductivity of the NPs due to increased tin vacancy. Dielectric experiments on SnS NPs suggested an electronic polarizations effect to be responsible for changing dielectric properties of the particles, in terms of frequency. Finally, photocatalytic experiments revealed that high degradation power can be obtained using In-doped SnS NPs.

  18. Study of Bi-2212 phase doped Sn(Pb) by means of pat

    International Nuclear Information System (INIS)

    Ma Qingzhu; Huang Xiaoqian; Xiong Xiaotao

    1997-01-01

    Investigation on the effect of Sn/Pb-doped Bi-2212 superconductors has been carried out by the simultaneous measurements of the spectra of positron annihilation lifetime and positron Doppler broadening, together with X-ray diffraction. The results of samples with different doping level show the occupation of Sn atoms on Bi sites. At weak doping level, Sn doping results in a enhancement of cooperation between layers and increment of superconducting transition temperature. At the strong doping level, Sn atoms occupy the sites of Cu-O layers, and at the same time, the other nonsuperconducting phases appear, which results in a decline of the superconducting transition temperature

  19. Influence of dopant segregation on the work function and electrical properties of Ge-doped in comparison to Sn-doped In{sub 2}O{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hoyer, Karoline L.; Hubmann, Andreas H.; Klein, Andreas [Surface Science Division, Institute of Materials Science, Technische Universitaet Darmstadt (Germany)

    2017-02-15

    Ge-doped In{sub 2}O{sub 3} thin films prepared by magnetron sputtering are studied using photoelectron spectroscopy and Hall effect measurements. Carrier conductivities of up to 8.35 x 10{sup 3} S cm{sup -1} and carrier mobilities of up to 57 cm{sup 2} V{sup -1}s{sup -1} are observed. The surface Ge concentration is enhanced by a factor of 2-3 compared to the concentration in the interior of the films. The surface Ge concentration increases with more oxidizing deposition conditions, in opposite to what has been reported for Sn-doped In{sub 2}O{sub 3}. Ge-doped In{sub 2}O{sub 3} films exhibit higher work functions as compared to Sn-doped films, in particular at oxidizing conditions. This is attributed to the formation of a GeO{sub 2} surface phase. While segregation of Sn reduces the carrier mobility due to grain boundary scattering, Ge segregation does not show such an effect. The differences are attributed to the different oxidation states of the segregated dopants, in agreement with the observed dependence of segregation on oxygen activity. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Synthesis and optical properties of SiO2–Al2O3–MgO–K2CO3–CaO ...

    Indian Academy of Sciences (India)

    Synthesis and optical properties of SiO 2 –Al 2 O 3 –MgO–K 2 CO 3 –CaO–MgF 2La 2 O 3 glasses. C R GAUTA. Volume 39 Issue 3 June 2016 pp 677-682 ... Author Affiliations. C R GAUTA1. Advanced Glass and Glass Ceramic Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226007, India ...

  1. Sol–gel synthesis of SnO{sub 2}–MgO nanoparticles and their photocatalytic activity towards methylene blue degradation

    Energy Technology Data Exchange (ETDEWEB)

    Bayal, Nisha; Jeevanandam, P., E-mail: jeevafcy@iitr.ernet.in

    2013-10-15

    Graphical abstract: - Highlights: • A simple sol–gel method for the synthesis of SnO{sub 2}–MgO nanoparticles is reported. • Band gap of SnO{sub 2} can be tuned by varying the magnesium content in SnO{sub 2}–MgO. • SnO{sub 2}–MgO shows good photocatalytic activity towards degradation of methylene blue. - Abstract: SnO{sub 2}–MgO mixed metal oxide nanoparticles were prepared by a simple sol–gel method. The nanoparticles were characterized by power X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The XRD results indicate the formation of mixed metal oxide nanoparticles and also a decrease of SnO{sub 2} crystallite size in the mixed metal oxide nanoparticles with increasing magnesium oxide content. The reflectance spectroscopy results show a blue shift of the band gap of SnO{sub 2} in the mixed metal oxide nanoparticles. The photocatalytic activity of the SnO{sub 2}–MgO nanoparticles was tested using the photodegradation of aqueous methylene blue in the presence of sunlight. The results indicate that the mixed metal oxide nanoparticles possess higher efficiency for the photodegradation of methylene blue compared to pure SnO{sub 2} nanoparticles.

  2. Crystallization characteristics of Mg-doped Ge2Sb2Te5 films for phase change memory applications

    International Nuclear Information System (INIS)

    Fu Jing; Shen Xiang; Nie Qiuhua; Wang Guoxiang; Wu Liangcai; Dai Shixun; Xu Tiefeng; Wang, R.P.

    2013-01-01

    Highlights: ► Mg-doped Ge 2 Sb 2 Te 5 (GST) phase change films with higher resistance and better thermal stability have been proposed. ► The increase of Mg content result in an enhancement in crystallization temperature, activation energy and electrical resistance. ► The proper Mg addition in GST can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase. ► The formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhancement thermal stability in Mg-doped GST films. - Abstract: Mg-doped Ge 2 Sb 2 Te 5 (GST) films with different Mg doping concentrations have been prepared, and their crystallization behavior, structure and electrical properties have been systematically investigated for phase-change memory applications. The results show that the addition of Mg into GST films could result in an enhancement in crystallization temperature, activation energy and electrical resistance compared with the conventional GST films, indicating that a good amorphous thermal stability. On the other hand, the proper Mg concentration ranging from 13.6 to 31.1 at.% can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase and suppress the formation of the hexagonal close-packed (hcp) crystalline phase. X-ray photoelectron spectra (XPS) further confirm that the formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhanced thermal stability in Mg-doped GST films.

  3. Chemical bond properties and Mossbauer spectroscopy in (La1-xMx)2CuO4 (M=Ba, Sr)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By using the average band-gap model, the chemical bond properties of (La1-x Mx)2CuO4(M=Ba, Sr) were calculated . The calculated covalencies for Cu(O and La(O bond in the compounds are 0.3 and 0.03 respectively. M?ssbauer isomer shifts of 57Fe doped in La2CuO4 and 119Sn doped in La2CuO4 were calculated by using the chemical surrounding factor defined by covalency and electronic polarizability. Four valence state tin and three valence iron sites were identified in 57Fe and 119Sn doped La2CuO4.

  4. Ultrafast one-step combustion synthesis and thermoelectric properties of In-doped Cu{sub 2}SnSe{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuyang [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Liu, Guanghua, E-mail: liugh02@163.com [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China); Li, Jiangtao, E-mail: lijiangtao@mail.ipc.ac.cn [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China); Chen, Kexin [State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084 (China); He, Gang; Yang, Zengchao; Han, Yemao; Zhou, Min; Li, Laifeng [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

    2016-07-01

    Bulk In-doped Cu{sub 2}SnSe{sub 3} samples were prepared by a fast and one-step method of high-gravity combustion synthesis. All the synthesized samples were dense with relative densities of >98%. The influence of Indium-doping on the phase composition of the samples was investigated. SEM and EDS measurements confirm the existence of SnSe and Cu{sub 2}Se as secondary phase in the Cu{sub 2}Sn{sub 1−x}In{sub x}Se{sub 3} samples. In addition, the experimental results show that there is a solubility limit of indium in the Cu{sub 2}SnSe{sub 3} matrix. The thermoelectric properties of the samples were measured in a temperature range from 323 K to 773 K, and the Cu{sub 2}Sn{sub 0.8}In{sub 0.2}Se{sub 3} sample achieved a maximum ZT of 0.65 at 773 K, which was comparable with the best-reported result for Cu{sub 2}SnSe{sub 3} materials prepared by conventional sintering approaches. With much reduced time and energy consumption, high-gravity combustion synthesis may offer a more efficient and economical way for producing thermoelectric materials. - Highlights: • Dense bulk Cu{sub 2}SnSe{sub 3} materials are prepared by one-step combustion synthesis. • The solubility limit of Indium into the Cu{sub 2}SnSe{sub 3} matrix has been discussed. • A maximum ZT of 0.65 is obtained for the Cu{sub 2}Sn{sub 1−x}In{sub x}Se{sub 3} (x = 0.2) at 773 K.

  5. Enhancement of Critical Current Density and Flux Pinning in Acetone and La2O3 Codoped MgB2 Tapes

    International Nuclear Information System (INIS)

    Gao Zhao-Shun; Ma Yan-Wei; Wang Dong-Liang; Zhang Xian-Ping; Awaji Satoshi; Watanabe Kazuo

    2010-01-01

    MgB 2 tape samples with simultaneous additions of acetone and La 2 O 3 were prepared by an in-situ processed powder-in-tube method. Compared to the pure and single doped tapes, both transport J c and fluxing pinning are greatly improved by acetone and La 2 O 3 codoping. Acetone supplies carbon into the MgB 2 crystal lattice and increases the upper critical field, while the La 2 O 3 reacts with B to form LaB 6 nanoparticles as effective flux pining centers. The improvement of the superconducting properties in codoped tapes can be attributed to the combined effects of improvement in H c2 and flux pinning. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Physical properties of electrically conductive Sb-doped SnO2 transparent electrodes by thermal annealing dependent structural changes for photovoltaic applications

    International Nuclear Information System (INIS)

    Leem, J.W.; Yu, J.S.

    2011-01-01

    Highlights: · The physical properties of sputtered Sb-doped SnO 2 after annealing were studied. · The figure of merit was estimated from the integral PFD and sheet resistance. · The characteristics of Sb-doped SnO 2 films were optimized by the figure of merit. · An optimized Sb-doped SnO 2 layer is promising for high efficiency photovoltaic cells. - Abstract: We have investigated the optical and electrical characteristics of antimony (Sb)-doped tin oxide (SnO 2 ) films with modified structures by thermal annealing as a transparent conductive electrode. The structural properties were analyzed from the relative void % by spectroscopic ellipsometry as well as the scanning electron microscopy images and X-ray diffraction patterns. As the annealing temperature was raised, Sb-doped SnO 2 films exhibited a slightly enhanced crystallinity with the increase of the grain size from 17.1 nm at 500 deg. C to 34.3 nm at 700 deg. C. Furthermore, the refractive index and extinction coefficient gradually decreased due to the increase in the relative void % within the film during the annealing. The resistivity decreased to 8.2 x 10 -3 Ω cm at 500 deg. C, but it increased rapidly at 700 deg. C. After thermal annealing, the optical transmittance was significantly increased. For photovoltaic applications, the photonic flux density and the figure of merit over the entire solar spectrum were obtained, indicating the highest values of 5.4 x 10 14 cm -2 s -1 nm -1 at 1.85 eV after annealing at 700 deg. C and 340.1 μA cm -2 Ω -1 at 500 deg. C, respectively.

  7. Iron doped SnO{sub 2}/Co{sub 3}O{sub 4} nanocomposites synthesized by sol-gel and precipitation method for metronidazole antibiotic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Shilpi [Department of Applied Chemistry, University of Johannesburg, Johannesburg (South Africa); Tyagi, Inderjeet [Department of Chemistry, Indian Institute of Technology Roorkee, 247667 (India); Gupta, Vinod Kumar, E-mail: vinodg@uj.ac.za [Department of Applied Chemistry, University of Johannesburg, Johannesburg (South Africa); Sohrabi, Maryam; Mohammadi, Sanaz [Department of Chemistry, Shahr-e-Qods Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Golikand, Ahmad Nozad, E-mail: anozad@aeoi.org.ir [Department of Chemistry, Shahr-e-Qods Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Jaber Research Laboratory, NSTRI, P.O. Box: 14395-836, Tehran (Iran, Islamic Republic of); Fakhri, Ali, E-mail: ali.fakhri88@yahoo.com [Young Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2017-01-01

    Sol-gel and precipitation reaction methods were used to synthesize Un-doped and Fe-doped SnO{sub 2}/Co{sub 3}O{sub 4} nanocomposites under UV light; the synthesized nanocomposites were applied for the photocatalytic degradation of metronidazole antibiotic. The developed photo catalyst was well characterized using energy dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FE-SEM), UV–Visible and photoluminescence (PL) spectroscopy. Effective parameters such as pH, photocatalyst dose and contact time was optimized and well investigated. From the obtained facts it is clear that the 98.3% of MTZ was degraded with in 15 min, pH 6 and 0.1 g catalyst when the Fe molar ratio was 1:1 at %. As compared to results obtained from un-doped SnO{sub 2}/Co{sub 3}O{sub 4} nanocomposites Fe doped SnO{sub 2}/Co{sub 3}O{sub 4} nanocomposites possess greater photocatalytic efficiency. - Graphical abstract: Surface textural and morphological presentation. - Highlights: • Un-doped and Fe-doped SnO{sub 2}/Co{sub 3}O{sub 4} nanocomposites were applied as photocatalyst. • The nanocomposites exhibited photocatalytic property under UV light. • The maximum degradation was observed for Fe-doped SnO{sub 2}/Co{sub 3}O{sub 4} (1:1) photocatalyst. • 0.1 g photocatalyst is sufficient to carry out 98.3% degradation of MTZ.

  8. Magnetic evolution of itinerant ferromagnetism and interlayer antiferromagnetism in cerium doped LaCo{sub 2}P{sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Yong; Kong, Yixiu; Liu, Kai; Zhang, Anmin [Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872 (China); He, Rui [Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614 (United States); Zhang, Qingming, E-mail: qmzhang@ruc.edu.cn [Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872 (China)

    2017-05-01

    ThCr{sub 2}Si{sub 2}-type phosphide ACo{sub 2}P{sub 2} (A=Eu, La, Pr, Nd, Ce) has the same structure as iron arsenides, but their magnetic behaviors are quite distinct. In this paper, we grew a series of La{sub 1−x}Ce{sub x}Co{sub 2}P{sub 2} single crystals (x=0.0 to1.0), made structural and magnetic characterizations. We found the introduction of cerium induces a rapid decrease of c-axis and a change from ferromagnetic to antiferromagnetic states. Compared to other trivalent doped compounds, the enhancement of ferromagnetism with doping is suppressed and the transition from ferromagnetism to antiferromagnetism appear earlier. By employing first-principles band-structure calculations, we identify the increase of Ce valence suppress the itinerant ferromagnetism and leading to formation of P-P bonding with the shortening of c-axis. The bonding effectively drives an increase of interlayer antiferromagnetic interaction, eventually leads to antiferromagnetic ordering of cobalt in high-doping region.

  9. Improvement of the optoelectronic properties of tin oxide transparent conductive thin films through lanthanum doping

    Energy Technology Data Exchange (ETDEWEB)

    Mrabet, C., E-mail: chokri.mrabet@hotmail.com; Boukhachem, A.; Amlouk, M.; Manoubi, T.

    2016-05-05

    This work highlights some physical investigations on tin oxide thin films doped with different lanthanum content (ratio La–to-Sn = 0–3%). Such doped thin films have been successfully grown by spray pyrolysis onto glass substrates at 450 °C. X-ray diffraction (XRD) patterns showed that SnO{sub 2}:La thin films were polycrystalline with tetragonal crystal structure. The preferred orientation of crystallites for undoped SnO{sub 2} thin film was along (110) plane, whereas La-doped ones have rather preferential orientations along (200) direction. Although the grain size values exhibited a decreasing tendency with increasing doping content confirming the role of La as a grain growth inhibitor, dislocation density and microstrain values showed an increasing tendency. Also, Raman spectroscopy shows the bands corresponding to the tetragonal structure for the entire range of La doping. The same technique confirms the presence of La{sub 2}O{sub 3} as secondary phase. Moreover, SEM images showed a porous architecture with presence of big clusters with different sizes and shapes resulting from the agglomeration of small grains round shaped. Photoluminescence spectra of SnO{sub 2}:La thin films exhibit a decrease in the emission intensity with La concentration due to the decrease in grain size. Optical transmittance spectra of the films showed high transparency (∼80%) in the visible region. The dispersion of the refractive index is discussed using both Cauchy model and Wemple–Di-Domenico method. The optical band gap values vary slightly with La doping and were found to be around 3.8 eV. It has been found that La doping causes a pronounced decrease in the sheet resistance by up to two orders of magnitude and allows improving the Haacke's figure of merit (Φ) of the sprayed thin films. Moreover, we have introduced for a first time a new figure of merit for qualifying photo-thermal conversion applications. The obtained high conducting and transparent SnO{sub 2}:La

  10. Stabilization of MgCr2O4 spinel in slags of the
    SiO2-CaO-MgO-Cr2O3 system

    Directory of Open Access Journals (Sweden)

    Arredondo-Torres, V.

    2006-12-01

    Full Text Available El objetivo de este estudio es analizar el efecto del contenido de MgO y la basicidad de la escoria sobre la estabilidad de las especies mineralógicas del sistema de escoria SiO2-CaOMgO-
    Cr2O3. Se realizaron ensayos al equilibrio a 1600 °C bajo condiciones reductoras (pO2=10-9atm. El contenido de MgO fue de 0 a 12 % masa, el Cr2O3 de 10% y la basicidad de 1 y 1,5. También se realizó un análisis termodinámico para determinar las fases mineralógicas más estables en la escoria. Los resultados experimentales y calculados muestran que el Cr2O3 se encuentra principalmente ligado en una fase espinela MgCr2O4, incluso a bajos contenidos de MgO. Los resultados obtenidos por microscopia electrónica de barrido (MEB-EDS, muestran la evidencia de tres estructuras cristalinas: (A Octaedros, los cuales
    corresponden a la espinela MgCr2O4, (B Cristales alargados que corresponden a la formación de silicatos cálcicos y (C Matriz de silicatos cálcicos con impurezas de Mg y Cr que no cristalizaron por completo.

    El objetivo de este estudio es analizar el efecto del contenido de MgO y la basicidad de la escoria sobre la estabilidad de las especies mineralógicas del sistema de escoria SiO2-CaOMgO-Cr2O3. Se realizaron ensayos al equilibrio a 1600 °C bajo condiciones reductoras (pO2=10-9atm. El contenido de MgO fue de 0 a 12 % masa, el Cr2O3 de 10% y la basicidad de 1 y 1,5. También se realizó un análisis termodinámico para determinar las fases mineralógicas más estables en la escoria. Los resultados experimentales y calculados muestran que el Cr2O3 se encuentra principalmente ligado en una fase espinela MgCr2O4, incluso a bajos contenidos de MgO. Los resultados obtenidos por

  11. An investigation of the Nb doping effect on structural, morphological, electrical and optical properties of spray deposited F doped SnO2 films

    Science.gov (United States)

    Turgut, G.; Keskenler, E. F.; Aydın, S.; Yılmaz, M.; Doǧan, S.; Düzgün, B.

    2013-03-01

    F and Nb + F co-doped SnO2 thin films were deposited on glass substrates by the spray pyrolysis method. The microstructural, morphological, electrical and optical properties of the 10 wt% F doped SnO2 (FTO) thin films were investigated specifically for niobium (Nb) doping in the range of 0-4 at.% with 1 at.% steps. As shown by the x-ray diffraction patterns, the films exhibited a tetragonal cassiterite structure with (200) preferential orientation. It was observed that grain sizes of the films for (200) and (301) peaks depended on the Nb doping concentration and varied in the range of 25.11-32.19 and 100.6-183.7 nm, respectively. The scanning electron microscope (SEM) micrographs showed that the FTO films were made of small pyramidal grains, while doubly doped films were made of small pyramidal grains and big polyhedron grains. From electrical studies, although 1 at.% Nb doped FTO films have the lowest sheet resistance and resistivity values, the highest figure-of-merit and optical band gap values obtained for FTO films were 16.2 × 10-2 Ω-1 and 4.21 eV, respectively. Also, infrared reflectivity values of the films were in the range of 97.39-98.98%. These results strongly suggest that these films are an attractive candidate for various optoelectronic applications and for photothermal conversion of solar energy.

  12. Electrical characterisation of Sn doped InAs grown by MOVPE

    International Nuclear Information System (INIS)

    Shamba, P.; Botha, L.; Krug, T.; Venter, A.; Botha, J.R.

    2008-01-01

    The feasibility of tetraethyl tin (TESn) as an n-type dopant for InAs is investigated. The electrical properties of Sn doped InAs films grown on semi-insulating GaAs substrates by MOVPE are extensively studied as a function of substrate temperature, V/III ratio, substrate orientation and TESn flow rate. Results from this study show that Sn concentrations can be controlled over 2 orders of magnitude. The Sn doped InAs layers exhibit carrier concentrations between 2.7 x 10 17 and 4.7 x 10 19 cm -3 with 77 K mobilities ranging from 12 000 to 1300 cm 2 /Vs. Furthermore, the influence of the variation of these parameters on the structural properties of InAs are also reported. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Hydrothermal synthesis and characteristic photoluminescence of Er-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tuan, Pham Van; Hieu, Le Trung; Nga, La Quynh [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Dung, Nguyen Duc [Advanced Institute of Science and Technology, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Khiem, Tran Ngoc, E-mail: khiem@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam)

    2016-11-15

    We report the characteristic photoluminescence (PL) spectra of erbium ion (Er{sup 3+})-doped tin dioxide (SnO{sub 2})nanoparticles. The materials were prepared via hydrothermal method at 180 °C with in 20 h by using various Er{sup 3+} ion concentrations ranging from 0.0 to 1.0 at%. After the synthesis, the materials were characterized through X-ray diffraction and high-resolution transmission electron microscopy. Crystallite SnO{sub 2} and its average particle diameter of approximately 5 nm did not change with Er{sup 3+} ion dopant concentration. Photoluminescence spectra showed the characteristic light emission from the Er{sup 3+} ions. The PL excitation spectra referred to an efficient energy transfer to Er{sup 3+} ions in the presence of SnO{sub 2}nanoparticles. The most intense Er-related emission of SnO{sub 2}:Er{sup 3+} nanoparticles in near infrared region was found in samples containing an Er{sup 3+} ion concentration of 0.25 at%. Although the absorption bandgaps of the materials were identified at approximately 3.8 eV, we found that efficient excitation comes with low excitation energy band edge. Excitation is possibly involved in shallow defects in SnO{sub 2} nanoparticles.

  14. A comparative study on the flux pinning properties of Zr-doped YBCO film with those of Sn-doped one prepared by metal-organic deposition

    International Nuclear Information System (INIS)

    Choi, S. M.; Shin, G. M.; Joo, Y.S.; Yoo, S. I.

    2013-01-01

    We investigated the flux pinning properties of both 10 mol% Zr-and Sn-doped YBa 2 Cu 3 O 7-δ (YBCO) films with the same thickness of ∽350 nm for a comparative purpose. The films were prepared on the SrTiO 3 (STO) single crystal substrate by the metal-organic deposition (MOD) process. Compared with Sn-doped YBCO film, Zr-doped one exhibited a significant enhancement in the critical current density (J c ) and pinning force density (F p ). The anisotropic J c ,min/J c ,max ratio in the field-angle dependence of J c at 77 K for 1 T was also improved from 0.23 for Sn-doped YBCO to 0.39 for Zr-doped YBCO. Thus, the highest magnetic J c values of 9.0 and 2.9 MA/cm 2 with the maximum F p (F p ,max) values of 19 and 5 GN/m 3 at 65 and 77 K for H // c, respectively, could be achieved from Zr-doped YBCO film. The stronger pinning effect in Zr-doped YBCO film is attributable to smaller BaZrO-3 (BZO) nanoparticles (the average size ≈ 28.4 nm) than YBa 2 SnO 5. 5 (YBSO) nanoparticles (the average size ≈ 45.0 nm) incorporated in Sn-doped YBCO film since smaller nanoparticles can generate more defects acting as effective flux pinning sites due to larger incoherent interfacial area for the same doping concentration.

  15. Comparison of electrocatalytic characterization of boron-doped diamond and SnO2 electrodes

    International Nuclear Information System (INIS)

    Lv, Jiangwei; Feng, Yujie; Liu, Junfeng; Qu, Youpeng; Cui, Fuyi

    2013-01-01

    Boron-doped diamond (BDD) and SnO 2 electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) and sol–gel method, respectively. Electrochemical characterization of the two electrodes were investigated by phenol electrochemical degradation, accelerated service life test, cyclic voltammetry (CV) in phenol solution, polarization curves in H 2 SO 4 . The surface morphology and crystal structure of two electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The results showed a considerable difference between the two electrodes in their electrocatalytic activity, electrochemical stability and surface properties. Phenol was readily mineralized to CO 2 at BDD electrode, favoring electrochemical combustion, but its degradation was much slower at SnO 2 electrode. The service life of BDD electrode was 10 times longer than that of SnO 2 . Higher electrocatalytic activity and electrochemical stability of BDD electrode arise from its high oxygen evolution potential and the physically absorbed hydroxyl radicals (·OH) on electrode surface.

  16. Polycrystalline Mg2Si thin films: A theoretical investigation of their electronic transport properties

    International Nuclear Information System (INIS)

    Balout, H.; Boulet, P.; Record, M.-C.

    2015-01-01

    The electronic structures and thermoelectric properties of a polycrystalline Mg 2 Si thin film have been investigated by first-principle density-functional theory (DFT) and Boltzmann transport theory calculations within the constant-relaxation time approximation. The polycrystalline thin film has been simulated by assembling three types of slabs each having the orientation (001), (110) or (111) with a thickness of about 18 Å. The effect of applying the relaxation procedure to the thin film induces disorder in the structure that has been ascertained by calculating radial distribution functions. For the calculations of the thermoelectric properties, the energy gap has been fixed at the experimental value of 0.74 eV. The thermoelectric properties, namely the Seebeck coefficient, the electrical conductivity and the power factor, have been determined at three temperatures of 350 K, 600 K and 900 K with respect to both the energy levels and the p-type and n-type doping levels. The best Seebeck coefficient is obtained at 350 K: the S yy component of the tensor amounts to about ±1000 μV K −1 , depending on the type of charge carriers. However, the electrical conductivity is much too small which results in low values of the figure of merit ZT. Structure–property relationship correlations based on directional radial distribution functions allow us to tentatively draw some explanations regarding the anisotropy of the electrical conductivity. Finally, the low ZT values obtained for the polycrystalline Mg 2 Si thin film are paralleled with those recently reported in the literature for bulk chalcogenide glasses. - Graphical abstract: Structure of the polycrystalline thin film of Mg 2 Si. - Author-Highlights: • Polycrystalline Mg 2 Si film has been modelled by DFT approach. • Thermoelectric properties have been evaluated by semi-classical Boltzmann theory. • The structure was found to be slightly disordered after relaxation. • The highest value of Seebeck

  17. Epitaxial Sb-doped SnO{sub 2} and Sn-doped In{sub 2}O{sub 3} transparent conducting oxide contacts on GaN-based light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Min-Ying [Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106 (United States); Bierwagen, Oliver, E-mail: bierwagen@pdi-berlin.de [Materials Department, University of California, Santa Barbara, CA 93106 (United States); Paul-Drude-Insitut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Speck, James S. [Materials Department, University of California, Santa Barbara, CA 93106 (United States)

    2016-04-30

    We demonstrate the growth of epitaxial (100)-oriented, rutile Sb-doped SnO{sub 2} (ATO) and (111)-oriented, cubic Sn-doped In{sub 2}O{sub 3} (ITO) transparent conducting oxide (TCO) contacts on top of an InGaN/GaN(0001) light emitting diode (LED) by plasma-assisted molecular beam epitaxy (PAMBE). Both oxides form rotational domains. The in-plane epitaxial alignment of the two ITO(111) rotational domains to the GaN(0001) was: GaN [21-10]|| ITO{sub Domain1}[‐ 211]|| ITO{sub Domain2}[‐ 1‐12]. A growth temperature as low as 600 °C was necessary to realize a low contact resistance between ATO and the top p-GaN layer of the LED but resulted in non-optimal resistivity (3.4 × 10{sup −} {sup 3} Ω cm) of the ATO. The current–voltage characteristics of a processed LED, however, were comparable to that of a reference LED with a standard electron-beam evaporated ITO top contact. At short wavelengths, the optical absorption of ATO was lower than that of ITO, which is beneficial even for blue LEDs. Higher PAMBE growth temperatures resulted in lower resistive ATO but higher contact resistance to the GaN, likely by the formation of an insulating Ga{sub 2}O{sub 3} interface layer. The ITO contact grown by PAMBE at 600 °C showed extremely low resistivity (10{sup −4} Ω cm) and high crystalline and morphological quality. These proof-of-principle results may lead to the development of epitaxial TCO contacts with low resistivity, well-defined interfaces to the p-GaN to help minimize contact losses, and enable further epitaxy on top of the TCO. - Highlights: • Plasma-assisted molecular beam epitaxy of SnO{sub 2}:Sb (ATO) and In{sub 2}O{sub 3}:Sn (ITO) contacts • Working light emitting diodes processed with the ATO contact on the top p-GaN layer • Low growth temperature ensures low contact resistance (limiting interface reaction). • ITO showed significantly better structural and transport properties than ATO. • ATO showed higher optical transmission at short

  18. SiO{sub 2} effect on spectral and colorimetric properties of europium doped SrO{sub 2}-MgO-xSiO{sub 2} (0.8 {<=} x {<=} 1.6) phosphor for white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Chen, B J; Jang, K W; Lee, H S; Jayasimhadri, M; Cho, E J [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Yi, S S [Department of Photonics, Silla University, Pusan 617-736 (Korea, Republic of); Jeong, J H [Department of Physics, Pukyong National University, Pusan 608-737 (Korea, Republic of)], E-mail: kwjang@changwon.ac.kr

    2009-05-21

    Silicate phosphors with compositions 1.99 SrO{sub 2}-1.0 MgO-xSiO{sub 2}-0.01 Eu{sub 2}O{sub 3} (x = 0.8, 1.0, 1.2, 1.4 and 1.6) were prepared in a reducing atmosphere via a solid state reaction. The resultant phosphors were examined by using x-ray diffraction and confirmed to be a mixture of monoclinic Sr{sub 2}SiO{sub 4} and orthorhombic Mg{sub 2}(Si{sub 2}O{sub 4}). The scanning electron microscope images revealed that SiO{sub 2} content does not influence the morphology of the resultant phosphors. It was also observed that the excitation spectra are dependent on the monitored emission wavelength, and the emission spectra are dependent on the excitation wavelength and the SiO{sub 2} content. The energy transfer between Eu{sup 2+} ions occupying different Sr{sup 2+} sites was discussed. The colour coordinates for these phosphors are tunable based on both the excitation wavelength and the SiO{sub 2} content.

  19. Electron irradiation response on Ge and Al-doped SiO 2 optical fibres

    Science.gov (United States)

    Yaakob, N. H.; Wagiran, H.; Hossain, I.; Ramli, A. T.; Bradley, D. A.; Hashim, S.; Ali, H.

    2011-05-01

    This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

  20. Electron irradiation response on Ge and Al-doped SiO2 optical fibres

    International Nuclear Information System (INIS)

    Yaakob, N.H.; Wagiran, H.; Hossain, I.; Ramli, A.T.; Bradley, D.A; Hashim, S.; Ali, H.

    2011-01-01

    This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

  1. Unusually large chemical potential shift in a degenerate semiconductor: Angle-resolved photoemission study of SnSe and Na-doped SnSe

    Science.gov (United States)

    Maeda, M.; Yamamoto, K.; Mizokawa, T.; Saini, N. L.; Arita, M.; Namatame, H.; Taniguchi, M.; Tan, G.; Zhao, L. D.; Kanatzidis, M. G.

    2018-03-01

    We have studied the electronic structure of SnSe and Na-doped SnSe by means of angle-resolved photoemission spectroscopy. The valence-band top reaches the Fermi level by the Na doping, indicating that Na-doped SnSe can be viewed as a degenerate semiconductor. However, in the Na-doped system, the chemical potential shift with temperature is unexpectedly large and is apparently inconsistent with the degenerate semiconductor picture. The large chemical potential shift and anomalous spectral shape are key ingredients for an understanding of the novel metallic state with the large thermoelectric performance in Na-doped SnSe.

  2. SiSn diodes: Theoretical analysis and experimental verification

    KAUST Repository

    Hussain, Aftab M.

    2015-08-24

    We report a theoretical analysis and experimental verification of change in band gap of silicon lattice due to the incorporation of tin (Sn). We formed SiSn ultra-thin film on the top surface of a 4 in. silicon wafer using thermal diffusion of Sn. We report a reduction of 0.1 V in the average built-in potential, and a reduction of 0.2 V in the average reverse bias breakdown voltage, as measured across the substrate. These reductions indicate that the band gap of the silicon lattice has been reduced due to the incorporation of Sn, as expected from the theoretical analysis. We report the experimentally calculated band gap of SiSn to be 1.11 ± 0.09 eV. This low-cost, CMOS compatible, and scalable process offers a unique opportunity to tune the band gap of silicon for specific applications.

  3. Study on adsorption of O{sub 2} on LaFe{sub 1-x}Mg{sub x}O{sub 3} (0 1 0) surface by density function theory calculation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xing, E-mail: liuxing0108@mail.sdu.edu.cn [Civil Engineer Department, Qingdao Technological University (Linyi), Easter Outer Ring Road 1, Linyi, 273400 (China); Cheng, Bin [Civil Engineer Department, Qingdao Technological University (Linyi), Easter Outer Ring Road 1, Linyi, 273400 (China); Hu, Jifan; Qin, Hongwei [State Key Laboratory of Crystal Material, Department of Physics, Shandong University, Hongjialou 5, Jinan, 250100 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Mg-doping can change the electronic properties of LaFeO{sub 3} (0 1 0) surface by decreasing the band gap. Black-Right-Pointing-Pointer The position and content of Mg-doping can both affect the ability to adsorb O{sub 2}. Black-Right-Pointing-Pointer The strong hybridization between O{sub 2} p and Fe d orbital is the origin of binding mechanism. - Abstract: The adsorption of O{sub 2} on the clean and Mg doped LaFeO{sub 3} (0 1 0) surface has been investigated using the density functional theory (DFT) method. Calculation results show that Mg-doping can change the electronic properties of LaFeO{sub 3} (0 1 0) surface by decreasing the band gap. When Mg ions were not on the first layer of the surface, with increasing Mg content the adsorption of O{sub 2} was enhanced. When Mg ions were on the first layer, the adsorption of O{sub 2} was weakened with the increase of Mg content. The analysis results of the DOS indicated that the Mg ion and adsorbed O{sub 2} had no strong hybridization, and the bonding mechanism was originated from the strong hybridization between the O p and Fe d orbital. Referring to all the calculation results, it was found that except for the increase of stability of oxygen adsorption, the Mg doping could not improve the sensitivity to O{sub 2}.

  4. Rapid Synthesis and Formation Mechanism of Core-Shell-Structured La-Doped SrTiO3 with a Nb-Doped Shell

    Directory of Open Access Journals (Sweden)

    Nam-Hee Park

    2015-07-01

    Full Text Available To provide a convenient and practical synthesis process for metal ion doping on the surface of nanoparticles in an assembled nanostructure, core-shell-structured La-doped SrTiO3 nanocubes with a Nb-doped surface layer were synthesized via a rapid synthesis combining a rapid sol-precipitation and hydrothermal process. The La-doped SrTiO3 nanocubes were formed at room temperature by a rapid dissolution of NaOH pellets during the rapid sol-precipitation process, and the Nb-doped surface (shell along with Nb-rich edges formed on the core nanocubes via the hydrothermal process. The formation mechanism of the core-shell-structured nanocubes and their shape evolution as a function of the Nb doping level were investigated. The synthesized core-shell-structured nanocubes could be arranged face-to-face on a SiO2/Si substrate by a slow evaporation process, and this nanostructured 10 μm thick thin film showed a smooth surface.

  5. Photoluminescence of Eu2+-doped CaMgSi2xO6+2x (1.00≤x≤1.20) phosphors in UV-VUV region

    International Nuclear Information System (INIS)

    Zhang Zhiya; Wang Yuhua

    2008-01-01

    Alkaline-earth silicate phosphors CaMgSi 2x O 6+2x :Eu 2+ (1.00≤x≤1.20) were prepared by traditional solid-state reaction. The phosphors showed an intense blue emission centered around 453 nm, with both 254 and 147 nm excitations. The host absorption below 200 nm in the excitation spectra consisted of two bands around 160 and 190 nm. The band around 160 nm was ascertained to be associated with the SiO 4 -tetrahedra and MgO 6 -polyhedra, and that around 190 nm was due to the CaO 8 -polyhedra or some impurities. The incorporation of excess Si of less than 15% would not lead to formation of impurities and the results indicated that an appropriate Si excess could improve the Photoluminescence (PL) intensity in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions

  6. Magnetism tuned by the charge states of defects in bulk C-doped SnO2 materials.

    Science.gov (United States)

    Lu, Ying-Bo; Ling, Z C; Cong, Wei-Yan; Zhang, Peng

    2015-10-21

    To analyze the controversial conclusions on the magnetism of C-doped SnO2 (SnO2:C) bulk materials between theoretical calculations and experimental observations, we propose the critical role of the charge states of defects in the geometric structures and magnetism, and carry out a series of first principle calculations. By changing the charge states, we can influence Bader charge distributions and atomic orbital occupancies in bulk SnO2:C systems, which consequently conduct magnetism. In all charged SnO2:C supercells, C-2px/py/pz electron occupancies are significantly changed by the charge self-regulation, and thus they make the C-2p orbitals spin polarized, which contribute to the dominant magnetic moment of the system. When the concentration of C dopant in the SnO2 supercell increases, the charge redistribution assigns extra electrons averagely to each dopant, and thus effectively modulates the magnetism. These findings provide an experimentally viable way for controlling the magnetism in these systems.

  7. Study of sub band gap absorption of Sn doped CdSe thin films

    International Nuclear Information System (INIS)

    Kaur, Jagdish; Rani, Mamta; Tripathi, S. K.

    2014-01-01

    The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively

  8. Study of sub band gap absorption of Sn doped CdSe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Jagdish; Rani, Mamta [Department of Physics, Panjab University, Chandigarh- 160014 (India); Tripathi, S. K., E-mail: surya@pu.ac.in [Centre of Advanced Study in Physics, Panjab University, Chandigarh- 160014 (India)

    2014-04-24

    The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively.

  9. Fe-N co-doped SiO2@TiO2 yolk-shell hollow nanospheres with enhanced visible light photocatalytic degradation

    Science.gov (United States)

    Wan, Hengcheng; Yao, Weitang; Zhu, Wenkun; Tang, Yi; Ge, Huilin; Shi, Xiaozhong; Duan, Tao

    2018-06-01

    SiO2@TiO2 yolk@shell hollow nanospheres (STNSs) is considered as an outstanding photocatalyst due to its tunable structure and composition. Based on this point, we present an unprecedentedly excellent photocatalytic property of STNSs toward tannic acid via a Fe-N co-doped strategy. Their morphologies, compositions, structure and properties are characterized. The Fe-N co-doped STNSs formed good hollow yolk@shell structure. The results show that the energy gap of the composites can be downgraded to 2.82 eV (pure TiO2 = 3.2 eV). Photocatalytic degradation of tannic acid (TA, 30 mg L-1) under visible light (380 nm TiO2 nanospheres, non-doped STNSs and N-doped STNSs, the Fe-N co-doped STNSs exhibits the highest activity, which can degrade 99.5% TA into CO2 and H2O in 80 min. The probable degradation mechanism of the composites is simultaneously proposed, the band gap of STNSs becomes narrow by co-doping Fe-N, so that the TiO2 shell can stimulate electrons under visible light exposure, generate the ions of radOH and radO2- with a strong oxidizing property. Therefore this approach works is much desired for radioactive organic wastewater photocatalytic degradation.

  10. Hydrogen peroxide route to Sn-doped titania photocatalysts

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Matys Grygar, Tomáš; Henych, Jiří; Kormunda, M.

    2012-01-01

    Roč. 6, č. 1 (2012), s. 113 ISSN 1752-153X Institutional support: RVO:61388980 Keywords : photocatalysis * Sn doping * TiO2 * Vis light * Wet synthesis Subject RIV: CA - Inorganic Chemistry Impact factor: 1.312, year: 2012

  11. Microstructure, corrosion behavior and cytotoxicity of biodegradable Mg-Sn implant alloys prepared by sub-rapid solidification.

    Science.gov (United States)

    Zhao, Chaoyong; Pan, Fusheng; Zhao, Shuang; Pan, Hucheng; Song, Kai; Tang, Aitao

    2015-09-01

    In this study, biodegradable Mg-Sn alloys were fabricated by sub-rapid solidification, and their microstructure, corrosion behavior and cytotoxicity were investigated by using optical microscopy, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction, immersion test, potentiodynamic polarization test and cytotoxicity test. The results showed that the microstructure of Mg-1Sn alloy was almost equiaxed grain, while the Mg-Sn alloys with higher Sn content (Sn≥3 wt.%) displayed α-Mg dendrites, and the secondary dendrite arm spacing of the primary α-Mg decreased significantly with increasing Sn content. The Mg-Sn alloys consisted of primary α-Mg matrix, Sn-rich segregation and Mg2Sn phase, and the amount of Mg2Sn phases increased with increasing Sn content. Potentiodynamic polarization and immersion tests revealed that the corrosion rates of Mg-Sn alloys increased with increasing Sn content. Cytotoxicity test showed that Mg-1Sn and Mg-3Sn alloys were harmless to MG63 cells. These results of the present study indicated that Mg-1Sn and Mg-3Sn alloys were promising to be used as biodegradable implants. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Efficient photocatalytic degradation of phenol in aqueous solution by SnO{sub 2}:Sb nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdi, Abdullah M., E-mail: Abdullah.Al.Hamdi@lut.fi [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Chemistry Department, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Bora, Tanujjal [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Dutta, Joydeep [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Functional Materials Division, ICT, KTH Royal Institute of Technology, Isafjordsgatan 22, SE-164 40 KistaStockholm (Sweden)

    2016-05-01

    Highlights: • Sb doped SnO{sub 2} nanoparticles were synthesized using sol–gel process. • Photocatalytic degradation of phenol were studies using SnO{sub 2}:Sb nanoparticles. • Under solar light phenol was degraded within 2 h. • Phenol mineralization and intermediates were investigated by using HPLC. - Abstract: Photodegradation of phenol in the presence of tin dioxide (SnO{sub 2}) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO{sub 2}. In this study antimony (Sb) doped tin dioxide (SnO{sub 2}) nanoparticles were prepared at a low temperature (80 °C) by a sol–gel method and studied for its photocatalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO{sub 2}:Sb was found to be a maximum for 0.6 wt.% Sb doped SnO{sub 2} nanoparticles with 10 mg L{sup −1} phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.

  13. Hydrogen desorption properties of MgH2–Ni–Ni2Si composites prepared by mechanochemical method

    International Nuclear Information System (INIS)

    Shimada, Motoki; Higuchi, Eiji; Inoue, Hiroshi

    2013-01-01

    Highlights: ► The MgH 2 –Ni composite showed fast hydrogen desorption rate at 250 °C. ► The MgH 2 –Ni–Ni 2 Si composite showed fast hydrogen desorption rate at 220 °C. ► Nanocrystalline Mg 2 Ni and Mg 2 Si were formed between Mg and adjacent Ni or Si. ► Ni 2 Si did not form any alloys and work as a catalyst. -- Abstract: To improve hydrogen desorbability of Mg, some composites were prepared from MgH 2 , Ni and Ni 2 Si mixed powders by the mechanochemical method. The MgH 2 –Ni(2 mol%)–Ni 2 Si(1 mol%) composite was slower in hydrogen desorption rate at 250 °C than the MgH 2 –Ni(2 mol%) composite, while the hydrogen desorption rate at 220 °C for the former was faster than that for the latter. The XRD pattern of the MgH 2 –Ni(2 mol%) composite showed that after hydrogen desorption at 400 °C small diffraction peaks assigned to Mg 2 Ni were observed with peaks assigned to Mg. They shifted to smaller angles after hydrogen absorption at 250 °C and come back to the original positions after hydrogen desorption at 250 °C, suggesting reversible hydrogen absorption/desorption of Mg 2 Ni. In contrast, Ni 2 Si was not changed over the whole processes. These results indicated that Ni 2 Si worked as a catalyst for hydrogen desorption, leading to the improvement of desorbability at 220 °C

  14. Enhancement of the catalytic activity of Pt nanoparticles toward methanol electro-oxidation using doped-SnO2 supporting materials

    Science.gov (United States)

    Merati, Zohreh; Basiri Parsa, Jalal

    2018-03-01

    Catalyst supports play important role in governing overall catalyst activity and durability. In this study metal oxides (SnO2, Sb and Nb doped SnO2) were electrochemically deposited on titanium substrate (Ti) as a new support material for Pt catalyst in order to electro-oxidation of methanol. Afterward platinum nanoparticles were deposited on metal oxide film via electro reduction of platinum salt in an acidic solution. The surface morphology of modified electrodes were evaluated by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX) techniques. The electro-catalytic activities of prepared electrodes for methanol oxidation reaction (MOR) and oxidation of carbon monoxide (CO) absorbed on Pt was considered with cyclic voltammetry. The results showed high catalytic activity for Pt/Nb-SnO2/Ti electrode. The electrochemical surface area (ECSA) of a platinum electro-catalyst was determined by hydrogen adsorption. Pt/Nb-SnO2/Ti electrode has highest ECSA compared to other electrode resulting in high activity toward methanol electro-oxidation and CO stripping experiments. The doping of SnO2 with Sb and Nb improved ECSA and MOR activity, which act as electronic donors to increase electronic conductivity.

  15. A theoretical investigation of the N2O + SO2 reaction on surfaces of P-doped C60 nanocage and Si-doped B30N30 nanocage

    Directory of Open Access Journals (Sweden)

    Meysam Najafi

    Full Text Available The mechanism of N2O reduction via SO2 on surfaces of P-doped C60 and Si-doped B30N30 by density functional theory were investigated. The P and Si adsorption energies on surface of C60 and B30N30 were calculated to be −287.5 and −312.1 kcal/mol, respectively. The decomposition of C60-P-N2O and B30N30-Si-N2O and reduction of C60-P-O∗ and B30N30-Si-O∗ by SO2 molecule were investigated. The B30N30-Si-O∗ has lower activation energy and has more negative ΔGad rather than C60-P-O∗ and therefore the process of B30N30-Si-O∗ + SO2 → B30N30-Si + SO3 was spontaneous more than C60-P-O∗ + SO2 → C60-P + SO3 from thermodynamic view point. Results show that activation energies for B30N30-Si-O∗ + N2O → B30N30-Si-O2 + N2 and C60-P-O∗ + N2O → C60-P-O2 + N2 reactions were 33.23 and 35.82 kcal/mol, respectively. The results show that P-doped C60 and Si-doped B30N30 can be observed as a real catalysts for the reduction of N2O. Keywords: Atom doping, Catalyst, Nanocage, Adsorption, N2O reduction

  16. High blocking temperature in SnO{sub 2} based super-paramagnetic diluted magnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Mounkachi, O., E-mail: o.mounkachi@mascir.com [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Salmani, E. [LMPHE, associé au CNRST (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); El Moussaoui, H. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Masrour, R. [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Safi (Morocco); Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Ez-Zahraouy, H. [LMPHE, associé au CNRST (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Benyoussef, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE, associé au CNRST (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco)

    2014-11-25

    Highlights: • Simple doping, (Sn,Fe)O{sub 2} exhibits a soft ferromagnetism at low temperature. • High blocking temperature was observed for Cu doped (Sn,Fe)O{sub 2} nanocrystalline. • Experimental results are confirmed by ab initio calculations. - Abstract: (Fe,Cu)-doped SnO{sub 2} nanocrystals was synthesized using the co-precipitation method. Magnetic Properties Measurement System (MPMS) revealed that for simple doping, Fe-doped SnO{sub 2} soft ferromagnetism at low temperature appears, while the ferromagnetic phase is stable at temperature higher than room temperature for Cu co-doping element. The ferromagnetism is significantly enhanced by the Cu addition to Fe-doped SnO{sub 2}, according to the ZFC and FC magnetizations and the hysteresis loops. The evidences for the existence of superparamagnetism are characterized and high blocking temperature super-paramagnetism in (Fe,Cu)-doped SnO{sub 2} nanocrystals was observed. Based on first-principles calculations, we have investigated electronic structures and magnetic properties of Fe-doped SnO{sub 2} and (Fe,Cu)-doped SnO{sub 2} with and without defect with LDA and LDA-SIC approximations. The results suggest that the oxygen vacancies (V{sub O}) play a critical role in the activation of ferromagnetism in Fe doped SnO{sub 2}. For (Fe,Cu)-doped SnO{sub 2} the results exhibit that Cu strongly influences on the magnetic properties of these doped systems which are in good agreement with the experimental observations. Electronic structure show that the presence of Cu promote the ferromagnetic bound magnetic polaron interaction through the carriers introduce by d (Cu)

  17. N–Mg dual-acceptor co-doping in CuCrO{sub 2} studied by first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ying, E-mail: 1080071@hnust.edu.cn [School of Physics, Hunan University of Science and Technology, Xiangtan 411201 (China); Nie, Guo-Zheng [School of Physics, Hunan University of Science and Technology, Xiangtan 411201 (China); Zou, Daifeng [School of Physics, Hunan University of Science and Technology, Xiangtan 411201 (China); Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Tang, Jing-Wu [School of Physics, Hunan University of Science and Technology, Xiangtan 411201 (China); Ao, Zhimin, E-mail: Zhimin.Ao@gdut.edu.cn [Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2016-11-25

    In this paper, N–Mg dual-acceptor co-doping in CuCrO{sub 2} is investigated by first-principles calculations. The electronic structure and formation energies of Mg substituting Cr-site, N substituting O-site, and co-doping of both Mg on Cr-site and N on O-site in CuCrO{sub 2} are calculated. It is found that the structure with N and Mg codoped at the nearest sites has the lowest energy due to a modest attractive interaction between the two dopants. Compared with single N or Mg doped CuCrO{sub 2}, the N–Mg codoped CuCrO{sub 2} has a lower formation energy and shallower transition level. In addition, the total density of states (DOS) analysis shows that more hole states appear above the Fermi level and higher DOS for N–Mg co-doping is obtained in the N–Mg codoped CuCrO{sub 2}, which is good to enhance the p-type conductivity in CuCrO{sub 2}. - Highlights: • N–Mg dual-acceptor co-doping in CuCrO{sub 2} is investigated. • N–Mg complex has a lower formation energy and shallower transition level. • More hole states appear above the Fermi level for N–Mg co-doping. • N–Mg co-doping in CuCrO{sub 2} can be expected to have more stable p-type conductivity.

  18. N{sub 2}O + CO reaction over Si- and Se-doped graphenes: An ab initio DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Gholizadeh, Reza [Laboratory of Chemical Engineering Thermodynamics, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Yu, Yang-Xin, E-mail: yangxyu@mail.tsinghua.edu.cn [Laboratory of Chemical Engineering Thermodynamics, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

    2015-12-01

    Graphical abstract: Si-doped graphene can be one of efficient green catalysts for conversion of the airborne pollutants. - Highlights: • N{sub 2}O can be efficiently reduced by CO over Si-doped graphenes. • Enough charge transferred from Si to N{sub 2}O makes the N{sub 2}–O bond break easily. • Si-doped graphene is efficient green catalysts for conversion of the airborne pollutants. • vdW interaction and ZPE energy significantly influence the predictions of activation energies. - Abstract: Catalytic conversion of non-CO{sub 2} green house gases and other harmful gases is a promising way to protect the atmospheric environment. Non-metal atom-doped graphene is attractive for use as a catalyst in the conversion due to its unique electronic properties, relatively low price and leaving no burden to the environment. To make an attempt on the development of green catalysts for the conversion, ab initio density functional theory is used to investigate the mechanisms of N{sub 2}O reduction by CO on Si- and Se-doped graphenes. We have calculated the geometries and adsorption energies of reaction species (N{sub 2}O, CO, N{sub 2} and CO{sub 2}) as well as energy profiles along the reaction pathways. The activation energies of N{sub 2}O decomposition and CO oxidation on both Si- and Se-doped graphenes have been obtained. Our calculated results indicate that the catalytic activity of Si-doped graphene is better than the Fe{sup +} in gas phase and comparable to the single Fe atom embedded on graphene. In the calculations, we found that van der Waals interactions and zero-point energy are two non-negligible factors for the predictions of the activation energies. Further discussion shows that Si-doped graphene can be one of efficient green catalysts for conversion of the airborne pollutants and Se-doped graphene can be a candidate for oxidizing CO by atomic oxygen.

  19. Dependence of open-circuit voltage of SnO2-nSi solar cells; SnO2-nSi taiyo denchi no sanka ondo menhoi izonsei

    Energy Technology Data Exchange (ETDEWEB)

    Shinoda, S; Shimizu, A; Yano, K; Kasuga, M [Yamanashi University, Yamanashi (Japan). Faculty of Engineering

    1997-11-25

    Although metal(or semiconductor)-semiconductor solar cells, SnO2-nSi solar cell for example, are superior in cost and efficiency, its barrier height and open-circuit voltage V(oc) are lower than those of p-n junctions. To improve these defects, study was made on the dependence of V(oc) on oxidation temperature and surface orientation using various solar cells prepared from (100)Si and (111)Si under various oxidation conditions. As a result, the density of surface states increases with a decrease in oxidation temperature of Si substrates, resulting in an increase in diode factor and V(oc). In this case, since oxide films are extremely thin and contribution of non-terminated bonds is large in the initial oxidation stage, the quantity of dangling bonds is larger in (100) plane than (111) plane, resulting in an increase in diode factor and V(oc). Since the surface energy level (the degree of electrons dominated by acceptor-like surface state from this level to the top of a valence band) of (100) Si is lower than that of (111) Si, the effective barrier height and V(oc) increase. 28 refs., 6 figs., 2 tabs.

  20. Effect of Mg and Si co-substitution on microstructure and strength of tricalcium phosphate ceramics.

    Science.gov (United States)

    García-Páez, Ismael H; Carrodeguas, Raúl García; De Aza, Antonio H; Baudín, Carmen; Pena, Pilar

    2014-02-01

    Magnesium and silicon co-doped tricalcium phosphate (TCP) ceramics with compositions corresponding to 0, 5 and 10wt% CaMg(SiO3)2 in the system Ca3(PO4)2-CaMg(SiO3)2 were obtained by conventional sintering of compacted mixtures of Ca3(PO4)2, MgO, SiO2 and CaCO3 powders at temperatures between 1100 and 1450°C. Microstructural analyses were performed by X-ray diffraction and field emission scanning electron microscopy with energy dispersive spectroscopy. Major phases in the obtained ceramics were β- or α+β-tricalcium phosphate containing Mg and Si in solid solution. Certain amounts of liquid were formed during sintering depending on composition and temperature. There were found significant differences in distributions of strength determined by the diametral compression of disc tests (DCDT). Failure strengths were controlled by microstructural defects associated with phase development. Mg and Si additions were found to be effective to improve densification and associated strength of TCP bioceramics due to the enhancement of sintering by the low viscosity liquids formed. The highest density and strength were obtained for the TCP ceramic containing 5wt% CaMg(SiO3)2 sintered at 1300°C. Cracking and porosity increased at higher temperatures due to grain growth and swelling. © 2013 Published by Elsevier Ltd.

  1. Fabrication of a transparent ultraviolet detector by using n-type Ga2O3 and p-type Ga-doped SnO2 core-shell nanowires.

    Science.gov (United States)

    Hsu, Cheng-Liang; Lu, Ying-Ching

    2012-09-21

    This study investigates the feasibility of synthesizing high-density transparent Ga(2)O(3)/SnO(2):Ga core-shell nanowires on a sapphire substrate at 1000 °C by VLS. The doping Ga concentrations are 0.46, 1.07, 2.30 and 17.53 atomic%. The XRD spectrum and HR-TEM reveal Ga(2)O(3) and SnO(2) as having monoclinic and tetragonal rutile structures, respectively. Experimental results indicate that the XRD peak shift of SnO(2) to a larger angle increases with the increasing amount of Ga doping. According to the CL spectrum, SnO(2) and Ga(2)O(3) peak at approximately 528-568 nm and 422-424 nm, respectively. The maximum quantum efficiency of Ga(2)O(3)/SnO(2):Ga core-shell nanowires is around 0.362%. The UV light on-off current contrast ratio of Ga(2)O(3)/SnO(2):Ga core-shell nanowires is around 1066.7 at a bias of 5 V. Moreover, the dynamic response of Ga(2)O(3)/SnO(2):Ga core-shell nanowires has an on-off current contrast ratio of around 16. Furthermore, the Ga(2)O(3) region functions similar to a capacitor and continues to accumulate SnO(2):Ga excited electrons under UV light exposure.

  2. Molybdenum Doped SnO2 Thin Films as a Methanol Vapor Sensor

    Directory of Open Access Journals (Sweden)

    Patil Shriram B.

    2013-02-01

    Full Text Available The molybdenum doped SnO2 thin films were synthesized by conventional spray pyrolysis route and has been investigated for the methanol vapor sensing. The structural and elemental composition analysis of thin films was carried out by X- ray diffraction and Scanning Electron Microscopy (SEM and Energy Dispersive X-ray spectroscopy (EDAX.The XRD spectrum revealed that the thin films have the polycrystalline nature with a mixed phase comprising of SnO2 and MoO3. The scanning Electron Microscopy (SEM clears that the surface morphology observed to be granular, uniformly covering the entire surface area of the thin film. The methanol vapor sensing studies were performed in dry air at the different temperatures. The influence of the concentration of Molybdenum and operating temperature on the sensor performance has been investigated.

  3. Efecto del dopado con Si sobre la estructura de defectos en sistemas heteroepitaxiales GaN/AlN/Si(111

    Directory of Open Access Journals (Sweden)

    Sánchez, A. M.

    2000-08-01

    Full Text Available The Si doping effect on the defect structure in GaN epilayers grown by molecular beam epitaxy on Si(111 substrates using AlN buffer layers has been studied. Transmission electron microscopy and related techniques have been used to carry out the structural characterization. The Si doping affects both the subgrain size and misorientation in GaN epilayer mosaic structure. The Si doping also leads to an increase of the planar defect density, as well as a decrease of the threading dislocation density. The enlargement of the subgrain tilt and the planar defect density explain the reduction of the dislocation density reaching the GaN free surface.

    En el presente artículo se lleva a cabo el análisis del efecto que el dopado con Si tiene sobre la estructura de defectos en epicapas de GaN crecidas por epitaxia de haces moleculares sobre sustratos de Si (111 utilizando capas amortiguadoras de AlN. La caracterización estructural se llevó a cabo mediante microscopía electrónica de transmisión convencional y de alta resolución. El dopado con Si afecta a la desorientación y tamaño de los subgranos que constituyen la estructura mosaico de la epicapa de GaN. El dopado con Si provoca un aumento en la densidad de defectos planares, así como una disminución en la densidad de dislocaciones de propagación. El incremento en el grado de desorientación de inclinación, así como en la densidad de defectos planares que se produce conforme aumenta el dopado con Si explican la disminución en la densidad de dislocaciones que alcanzan la superficie libre de GaN.

  4. Sn doped TiO{sub 2} nanotube with oxygen vacancy for highly efficient visible light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jinliang; Xu, Xingtao [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, Department of Physics, East China Normal University, Shanghai 200062 (China); Liu, Xinjuan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Yu, Caiyan; Yan, Dong; Sun, Zhuo [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, Department of Physics, East China Normal University, Shanghai 200062 (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, Department of Physics, East China Normal University, Shanghai 200062 (China)

    2016-09-15

    Sn doped TiO{sub 2} nanotube with oxygen vacancy (V{sub o}-Sn−TiO{sub 2}) was successfully synthesized via a facile hydrothermal process and subsequent annealing in nitrogen atmosphere. The morphology, structure and photocatalytic performance of V{sub o}-Sn−TiO{sub 2} in the degradation of nitrobenzene were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy, nitrogen adsorption-desorption and electrochemical impedance spectra, respectively. The inner diameter, outer diameter and specific surface area of V{sub o}-Sn−TiO{sub 2} are about 5 nm, 15 nm and 235.54 m{sup 2} g{sup −1}, respectively. The experimental results show that the V{sub o}-Sn−TiO{sub 2} exhibits excellent photocatalytic performance with a maximum degradation rate of 92% in 300 min for nitrobenzene and 94% in 100 min for Rhodamine B and corresponding mineralization rates of 68% and 70% under visible light irradiation. The improved photocatalytic performance is ascribed to the enhanced light absorption and specific surface area as well as the reduced electron-hole pair recombination with the presence of oxygen vacancy and Sn doping in the TiO{sub 2} nanotube. - Highlights: • Photocatalysis is an environmental-friendly technology for nitrobenzene removal. • Sn doped TiO{sub 2} nanotube with oxygen vacancy is fabricated for the first time. • It exhibits excellent photocatalytic performance in degradation of nitrobenzene. • A high degradation rate of 92% is achieved under visible light irradiation.

  5. Influence of the Si content on the microstructure and mechanical properties of Ti-Ni-Cu-Si-Sn nanocomposite alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fornell, J., E-mail: Jordinafornell@gmail.com [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Van Steenberge, N. [OCAS N.V., Pres. J.F. Kennedylaan 3, BE-9060 Zelzate (Belgium); Surinach, S.; Baro, M.D. [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Sort, J. [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Institucio Catalana de Recerca i Estudis Avancats (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer We study the effects of Si addition of Ti-Ni-Cu-Si-Sn alloy. Black-Right-Pointing-Pointer The microstructure evolution is correlated with the obtained mechanical and elastic properties. Black-Right-Pointing-Pointer Higher Young's modulus and larger hardness values are obtained in samples with higher Si contents. - Abstract: (Ti{sub 48}Ni{sub 32}Cu{sub 8}Si{sub 8}Sn{sub 4}){sub 100-x}Si{sub x} (x = 0, 2, 4 and 6) alloys were prepared by levitation melting mixtures of the high purity elements in an Ar atmosphere. Rods of 3 mm in diameter were obtained from the melt by copper mould casting. The effects of Si addition on the microstructure, elastic and mechanical properties of the Ti{sub 48}Ni{sub 32}Cu{sub 8}Si{sub 8}Sn{sub 4} alloy were investigated by scanning electron microscopy, X-ray diffraction, acoustic measurements and nanoindentation. The main phases composing the Ti{sub 48}Ni{sub 32}Cu{sub 8}Si{sub 8}Sn{sub 4} alloy are B2 NiTi, B19 Prime NiTi and tetragonal Ti{sub 2}Ni. Additional phases, like Ti{sub 5}Si{sub 3} or Ni{sub 2}Ti{sub 2}Si, become clearly visible in samples with higher Si contents. The microstructure evolution is correlated with the obtained mechanical and elastic properties. These alloys exhibit very high hardness values, which increase with the Si content, from 9 GPa (for x = 0) to around 10.5 GPa (for x = 6). The Young's modulus of Ti{sub 48}Ni{sub 32}Cu{sub 8}Si{sub 8}Sn{sub 4} (around 115 GPa) also increases significantly with Si addition, up to 160 GPa for x = 6.

  6. Synthesis, characterization and luminescence study of Eu3+ doped Y2Sn2O7 nano-particles

    International Nuclear Information System (INIS)

    Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2011-01-01

    In recent years, advanced materials derived from Pyrochlore-type oxides (A 2 B 2 O 7 ), have been of extensive scientific and technological interest. Chemical substitution of A or B sites of pyrochlore oxide by rare earth ions is a widely used approach to prepare thermally stable, lanthanide ion doped luminescent materials. The present study deals with the synthesis and characterization of Eu 3+ doped Y 2 Sn 2 O 7 : nanoparticles prepared by the hydrolysis of Y 3+ , Sn 4+ , and Eu 3+ in ethylene glycol medium followed by heating at 700 deg C for 4 hours. As prepared samples are amorphous in nature and 700 deg C heated sample showed well crystalline pyrochlore structure in XRD studies. Average particle size is calculated from the width of the X-ray diffraction peaks and found to t be around 5 nm. Luminescence measurements were carried out for as prepared and 700 deg C heated samples. The undoped as prepared sample showed a broad emission peak around 420 nm after excitation at 285 nm. While for 700 deg C undoped heated sample, the peak maxima was shifted to 435 nm. The emission spectrum for doped as prepared samples is characterized by both host emission around 420 nm along with the characteristic Eu 3+ emission peaks in the visible region. However, very poor Eu 3+ emission from heated sample was observed

  7. Low-leakage-current AlGaN/GaN HEMTs on Si substrates with partially Mg-doped GaN buffer layer by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Li Ming; Wang Yong; Wong Kai-Ming; Lau Kei-May

    2014-01-01

    High-performance low-leakage-current AlGaN/GaN high electron mobility transistors (HEMTs) on silicon (111) substrates grown by metal organic chemical vapor deposition (MOCVD) with a novel partially Magnesium (Mg)-doped GaN buffer scheme have been fabricated successfully. The growth and DC results were compared between Mg-doped GaN buffer layer and a unintentionally one. A 1-μm gate-length transistor with Mg-doped buffer layer exhibited an OFF-state drain leakage current of 8.3 × 10 −8 A/mm, to our best knowledge, which is the lowest value reported for MOCVD-grown AlGaN/GaN HEMTs on Si featuring the same dimension and structure. The RF characteristics of 0.25-μm gate length T-shaped gate HEMTs were also investigated

  8. Ternary silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and quaternary derivatives RERh{sub 4}Si{sub 2-x}Sn{sub x} (RE = Y, Nd, Sm, Gd-Lu) - structure, chemical bonding, and solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vosswinkel, Daniel; Benndorf, Christopher; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics; Matar, Samir F. [Bordeaux Univ., CNRS, ICMCB, UPR 9048, Pessac (France)

    2016-11-01

    The silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and silicide stannides RERh{sub 4}Si{sub 2-x}Sn{sub x}(RE = Y, Nd, Sm, Gd-Lu) were synthesized from the elements by arc-melting and subsequent annealing. The new compounds crystallize with the orthorhombic YRh{sub 4}Ge{sub 2} type structure, space group Pnma. They were characterized by X-ray powder patterns and several structures were refined from single crystal X-ray diffractometer data. The main structural motifs of this series of silicides are tricapped trigonal prisms formed by the transition metal and rare earth atoms. One of the two crystallographically independent silicon sites allows for formation of solid solutions with tin, exemplarily studied for ErRh{sub 4}Si{sub 2-x}Sn{sub x}. Electronic structure calculations reveal strong covalent Rh-Si bonding as the main stability factor. Multinuclear ({sup 29}Si, {sup 45}Sc, and {sup 89}Y) magic-angle spinning (MAS) NMR spectra of the structure representatives with diamagnetic rare-earth elements (Sc, Y, Lu) are found to be consistent with the crystallographic data and specifically confirm the selective substitution of Sn in the Si2 sites in the quaternary compounds YRh{sub 4}SiSn and LuRh{sub 4}SiSn.

  9. Investigation of fluorine adsorption on nitrogen doped MgAl{sub 2}O{sub 4} surface by first-principles

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Xiaojun; Xu, Zhenming [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Li, Jie, E-mail: 15216105346@163.com [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Chen, Jiangan [Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Liu, Qingsheng [Faculty of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)

    2016-07-15

    Graphical abstract: First-principles calculations indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, but hydrophobic. N doped MgAl{sub 2}O{sub 4} (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). N doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Highlights: • MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} > Al{sub 2}O{sub 3} > MgAl{sub 2}O{sub 4} > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl{sub 2}O{sub 4} surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl{sub 2}O{sub 4} (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl{sub 2}O{sub 4} attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these

  10. Superconductivity in the ternary rare-earth (Y, La, and Lu) compounds RPd2Si2 and RRh2Si2

    NARCIS (Netherlands)

    Palstra, T.T.M.; Lu, G.; Menovsky, A.A.; Nieuwenhuys, G.J.; Kes, P.H.; Mydosh, J.A.

    1986-01-01

    We have investigated the superconducting and metallurgical properties of the ternary compounds RPd2Si2 and RRh2Si2 with R = Y, La, and Lu. All RPd2Si2 compounds and LaRh2Si2 were found to be type-I superconductors below 1 K. A detailed metallurgical analysis shows that segregation of second phases

  11. Synthesis and characterization of SnO2 doped with fluorine by the technique of polymeric precursors; Sintese e caracterizacao de SnO2 dopado com fluor pela tecnica dos precursores polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Gilberto J.; Lopes, Rafael Ialago, E-mail: gilbertop@fei.edu.br [Centro Universitario FEI, Sao Bernardo do Campo, SP (Brazil). Departamento de Engenharia de Materiais

    2016-07-01

    The present work deals with the synthesis of tin dioxide powders doped with fluorine and chlorine anions to evaluate the influence of these on the physico-chemical properties of SnO2, as well as to verify if the dopant does not make a solid solution with the material and its possible use as sintering additive. The samples were synthesized by Pechini method (polymer precursors) with tin oxalate as a source not contaminated with chlorine of this metal. Specific surface area characterization (BET method) and X-ray diffractometry (XRD) show that doping reduces the particle size of SnO2, being more effective at lower dopant levels. The dilatometry of the doped powders shows a reduction in the beginning and end temperatures of the sintering of the tin dioxide when compared with values in the literature.

  12. Materiales vitrocerámicos del sistema MgO-Al2O3-SiO2 a partir de ceniza de cáscara de arroz

    Directory of Open Access Journals (Sweden)

    Romero, M.

    2011-08-01

    Full Text Available This wok shows the results of a valorisation study to use rice husk ash as raw material to develop glass-ceramic materials. An original glass has been formulated in the base system MgO-Al2O3-SiO2 with addition of B2O3 and Na2O to facilitate the melting and poring processes. Glass characterization was carried out by determining its chemical composition. Sintering behaviour has been examined by Hot Stage Microscopy (HSM. Thermal stability and crystallization mechanism have been studied by Differential Thermal Analysis (DTA. Mineralogy analyses of the glass-ceramic materials were carried out using X-ray Diffraction (XRD. Results show that it is possible to use ash rice husk to produce glass-ceramic materials by a sintercrystallization process, with nepheline (Na2O·Al2O3 · SiO2 as major crystalline phase in the temperature interval 700-950ºC and forsterite (2MgO·SiO2 at temperatures above 950ºC.En este trabajo se muestran los resultados de un estudio de valorización de la ceniza de cáscara de arroz como materia prima en la obtención de materiales vitrocerámicos. Se ha formulado un vidrio en el sistema base MgO-Al2O3-SiO2 incorporando B2O3 y Na2O para facilitar los procesos de fusión y colado del vidrio. El vidrio se ha caracterizado mediante la determinación de su composición química. Su comportamiento frente a la sinterización se ha llevado a cabo mediante Microscopía de Calefacción (MC. La estabilidad térmica de las muestras y el mecanismo de cristalización preferente se ha estudiado mediante Análisis Térmico Diferencial (ATD. La mineralogía de los materiales vitrocerámicos se ha llevado a cabo por Difracción de rayos-X (DRX. Los resultados obtenidos muestran que es posible utilizar ceniza de cáscara de arroz para producir materiales vitrocerámicos mediante un proceso de sinterización seguido de cristalización, con nefelina (Na2O·Al2O3·2SiO2 como fase cristalina mayoritaria en el intervalo de temperatura 700º-950ºC y

  13. Pd-Doped SnO2-Based Sensor Detecting Characteristic Fault Hydrocarbon Gases in Transformer Oil

    Directory of Open Access Journals (Sweden)

    Weigen Chen

    2013-01-01

    Full Text Available Methane (CH4, ethane (C2H6, ethylene (C2H4, and acetylene (C2C2 are important fault characteristic hydrocarbon gases dissolved in power transformer oil. Online monitoring these gaseous components and their generation rates can present the operational state of power transformer timely and effectively. Gas sensing technology is the most sticky and tricky point in online monitoring system. In this paper, pure and Pd-doped SnO2 nanoparticles were synthesized by hydrothermal method and characterized by X-ray powder diffraction, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The gas sensors were fabricated by side-heated preparation, and their gas sensing properties against CH4, C2H6, C2H4, and C2H2 were measured. Pd doping increases the electric conductance of the prepared SnO2 sensors and improves their gas sensing performances to hydrocarbon gases. In addition based on the frontier molecular orbital theory, the highest occupied molecular orbital energy and the lowest unoccupied molecular orbital energy were calculated. Calculation results demonstrate that C2H4 has the highest occupied molecular orbital energy among CH4, C2H6, C2H4, and C2H2, which promotes charge transfer in gas sensing process, and SnO2 surfaces capture a relatively larger amount of electric charge from adsorbed C2H4.

  14. Facile fabrication of Si-doped TiO2 nanotubes photoanode for enhanced photoelectrochemical hydrogen generation

    Science.gov (United States)

    Dong, Zhenbiao; Ding, Dongyan; Li, Ting; Ning, Congqin

    2018-04-01

    Photoelectrochemical (PEC) water splitting based doping modified one dimensional (1D) titanium dioxide (TiO2) nanostructures provide an efficient method for hydrogen generation. Here we first successfully fabricated 1D Si-doped TiO2 (Ti-Si-O) nanotube arrays through anodizing Ti-Si alloys with different Si amount, and reported the PEC properties for water splitting. The Ti-Si-O nanotube arrays fabricated on Ti-5 wt.% Si alloy and annealed at 600 °C possess higher PEC activity, yielding a higher photocurrent density of 0.83 mA/cm2 at 0 V vs. Ag/AgCl. The maximum photoconversion efficiency was 0.54%, which was 2.7 times the photoconversion efficiency of undoped TiO2.

  15. Nanocrystal in Er3+-doped SiO2-ZrO2 Planar Waveguide with Yb3+ Sensitizer

    International Nuclear Information System (INIS)

    Razaki, N. Iznie; Jais, U. Sarah; Abd-Rahman, M. Kamil; Bhaktha, S. N. B.; Chiasera, A.; Ferrari, M.

    2010-01-01

    Higher doping of Er 3+ in glass ceramic waveguides would cause concentration and pair-induced quenching which lead to inhomogeneous line-width of luminescence spectrum thus reduce output intensity. Concentration quenching can be overcome by introducing ZrO 2 in the glass matrix while co-doping with Yb 3+ which acts as sensitizer would improve the excitation efficiency of Er 3+ . In this study, SiO 2 -ZrO 2 planar waveguides having composition in mol percent of 70SiO 2 -30ZrO 2 doped with Er 3+ and co-doped with Yb 3+ , were prepared via sol-gel route. Narrower and shaper peaks of PL and XRD shows the formation of nanocrystals. Intensity is increase with addition amount of Yb 3+ shows sensitizing effect on Er 3+ .

  16. Binding energy, phonon spectra and thermodynamic properties of elements with type structures A1 (Al, Cu), A2 (V, Ti2), A3 (Mg, Tiβ), A4 (Si, Sn)

    International Nuclear Information System (INIS)

    Sirota, N.N.; Soshnina, T.M.; Sirota, I.M.; Sokolovskij, T.D.

    2001-01-01

    One calculated dependences of binding energy on spacing between the nearest atoms of Al and Cu elements with A 1 type structure, of V and Ti α elements with A 2 type structure, of Mg and Ti β elements with A 3 type structure, Si and Sn elements with A 4 type structure. To calculate one applied the methods based on the Thomas-Fermi statistic theory of atom. The derived dependences were approximated using the expression in the form of the Mie-Grueneisen potential. On the basis of the Born-von-Karman model of solid body one calculated the phonon spectra using which one determined temperature dependences of specific heat, free and internal energy of the investigated elements. The calculated values of energy of atomization, equilibrium closest interatomic spacing and temperature dependences of specific heat are in compliance with the experimental data [ru

  17. Synthesis And Characterization Of SiO2, SnO2 And TiO2 Metal Oxide Shells Covering Cu2O Particles

    Directory of Open Access Journals (Sweden)

    Yu Ri

    2015-06-01

    Full Text Available In this work is described a means of improving the chemical stability of Cu2O@SiO2, Cu2O@SnO2 and Cu2O@TiO2 materials. The SiO2, SnO2 and TiO2 coated samples were stable from pH 3 to pH 10 for up to seven days. To determine the stability of the coated nanoparticles, and their colloidal solutions under acidic and basic conditions, colloidal nanoparticle solutions with various pH values were prepared and monitored over time. Details of the effect of variations in pH on the phase stability of core-shell type Cu2O were characterized using transmission electron microscopy and X-ray diffraction.

  18. Structural, elastic, electronic, bonding, and optical properties of BeAZ2 (A = Si, Ge, Sn; Z = P, As) chalcopyrites

    International Nuclear Information System (INIS)

    Fahad, Shah; Murtaza, G.; Ouahrani, T.; Khenata, R.; Yousaf, Masood; Omran, S.Bin; Mohammad, Saleh

    2015-01-01

    A first principles density functional theory (DFT) technique is used to study the structural, chemical bonding, electronic and optical properties of BeAZ 2 (A = Si, Ge, Sn; Z = P, As) chalcopyrite materials. The calculated parameters are in good agreement with the available experimental results. The lattice constants and the equilibrium volume increased as we moved from Si to Ge to Sn, whereas the c/a and internal parameters u decreased by shifting the cation from P to As. These compounds are elastically stable. An investigation of the band gap using the WC-GGA, EV-GGA, PBE-GGA and mBJ-metaGGA potentials suggested that BeSiP 2 and BeSiAs 2 are direct band gap compounds, whereas BeGeP 2, BeGeAs 2, BeSnP 2, BeSnAs 2 are indirect band gap compounds. The energy band gaps decreased by changing B from Si to Sn and increased by changing the anion C from P to As. The bonding among the cations and anions is primarily ionic. In the optical properties, the real and imaginary parts of the dielectric functions, reflectivity and optical conductivity have been studied over a wide energy range. - Highlights: • The compounds are studied by FP-LAPW method within mBJ approximation. • All of the studied materials show isotropic behaviour. • All the compounds show direct band gap nature. • Bonding nature is mostly covalent among the studied compounds. • High absorption peaks and reflectivity ensures there utility in optoelectronic devices

  19. Effects of Third Constituent on As-cast Microstructures and Mechanical Properties of Mg-Sn Alloy

    Directory of Open Access Journals (Sweden)

    HUANG Zheng-hua

    2016-06-01

    Full Text Available As-cast microstructures and phase compositions of Mg-3.52Sn-xM and Mg-6.54Sn-xM (M=Al, Zn, Nd, Gd alloys were investigated by optical microscope, scanning electron microscope and X-ray diffraction. Meanwhile, the tensile mechanical properties were tested. The results show that the coarse dendrite is refined slightly and few block Mg2Sn phase still exists when 0.91% (mass fraction, the same below Al and 1.03%Zn are added into Mg-3.52Sn alloy, respectively. When 0.92%Nd and 1.10%Gd are added respectively, the dendrite weakens obviously and many small block or fine short rod-shaped compounds Mg-Sn-Nd and Mg-Sn-Gd can be observed. When 0.93%Al and 1.08%Zn are added into Mg-6.54Sn respectively, the dendrite is refined obviously and Mg2Sn phase tending to precipitate in the state of continuous net begins to break slightly. When 0.86%Nd and 0.74%Gd are added respectively, the dendrite weakens significantly and Mg2Sn phase has already broken into small block completely or significantly. Meanwhile, many small block or fine short rod-shaped compounds Mg-Sn-Nd and Mg-Sn-Gd can also be observed. The respective addition of about 1%Al and Zn into the Mg-3.52Sn and Mg-6.54Sn binary alloys respectively can enhance the tensile mechanical properties namely the ambient and elevated temperatures effectively, while the respective addition of about 1%Nd and Gd cannot enhance them effectively, especially for the addition of Nd.

  20. Electron irradiation response on Ge and Al-doped SiO{sub 2} optical fibres

    Energy Technology Data Exchange (ETDEWEB)

    Yaakob, N.H.; Wagiran, H. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Hossain, I., E-mail: imamhossain@utm.m [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ramli, A.T. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Bradley, D.A [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Hashim, S. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ali, H. [Department of Radiotherapy and Oncology, Hospital Sultan Ismail, Johor Darul Takzim (Malaysia)

    2011-05-01

    This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO{sub 2} optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO{sub 2} optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

  1. Efficient photocatalytic activity with carbon-doped SiO2 nanoparticles

    KAUST Repository

    Zhang, Dongen; Wu, Jinbo; Zhou, Bingpu; Hong, Yaying; Li, Shunbo; Wen, Weijia

    2013-01-01

    by thermogravimetric analysis, X-ray diffraction, standard and high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The C-doped SiO2 displayed outstanding photocatalytic properties, as evidenced by its catalysis of Rhodamine B

  2. Mechanical Properties and Fabrication of Nanostructured Mg_2SiO_4-MgAl_2O_4 Composites by High-Frequency Induction Heated Combustion

    International Nuclear Information System (INIS)

    Shon, In-Jin; Kang, Hyun-Su; Hong, Kyung-Tae; Doh, Jung-Mann; Yoon, Jin-Kook

    2011-01-01

    Nanopowders of MgO, Al_2O_3 and SiO_2 were made by high energy ball milling. The rapid sintering of nanostructured MgAl_2O_4-Mg_2SiO_4 composites was investigated by a high-frequency induction heating sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. Highly dense nanostructured MgAl_2O_4-Mg_2SiO_4 composites were produced with simultaneous application of 80 MPa pressure and induced output current of total power capacity (15 kW) within 2 min. The sintering behavior, gain size and mechanical properties of MgAl_2O_4-Mg_2SiO_4 composites were investigated.

  3. Influences of Mg Doping on the Electrochemical Performance of TiO2 Nanodots Based Biosensor Electrodes

    Directory of Open Access Journals (Sweden)

    M. S. H. Al-Furjan

    2014-01-01

    Full Text Available Electrochemical biosensors are essential for health monitors to help in diagnosis and detection of diseases. Enzyme adsorptions on biosensor electrodes and direct electron transfer between them have been recognized as key factors to affect biosensor performance. TiO2 has a good protein adsorption ability and facilitates having more enzyme adsorption and better electron transfer. In this work, Mg ions are introduced into TiO2 nanodots in order to further improve electrode performance because Mg ions are considered to have good affinity with proteins or enzymes. Mg doped TiO2 nanodots on Ti substrates were prepared by spin-coating and calcining. The effects of Mg doping on the nanodots morphology and performance of the electrodes were investigated. The density and size of TiO2 nanodots were obviously changed with Mg doping. The sensitivity of 2% Mg doped TiO2 nanodots based biosensor electrode increased to 1377.64 from 897.8 µA mM−1 cm−2 and its KMapp decreases to 0.83 from 1.27 mM, implying that the enzyme achieves higher catalytic efficiency due to better affinity of the enzyme with the Mg doped TiO2. The present work could provide an alternative to improve biosensor performances.

  4. Energy band alignment of antiferroelectric (Pb,La)(Zr,Sn,Ti)O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Andreas, E-mail: aklein@surface.tu-darmstadt.de [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); Lohaus, Christian [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); Reiser, Patrick [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); InnovationLab GmbH, Speyerer Straße 4, 69115 Heidelberg (Germany); Dimesso, Lucangelo [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); Wang, Xiucai; Yang, Tongqing [Tongji University, Key Laboratory of Advanced Civil Engineering Materials (Ministry of Education), Functional Materials Research Laboratory, College of Materials Science and Engineering, Cao’an Road 4800, Shanghai 201804 (China)

    2017-06-15

    Highlights: • Energy band alignment of antiferroelectric PLZST studied by XPS. • A deconvolution procedure is applied to study band alignment of insulating materials. • Contribution of Pb 6s orbitals leads to higher valence band maximum. • Ferroelectric polarization does not contribute to valence band maximum energy. • The variation of Schottky barrier heights indicates no Fermi level pinning in PLZST. - Abstract: The energy band alignment of antiferroelectric (Pb,La)(Zr,Sn,Ti)O{sub 3} is studied with photoelectron spectroscopy using interfaces with high work function RuO{sub 2} and low work function Sn-doped In{sub 2}O{sub 3} (ITO). It is demonstrated how spectral deconvolution can be used to determine absolute Schottky barrier heights for insulating materials with a high accuracy. Using this approach it is found that the valence band maximum energy of (Pb,La)(Zr,Sn,Ti)O{sub 3} is found to be comparable to that of Pb- and Bi-containing ferroelectric materials, which is ∼1 eV higher than that of BaTiO{sub 3}. The results provide additional evidence for the occupation of the 6s orbitals as origin of the higher valence band maximum, which is directly related to the electrical properties of such compounds. The results also verify that the energy band alignment determined by photoelectron spectroscopy of as-deposited electrodes is not influenced by polarisation. The electronic structure of (Pb,La)(Zr,Sn,Ti)O{sub 3} should enable doping of the material without strongly modifying its insulating properties, which is crucial for high energy density capacitors. Moreover, the position of the energy bands should result in a great freedom of selecting electrode materials in terms of avoiding charge injection.

  5. Synthesis of PtSn nanostructured catalysts supported over TiO{sub 2} and Ce-doped TiO{sub 2} particles for the electro-oxidation of ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, A.E. [Instituto de Ingeniería Electroquímica y Corrosión (INIEC), CONICET, Universidad Nacional del Sur. Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Gravina, A.N. [Departamento de Química, INQUISUR, CONICET, Universidad Nacional del Sur, Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Sieben, J.M., E-mail: jmsieben@uns.edu.ar [Instituto de Ingeniería Electroquímica y Corrosión (INIEC), CONICET, Universidad Nacional del Sur. Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Messina, P.V. [Departamento de Química, INQUISUR, CONICET, Universidad Nacional del Sur, Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Duarte, M.M.E. [Instituto de Ingeniería Electroquímica y Corrosión (INIEC), CONICET, Universidad Nacional del Sur. Av. Alem 1253, Bahía Blanca B8000CPB (Argentina)

    2016-09-15

    Highlights: • PtSn particles supported on TiO2 and Ce-doped TiO2 were evaluated as catalysts for EOR. • PtSn/TiO2 showed better mass current and higher TON than PtSn/Ce–TiO2 materials. • The activity for EOR decreased markedly with increasing Ce content in the TiO2. - Abstract: PtSn/TiO2 and PtSn/Ce-doped TiO2 catalysts were synthesized and evaluated for ethanol electro-oxidation in acid media. Titanium dioxide and Ce-doped TiO2 nanoparticles were prepared by hydrothermal method followed by calcination at 923 K. Bimetallic PtSn catalysts supported on the oxide materials were synthesized by microwave assisted reduction in ethylene glycol (EG). The structural properties of the resulting materials were evaluated via TEM and XRD, and the compositions were assessed by EDX and ICP-AES analysis. PtSn nanoparticles of about 3–4 nm were deposited on TiO2 and Ce–TiO2 particles. It was found that the catalyst composition is scarcely influenced by the cerium content in the mixed oxides while the electrochemical surface area per unit mass decreases upon the incorporation of Ce in the anatase lattice. The electrochemical tests pointed out that the electrocatalytic activity for ethanol oxidation decreases markedly as the Ce content increases. The results indicate that the presence of cerium in the titanium dioxide crystalline network induces local structural and electronic modifications, thereby leading to a reduction of the crystallinity, surface conductivity and the amount of OH species adsorbed on the surface of the oxide support.

  6. Cristalización de Cordierita en vidrios derivados del sistema cuaternario CaO-MgO-Al2O3-SiO2. Influencia de la composición del vidrio

    Directory of Open Access Journals (Sweden)

    Alarcón, J.

    1998-10-01

    Full Text Available It has been studied the calcium effect on the crystallization of cordierite for obtaining a glassceramic material into the CaOáMgOáAl2O3áSiO2 quaternary system. With this propose it has been selected six compositions into de cordierite primary field of crystallization and obtained the original glasses. The obtained samples have been analysed after a thermal treatment in three steps (glass transformation, nucleation and growth by X-ray diffraction (XRD. The composition of phases in microstructures have been analysed by scanning electron microscopy (SEM. The microstructures have been related with the crystalline phases by energy dispersive X-ray microanalysis (EDX. The amount of CaO in glasses is directly related with the anorthite crystallization, suggesting that the great amount of crystallized anorthite in relation with the low amount of CaO in the original glasses is due to the formation of one anorthite-diopside solid solution, what was tested by EDX. At growth temperature almost every samples partly crystallized, as primary or secondary cordierite phase. The anorthite microstructure was very particulated in spherulites forms of radius near to 250 nm, while the cordierite phase showed different morphologies, from almost-spherulitic crystallization nucleus ("rosettes" of μ-cordierite for direct crystallization from glass, to dense dendrites coming from μ transformation. Finally it can be found homogeneous blocks of α-cordierite with dimension of 10 x 10 μm2.Se ha estudiado el efecto del calcio en la cristalización de cordierita para la obtención de un material vitrocerámico dentro del sistema cuaternario CaO-MgO-Al2O3-SiO2. Con este objetivo se han seleccionado seis composiciones dentro del campo primario de cristalización de la cordierita y se han obtenido por fusión sus correspondientes vidrios. Se han analizado las muestras obtenidas tras un tratamiento térmico en tres etapas (transformación vítrea, nucleación y crecimiento

  7. Effect of La doping on interface barrier between Si-passivated Ge and insulating HfO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kolomiiets, Nadiia M.; Afanas' ev, Valery V.; Madia, Oreste; Stesmans, Andre [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); Cott, Daire J.; Collaert, Nadine [Imec, Kapeldreef 75, 3001 Leuven (Belgium); Thean, Aaron [Imec, Kapeldreef 75, 3001 Leuven (Belgium); National University of Singapore (Singapore)

    2016-12-15

    By analyzing internal photoemission of electrons from Si/SiO{sub x}-passivated Ge into insulating HfO{sub 2} we found that insertion of additional La interlayer between SiO{sub x} and HfO{sub 2} leads to dramatic increase (more than by factor of 20) of the barrier transparency. However, no measurable variation of the interface barrier height is observed suggesting that La induces intermixing of near-interface oxide stack resulting in development of additional density of states corresponding to conduction band of LaO{sub x} and HfO{sub x} sub-networks. At the same time, photoemission results indicate the presence of discrete positive charges in the near-interface oxide layer which may explain the observed ∝1 V shift of capacitance-voltage curves. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Moessbauer studies of SnO2 powders doped with dilute 57Fe, prepared by a sol-gel method

    International Nuclear Information System (INIS)

    Nomur, K.; Sakuma, J.; Takeda, M.

    2006-01-01

    Diluted magnetic semiconductor (DMS) is prospected as new materials with both semiconductor and magnetic properties. In order to confirm these phenomena, we prepared the powders of SnO 2 doped with various amount of 57 Fe by a sol-gel method. Various compositions of Sn 1-x 57 Fe x O 2 were obtained by mixing some ratio of Fe 3+ nitrate solution and acetylacetonate Sn 4+ complex in the ethylene glycol and citric acid solution. The solutions were evaporated, ashed at around 200 grad C, and finally annealed at 500 grad C, 600 grad C, and 650 grad C, respectively. These Sn 1-x 57 Fe x O 2 (x=0.005, 0.01, 0.03 and 0.05) were measured by XRD, VSM, and Moessbauer spectrometry. The prepared powder samples were confirmed to be a rutile structure, but iron compounds were not detected by XRD. Moessbauer spectra of Sn 1-x 57 Fe x O 2 prepared at 500 grad C were shown in Fig. 1. A small amount of broad sextets were observed in MS spectra of Sn 1-x 57 Fe x O 2 in addition to paramagnetic components. The relative intensity seems to be strong with the decrease of the amount of doped Fe. Moessbauer spectrum at 10 K shows clearly the magnetic components. The magnetic sextet was observed in MS spectra of samples prepared at 650 grad C, but the magnetic behavior weakened because of antiferromagnetic α-Fe 2 O 3 , produced due to the phase separation at high temperatures. (authors)

  9. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  10. Mg-doped VO2 nanoparticles: hydrothermal synthesis, enhanced visible transmittance and decreased metal-insulator transition temperature.

    Science.gov (United States)

    Zhou, Jiadong; Gao, Yanfeng; Liu, Xinling; Chen, Zhang; Dai, Lei; Cao, Chuanxiang; Luo, Hongjie; Kanahira, Minoru; Sun, Chao; Yan, Liuming

    2013-05-28

    This paper reports the successful preparation of Mg-doped VO2 nanoparticles via hydrothermal synthesis. The metal-insulator transition temperature (T(c)) decreased by approximately 2 K per at% Mg. The Tc decreased to 54 °C with 7.0 at% dopant. The composite foils made from Mg-doped VO2 particles displayed excellent visible transmittance (up to 54.2%) and solar modulation ability (up to 10.6%). In addition, the absorption edge blue-shifted from 490 nm to 440 nm at a Mg content of 3.8 at%, representing a widened optical band gap from 2.0 eV for pure VO2 to 2.4 eV at 3.8 at% doping. As a result, the colour of the Mg-doped films was modified to increase their brightness and lighten the yellow colour over that of the undoped-VO2 film. A first principle calculation was conducted to understand how dopants affect the optical, Mott phase transition and structural properties of VO2.

  11. Tunable Schottky diodes fabricated from crossed electrospun SnO{sub 2}/PEDOT-PSSA nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Carrasquillo, Katherine V. [Department of Physics and Electronics, University of Puerto Rico-Humacao, Humacao, PR 00792 (Puerto Rico); Pinto, Nicholas J., E-mail: nicholas.pinto@upr.edu [Department of Physics and Electronics, University of Puerto Rico-Humacao, Humacao, PR 00792 (Puerto Rico)

    2012-06-25

    Graphical abstract: Crossed SnO{sub 2}/PEDOT-PSSA nanoribbon Schottky diodes. Highlight: Black-Right-Pointing-Pointer An inexpensive electrospinning technique is used to fabricate crossed nanoribbons of n-doped tin oxide and p-PEDOT. Black-Right-Pointing-Pointer Each intersection is a localized Schottky diode that is completely exposed to the environment after electrodes deposition. Black-Right-Pointing-Pointer This makes it useful as a gas and light sensor. Black-Right-Pointing-Pointer In addition, the ability to tune the diode parameters via a back gate truly makes this device multifunctional. Black-Right-Pointing-Pointer A half wave rectifier has been demonstrated with this device under UV illumination. - Abstract: Schottky diodes have been fabricated on doped Si/SiO{sub 2} substrates in air, by simply crossing individual electrospun tin oxide (SnO{sub 2}) and poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT-PSSA) nanoribbons. The conductivity of PEDOT-PSSA was {approx}6 S/cm with no observable field effect, while SnO{sub 2} exhibited n-doped field effect behavior with a charge mobility of {approx}3.1 cm{sup 2}/V-s. The diodes operate in air or in vacuum, under ambient illumination or in the dark, with low turn-on voltages and device parameters that are tunable via a back gate bias or a UV light source. Their unique design involves a highly localized active region that is completely exposed to the surrounding environment, making them potentially attractive for use as sensors. The standard thermionic emission model of a Schottky junction was applied to analyze the forward bias diode characteristics and was successfully tested as a half wave rectifier.

  12. Ultraviolet emission from low resistance Cu2SnS3/SnO2 and CuInS2/Sn:In2O3 nanowires

    Directory of Open Access Journals (Sweden)

    E. Karageorgou

    2014-11-01

    Full Text Available SnO2 and Sn:In2O3 nanowires were grown on Si(001, and p-n junctions were fabricated in contact with p-type Cu2S which exhibited rectifying current–voltage characteristics. Core-shell Cu2SnS3/SnO2 and CuInS2/Sn:In2O3 nanowires were obtained by depositing copper and post-growth processing under H2S between 100 and 500 °C. These consist mainly of tetragonal rutile SnO2 and cubic bixbyite In2O3. We observe photoluminescence at 3.65 eV corresponding to band edge emission from SnO2 quantum dots in the Cu2SnS3/SnO2 nanowires due to electrostatic confinement. The Cu2SnS3/SnO2 nanowires assemblies had resistances of 100 Ω similar to CuInS2/In2O3 nanowires which exhibited photoluminescence at 3.0 eV.

  13. Fluorine-doped SnO2 nanoparticles anchored on reduced graphene oxide as a high-performance lithium ion battery anode

    Science.gov (United States)

    Cui, Dongming; Zheng, Zhong; Peng, Xue; Li, Teng; Sun, Tingting; Yuan, Liangjie

    2017-09-01

    The composite of fluorine-doped SnO2 anchored on reduced graphene oxide (F-SnO2/rGO) has been synthesized through a hydrothermal method. F-SnO2 particles with average size of 8 nm were uniformly anchored on the surfaces of rGO sheets and the resulting composite had a high loading of F-SnO2 (ca. 90%). Benefiting from the remarkably improved electrical conductivity and Li-ion diffusion in the electrode by F doping and rGO incorporation, the composite material exhibited high reversible capacity, excellent long-term cycling stability and superior rate capability. The electrode delivered a large reversible capacity of 1037 mAh g-1 after 150 cycles at 100 mA g-1 and high rate capacities of 860 and 770 mAh g-1 at 1 and 2 A g-1, respectively. Moreover, the electrode could maintain a high reversible capacities of 733 mAh g-1 even after 250 cycles at 500 mA g-1. The outstanding electrochemical performance of the as-synthesized composite make it a promising anode material for high-energy lithium ion batteries.

  14. The superconducting properties of co-doped polycrystalline MgB2

    International Nuclear Information System (INIS)

    Moore, J D; Perkins, G K; Branford, W; Yates, K A; Caplin, A D; Cohen, L F; Chen, Soo Kien; Rutter, N A; MacManus-Driscoll, Judith L

    2007-01-01

    In this study we compare the critical current density, the irreversibility line and the upper critical field of four MgB 2 polycrystalline samples, which are either undoped or have 5% carbon or 5% carbon plus either 1% aluminium or 2% zirconium. We discuss how care must be taken for the extraction of the irreversibility line in such samples. We also show how ac susceptibility and Hall probe imaging can be used to examine whether the samples remain fully connected to the highest available fields. Compared to simple 5% carbon doping we find that co-doping provides modest improvement in the pinning properties at intermediate fields in the carbon plus zirconium doped sample

  15. UV Thermoluminescence and Phosphorescence Properties of Mg2+ and Nd3+ Doped Nanostructured Al2O3

    International Nuclear Information System (INIS)

    Bitencourt, J F S; Goncalves, K A; Tatumi, S H; Marcos, P J B

    2010-01-01

    Mg 2+ and Nd 3+ doped aluminium oxide samples were produced by polymer calcination method. Mg 2+ doped samples did not exhibited significant fluorescence emission, using IR (LED, emission centered at 862nm) or green (Xe-lamp plus optical filter, emission centered at 520 nm) sources. Nonetheless, high thermostimulated luminescence was detected, with high emission peak at 190 0 C. A nanoscopic layer (about 50 nm width) of magnesium spinel was observed by Transmission Electronic Microscopy (TEM) for 2.61mol% doped sample; this layer can be the responsible for TL enhancement. Nd 3+ doped sample exhibited low phosphorescence emission in the UV (Schott U-340) using IR source. TL peaks were detected at 185 and 265 0 C; the intermediary peak showed the highest emission. Occurrence of NdAl and NdAl 2 structures were detected in 5 mol% doped sample and NdAl 2 and NdAl 4 structures in 10 mol% doped sample.

  16. Recent Progress of B-Ga2O3 MOSFETs for Power Electronic Applications

    Science.gov (United States)

    2017-03-20

    Ge Si Sn M ob ilit y (c m 2 /V *s ) Measured Nd - Na (cm -3) MBE Figure 4. Mobility as a...100 LPCVD MOVPE MOVPE Sn Si Ge C on ta ct R es is ta nc e ( m m ) Measured Nd - Na(cm -3) MBE MOVPE Figure 5. Contact Resistance (Ω*mm) is... Deposition (LPCVD). Epitaxy was grown on compensation doped (Mg or Fe) single crystal substrate with (010) or (100) crystal orientations.

  17. One-pot electrospinning and gas-sensing properties of LaMnO3 perovskite/SnO2 heterojunction nanofibers

    Science.gov (United States)

    Chen, Dongdong; Yi, Jianxin

    2018-03-01

    Using nanostructured composite materials is an effective way to obtain high-performance gas sensors. This work used p-type LaMnO3 perovskite-structured semiconductor as a novel promoter for SnO2 nanofibers and studied the gas-sensing characteristics. Nanofibers of 0-2.5-mol% LaMnO3/SnO2 were synthesized via one-pot electrospinning. Compared with pristine SnO2, LaMnO3/SnO2 composite nanofibers exhibited smaller particle size (10-30 nm) and higher BET surface area. XPS revealed that oxygen surface absorption decreased with increasing LaMnO3 content. 0.3-mol% LaMnO3/SnO2 exhibited significantly enhanced ethanol sensitivity relative to pristine SnO2. A response of 20 was obtained at the optimum temperature of 260 °C for 100-ppm ethanol. Higher LaMnO3 loading led to decrease of the ethanol response. The impact of LaMnO3 loading on the sensing behavior of SnO2 nanofibers was discussed in terms of p-n heterojunction formation and changes in the microstructure and catalytic properties.

  18. Different valence Sn doping - A simple way to detect oxygen concentration variation of ZnO quantum dots synthesized under ultrasonic irradiation.

    Science.gov (United States)

    Yang, Weimin; Zhang, Bing; Zhang, Qitu; Wang, Lixi; Song, Bo; Wu, Fan; Wong, C P

    2017-09-01

    An ultrasonic method is employed to synthesize the Sn doped Zn 0.95 Sn 0.05 O quantum dots with green light emission. Sn 2+ and Sn 4+ ions are used to create different optical defects inside Zn 0.95 Sn 0.05 O quantum dots and the changing trend of oxygen concentration under different ultrasonic irradiation power are investigated. The photoluminescence spectra are employed to characterize the optical defects of Zn 0.95 Sn 0.05 O quantum dots. The UV-vis spectra are used to study the band gap of Zn 0.95 Sn 0.05 O quantum dots, which is influenced by their sizes. The results indicate that ultrasonic power would influence the size of Zn 0.95 Sn 0.05 O quantum dots as well as the type and quantity of defects in ZnO quantum dots. Changing trends in size of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are quite similar with each other, while the changing trends in optical defects types and concentration of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are different. The difference of the optical defects concentration changing between Sn 2+ doped Zn 0.95 Sn 0.05 O quantum dots (V O defects) and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots (O Zn and O i defects) shows that the formation process of ZnO under ultrasonic irradiation wiped oxygen out. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Effect of Sn-doped on microstructural and optical properties of ZnO thin films deposited by sol-gel method

    International Nuclear Information System (INIS)

    Tsay, C.-Y.; Cheng, H.-C.; Tung, Y.-T.; Tuan, W.-H.; Lin, C.-K.

    2008-01-01

    In this study, transparent thin films of Sn-doped ZnO (ZnO:Sn) were deposited onto alkali-free glass substrates by a sol-gel method; the effect of Sn doping on crystallinity, microstructural and optical properties was investigated. The atomic percentages of dopant in ZnO-based sols were Sn/Zn = 0, 1, 2, 3, and 5 at.%. The as-deposited films were pre-heated at 300 deg. C for 10 min and then annealed in air at 500 deg. C for 1 h. The results show that Sn-doped ZnO thin films demonstrate obviously improved surface roughness, enhanced transmittance in the 400-600 nm wavelength range and reduced average crystallite size. Among all of the annealed ZnO-based films in this study, films doped with 2 at.% Sn concentration exhibited the best properties, namely an average transmittance of 90%, an RMS roughness value of 1.92 nm and a resistivity of 9.3 x 10 2 Ω-cm

  20. Theoretical calculation of performance enhancement in lattice-matched SiGeSn/GeSn p-channel tunneling field-effect transistor with type-II staggered tunneling junction

    Science.gov (United States)

    Wang, Hongjuan; Han, Genquan; Wang, Yibo; Peng, Yue; Liu, Yan; Zhang, Chunfu; Zhang, Jincheng; Hu, Shengdong; Hao, Yue

    2016-04-01

    In this work, a lattice-matched SiGeSn/GeSn heterostructure p-channel tunneling field-effect transistor (hetero-PTFET) with a type-II staggered tunneling junction (TJ) is investigated theoretically. Lattice matching and type-II band alignment at the Γ-point is obtained at the SiGeSn/GeSn interface by tuning Sn and Si compositions. A steeper subthreshold swing (SS) and a higher on state current (I ON) are demonstrated in SiGeSn/GeSn hetero-PTFET than in GeSn homo-PTFET. Si0.31Ge0.49Sn0.20/Ge0.88Sn0.12 hetero-PTFET achieves a 2.3-fold higher I ON than Ge0.88Sn0.12 homo-PTFET at V DD of 0.3 V. Hetero-PTFET achieves a more abrupt hole profile and a higher carrier density near TJ than the homo-PTFET, which contributes to the significantly enhanced band-to-band tunneling (BTBT) rate and tunneling current in hetero-PTFET.

  1. Synthesis and characterization of erbium-doped SiO2 nanoparticles fabricated by using reverse micelle and sol-gel processing

    International Nuclear Information System (INIS)

    Park, Hoyyul; Bae, Dongsik

    2012-01-01

    Erbium-doped SiO 2 nanoparticles have been synthesized using a reverse micelle technique combined with metal-alkoxide hydrolysis and condensation. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles could be changed by varying the molar ratio of water to surfactant. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles were examined by using a transmission electron microscope. The average size of synthesized erbium-doped SiO 2 nanoparticles was approximately 20 - 25 nm and that of the erbium particles was 3 - 5 nm. The effects of the synthesis parameters, such as the molar ratio of water to surfactant, are discussed.

  2. Structural and optical properties of vanadium doped SnO{sub 2} nanoparticles with high photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Ch. Venkata [School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Babu, B. [Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Vattikuti, S.V. Prabhakar [School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Ravikumar, R.V.S.S.N. [Department of Physics, Acharya Nagarjuna University, Guntur, A.P. 522510 (India); Shim, Jaesool, E-mail: Jshim@ynu.ac.kr [School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of)

    2016-11-15

    Vanadium (0.01, 0.03 and 0.05 mol%) doped SnO{sub 2} nanoparticles have been synthesized using combustion synthesis method. The as-prepared nanoparticles were characterized using various measurements such as XRD, SEM with EDS, HRTEM, Raman spectroscopy, optical, PL, XPS and FT-IR techniques. The crystal structure and average particle sizes of the prepared nanoparticles were confirmed from the XRD. The average crystalline particle sizes were decreased by increasing the vanadium dopant concentration. The presence of vanadium as V{sup 4+} species in the host lattice was confirmed by X-ray photoelectron spectroscopy. The band gap energies were decreased by increasing dopant concentration. The 0.05 mol% doped sample showed higher photocatalytic activity than undoped, V-1 and V-3 in decomposing rhodamine B (RhB) under UV light irradiation. The Raman and IR spectra confirm the fundamental vibration of SnO{sub 2} host molecules.

  3. Synthesis, characterization and photoluminescence properties of Dy{sup 3+}-doped nano-crystalline SnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Pillai, Sreejarani K.; Sikhwivhilu, Lucky M. [National Centre for Nano-Structured Materials, CSIR, PO Box 395, Pretoria 0001 (South Africa); Hillie, Thembela K., E-mail: thillie@csir.co.za [National Centre for Nano-Structured Materials, CSIR, PO Box 395, Pretoria 0001 (South Africa); Physics Department, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2010-04-15

    Nano-crystalline of tin oxide doped with varying wt% of Dy{sup 3+} was prepared using chemical co-precipitation method and characterised by various advanced techniques such as BET-surface area, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy and photoluminescence measurements. Analytical results demonstrated that the nanocrystalline tin oxide is in tetragonal crystalline phase and doping with Dy{sup 3+} could inhibit the phase transformation, increases surface area and decreases the crystallite size. The experimental result on photoluminescence characteristics originating from Dy{sup 3+}-doping in nanocrystalline SnO{sub 2} reveals the dependence of the luminescent intensity on dopant concentration.

  4. Doping effect in Si nanocrystals

    Science.gov (United States)

    Li, Dongke; Xu, Jun; Zhang, Pei; Jiang, Yicheng; Chen, Kunji

    2018-06-01

    Intentional doping in semiconductors is a fundamental issue since it can control the conduction type and ability as well as modify the optical and electronic properties. To realize effective doping is the basis for developing semiconductor devices. However, by reducing the size of a semiconductor, like Si, to the nanometer scale, the doping effects become complicated due to the coupling between the quantum confinement effect and the surfaces and/or interfaces effect. In particular, by introducing phosphorus or boron impurities as dopants into material containing Si nanocrystals with a dot size of less than 10 nm, it exhibits different behaviors and influences on the physical properties from its bulk counterpart. Understanding the doping effects in Si nanocrystals is currently a challenge in order to further improve the performance of the next generation of nano-electronic and photonic devices. In this review, we present an overview of the latest theoretical studies and experimental results on dopant distributions and their effects on the electronic and optical properties of Si nanocrystals. In particular, the advanced characterization techniques on dopant distribution, the carrier transport process as well as the linear and nonlinear optical properties of doped Si nanocrystals, are systematically summarized.

  5. Magnetocaloric effect and transport properties of Gd5Ge2(Si1-x Sn x )2 (x=0.23 and 0.40) compounds

    International Nuclear Information System (INIS)

    Campoy, J.C.P.; Plaza, E.J.R.; Nascimento, F.C.; Coelho, A.A.; Pereira, M.C.; Fabris, J.D.; Raposo, M.T.; Cardoso, L.P.; Persiano, A.I.C.; Gama, S.

    2007-01-01

    We report a study about the structural properties of polycrystalline samples of nominal composition Gd 5 Ge 2 (Si 1- x Sn x ) 2 (x=0.23, 0.40) that closely influence their physical behavior particularly related to electric resistivity and magnetocaloric (MCE) effect. The samples were characterized by X-ray diffraction (XRD) using the Rietveld refinement method, metallographic analyses, 119 Sn Moessbauer spectroscopy, DC magnetization and electrical transport measurements. It was identified a Gd 5 Si 2 Ge 2 -monoclinic phase for x=0.23 and a Sm 5 Sn 4 -orthorhombic phase (type II) for x=0.40, both with two non-equivalent crystallographic sites for the Sn ions. We were able to infer on the role of tin on the magnetic and transport properties in these compounds

  6. Synthesis, electrochemical investigation and structural analysis of doped Li[Ni0.6Mn0.2Co0.2-xMx]O2 (x = 0, 0.05; M = Al, Fe, Sn) cathode materials

    Science.gov (United States)

    Eilers-Rethwisch, Matthias; Winter, Martin; Schappacher, Falko Mark

    2018-05-01

    Layered Ni-rich Li[Ni0.6Mn0.2Co0.2-xMx]O2 cathode materials (x = 0, 0.05; M = Al, Fe, Sn) are synthesized via a co-precipitation synthesis route and the effect of dopants on the structure and electrochemical performance is investigated. All synthesized materials show a well-defined layered structure of the hexagonal α-NaFeO2 phase investigated by X-ray diffraction (XRD). Undoped LiNi0.6Mn0.2Co0.2O2 exhibits a discharge capacity of 170 mAh g-1 in Li-metal 2032 coin-type cells. Doped materials reach lower capacities between 145 mAh g-1 for Al and 160 mAh g-1 for Sn. However, all doped materials prolong the cycle life by up to 20%. Changes of the lattice parameter before and after delithiation yield information about structural stability. A smaller repulsion of the transition metal layer during delithiation in the Sn-doped material leads to a smaller expansion of the unit cell, which results in enhanced structural stability of the material. The improved structural stability of Sn-doped NMC cathode active material is proven by thermal investigations with the help of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA).

  7. Structural, elastic, electronic, bonding, and optical properties of BeAZ{sub 2} (A = Si, Ge, Sn; Z = P, As) chalcopyrites

    Energy Technology Data Exchange (ETDEWEB)

    Fahad, Shah [Department of Physics, Hazara University Mansehra, KPK, Mansehra (Pakistan); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Laboratory, Department of Physics, Islamia College University, Peshawar (Pakistan); Ouahrani, T. [Laboratoire de Physique Théorique, B.P. 230, Université de Tlemcen, Tlemcen 13000 (Algeria); Ecole Préparatoire en Sciences et Techniques, BP 165 R.P., 13000 Tlemcen (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria); Yousaf, Masood [Center for Multidimensional Carbon Materials, Institute for Basic Science, Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Omran, S.Bin [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Mohammad, Saleh [Department of Physics, Hazara University Mansehra, KPK, Mansehra (Pakistan)

    2015-10-15

    A first principles density functional theory (DFT) technique is used to study the structural, chemical bonding, electronic and optical properties of BeAZ{sub 2} (A = Si, Ge, Sn; Z = P, As) chalcopyrite materials. The calculated parameters are in good agreement with the available experimental results. The lattice constants and the equilibrium volume increased as we moved from Si to Ge to Sn, whereas the c/a and internal parameters u decreased by shifting the cation from P to As. These compounds are elastically stable. An investigation of the band gap using the WC-GGA, EV-GGA, PBE-GGA and mBJ-metaGGA potentials suggested that BeSiP{sub 2} and BeSiAs{sub 2} are direct band gap compounds, whereas BeGeP{sub 2,} BeGeAs{sub 2,} BeSnP{sub 2,} BeSnAs{sub 2} are indirect band gap compounds. The energy band gaps decreased by changing B from Si to Sn and increased by changing the anion C from P to As. The bonding among the cations and anions is primarily ionic. In the optical properties, the real and imaginary parts of the dielectric functions, reflectivity and optical conductivity have been studied over a wide energy range. - Highlights: • The compounds are studied by FP-LAPW method within mBJ approximation. • All of the studied materials show isotropic behaviour. • All the compounds show direct band gap nature. • Bonding nature is mostly covalent among the studied compounds. • High absorption peaks and reflectivity ensures there utility in optoelectronic devices.

  8. An innovative technique to synthesize C-doped MgB2 by using chitosan as the carbon source

    International Nuclear Information System (INIS)

    Bovone, G; Kawale, S; Siri, A S; Vignolo, M; Bernini, C

    2014-01-01

    Here, we report a new technique to synthesize carbon-doped MgB 2 powder. Chitosan was innovatively used as the carbon source during the synthesis of boron from boron oxide. This allowed the introduction of local defects, which later on served as pinning centers in MgB 2 , in the boron lattice itself, avoiding the traditional and time consuming ways of ex situ MgB 2 doping (e.g. ball milling). Two volume percentages of C-doping have been tried and its effect on the superconducting properties, evaluated by magnetic and transport measurements, are discussed here. Morphological analysis by scanning electron microscopy revealed nano-metric grains’ distribution in the boron and MgB 2 powder. Mono-filamentary MgB 2 wires have been fabricated by an ex situ powder-in-tube technique by using the thus prepared carbon-doped MgB 2 and pure MgB 2 powders. Transport property measurements on these wires were made and compared with MgB 2 wire produced using commercial boron. (fast track communication)

  9. The effect of the film thickness and doping content of SnO2:F thin films prepared by the ultrasonic spray method

    International Nuclear Information System (INIS)

    Rahal Achour; Benramache Said; Benhaoua Boubaker

    2013-01-01

    This paper reports on the effects of film thickness and doping content on the optical and electrical properties of fluorine-doped tin oxide. Tin (II) chloride dehydrate, ammonium fluoride dehydrate, ethanol and HCl were used as the starting materials, dopant source, solvent and stabilizer, respectively. The doped films were deposited on a glass substrate at different concentrations varying between 0 and 5 wt% using an ultrasonic spray technique. The SnO 2 :F thin films were deposited at a 350 °C pending time (5, 15, 60 and 90 s). The average transmission was about 80%, and the films were thus transparent in the visible region. The optical energy gap of the doped films with 2.5 wt% F was found to increase from 3.47 to 3.89 eV with increasing film thickness, and increased after doping at 5 wt%. The decrease in the Urbach energy of the SnO 2 :F thin films indicated a decrease in the defects. The increase in the electrical conductivity of the films reached maximum values of 278.9 and 281.9 (Ω·cm) −1 for 2.5 and 5 wt% F, respectively, indicating that the films exhibited an n-type semiconducting nature. A systematic study on the influence of film thickness and doping content on the properties of SnO 2 :F thin films deposited by ultrasonic spray was reported. (semiconductor materials)

  10. van der Waals epitaxy of SnS film on single crystal graphene buffer layer on amorphous SiO2/Si

    Science.gov (United States)

    Xiang, Yu; Yang, Yunbo; Guo, Fawen; Sun, Xin; Lu, Zonghuan; Mohanty, Dibyajyoti; Bhat, Ishwara; Washington, Morris; Lu, Toh-Ming; Wang, Gwo-Ching

    2018-03-01

    Conventional hetero-epitaxial films are typically grown on lattice and symmetry matched single crystal substrates. We demonstrated the epitaxial growth of orthorhombic SnS film (∼500 nm thick) on single crystal, monolayer graphene that was transferred on the amorphous SiO2/Si substrate. Using X-ray pole figure analysis we examined the structure, quality and epitaxy relationship of the SnS film grown on the single crystal graphene and compared it with the SnS film grown on commercial polycrystalline graphene. We showed that the SnS films grown on both single crystal and polycrystalline graphene have two sets of orientation domains. However, the crystallinity and grain size of the SnS film improve when grown on the single crystal graphene. Reflection high-energy electron diffraction measurements show that the near surface texture has more phases as compared with that of the entire film. The surface texture of a film will influence the growth and quality of film grown on top of it as well as the interface formed. Our result offers an alternative approach to grow a hetero-epitaxial film on an amorphous substrate through a single crystal graphene buffer layer. This strategy of growing high quality epitaxial thin film has potential applications in optoelectronics.

  11. Electrical properties of Si/Si1-xGex/Si inverted modulation doped structures

    International Nuclear Information System (INIS)

    Sadeghzadeh, M.A.

    1998-12-01

    This thesis is a report of experimental investigations of growth strategy and electrical properties of Si/Si 1-x Ge x /Si inverted Modulation Doped (MD) structures grown by solid source Molecular Beam Epitaxy (MBE). If the grown Si layer is B-doped at some distance (as spacer) before or after the alloy layer, this remote doping induces the formation of a quasi Two Dimensional Hole Gas (2-DHG) near to the inverted (SiGe on Si) or normal (Si on SiGe) heterointerfaces of the Si/Si 1-x Ge x /Si quantum well, respectively. The latter arrangement is the well known 'normal' MD structure but the former one is the so-called 'inverted' MD structure which is of great interest for Field Effect Transistor (FET) applications. A reproducible growth strategy was employed by the use of a thick (400nm) Si cap for inverted MD structures with Ge composition in the range of 16-23%. Boron segregation and cap surface charges are significant in these inverted structures with small ( 20nm) spacer layers, respectively. It was demonstrated by secondary ion mass spectroscopy (SIMS) that boron segregation, which causes a reduction in the effective spacer dimension, can be suppressed by growth interruption after boron doping. The enhancement in hole sheet density with increasing Si cap layer thickness, is attributed to a reduction in the influence of positive surface charges in these structures. Top-gated devices were fabricated using these structures and the hole sheet density could be varied by applying a voltage to the metal-semiconductor gate, and the maximum Hall mobility of 5550 cm 2 V -1 s -1 with 4.2x10 11 cm -2 was measured (at 1.6K) in these structures. Comparison of measured Hall mobility (at 4.2K) as a function of hole sheet density in normal and inverted MD structures implies that both 2-DHG confined at normal and/or inverted structures are subjected to very similar interface charge, roughness, and alloy scattering potentials. Low temperatures magnetotransport measurements (down to

  12. Phosphorus doping of Si nanocrystals: Interface defects and charge compensation

    International Nuclear Information System (INIS)

    Stegner, A.R.; Pereira, R.N.; Klein, K.; Wiggers, H.; Brandt, M.S.; Stutzmann, M.

    2007-01-01

    Using electron paramagnetic resonance (EPR), Fourier-transform infrared absorption (FTIR) and temperature programmed desorption (TPD), we have investigated the doping of silicon nanocrystals (Si-ncs) and the interaction between intrinsic defects and dopants. Si-ncs were produced in a low-pressure microwave plasma reactor using silane as precursor gas. Phosphorus doping was achieved by addition of phosphine to the precursor gas. The low temperature EPR spectra of all P-doped samples display a line at g=1.998, which is the fingerprint of substitutional P in crystalline silicon for [P]>10 18 cm -3 . In addition, the characteristic hyperfine signature of P in Si is also observed for samples with nominal P doping levels below 10 19 cm -3 . Two more features are observed in our EPR spectra: a broad band located at g=2.0056, due to isotropic Si dangling bonds (Si-dbs), and an axially symmetric powder pattern (g perpendicular =2.0087,g parallel =2.0020) arising from Si-dbs at the interface between the crystalline Si core and a native oxide shell. The formation of this oxide layer and the presence of different H-termination configurations are revealed by FTIR spectroscopy. The density of Si-dbs is reduced in P-doped samples, indicating a sizable compensation of the doping by Si-dbs. This compensation effect was verified by H desorption, which enhances the density of Si-dbs, in combination with TPD and FTIR

  13. Auto-combustion synthesis and characterization of Mg doped CuAlO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Shraddha, E-mail: shraddhaa32@gmail.com; Parveen, Azra; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg.& Technology, Aligarh Muslim University, Aligarh-202002 (India)

    2015-06-24

    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO{sub 2}nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO{sub 2} sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO{sub 2} has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  14. Improved Dehydrogenation Properties of 2LiNH2-MgH2 by Doping with Li3AlH6

    Directory of Open Access Journals (Sweden)

    Shujun Qiu

    2017-01-01

    Full Text Available Doping with additives in a Li-Mg-N-H system has been regarded as one of the most effective methods of improving hydrogen storage properties. In this paper, we prepared Li3AlH6 and evaluated its effect on the dehydrogenation properties of 2LiNH2-MgH2. Our studies show that doping with Li3AlH6 could effectively lower the dehydrogenation temperatures and increase the hydrogen content of 2LiNH2-MgH2. For example, 2LiNH2-MgH2-0.1Li3AlH6 can desorb 6.43 wt % of hydrogen upon heating to 300 °C, with the onset dehydrogenation temperature at 78 °C. Isothermal dehydrogenation testing indicated that 2LiNH2-MgH2-0.1Li3AlH6 had superior dehydrogenation kinetics at low temperature. Moreover, the release of byproduct NH3 was successfully suppressed. Measurement of the thermal diffusivity suggests that the enhanced dehydrogenation properties may be ascribed to the fact that doping with Li3AlH6 could improve the heat transfer for solid–solid reaction.

  15. Nonlinear I-V characteristics of doped SnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dhage, S.R.; Choube, Vandana; Ravi, V

    2004-07-15

    When tin oxide is doped with Sb{sub 2}O{sub 3} and CoO, it shows highly nonlinear current (I)-voltage (V) characteristics. Addition of CoO leads to creation of oxygen vacancies and helps in sintering of SnO{sub 2}. Antimony oxide acts as a donor and increases the conductivity. The results are nearly same when antimony oxide is replaced by tantalum oxide. The grain size of these sintered ceramics varies from 5 to 7 {mu}m and the grain boundary barrier height (PHI{sub B}) is in the range of 0.5 eV. The observed nonlinear coefficient ({alpha}) is 25 and 27 for antimony and tantalum oxide, respectively and the breakdown field is in the range of 1250 V cm{sup -1}.

  16. First-principles study on band structures and electrical transports of doped-SnTe

    Directory of Open Access Journals (Sweden)

    Xiao Dong

    2016-06-01

    Full Text Available Tin telluride is a thermoelectric material that enables the conversion of thermal energy to electricity. SnTe demonstrates a great potential for large-scale applications due to its lead-free nature and the similar crystal structure to PbTe. In this paper, the effect of dopants (i.e., Mg, Ca, Sr, Ba, Eu, Yb, Zn, Cd, Hg, and In on the band structures and electrical transport properties of SnTe was investigated based on the first-principles density functional theory including spin–orbit coupling. The results show that Zn and Cd have a dominant effect of band convergence, leading to power factor enhancement. Indium induces obvious resonant states, while Hg-doped SnTe exhibits a different behavior with defect states locating slightly above the Fermi level.

  17. Synthesis, structure, magnetic, electrical and electrochemical properties of Al, Cu and Mg doped MnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hashem, Ahmed M., E-mail: ahmedh242@yahoo.com [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Abuzeid, Hanaa M. [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Narayanan, N. [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Ehrenberg, Helmut [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Julien, C.M. [Universite Pierre et Marie Curie, Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), 4 place Jussieu, 75005 Paris (France)

    2011-10-17

    Highlights: {yields} Al, Mg and Cu doped MnO{sub 2} as cathode in Li-ion batteries. {yields} Pure phase MnO{sub 2} for virgin and doped MnO{sub 2} were obtained. {yields} Doping elements improve the electrical conductivity of MnO{sub 2}. {yields} Electrochemical behaviour of MnO{sub 2} improved after doping by Al, Mg and Cu. - Abstract: Pure and doped manganese dioxides were prepared by wet-chemical method using fumaric acid and potassium permanganate as raw materials. X-ray diffraction patterns show that pure and Al, Cu and Mg doped manganese dioxides (d-MnO{sub 2}) crystallized in the cryptomelane-MnO{sub 2} structure. Thermal analysis show that, with the assistance of potassium ions inside the 2 x 2 tunnel, the presence of Al, Cu and Mg doping elements increases the thermal stability of d-MnO{sub 2}. The electrical conductivity of d-MnO{sub 2} increases in comparison with pure MnO{sub 2}, while Al-doped MnO{sub 2} exhibits the lower resistivity. As shown in the magnetic measurements, the value of the experimental effective magnetic moment of Mn ions decreases with introduction of dopants, which is attributed to the presence of a mixed valency of high-spin state Mn{sup 4+}/Mn{sup 3+}. Doped MnO{sub 2} materials show good capacity retention in comparison with virgin MnO{sub 2}. Al-doped MnO{sub 2} shows the best electrochemical results in terms of capacity retention and recharge efficiency.

  18. A spot laser modulated resistance switching effect observed on n-type Mn-doped ZnO/SiO2/Si structure.

    Science.gov (United States)

    Lu, Jing; Tu, Xinglong; Yin, Guilin; Wang, Hui; He, Dannong

    2017-11-09

    In this work, a spot laser modulated resistance switching (RS) effect is firstly observed on n-type Mn-doped ZnO/SiO 2 /Si structure by growing n-type Mn-doped ZnO film on Si wafer covered with a 1.2 nm native SiO 2 , which has a resistivity in the range of 50-80 Ω∙cm. The I-V curve obtained in dark condition evidences the structure a rectifying junction, which is further confirmed by placing external bias. Compared to the resistance state modulated by electric field only in dark (without illumination), the switching voltage driving the resistance state of the structure from one state to the other, shows clear shift under a spot laser illumination. Remarkably, the switching voltage shift shows a dual dependence on the illumination position and power of the spot laser. We ascribe this dual dependence to the electric filed produced by the redistribution of photo-generated carriers, which enhance the internal barrier of the hetero-junction. A complete theoretical analysis based on junction current and diffusion equation is presented. The dependence of the switching voltage on spot laser illumination makes the n-type Mn-doped ZnO/SiO 2 /Si structure sensitive to light, which thus allows for the integration of an extra functionality in the ZnO-based photoelectric device.

  19. Rare earths (Ce, Eu, Tb) doped Y2Si2O7 phosphors for white LED

    International Nuclear Information System (INIS)

    Sokolnicki, Jerzy

    2013-01-01

    Nanocrystalline yttrium pyrosilicate Y 2 Si 2 O 7 (YPS) singly, doubly or triply doped with Ce 3+ , Eu 3+ , Tb 3+ was obtained by the reaction of nanostructured Y 2 O 3 :Ln 3+ and colloidal SiO 2 at high temperatures. X-ray diffraction analysis confirmed the formation of a single phase of α-YPS at 1200 °C. Two series of YPS samples doped with Eu 3+ or Eu 3+ /Tb 3+ were obtained by applying the reducing atmosphere (75%N 2 +25%H 2 ) at different temperatures. The luminescence and excitation spectra are reported. The singly Eu 3+ doped YPS emit from both Eu 3+ and Eu 2+ ions, with the spectral position and width of the Eu 2+ emission different in both series. The presence of Eu 2+ in the samples was confirmed by electron paramagnetic resonance (EPR) spectra. A broadband emission of Eu 2+ (380–650 nm), combined with the red emission of Eu 3+ is perceived by the naked eye as white light. Co-doping of YPS:Eu 3+ with Tb 3+ results in enhancement of the green component of the emission, and well-balanced white luminescence. The colour of this emission is tunable, and it is possible to get Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.327, 0.327), colour-rendering index (CRI) of 85, and quantum efficiency (QE) of 71%. These phosphors are efficiently excited in the wavelength range of 300–420 nm, which perfectly matches a near UV-emitting InGaN chip. It was shown that for triply (Ce 3+ , Eu 3+ and Tb 3+ ) doped samples the three emissions from the particular activators can be generated using one excitation wavelength. The white light resulting from the superposition of the blue (Ce 3+ ), green (Tb 3+ ) and red (Eu 3+ ) emissions can be obtained by varying the concentration of the active ions and the treating atmosphere, i.e. reducing or oxidising. Eu 2+ was not detected in the triply doped samples, and hence line emissions mostly exhibit CRI values equal to or below 30. - Highlights: ► Nanocrystalline Y 2 Si 2 O 7 was obtained by the

  20. Electrochemical performance of La-doped Sr{sub 2}MgMoO{sub 6-{delta}} in natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yuan [Texas Materials Institute, ETC 9.102, The University of Texas at Austin, Austin, TX 78712 (United States); College of Physics, Jilin University, 2519 Jiefang Road, Changchun 130023, Jilin Province (China); Huang, Yun-Hui; Goodenough, John B. [Texas Materials Institute, ETC 9.102, The University of Texas at Austin, Austin, TX 78712 (United States); Ying, Jie-Rong [Texas Materials Institute, ETC 9.102, The University of Texas at Austin, Austin, TX 78712 (United States); Institute of Nuclear and New Energy Technology, Tsinghua University, P.O. Box 1021, Beijing 102201 (China)

    2007-08-15

    Modification of the double perovskite Sr{sub 2}MgMoO{sub 6-{delta}} by La substitution has shown that Sr{sub 2-x}La{sub x}MgMoO{sub 6-{delta}} with 0.6 {<=} x {<=} 0.8 has better performance as the anode of a solid oxide fuel cell. With a Sr{sub 1.2}La{sub 0.8}MgMoO{sub 6-{delta}} anode, LSGM electrolyte, SrCo{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} cathode, and a La{sub 0.5}Ce{sub 0.4}O{sub 1.7-{delta}} buffer layer between the anode and the electrolyte, a maximum power density of 550 mW/cm{sup 2} has been obtained for a SOFC operating on wet methane (3%H{sub 2}O) at 800 C. The performance of the SOFC using C{sub 2}H{sub 6} fuel, like that of CH{sub 4}, changes little on switching from dry C{sub 2}H{sub 6} to 3% H{sub 2}O/C{sub 2}H{sub 6}, but improvement with wet C{sub 3}H{sub 8} shows that some steam will need to be added to a moderately desulfurized natural-gas fuel. (author)

  1. Photoluminescence of Eu{sup 2+}-doped CaMgSi{sub 2x}O{sub 6+2x} (1.00{<=}x{<=}1.20) phosphors in UV-VUV region

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiya [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang Yuhua [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)], E-mail: wyh@lzu.edu.cn

    2008-03-15

    Alkaline-earth silicate phosphors CaMgSi{sub 2x}O{sub 6+2x}:Eu{sup 2+} (1.00{<=}x{<=}1.20) were prepared by traditional solid-state reaction. The phosphors showed an intense blue emission centered around 453 nm, with both 254 and 147 nm excitations. The host absorption below 200 nm in the excitation spectra consisted of two bands around 160 and 190 nm. The band around 160 nm was ascertained to be associated with the SiO{sub 4}-tetrahedra and MgO{sub 6}-polyhedra, and that around 190 nm was due to the CaO{sub 8}-polyhedra or some impurities. The incorporation of excess Si of less than 15% would not lead to formation of impurities and the results indicated that an appropriate Si excess could improve the Photoluminescence (PL) intensity in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions.

  2. Effect of Ni on eutectic structural evolution in hypereutectic Al-Mg2Si cast alloys

    International Nuclear Information System (INIS)

    Li Chong; Wu Yaping; Li Hui; Wu Yuying; Liu Xiangfa

    2010-01-01

    Research highlights: → By the injection of rod-like NiAl 3 phase in Al-Mg 2 Si alloys, Al-Mg 2 Si binary eutectic structure gradually evolves into Al-Mg 2 Si-NiAl 3 ternary eutectic. → The ternary eutectic presents a unique double rod structure that rod-like NiAl 3 and Mg 2 Si uniformly distribute in Al matrix. → The mechanism of structural evolution was analyzed in terms of the detailed microstructural observations. → The high temperature (350 deg. C) tensile strength of the alloy increases by 23% due to the eutectic structural evolution. - Abstract: The aim of this work is to investigate the eutectic structural evolution of hypereutectic Al-20% Mg 2 Si with Ni addition under a gravity casting process. Three-dimensional morphologies of eutectic phases were observed in detail using field emission scanning electron microscopy, after Al matrix was removed by deep etching or extraction. The results show that Al-Mg 2 Si binary eutectic gradually evolves into Al-Mg 2 Si-NiAl 3 ternary eutectic with the increase of Ni content, and flake-like eutectic Mg 2 Si transforms into rods. The ternary eutectic presents a unique double rod structure that rod-like NiAl 3 and Mg 2 Si uniformly distribute in Al matrix. Further, the high temperature (350 deg. C) tensile strength of the alloy increases by 23% due to the eutectic structure evolution, and the mechanism of structural evolution was discussed and analyzed in terms of the detailed microstructural observations.

  3. Comparison between nano-diamond and carbon nanotube doping effects on critical current density and flux pinning in MgB2

    International Nuclear Information System (INIS)

    Cheng, C H; Yang, Y; Munroe, P; Zhao, Y

    2007-01-01

    Doping effects of nano-diamond and carbon nanotubes (CNTs) on critical current density of bulk MgB 2 have been studied. CNTs are found prone to be doped into the MgB 2 lattice whereas nano-diamond tends to form second-phase inclusions in the MgB 2 matrix, leading to a more significant improvement of J c (H) by doping by nano-diamond than by CNTs in MgB 2 . TEM reveals tightly packed MgB 2 nanograins (50-100 nm) with a dense distribution of diamond nanoparticles (10-20 nm) inside MgB 2 grains in nano-diamond-doped samples. Such a unique microstructure leads to a flux pinning behaviour different from that in CNTs-doped MgB 2

  4. Synthesis and electrochemical performance of Sn-doped Li3V2(PO4)3/C cathode material for lithium ion battery by microwave solid-state technique

    International Nuclear Information System (INIS)

    Liu, Haiping; Bi, Sifu; Wen, Guangwu; Teng, Xiangguo; Gao, Peng; Ni, Zujun; Zhu, Yongming; Zhang, Fang

    2012-01-01

    Highlights: ► Li 3 V 2−x Sn x (PO 4 ) 3 /C (0 ⩽ x ⩽ 0.10) cathode is first reported. ► Sn doping improves the initial discharge capacity and the cycle stability of Li 3 V 2 (PO 4 ) 3 /C. ► Sn doping improves the conductivity and reversibility of the Li 3 V 2 (PO 4 ) 3 /C. - Abstract: Li 3 V 2−x Sn x (PO 4 ) 3 /C cathode materials with uniform and fine particle sizes were successfully and fast synthesized by a microwave solid-state synthesis method. X-ray diffraction patterns demonstrated that the appropriate addition of Sn did not destroy the lattice structure of Li 3 V 2 (PO 4 ) 3 /C, but decreased the unit cell volume. X-ray photoelectron spectroscopy analysis demonstrated that the main chemical state of V in the Li 3 V 1.95 Sn 0.05 (PO 4 ) 3 /C composite is +3 valence, while the chemical state of Sn in the Li 3 V 1.95 Sn 0.05 (PO 4 ) 3 /C is +4 valence. Scanning electron microscope analysis illustrated that the addition of Sn slightly affected the morphology of samples. As the cathode materials for Li-ion batteries, Li 3 V 2−x Sn x (PO 4 ) 3 /C (x ⩽ 0.10) exhibited higher discharge capacity and better cycle stability than the pure one. At a discharge rate of 0.5 C in the potential range of 2.5–4.5 V at room temperature, the initial discharge capacity of Li 3 V 1.95 Sn 0.05 (PO 4 ) 3 /C was 136 mA h/g. The low charge-transfer resistances and large lithium ion diffusion coefficients confirmed that Sn-doped Li 3 V 2 (PO 4 ) 3 /C samples possessed better electronic conductivity and lithium ion mobility. These improved electrochemical performances can be attributed to the appropriate amount of Sn doping in Li 3 V 2 (PO 4 ) 3 /C system by enhancing structural stability and electrical conductivity. The present study also demonstrates that the microwave processing is a fast, simple and useful method for the fabrication of Li 3 V 2 (PO 4 ) 3 /C crystals.

  5. Physical and photoelectrochemical properties of Sb-doped SnO2 thin films deposited by chemical vapor deposition: application to chromate reduction under solar light

    Science.gov (United States)

    Outemzabet, R.; Doulache, M.; Trari, M.

    2015-05-01

    Sb-doped SnO2 thin films (Sb-SnO2) are prepared by chemical vapor deposition. The X-ray diffraction indicates a rutile phase, and the SEM analysis shows pyramidal grains whose size extends up to 200 nm. The variation of the film thickness shows that the elaboration technique needs to be optimized to give reproducible layers. The films are transparent over the visible region. The dispersion of the optical indices is evaluated by fitting the diffuse reflectance data with the Drude-Lorentz model. The refractive index ( n) and absorption coefficient ( k) depend on both the conditions of preparation and of the doping concentration and vary between 1.4 and 2.0 and 0.2 and 0.01, respectively. Tin oxide is nominally non-stoichiometric, and the conduction is dominated by thermally electrons jump with an electron mobility of 12 cm2 V-1 s-1 for Sb-SnO2 (1 %). The ( C 2- V) characteristic in aqueous electrolyte exhibits a linear behavior from which an electrons density of 4.15 × 1018 cm-3 and a flat-band potential of -0.83 V SCE are determined. The electrochemical impedance spectroscopy shows a semicircle attributed to a capacitive behavior with a low density of surface states. The center lies below the real axis with a depletion angle (12°), due to a constant phase element, i.e., a deviation from a pure capacitive behavior, presumably attributed to the roughness and porosity of the film. The straight line at low frequencies is attributed to the Warburg diffusion. The energy diagram reveals the photocatalytic feasibility of Sb-SnO2. As application, 90 % of the chromate concentration (20 mg L-1, pH ~3) disappears after 6 h of exposure to solar light.

  6. Characteristics of Mg-doped and In-Mg co-doped p-type GaN epitaxial layers grown by metal organic chemical vapour deposition

    International Nuclear Information System (INIS)

    Chung, S J; Lee, Y S; Suh, E-K; Senthil Kumar, M; An, M H

    2010-01-01

    Mg-doped and In-Mg co-doped p-type GaN epilayers were grown using the metal organic chemical vapour deposition technique. The effect of In co-doping on the physical properties of p-GaN layer was examined by high resolution x-ray diffraction (HRXRD), transmission electron microscopy (TEM), Hall effect, photoluminescence (PL) and persistent photoconductivity (PPC) at room temperature. An improved crystalline quality and a reduction in threading dislocation density are evidenced upon In doping in p-GaN from HRXRD and TEM images. Hole conductivity, mobility and carrier density also significantly improved by In co-doping. PL studies of the In-Mg co-doped sample revealed that the peak position is blue shifted to 3.2 eV from 2.95 eV of conventional p-GaN and the PL intensity is increased by about 25%. In addition, In co-doping significantly reduced the PPC effect in p-type GaN layers. The improved electrical and optical properties are believed to be associated with the active participation of isolated Mg impurities.

  7. Microstructure, Tensile Properties, and Corrosion Behavior of Die-Cast Mg-7Al-1Ca- xSn Alloys

    Science.gov (United States)

    Wang, Feng; Dong, Haikuo; Sun, Shijie; Wang, Zhi; Mao, Pingli; Liu, Zheng

    2018-02-01

    The microstructure, tensile properties, and corrosion behavior of die-cast Mg-7Al-1Ca- xSn ( x = 0, 0.5, 1.0, and 2.0 wt.%) alloys were studied using OM, SEM/EDS, tensile test, weight loss test, and electrochemical test. The experimental results showed that Sn addition effectively refined grains and intermetallic phases and increased the amount of intermetallic phases. Meanwhile, Sn addition to the alloys suppressed the formation of the (Mg,Al)2Ca phase and resulted in the formation of the ternary CaMgSn phase and the binary Mg2Sn phase. The Mg-7Al-1Ca-0.5Sn alloy exhibited best tensile properties at room temperature, while Mg-7Al-1Ca-1.0Sn alloy exhibited best tensile properties at elevated temperature. The corrosion resistance of studied alloys was improved by the Sn addition, and the Mg-7Al-1Ca-0.5Sn alloy presented the best corrosion resistance.

  8. Electrical and optical characteristics of ITO films by pulsed laser deposition using a 10 wt.% SnO2-doped In2O3 ceramic target

    International Nuclear Information System (INIS)

    Kim, Sang Hyeob; Park, Nae-Man; Kim, TaeYoub; Sung, GunYong

    2005-01-01

    We have investigated the effect of the oxygen pressure and the deposition temperature on the electrical and optical properties of the Sn-doped indium oxide (ITO) films on quartz glass substrate by pulsed laser deposition (PLD) using a 10 wt.% SnO 2 -doped In 2 O 3 target. The resistivity and the carrier concentration of the films were decreased due to the decrease of the oxygen vacancy while increasing the oxygen pressure. With increasing deposition temperature, the resistivity of the films was decreased and the carrier concentration was increased due to the grain growth and the enhancement of the Sn diffusion. We have optimized the PLD process to deposit a highly conductive and transparent ITO film, which shows the optical transmittance of 88% and the resistivity of 2.49x10 -4 Ω cm for the film thickness of 180 nm

  9. Influence of Mg{sup 2+} doping on the structure and electrochemical performances of layered LiNi{sub 0.6}Co{sub 0.2-x}Mn{sub 0.2}Mg{sub x}O{sub 2} cathode materials

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenjun; Wang, Zhixing, E-mail: zxwang.csu@hotmail.com; Guo, Huajun; Li, Xinhai

    2016-06-25

    Introducing the Mg ion into host lattice is applied to improving the electrochemical performance of LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2}. The effect of Mg substitution for Co on the structure, morphology, electrochemical properties and Li{sup +} diffusion coefficients are investigated in details. Rietveld refinement results reveal that Mg is incorporated into the bulk lattice, which results in reduced cation mixing and expand c-lattice parameter. All Mg-doped sample exhibit better cycle and rate performances, although the Mg substitution for Co led to decreasing a part of capacity. The Li diffusion coefficients obtained by galvanostatic intermittent titration technique (GITT) are increased with increases of Mg content. - Highlights: • Mg-doped sample exhibits better electrochemical performance. • The change of crystal structure by Mg doping are studied. • The Mg doping improves the lithium ion diffusion coefficient.

  10. CO{sub 2} capture in Mg oxides doped with Fe and Ni; Captura de CO{sub 2} en oxidos de Mg dopados con Fe y Ni

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez S, I. F.

    2016-07-01

    In this work the CO{sub 2} capture-desorption characteristics in Mg oxides doped with Fe and Ni obtained by the direct oxidation of Mg-Ni and Mg-Fe mixtures are presented. Mixtures of Mg-Ni and Mg-Fe in a different composition were obtained by mechanical milling in a Spex-type mill in a controlled atmosphere of ultra high purity argon at a weight / weight ratio of 4:1 powder using methanol as a lubricating agent, for 20 h. The powders obtained by mechanical milling showed as main phase, the Mg with nanocrystalline structure. Subsequently, the mixtures of Mg-Ni and Mg-Fe were oxidized within a muffle for 10 min at 600 degrees Celsius. By means of X-ray diffraction analysis, the Mg O with nano metric grain size was identified as the main phase, which was determined by the Scherrer equation. In the Mg O doped with Ni, was identified that as the Ni amount 1 to 5% by weight dispersed in the Mg O matrix was increased, the main peak intensity of the Ni phase increased, whereas in the Mg O doped with Fe was observed by XRD, that the Fe{sub 2}O{sub 3} phase was present and by increasing the amount of Fe (1 to 5% by weight) dispersed in the crystalline phase of Mg O, the intensity of this impurity also increased. Sem-EDS analysis showed that the Ni and Fe particles are dispersed homogeneously in the Mg O matrix, and the particles are porous, forming agglomerates. Through energy dispersive spectroscopy analysis, the elemental chemical composition obtained is very close to the theoretical composition. The capture of CO{sub 2} in the Mg O-1% Ni was carried out in a Parr reactor at different conditions of pressure, temperature and reaction time. Was determined that under the pressure of 0.2 MPa at 26 degrees Celsius for 1 h of reaction, the highest CO{sub 2} capture of 7.04% by weight was obtained, while in Mg O-1% Fe the CO{sub 2} capture was 6.32% by weight. The other magnesium oxides doped in 2.5 and 5% by weight Ni and Fe showed lower CO{sub 2} capture. The different stages

  11. Intermodulation distortion and surface resistance in impurity-doped YBCO and MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Agassi, Y.D. [Naval Surface Warfare Center, Carderock Division, Bethesda, MD 20817 (United States); Oates, D.E., E-mail: oates@ll.mit.edu [MIT-Lincoln Laboratory, Lexington, MA 02420 (United States)

    2014-11-15

    Highlights: • Calculations of impurity-doping effects on surface resistance and intermodulation distortion. • The calculations are compared with previously published measurements in YBCO and MgB{sub 2}. • Excellent agreement between calculations and experiments are shown. • The effects of the symmetry of the energy gap are presented and discussed. - Abstract: Calculations of the microwave intermodulation distortion (IMD) and surface resistance of impurity-doped YBCO, MgB{sub 2} and Nb are presented. These are qualitatively distinct superconductors due to their energy-gap symmetries, d-wave (ℓ = 2), i-wave (ℓ = 6) and s-wave (ℓ = 0), respectively. The calculations are compared with previously published IMD and surface-resistance measurements of impurity-doped YBCO and Nb. The agreement between the data and fitted calculations is excellent in all cases. In the absence of IMD and surface-resistance measurements for doped MgB{sub 2}, we present representative predictions. The calculations are based on a Green’s-function approach that yields analytical expressions for the penetration depth and the nonlinear kernel in the constitutive relation. This penetration-depth expression reproduces the measured T{sup 2} low-temperature variation for doped superconductors and the surface-resistance reduction over that of the pure material. Regarding the IMD in superconductors with a nodal energy gap, the effect of doping is to enhance its magnitude and suppress its low-temperature 1/T{sup 2} divergence predicted by the nonlinear Meissner effect.

  12. Next Generation, Si-Compatible Materials and Devices in the Si-Ge-Sn System

    Science.gov (United States)

    2015-10-09

    and conclusions The work initially focused on growth of next generation Ge1-ySny alloys on Ge buffered Si wafers via UHV CVD depositions of Ge3H8...Abstract The work initially focused on growth of next generation Ge1-ySny alloys on Ge buffered Si wafers via UHV CVD depositions of Ge3H8, SnD4. The...AFRL-AFOSR-VA-TR-2016-0044 Next generation, Si -compatible materials and devices in the Si - Ge -Sn system John Kouvetakis ARIZONA STATE UNIVERSITY Final

  13. Electron paramagnetic resonance and Raman spectroscopy studies on carbon-doped MgB2 superconductor nanomaterials

    International Nuclear Information System (INIS)

    Bateni, Ali; Somer, Mehmet; Erdem, Emre; Repp, Sergej; Weber, Stefan; Acar, Selcuk; Kokal, Ilkin; Häßler, Wolfgang

    2015-01-01

    Undoped and carbon-doped magnesium diboride (MgB 2 ) samples were synthesized using two sets of mixtures prepared from the precursors, amorphous nanoboron, and as-received amorphous carbon-doped nanoboron. The microscopic defect structures of carbon-doped MgB 2 samples were systematically investigated using X-ray powder diffraction, Raman and electron paramagnetic resonance spectroscopy. Mg vacancies and C-related dangling-bond active centers could be distinguished, and sp 3 -hybridized carbon radicals were detected. A strong reduction in the critical temperature T c was observed due to defects and crystal distortion. The symmetry effect of the latter is also reflected on the vibrational modes in the Raman spectra

  14. N{sub 2}O + SO{sub 2} reaction over Si- and C-doped boron nitride nanotubes: A comparative DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Esrafili, Mehdi D., E-mail: esrafili@maragheh.ac.ir; Saeidi, Nasibeh

    2017-05-01

    Highlights: • The mechanisms of N{sub 2}O + SO{sub 2} reaction are investigated over Si- and C-doped BNNTs. • Both Si- and C-doped BNNTs can be used as an efficient catalyst for the N{sub 2}O + SO{sub 2} reaction. • The 2N{sub 2}O → O{sub 2} + N{sub 2} reaction needs a large activation energy over both surfaces. - Abstract: Density functional theory calculations are performed to investigate the mechanisms of N{sub 2}O reduction by SO{sub 2} over Si- and C-doped (6,0) boron nitride nanotubes (BNNTs). According to our results, the Si or C adatom can be strongly stabilized over the vacancy defect of the BNNT. The adsorption energy of Si and C atoms over defective BNNT is calculated to be −297.3 and −333.7 kcal/mol, respectively, indicating a strong interaction between these dopant atoms and the tube surface. The N{sub 2}O reduction reaction includes the decomposition of N{sub 2}O (i.e. N{sub 2}O → N{sub 2} + O*), followed by the reduction of O* by SO{sub 2} molecule (i.e. SO{sub 2} + O* → SO{sub 3}). The calculated energy barrier of the SO{sub 2} + O* → SO{sub 3} reaction on Si- and C-doped BNNTs is 2.4 and 5.4 kcal/mol, respectively. Moreover, the effects of tube diameter and length on the N{sub 2}O reduction are studied in detail. The disproportionation of N{sub 2}O molecules (2N{sub 2}O → 2N{sub 2} + O{sub 2}) over both surfaces needs a quite large activation energy, which indicates the impossibility of this reaction at ambient condition. The results show that both Si- and C-doped BNNTs can be viewed as an effective green catalyst for the reduction of N{sub 2}O.

  15. Effects of glucose doping on the MgB{sub 2} superconductors using cheap crystalline boron

    Energy Technology Data Exchange (ETDEWEB)

    Parakkandy, Jafar Meethale [Department of Physics and Astronomy, College of Science, PO Box 2455, King Saud University, Riyadh 11451,Saudi Arabia (Saudi Arabia); Shahabuddin, Mohammed, E-mail: mshahab@ksu.edu.sa [Department of Physics and Astronomy, College of Science, PO Box 2455, King Saud University, Riyadh 11451,Saudi Arabia (Saudi Arabia); Shah, M. Shahabuddin; Alzayed, Nasser S.; Qaid, Salem A.S.; Madhar, Niyaz Ahmad; Ramay, Shahid M. [Department of Physics and Astronomy, College of Science, PO Box 2455, King Saud University, Riyadh 11451,Saudi Arabia (Saudi Arabia); Shar, Muhammad Ali [Mechanical Engineering Department, College of Engineering, P.O. Box 800, King Saud University, Riyadh 11421 (Saudi Arabia)

    2015-12-15

    Highlights: • First report on glucose doped MgB{sub 2} superconductor by single step dry mixing approach. • Cheap crystalline boron used for the sample preparation. • Microstructure and superconducting properties of the superconductors are discussed. • Less degradation in low field critical current density observed. • MgB{sub 2} with 2 at. % glucose doped showed the highest J{sub c}, ≈ 2 × 10{sup 4}A/cm{sup 2} for 20 K at 3 T. - Abstract: We report the effect of glucose (C{sub 6}H{sub 12}O{sub 6}) doping on the structural and electromagnetic properties of MgB{sub 2} superconductor fabricated by dry mixing using planetary ball milling. Herein, as-prepared bulk polycrystalline Mg (B{sub 1–x}C{sub x}) {sub 2} samples with different doping levels (x = 0, 2, 4, and 6 at. %) were systematically studied by X-ray diffraction, magnetic and resistivity measurements, and microstructure analysis. When carbon doped, the reduction in critical transition temperature and shrinkage in a-lattice were obviously observed. This resulted in structural distortion of the MgB{sub 2} lattice, and thereby, enhanced an impurity scattering. In addition to these, upper critical field and high-field critical current densities were also enhanced. On the other hand, both pinning force and low-field critical current density are decreased. The high field enhancement and low field degradation are due to increase in impurity scattering and decrease in pinning force respectively.

  16. A simple method to deposit palladium doped SnO2 thin films using plasma enhanced chemical vapor deposition technique

    International Nuclear Information System (INIS)

    Kim, Young Soon; Wahab, Rizwan; Shin, Hyung-Shik; Ansari, S. G.; Ansari, Z. A.

    2010-01-01

    This work presents a simple method to deposit palladium doped tin oxide (SnO 2 ) thin films using modified plasma enhanced chemical vapor deposition as a function of deposition temperature at a radio frequency plasma power of 150 W. Stannic chloride (SnCl 4 ) was used as precursor and oxygen (O 2 , 100 SCCM) (SCCM denotes cubic centimeter per minute at STP) as reactant gas. Palladium hexafluroacetyleacetonate (Pd(C 5 HF 6 O 2 ) 2 ) was used as a precursor for palladium. Fine granular morphology was observed with tetragonal rutile structure. A peak related to Pd 2 Sn is observed, whose intensity increases slightly with deposition temperature. Electrical resistivity value decreased from 8.6 to 0.9 mΩ cm as a function of deposition temperature from 400 to 600 deg. C. Photoelectron peaks related to Sn 3d, Sn 3p3, Sn 4d, O 1s, and C 1s were detected with varying intensities as a function of deposition temperature.

  17. A new Ti-Zr-Hf-Cu-Ni-Si-Sn bulk amorphous alloy with high glass-forming ability

    International Nuclear Information System (INIS)

    Huang, Y.J.; Shen, J.; Sun, J.F.; Yu, X.B.

    2007-01-01

    The effect of Sn substitution for Cu on the glass-forming ability was investigated in Ti 41.5 Zr 2.5 Hf 5 Cu 42.5-x Ni 7.5 Si 1 Sn x (x = 0, 1, 3, 5, 7) alloys by using differential scanning calorimetry (DSC) and X-ray diffractometry. The alloy containing 5% Sn shows the highest glass-forming ability (GFA) among the Ti-Zr-Hf-Cu-Ni-Si-Sn system. Fully amorphous rod sample with diameters up to 6 mm could be successfully fabricated by the copper mold casting Ti 41.5 Zr 2.5 Hf 5 Cu 37.5 Ni 7.5 Si 1 Sn 5 alloy. The activation energies for glass transition and crystallization for Ti 41.5 Zr 2.5 Hf 5 Cu 37.5 Ni 7.5 Si 1 Sn 5 amorphous alloy are both larger than those values for the Sn-free alloy. The enhancement in GFA and thermal stability after the partial replacement of Cu by Sn may be contributed to the strong atomic bonding nature between Ti and Sn and the increasing of atomic packing density. The amorphous Ti 41.5 Zr 2.5 Hf 5 Cu 37.5 Ni 7.5 Si 1 Sn 5 alloy also possesses superior mechanical properties

  18. Effect of both deposition temperature and indium doping on the properties of sol-gel dip-coated SnO2 films.

    Science.gov (United States)

    Caglar, Mujdat; Atar, Kadir Cemil

    2012-10-01

    Using indium chloride as an In source, In-doped SnO(2) films were fabricated by sol-gel method through dip-coating on borofloat glass substrates. The undoped SnO(2) films were deposited in air between 400 and 600 °C to get optimum deposition temperature in terms of crystal quality and hence In-doped SnO(2) films were deposited in air at 600 °C. The effect of both deposition temperature and In content on structural, morphological, optical and electrical properties was investigated. The crystalline structure and orientation of the films were investigated by X-ray diffraction (XRD) and surface morphology was studied by a field emission scanning electron microscope (FESEM). The compositional analysis of the films was confirmed by energy dispersive X-ray spectrometer (EDS). The absorption band edge of the SnO(2) films shifted from 3.88 to 3.66 eV with In content. The van der Pauw method was used to measure the sheet resistance of the films. The sheet resistance was affected significantly by deposition temperature and In content. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Hybrid of Co(3)Sn(2)@Co nanoparticles and nitrogen-doped graphene as a lithium ion battery anode.

    Science.gov (United States)

    Mahmood, Nasir; Zhang, Chenzhen; Liu, Fei; Zhu, Jinghan; Hou, Yanglong

    2013-11-26

    A facile strategy was designed for the fabrication of hybrid of Co3Sn2@Co nanoparticles (NPs) and nitrogen-doped graphene (NG) sheets through a hydrothermal synthesis, followed by annealing process. Core-shell architecture of Co3Sn2@Co pin on NG is designed for the dual encapsulation of Co3Sn2 with adaptable ensembles of Co and NG to address the structural and interfacial stability concerns facing tin-based anodes. In the resulted unique architecture of Co3Sn2@Co-NG hybrid, the sealed cobalt cover prevents the direct exposer of Sn with electrolyte because of encapsulated structure and keeps the structural and interfacial integrity of Co3Sn2. However, the elastically strong, flexible and conductive NG overcoat accommodates the volume changes and therefore brings the structural and electrical stabilization of Co3Sn2@Co NPs. As a result, Co3Sn2@Co-NG hybrid exhibits extraordinary reversible capacity of 1615 mAh/g at 250 mA/g after 100 cycles with excellent capacity retention of 102%. The hybrid bears superior rate capability with reversible capacity of 793.9 mAh/g at 2500 mA/g and Coulombic efficiency nearly 100%.

  20. Intraband scattering studies in carbon- and aluminium-doped MgB2

    International Nuclear Information System (INIS)

    Samuely, P.; Szabo, P.; Hol'anova, Z.; Bud'ko, S.; Canfield, P.

    2006-01-01

    Magnetic field effect on the point-contact spectra of the Al- and C-substituted MgB 2 is presented. It is shown that suppression of the π-band contribution to the spectrum is different in the aluminium- and carbon-doped samples. The carbon substitution leads to a stronger enhancement of the π-band scattering while the Al-doping does not change the ratio between the π and σ scatterings

  1. Fabrication of textured SnO2 transparent conductive films using self-assembled Sn nanospheres

    Science.gov (United States)

    Fukumoto, Michitaka; Nakao, Shoichiro; Hirose, Yasushi; Hasegawa, Tetsuya

    2018-06-01

    We present a novel method to fabricate textured surfaces on transparent conductive SnO2 films by processing substrates through a bottom-up technique with potential for industrially scalable production. The substrate processing consists of three steps: deposition of precursor Sn films on glass substrates, formation of a self-assembled Sn nanosphere layer with reductive annealing, and conversion of Sn to SnO2 by oxidative annealing. Ta-doped SnO2 films conformally deposited on the self-assembled nanospherical SnO2 templates exhibited attractive optical and electrical properties, namely, enhanced haze values and low sheet resistances, for applications as transparent electrodes in photovoltaics.

  2. Progress in doping of ruthenium silicide (Ru2Si3)

    International Nuclear Information System (INIS)

    Vining, C.B.; Allevato, C.E.

    1992-01-01

    This paper reports that ruthenium silicide (Ru 2 Si 3 ) is currently under development as a promising thermoelectric material suitable for space power applications. Key to realizing the potentially high figure of merit values of this material is the development of appropriate doping techniques. In this study, manganese and iridium have been identified as useful p- and n-type dopants, respectively. Resistivity values have been reduced by more than 3 orders of magnitude. Anomalous Hall effect results, however, complicate interpretation of some of the results and further effort is required to achieve optimum doping levels

  3. Electrochemical synthesis of nanostructured Se-doped SnS: Effect of Se-dopant on surface characterizations

    Science.gov (United States)

    Kafashan, Hosein; Azizieh, Mahdi; Balak, Zohre

    2017-07-01

    SnS1-xSex nanostructures with different Se-dopant concentrations were deposited on fluorine doped tin oxide (FTO) substrate through cathodic electrodeposition technique. The pH, temperature, applied potential (E), and deposition time remained were 2.1, 60 °C, -1 V, and 30 min, respectively. SnS1-xSex nanostructures were characterized using X-ray diffraction (XRD), field emission scanning electron microcopy (FESEM), energy dispersive X-ray spectroscopy (EDX), room temperature photoluminescence (PL), and UV-vis spectroscopy. The XRD patterns revealed that the SnS1-xSex nanostructures were polycrystalline with orthorhombic structure. FESEM showed various kinds of morphologies in SnS1-xSex nanostructures due to Se-doping. PL and UV-vis spectroscopy were used to evaluate the optical properties of SnS1-xSex thin films. The PL spectra of SnS1-xSex nanostructures displayed four emission peaks, those are a blue, a green, an orange, and a red emission. UV-vis spectra showed that the optical band gap energy (Eg) of SnS1-xSex nanostructures varied between 1.22-1.65 eV, due to Se-doping.

  4. The electrical, optical, structural and thermoelectrical characterization of n- and p-type cobalt-doped SnO2 transparent semiconducting films prepared by spray pyrolysis technique

    International Nuclear Information System (INIS)

    Bagheri-Mohagheghi, Mohammad-Mehdi; Shokooh-Saremi, Mehrdad

    2010-01-01

    The electrical, optical and structural properties of Cobalt (Co) doped SnO 2 transparent semiconducting thin films, deposited by the spray pyrolysis technique, have been studied. The SnO 2 :Co films, with different Co-content, were deposited on glass substrates using an aqueous-ethanol solution consisting of tin and cobalt chlorides. X-ray diffraction studies showed that the SnO 2 :Co films were polycrystalline only with tin oxide phases and preferential orientations along (1 1 0) and (2 1 1) planes and grain sizes in the range 19-82 nm. Optical transmittance spectra of the films showed high transparency ∼75-90% in the visible region, decreasing with increase in Co-doping. The optical absorption edge for undoped SnO 2 films was found to be 3.76 eV, while for higher Co-doped films shifted toward higher energies (shorter wavelengths) in the range 3.76-4.04 eV and then slowly decreased again to 4.03 eV. A change in sign of the Hall voltage and Seebeck coefficient was observed for a specific acceptor dopant level ∼11.4 at% in film and interpreted as a conversion from n-type to p-type conductivity. The thermoelectric electro-motive force (e.m.f.) of the films was measured in the temperature range 300-500 K and Seebeck coefficients were found in the range from -62 to +499 μVK -1 for various Co-doped SnO 2 films.

  5. The electrical, optical, structural and thermoelectrical characterization of n- and p-type cobalt-doped SnO 2 transparent semiconducting films prepared by spray pyrolysis technique

    Science.gov (United States)

    Bagheri-Mohagheghi, Mohammad-Mehdi; Shokooh-Saremi, Mehrdad

    2010-10-01

    The electrical, optical and structural properties of Cobalt (Co) doped SnO 2 transparent semiconducting thin films, deposited by the spray pyrolysis technique, have been studied. The SnO 2:Co films, with different Co-content, were deposited on glass substrates using an aqueous-ethanol solution consisting of tin and cobalt chlorides. X-ray diffraction studies showed that the SnO 2:Co films were polycrystalline only with tin oxide phases and preferential orientations along (1 1 0) and (2 1 1) planes and grain sizes in the range 19-82 nm. Optical transmittance spectra of the films showed high transparency ∼75-90% in the visible region, decreasing with increase in Co-doping. The optical absorption edge for undoped SnO 2 films was found to be 3.76 eV, while for higher Co-doped films shifted toward higher energies (shorter wavelengths) in the range 3.76-4.04 eV and then slowly decreased again to 4.03 eV. A change in sign of the Hall voltage and Seebeck coefficient was observed for a specific acceptor dopant level ∼11.4 at% in film and interpreted as a conversion from n-type to p-type conductivity. The thermoelectric electro-motive force (e.m.f.) of the films was measured in the temperature range 300-500 K and Seebeck coefficients were found in the range from -62 to +499 μVK -1 for various Co-doped SnO 2 films.

  6. Synthesis and superconductivity of In-doped SnTe nanostructures

    Directory of Open Access Journals (Sweden)

    Piranavan Kumaravadivel

    2017-07-01

    Full Text Available InxSn1−xTe is a time-reversal invariant candidate 3D topological superconductor derived from doping the topological crystalline insulator SnTe with indium. The ability to synthesize low-dimensional nanostructures of indium-doped SnTe is key for realizing the promise they hold in future spintronic and quantum information processing applications. But hitherto only bulk synthesized crystals and nanoplates have been used to study the superconducting properties. Here for the first time we synthesize InxSn1−xTe nanostructures including nanowires and nanoribbons, which show superconducting transitions. In some of the lower dimensional morphologies, we observe signs of more than one superconducting transition and the absence of complete superconductivity. We propose that material inhomogeneity, such as indium inhomogeneity and possible impurities from the metal catalyst, is amplified in the transport characteristics of the smaller nanostructures and is responsible for this mixed behavior. Our work represents the first demonstration of InxSn1−xTe nanowires with the onset of superconductivity, and points to the need for improving the material quality for future applications.

  7. Electrical conductivity of cobalt doped La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ

    Science.gov (United States)

    Wang, Shizhong; Wu, Lingli; Liang, Ying

    La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10 -5 atm) and low oxygen partial pressure regions (lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number.

  8. Preparation of Aligned ZnO Nanorod Arrays on Sn-Doped ZnO Thin Films by Sonicated Sol-Gel Immersion Fabricated for Dye-Sensitized Solar Cell

    Directory of Open Access Journals (Sweden)

    I. Saurdi

    2014-01-01

    Full Text Available Aligned ZnO Nanorod arrays are deposited on the Sn-doped ZnO thin film via sonicated sol-gel immersion method. The structural, optical, and electrical properties of the Sn-doped ZnO thin films were investigated. Results show that the Sn-doped ZnO thin films with small grain size (~20 nm, high average transmittance (96% in visible region, and good resistivity 7.7 × 102 Ω·cm are obtained for 2 at.% Sn doping concentration. The aligned ZnO nanorod arrays with large surface area were also obtained for 2 at.% Sn-doped ZnO thin film. They were grown on sol-gel derived Sn-doped ZnO thin film, which acts as a seed layer, via sonicated sol-gel immersion method. The grown aligned ZnO nanorod arrays show high transmittance at visible region. The fabricated dye-sensitised solar cell based on the 2.0 at.% Sn-doped ZnO thin film with aligned ZnO nanorod arrays exhibits improved current density, open-circuit voltage, fill factor, and conversion efficiency compared with the undoped ZnO and 1 at.% Sn-doped ZnO thin films.

  9. Electrical conductivity of cobalt doped La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shizhong; Wu, Lingli; Liang, Ying [Department of Chemistry, Xiamen University, Xiamen 361005, Fujian (China)

    2007-03-30

    La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM8282), La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3-{delta}} (LSGMC5) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.115}Co{sub 0.085}O{sub 3-{delta}} (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10{sup -5} atm) and low oxygen partial pressure regions (<10{sup -15} atm). However, the electrical conductivity in LSGM8282 had no dependency on the oxygen partial pressure. At temperatures higher than 1073 K, P{sub O{sub 2}} dependencies of the free electron conductivities in LSGM8282, LSGMC5 and LSGMC8.5 were about -1/4, and P{sub O{sub 2}} dependencies of the electron hole conductivities were about 0.25, 0.12 and 0.07, respectively. Oxygen ion conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high and low oxygen partial pressure regions, which was due to the increase in the concentration of oxygen vacancies. The change in the concentration of oxygen vacancies and the valence of cobalt with oxygen partial pressure were determined using a thermo-gravimetric technique. Both the electronic conductivity and oxygen ion conductivity in cobalt doped lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number. (author)

  10. SiSn diodes: Theoretical analysis and experimental verification

    KAUST Repository

    Hussain, Aftab M.; Wehbe, Nimer; Hussain, Muhammad Mustafa

    2015-01-01

    We report a theoretical analysis and experimental verification of change in band gap of silicon lattice due to the incorporation of tin (Sn). We formed SiSn ultra-thin film on the top surface of a 4 in. silicon wafer using thermal diffusion of Sn

  11. Synthesis of chelating agent free-solid phase extractor (CAF-SPE) based on new SiO2/Al2O3/SnO2 ternary oxide and application for online preconcentration of Pb2+ coupled with FAAS

    International Nuclear Information System (INIS)

    Tarley, César R.T.; Scheel, Guilherme L.; Zappielo, Caroline D.; Suquila, Fabio A.C.; Ribeiro, Emerson S.

    2018-01-01

    A new online solid phase preconcentration method using the new SiO 2 /Al2O 3 /SnO 2 ternary oxide (designated as SiAlSn) as chelating agent free-solid phase extractor (CAF-SPE) coupled to flame atomic absorption spectrometry (FAAS) for Pb 2+ determination at trace levels in different kind of samples is proposed. The solid adsorbent has been characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence spectroscopy (XRF) and textural data. The method involves the preconcentration using time-based sampling of Pb 2+ solution at pH 4.3 through 100.0 mg of packed adsorbed into a mini-column under flow rate of 4.0 mL min -1 during 5 min. The elution step was accomplished by using 1.0 mol L -1 HCl. A wide range of analytical curve (5.0-400.0 μg L -1 ), high enrichment factor (40.5), low consumption index (0.5 mL) and low limits of quantification and detection, 5.0 and 1.5 μg L -1 , respectively, were obtained with the developed method. Practical application of method was tested on water samples, chocolate powder, Ginkgo biloba and sediment (certified reference material). On the basis of the results, the SiAlSn can be considered an effective adsorbent belonging to the class of CAF-SPE for Pb 2+ determination from different matrices. (author)

  12. Effects of rapid thermal annealing on structural, chemical, and electrical characteristics of atomic-layer deposited lanthanum doped zirconium dioxide thin film on 4H-SiC substrate

    International Nuclear Information System (INIS)

    Lim, Way Foong; Quah, Hock Jin; Lu, Qifeng; Mu, Yifei; Ismail, Wan Azli Wan; Rahim, Bazura Abdul; Esa, Siti Rahmah; Kee, Yeh Yee; Zhao, Ce Zhou

    2016-01-01

    Graphical abstract: - Highlights: • Studies of RTA temperatures on La doped ZrO2 atomic layer deposited on 4HSiC. • Oxygen vacancies improved insulating and catalytic properties of La doped ZrO2. • 700 °C annealed sample showed the highest EB, k value, and sensitivity on O2. • La doped ZrO2 was proposed as a potential metal reactive oxide on 4H-SiC. - Abstract: Effects of rapid thermal annealing at different temperatures (700–900 °C) on structural, chemical, and electrical characteristics of lanthanum (La) doped zirconium oxide (ZrO_2) atomic layer deposited on 4H-SiC substrates have been investigated. Chemical composition depth profiling analysis using X-ray photoelectron spectroscopy (XPS) and cross-sectional studies using high resolution transmission electron microscopy equipped with energy dispersive X-ray spectroscopy line scan analysis were insufficient to justify the presence of La in the investigated samples. The minute amount of La present in the bulk oxide was confirmed by chemical depth profiles of time-of-flight secondary ion mass spectrometry. The presence of La in the ZrO_2 lattice led to the formation of oxygen vacancies, which was revealed through binding energy shift for XPS O 1s core level spectra of Zr−O. The highest amount of oxygen vacancies in the sample annealed at 700 °C has yielded the acquisition of the highest electric breakdown field (∼ 6.3 MV/cm) and dielectric constant value (k = 23) as well as the highest current–time (I–t) sensor response towards oxygen gas. The attainment of both the insulating and catalytic properties in the La doped ZrO_2 signified the potential of the doped ZrO_2 as a metal reactive oxide on 4H-SiC substrate.

  13. Critical thickness of transition from 2D to 3D growth and peculiarities of quantum dots formation in GexSi1-x/Sn/Si and Ge1-ySny/Si systems

    Science.gov (United States)

    Lozovoy, Kirill A.; Kokhanenko, Andrey P.; Voitsekhovskii, Alexander V.

    2018-03-01

    Nowadays using of tin as one of the deposited materials in GeSi/Sn/Si, GeSn/Si and GeSiSn/Si material systems is one of the most topical problems. These materials are very promising for various applications in nanoelectronics and optoelectronics due to possibility of band gap management and synthesis of direct band semiconductors within these systems. However, there is a lack of theoretical investigations devoted to the peculiarities of germanium on silicon growth in the presence of tin. In this paper a new theoretical approach for modeling growth processes of binary and ternary semiconductor compounds during the molecular beam epitaxy in these systems is presented. The established kinetic model based on the general nucleation theory takes into account the change in physical and mechanical parameters, diffusion coefficient and surface energies in the presence of tin. With the help of the developed model the experimentally observed significant decrease in the 2D-3D transition temperatures for GeSiSn/Si system compared to GeSi/Si system is theoretically explained for the first time in the literature. Besides that, the derived expressions allow one to explain the experimentally observed temperature dependencies of the critical thickness, as well as to predict the average size and surface density of quantum dots for different contents and temperatures in growth experiment, that confirms applicability of the model proposed. Moreover, the established model can be easily applied to other material systems in which the Stranski-Krastanow growth mode occurs.

  14. Effects of alloy composition and Si-doping on vacancy defect formation in (InxGa1-x)2O3 thin films

    Science.gov (United States)

    Prozheeva, V.; Hölldobler, R.; von Wenckstern, H.; Grundmann, M.; Tuomisto, F.

    2018-03-01

    Various nominally undoped and Si-doped (InxGa1-x)2O3 thin films were grown by pulsed laser deposition in a continuous composition spread mode on c-plane α-sapphire and (100)-oriented MgO substrates. Positron annihilation spectroscopy in the Doppler broadening mode was used as the primary characterisation technique in order to investigate the effect of alloy composition and dopant atoms on the formation of vacancy-type defects. In the undoped samples, we observe a Ga2O3-like trend for low indium concentrations changing to In2O3-like behaviour along with the increase in the indium fraction. Increasing indium concentration is found to suppress defect formation in the undoped samples at [In] > 70 at. %. Si doping leads to positron saturation trapping in VIn-like defects, suggesting a vacancy concentration of at least mid-1018 cm-3 independent of the indium content.

  15. PROPERTIES OF Eu3+ LUMINESCENCE IN THE MONOCLINIC Ba2MgSi2O7

    Directory of Open Access Journals (Sweden)

    Shansh an Yao

    2011-09-01

    Full Text Available Red-emitting phosphors Ba2-xMgSi2O7: Eux3+ was prepared by combustion-assisted synthesis method and an efficient red emission under near-ultraviolet (UV was observed. The luminescence and crystallinity were investigated using luminescence spectrometry and X-ray diffractometer. The emission spectrum shows that the most intense peak is located at 614 nm, which corresponds to the 5D0 → 7F2 transitions of Eu3+. The phosphor has two main excitation peaks located at 394 and 465 nm, which match the emission of UV and blue light-emitting diodes, respectively. The effect of Eu3+ concentration on the emission spectrum of Ba2MgSi2O7:Eu3+ phosphor was studied. The results showed that the emission intensity increased with increasing Eu3+ concentration, and then decreased because of concentration quenching. The critical quenching concentration of Eu3+ in Ba2MgSi2O7: Eu3+ phosphor is about 0.05 mol. The mechanism of concentration quenching of Ba2MgSi2O7: Eu3+ luminescence is energy transfer between Eu3+ ions casued by the dipole-dipole interaction.

  16. Effects of substrate temperature on structural and electrical properties of SiO2-matrix boron-doped silicon nanocrystal thin films

    International Nuclear Information System (INIS)

    Huang, Junjun; Zeng, Yuheng; Tan, Ruiqin; Wang, Weiyan; Yang, Ye; Dai, Ning; Song, Weijie

    2013-01-01

    In this work, silicon-rich SiO 2 (SRSO) thin films were deposited at different substrate temperatures (T s ) and then annealed by rapid thermal annealing to form SiO 2 -matrix boron-doped silicon-nanocrystals (Si-NCs). The effects of T s on the micro-structure and electrical properties of the SiO 2 -matrix boron-doped Si-NC thin films were investigated using Raman spectroscopy and Hall measurements. Results showed that the crystalline fraction and dark conductivity of the SiO 2 -matrix boron-doped Si-NC thin films both increased significantly when the T s was increased from room temperature to 373 K. When the T s was further increased from 373 K to 676 K, the crystalline fraction of 1373 K-annealed thin films decreased from 52.2% to 38.1%, and the dark conductivity reduced from 8 × 10 −3 S/cm to 5.5 × 10 −5 S/cm. The changes in micro-structure and dark conductivity of the SiO 2 -matrix boron-doped Si-NC thin films were most possibly due to the different amount of Si-O 4 bond in the as-deposited SRSO thin films. Our work indicated that there was an optimal T s , which could significantly increase the crystallization and conductivity of Si-NC thin films. Also, it was illumined that the low-resistivity SiO 2 -matrix boron-doped Si-NC thin films can be achieved under the optimal substrate temperatures, T s .

  17. Large lateral photovoltaic effect with ultrafast relaxation time in SnSe/Si junction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianjie; Zhao, Xiaofeng; Hu, Chang; Zhang, Yang; Song, Bingqian; Zhang, Lingli; Liu, Weilong; Lv, Zhe; Zhang, Yu; Sui, Yu, E-mail: suiyu@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Tang, Jinke [Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071 (United States); Song, Bo, E-mail: songbo@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150001 (China)

    2016-07-11

    In this paper, we report a large lateral photovoltaic effect (LPE) with ultrafast relaxation time in SnSe/p-Si junctions. The LPE shows a linear dependence on the position of the laser spot, and the position sensitivity is as high as 250 mV mm{sup −1}. The optical response time and the relaxation time of the LPE are about 100 ns and 2 μs, respectively. The current-voltage curve on the surface of the SnSe film indicates the formation of an inversion layer at the SnSe/p-Si interface. Our results clearly suggest that most of the excited-electrons diffuse laterally in the inversion layer at the SnSe/p-Si interface, which results in a large LPE with ultrafast relaxation time. The high positional sensitivity and ultrafast relaxation time of the LPE make the SnSe/p-Si junction a promising candidate for a wide range of optoelectronic applications.

  18. Stacking faults and phase changes in Mg-doped InGaN grown on Si

    International Nuclear Information System (INIS)

    Liliental-Weber, Zuzanna; Yu, Kin M.; Reichertz, Lothar A.; Ager, Joel W.; Walukiewicz, Wladek; Schaff, William J.; Hawkridge, Michael E.

    2009-01-01

    We report evidence for the role of Mg in the formation of basal stacking faults and a phase transition in In x Ga 1-x N layers doped with Mg grown by molecular beam epitaxy on Si(111) substrates with AlN buffer layers. Several samples with varying In content between x∝0.1 and x∝0.3 are examined by transmission electron microscopy and other techniques. High densities of basal stacking faults are observed in the central region of the InGaN layer away from the substrate or layer surface, but at varying depths within this region. Selected area diffraction patterns show that while the InGaN layer is initially in the wurtzite phase (and of good quality) AlN buffer layer, there is a change to the zinc blende phase in the upper part of the InGaN layer. SIMS measurements show that the Mg concentration drops from a maximum to a steady concentration coinciding with the presence of the basal stacking faults. There is little change in In or Ga concentrations in the same area. High-resolution electron microscopy from the area of the stacking faults confirms that the change to the cubic phase is abrupt across one such fault. These results indicate that Mg plays a role in the formation of stacking faults and the phase change observed in In x Ga 1-x N alloys. We also consider the role of In in the formation of these defects. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Synthesis and room-temperature ferromagnetic properties of single-crystalline Co-doped SnO2 nanocrystals via a high magnetic field

    International Nuclear Information System (INIS)

    Xu Yongbin; Tang Yongjun; Li Chuanjun; Cao Guanghui; Ren Weili; Xu Hui; Ren Zhongming

    2009-01-01

    The magnetic field-assisted approach has been used in the synthesis of Co-doped SnO 2 diluted magnetic semiconductor nanocrystals. By annealing under the condition with or without magnetic field, 1D growth of the nanostructures can be induced, and the magnetic properties of the obtained nanocrystals are improved. Various techniques such as X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible spectrometry (UV-vis), Raman spectrometry and vibrating sample magnetometer (VSM) have been used to characterize the obtained products. The results show that the magnetic field holds important effects on the crystal growth of the Co-doped SnO 2 nanostructures, and improvement of magnetic properties. The intrinsic reasons are discussed.

  20. Mg concentration profile and its control in the low temperature grown Mg-doped GaN epilayer

    Science.gov (United States)

    Liu, S. T.; Yang, J.; Zhao, D. G.; Jiang, D. S.; Liang, F.; Chen, P.; Zhu, J. J.; Liu, Z. S.; Liu, W.; Xing, Y.; Zhang, L. Q.; Wang, W. J.; Li, M.; Zhang, Y. T.; Du, G. T.

    2018-01-01

    In this work, the Cp2Mg flux and growth pressure influence to Mg doping concentration and depth profiles is studied. From the SIMS measurement we found that a transition layer exists at the bottom region of the layer in which the Mg doping concentration changes gradually. The thickness of transition layer decreases with the increases of Mg doping concentration. Through analysis, we found that this is caused by Ga memory effect which the Ga atoms stay residual in MOCVD system will react with Mg source, leading a transition layer formation and improve the growth rate. And the Ga memory effect can be well suppressed by increasing Mg doping concentration and growth pressure and thus get a steep Mg doping at the bottom region of p type layer.