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Sample records for nitrogen co-doped titania

  1. Visible-Light Photodegradation of Dye on Co-Doped Titania Nanotubes Prepared by Hydrothermal Synthesis

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    Jung-Pin Wang

    2012-01-01

    Full Text Available Highly porous Co-doped TiO2 nanotubes synthesized from a hydrothermal treatment were used to photodecompose methylene blue (MB in liquid phase under visible light irradiation. The anatase-type titania nanotubes were found to have high specific surface areas of about 289–379 m2/g. These tubes were shown to be hollow scrolls with outer diameter of about 10–15 nm and length of several micrometers. UV absorption confirmed that Co doping makes the light absorption of nanotubes shift to visible light region. With increasing the dopant concentration, the optical band gap of nanotubes became narrower, ranging from 2.4 eV to 1.8 eV, determined by Kubelka-Munk plot. The Co-doped nanotubes exhibit not only liquid-phase adsorption ability, but also visible-light-derived photodegradation of MB in aqueous solution. The synergetic effect involves two key factors in affecting the photocatalytic activity of Co-doped titania nanotubes under fluorescent lamp, that is, high porosity and optical band gap. The merit of the present work is to provide an efficient route for preparing Co-doped TiO2 nanotubes and to clarifying their adsorption and photocatalytic activity under fluorescent lamp.

  2. Nitrogen and Phosphorous Co-Doped Graphene Monolith for Supercapacitors.

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    Wen, Yangyang; Rufford, Thomas E; Hulicova-Jurcakova, Denisa; Wang, Lianzhou

    2016-03-08

    The co-doping of heteroatoms has been regarded as a promising approach to improve the energy-storage performance of graphene-based materials because of the synergetic effect of the heteroatom dopants. In this work, a single precursor melamine phosphate was used for the first time to synthesise nitrogen/phosphorus co-doped graphene (N/P-G) monoliths by a facile hydrothermal method. The nitrogen contents of 4.27-6.58 at% and phosphorus levels of 1.03-3.00 at% could be controlled by tuning the mass ratio of melamine phosphate to graphene oxide in the precursors. The N/P-G monoliths exhibited excellent electrochemical performances as electrodes for supercapacitors with a high specific capacitance of 183 F g(-1) at a current density of 0.05 A g(-1), good rate performance and excellent cycling performance. Additionally, the N/P-G electrode was stable at 1.6 V in 1 m H2 SO4 aqueous electrolyte and delivered a high energy density of 11.33 Wh kg(-1) at 1.6 V. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Sulfur and Nitrogen Co-Doped Graphene Electrodes for High-Performance Ionic Artificial Muscles.

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    Kotal, Moumita; Kim, Jaehwan; Kim, Kwang J; Oh, Il-Kwon

    2016-02-24

    Sulfur and nitrogen co-doped graphene electrodes for bioinspired ionic artificial muscles, which exhibit outstanding actuation performances (bending strain of 0.36%, 4.5 times higher than PSS electrodes, and 96% of initial strain after demonstration over 18 000 cycles), provide remarkable electro-chemo-mech anical properties: specific capacitance, electrical conductivity, and large surface area with mesoporosity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Hydrophilic Nitrogen and Sulfur Co-doped Molybdenum Carbide Nanosheets for Electrochemical Hydrogen Evolution.

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    Ang, Huixiang; Tan, Hui Teng; Luo, Zhi Min; Zhang, Yu; Guo, Yuan Yuan; Guo, Guilue; Zhang, Hua; Yan, Qingyu

    2015-12-16

    Nitrogen and sulfur dual-doped Mo2 C nanosheets provide low operating potential (-86 mV for driving 10 mA cm(-2) of current density). Co-doping of N and S heteroatoms can improve the wetting property of the Mo2C electrocatalyst in aqueous solution and induce synergistic effects via σ-donation and π-back donation with hydronium cation.

  5. Carbon Nitrogen Co-Doped P25: Parameter Study on Photodegradation of Reactive Red 4

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    Azami M. S.

    2016-01-01

    Full Text Available Photocatalytic degradation rate of reactive red 4 (RR4 using carbon coated nitrogen doped TiO2 (C N co-doped TiO2 in photocatalysis process is main goal on this research. The main operating the parameters such as effect of initial dye concentration, catalyst loading, aeration flow rate and initial pH on degradation of RR4 under 45 W fluorescent lamp was investigated. photocatalytic activity of RR4 dye decreased with increasing RR4 dye concentration. The optimum loading is around 0.04 g and optimum aeration rate is about 25 mL min-1 of C N co-doped TiO2. Effect of pH was conducted based on the optimum loading and conclude that the photocatalytic degradation of RR4 became faster at pH 2 - 7. For the future work, the modification of doping with others element like non-metal or metal with C N co-doped TiO2 can be enhanced toward the higher efficieny of photodegradation under visible light. Moreover, the immobilized technique can be used in future to overcome the difficulty of filtration on suspension.

  6. Ab initio simulations on N and S co-doped titania nanotubes for photocatalytic applications

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    Chesnokov, Andrei; Lisovski, Oleg; Bocharov, Dmitry; Piskunov, Sergei; Zhukovskii, Yuri F.; Wessel, Michael; Spohr, Eckhard

    2015-09-01

    In this paper we present the results of quantum chemical modeling for energetically stable anatase (001) TiO2 nanotubes, undoped, doped, and codoped with N{}{{O}} and S{}{{O}} atoms. We calculate the electronic structure of one-dimensional (1D) nanotubes and zero-dimensional (0D) atomic fragments cut out from these nanotubes, employing hybrid density functional theory with a partial incorporation of an exact, nonlocal Hartree-Fock exchange within the formalism of the linear combination of atomic orbitals, as implemented in both CRYSTAL and NWChem total energy codes. Structural optimization of 1D nanotubes has been performed using CRYSTAL09 code, while the cut-out 0D fragments have been modelled using the NWChem code. The electronic properties of the studied systems prove that the band structure of the pristine TiO2 nanotube can be substantially modified by introducing substitutional impurity defects. The N-doped nanotube creates a midgap state that largely has a nitrogen 2p character. The S-doped nanotube has a defect state that almost coincides with the top of the valence bond for the pristine material. For nanotubes codoped with both S and N, we observe a downward shift of the gap state of nitrogen relative to the purely N-doped state by about 0.3 eV. This results in a system with a filled gap state about 0.3 eV below the O2/H2O oxidation level, making it a very promising candidate for photocatalytic hydrogen generation under visible light, because due to the presence of sulfur, the bottom of the conduction band is only about 2.2 eV above the occupied midgap state, and also, clearly above the standard hydrogen electrode level.

  7. Visible light induced photodegradation of organic pollutants on nitrogen and fluorine co-doped TiO2 photocatalyst

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    WANG Zheng-peng; XU Jun; CAI Wei-min; ZHOU Bao-xue; HE Zheng-guang; CAI Chun-guang; HONG Xiao-ting

    2005-01-01

    The nitrogen and fluorine co-doped TiO2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetrabutyl titanate with ammonium fluoride. Nitrogen and fluorine co-doping causes the absorption edge of TiO2 to shift to a lower energy region.The photocatalytic activity of co-doped TiO2 with anatase phases was found to be 2.4 times higher than that of the commercial TiO2photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co-doped TiO2 powders only contain anatase phases even at 1000℃. Apparently, ammonium fluoride added retarded phase transformation of the TiO2 powders from anatase to rutile.The substitutional fluorine and interstitial nitrogen atoms in co-doped TiO2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO2 to shift to a lower energy region.

  8. Preparation of nitrogen and sulfur co-doped ordered mesoporous carbon for enhanced microwave absorption performance

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    Yuan, Xiaoyan; Xue, Xingkun; Ma, Hailong; Guo, Shouwu; Cheng, Laifei

    2017-09-01

    Ordered mesoporous carbon nanomaterials (OMCs) co-doped with homogeneous nitrogen and sulfur heteroatoms were prepared by nanocasting with the pyrrole oligomer catalyzed by sulfuric acid as a precursor and ordered mesoporous silica SBA-15 as a hard-template. By multi-technique approach utilization, it was demonstrated that the N and S co-doped OMCs possessed high ordered mesoporous structures, large surface areas and homogeneous distribution of heteroatoms. As a microwave absorber, the as-prepared materials exhibited a minimum reflection loss (RL) of -32.5 dB at the thickness of 2.5 mm and an absorption bandwidth of 3.2 GHz (RL < -10 dB) in X-band (8.2-12.4 GHz). The good microwave absorption performance was mainly originated from the high electrical conductivity induced by the high surface activity and special structures. And microwave energy can be effectively attenuated through multiple reflections and absorptions in complex conductive network. The design strategy in this work would contribute to the production of a lightweight absorber, presenting a strong absorbency and a wide bandwidth in microwave frequency.

  9. Ultrahigh volumetric capacitance and cyclic stability of fluorine and nitrogen co-doped carbon microspheres

    Science.gov (United States)

    Zhou, Junshuang; Lian, Jie; Hou, Li; Zhang, Junchuan; Gou, Huiyang; Xia, Meirong; Zhao, Yufeng; Strobel, Timothy A.; Tao, Lu; Gao, Faming

    2015-09-01

    Highly porous nanostructures with large surface areas are typically employed for electrical double-layer capacitors to improve gravimetric energy storage capacity; however, high surface area carbon-based electrodes result in poor volumetric capacitance because of the low packing density of porous materials. Here, we demonstrate ultrahigh volumetric capacitance of 521 F cm-3 in aqueous electrolytes for non-porous carbon microsphere electrodes co-doped with fluorine and nitrogen synthesized by low-temperature solvothermal route, rivaling expensive RuO2 or MnO2 pseudo-capacitors. The new electrodes also exhibit excellent cyclic stability without capacitance loss after 10,000 cycles in both acidic and basic electrolytes at a high charge current of 5 A g-1. This work provides a new approach for designing high-performance electrodes with exceptional volumetric capacitance with high mass loadings and charge rates for long-lived electrochemical energy storage systems.

  10. Preparation of nitrogen-doped titania and its photocatalytic activity

    Institute of Scientific and Technical Information of China (English)

    QIN Haoli; GU Guobang; LIU Song

    2007-01-01

    Yellowish nitrogen-doped titania was produced through sol-gel method in mild condition, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using XRD, BET, TEM, XPS, and UV-Vis diffuse reflectance spectrophotometer, and their photocatalytic activities were evaluated under UV and visible light, respectively. The XRD results showed that all titania catalysts were anatase. More significantly, the crystallite size of nitrogen-doped titania increased with an increase in N/Ti proportion, and the doping of nitrogen could extend the absorption shoulder into the visible-light region, thus it possessed a higher visible-light activity illustrated by decolorization of methyl orange (65.3%) under the irradiation of visible light, whereas pure titania showed little of such kind of visible light activity.The UV-light activity of nitrogen-doped titania catalysts was worse than that of pure titania and Degussa P25. In the range of N/Ti proportion of 4-10 mol%, the activity of nitrogen-doped titania weakened appreciably in the visible-light region as the N/Ti proportion increased, whereas a reverse relationship existed under the irradiation of UV light.

  11. Enrichment of Pyrrolic Nitrogen by Hole Defects in Nitrogen and Sulfur Co-Doped Graphene Hydrogel for Flexible Supercapacitors.

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    Tran, Ngoc Quang; Kang, Bong Kyun; Woo, Moo Hyun; Yoon, Dae Ho

    2016-08-23

    The effect of the doping configuration and concentration of nitrogen (N) and sulfur (S) on the electrochemical performance of 3 D N and S co-doped hole defect graphene hydrogel (NS-HGH) electrodes is investigated. Surprisingly, by introducing a hole defect on the graphene surface, the difference in the doping concentrations of N and S can be used to effectively modulate the electrochemical behavior of the NS-HGH. The hole defects provide a rapid ion diffusion path. Finally, we showed that the intriguing specific capacitance (536 F g(-1) ) of the NS-HGH could enhance the overall performance of the pseudocapacitance and electric double layer capacitance. The rational design of the NS-HGH-based flexible solid state supercapacitor results in not only outstanding electrochemical performance with a maximum energy density of 14.8 Wh kg(-1) and power density of 5.2 KW kg(-1) but also in extraordinary mechanical flexibility and excellent cycle stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Nitrogen and sulfur co-doped TiO2 nanosheets with exposed {001} facets: synthesis, characterization and visible-light photocatalytic activity.

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    Xiang, Quanjun; Yu, Jiaguo; Jaroniec, Mietek

    2011-03-21

    Nitrogen and sulfur co-doped TiO(2) nanosheets with exposed {001} facets (N-S-TiO(2)) were prepared by a simple mixing-calcination method using the hydrothermally prepared TiO(2) nanosheets powder as a precursor and thiourea as a dopant. The resulting samples were characterized by transmission electron microscope, X-ray diffraction, N(2) adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and UV-Vis absorption spectroscopy. The electronic properties of N,S co-doped TiO(2) were studied using the first-principle density functional theory (DFT). The photocatalytic activity of N-S-TiO(2) was evaluated by degradation of 4-chlorophenol (4-CP) aqueous solution under visible light irradiation. The production of hydroxyl radicals (˙OH) on the surface of visible-light-irradiated samples was detected by photoluminescence technique using terephthalic acid as a probe molecule. The results show that nitrogen and sulfur atoms were successfully incorporated into the lattice of TiO(2), which resulted in N-S-TiO(2) samples exhibiting stronger absorption in the UV-visible range with a red shift in the band gap transition. The first-principle DFT calculations further confirm that N and S co-dopants can induce the formation of new energy levels in the band gap, which is associated with the response of N-S-TiO(2) nanosheets to visible light irradiation. Surprisingly, pure TiO(2) nanosheets show the visible-light photocatalytic activity for the degradation of 4-CP mainly due to the substrate-surface complexation of TiO(2) and 4-CP, which results in extending absorption of titania to visible light region through ligand-to-titanium charge transfer. The N-S-TiO(2) samples studied exhibited an enhanced visible-light photocatalytic activity than pure TiO(2). Especially, the doped TiO(2) sample at the nominal weight ratio of thiourea to TiO(2) powder of 2 showed the highest photocatalytic activity, which was about twice greater than that of Degussa P25. The enhanced activity of

  13. Preparation and characterization of visible-light-driven TiO2 photocatalyst Co-doped with nitrogen and erbium.

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    Chen, Guihua; Wang, Yong; Zhang, Juihui; Wu, Chenglin; Liang, Huading; Yang, Hui

    2012-05-01

    A series of nitrogen and erbium co-doped TiO2 photocatalyst was prepared by sol-hydrothermal method. The structure and properties of the photocatalyst were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra (DRS). The XRD and BET results showed that co-doping inhibited the increase of crystallite size and enlarged specific surface areas. XPS spectroscopy indicated nitrogen atoms were incorporated into TiO2 lattice, and erbium atoms mostly existed in the forms of Er2O3. A shift of the absorption edge to the lower energy and four absorption bands located at 654, 544, 524 and 489 nm attributed to the 4f transitions of 4I15/2 --> 4F2/9, 4I15/2 --> 4S3/2, 4I15/2 --> 2H11/2, 4I15/2 --> 4F7/2 of Er3+ were observed using DRS spectroscopy. The catalytic efficency was evaluated by the photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results showed that the photocatalytic performance of the co-doped TiO2 was related with the hydrothermal temperature and the molar ratio of N/Ti, and they showed higher acitivites than pure TiO2. Results determined by fluorescence technique revealed that irradiation (lambda > 400 nm) of TiO2 photocatalyst dispersed in MO solution induces the generation of the highly active hydroxyl radicals (OH). It indicated the photocatalytic activities of TiO2 photocatalyst were correlation with the formation rate of hydroxyl radicals (OH) and other active oxygen species.

  14. First-principles study of metallic carbon nanotubes with boron/nitrogen co-doping

    Institute of Scientific and Technical Information of China (English)

    Chen Ling-Na; Ma Song-Shan; OuYang Fang-Ping; Xiao Jin; Xu Hui

    2011-01-01

    Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes (MCNTs) with B/N pair co-doping. The results about formation energy show that the B/N pair co-doping configuration is a most stable structure. We find that the electronic structure and the transport properties are very sensitive to the doping concentration of the B/N pairs in MCNTs, where the energy gaps increase with doping concentration increasing both along the tube axis and around the tube, because the mirror symmetry of MCNT is broken by doping B/N pairs. In addition, we discuss conductance dips of the transmission spectrum of doped MCNTs. These unconventional doping effects could be used to design novel nanoelectronic devices.

  15. Nitrogen and carbon co-doped Ni-TiO2 spindles for high performance electrochemical capacitor electrodes

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    Liu, Yu; Cai, Xiaoyu; Jiang, Jinhui; Yan, Ming; Shi, Weidong

    2017-02-01

    Nitrogen and carbon co-doped Ni-TiO2 (nickel-titanium dioxide) spindles with hollow inner and good structural stability were facilely prepared by a direct precipitation method followed by annealing treatment. The unique composite shows a remarkably high capacitivity (223.7 F g-1 at 2 mV/s) and good rate capability (132.2 F g-1 at 100 mV s-1) when used as supercapacitor electrodes. In addition, the nitrogen and carbon co-doped Ni-TiO2 spindles also demonstrate good cycling stability (91.5% retention of the initial capacitance after 4000 cycles). The unique structure and seamlessly integration between different components generate synergistic effect to boost high performance and high electrical conductivity. The hollow inner also allows efficient diffusion of electrolyte and provides a more favorable path for charge penetration and transportation, which makes the good rate capability. The attractive performances make them potentially promising alternatives for the electrode materials of future energy storage devices.

  16. Photocatalytic performance of nitrogen, osmium co-doped TiO2 for removal of eosin yellow in water under simulated solar radiation.

    Science.gov (United States)

    Kuvarega, Alex T; Krause, Rui W M; Mamba, Bhekie B

    2013-07-01

    Nitrogen, osmium co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using ammonia as the nitrogen source and osmium tetroxide as the source of osmium. The role of rutile phase OsO2 in enhancing the photocatalytic activity of rutile TiO2 towards the degradation of Eosin Yellow was investigated. The materials were characterised by various techniques that include FTIR, Raman, XRD, SEM, EDS, TEM, TGA and DRUV-Vis. The amorphous, oven dried sample was transformed to the anatase and then the rutile phase with increasing calcination temperature. DRUV-Vis analysis revealed a red shift in absorption with increasing calcination temperature, confirmed by a decrease in the band gap of the material. The photocatalytic activity of N, Os co-doped TiO2 was evaluated using eosin yellow degradation and activity increased with increase in calcination temperature under simulated solar irradiation. The rutile phase of the co-doped TiO2 was found to be more effective in degrading the dye (k(a) = 1.84 x 10(-2) min(-1)) compared to the anatase co-doped phase (k(a) = 9.90 x 10(-3) min(-1)). The enhanced photocatalytic activity was ascribed to the synergistic effects of rutile TiO2 and rutile OsO2 in the N, Os co-doped TiO2.

  17. Boron/nitrogen pairs Co-doping in metallic carbon nanotubes: a first-principle study

    Institute of Scientific and Technical Information of China (English)

    Ouyang Fang-Ping; Peng Sheng-Lin; Chen Ling-Na; Sun Shu-Yuan; Xu Hui

    2011-01-01

    By using the first-principles calculations, the electronic structure and quantum transport properties of metallic carbon nanotubes with B/N pairs co-doping have been investigated. It is shown that the total energies of metallic carbon nanotubes are sensitive to the doping sites of the B/N pairs. The energy gaps of the doped metallic carbon nanotubes decrease with decreasing the concentration of the B/N pair not only along the tube axis but also around the tube. Moreover, the I-V characteristics and transmissions of the doped tubes are studied. Our results reveal that the conducting ability of the doped tube decreases with increasing the concentrations of the B/N pairs due to symmetry breaking of the system. This fact opens a new way to modulate band structures of metallic carbon nanotubes by doping B/N pair with suitable concentration and the novel characteristics are potentially useful in future applications.

  18. Erbium and nitrogen co-doped SrTiO{sub 3} with highly visible light photocatalytic activity and stability by solvothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jing [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Huaqiao University, Xiamen 361021 (China); Wei, Yuelin, E-mail: ylwei@hqu.edu.cn [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Huaqiao University, Xiamen 361021 (China); Huang, Yunfang; Wang, Jing; Zheng, Xuanqing [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Huaqiao University, Xiamen 361021 (China); College of Chemical Engineering, Huaqiao University, Xiamen 361021 (China); Sun, Zhixian [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Huaqiao University, Xiamen 361021 (China); Wu, Ying [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Huaqiao University, Xiamen 361021 (China); College of Chemical Engineering, Huaqiao University, Xiamen 361021 (China); Tao, Xinling [College of Chemical Engineering, Huaqiao University, Xiamen 361021 (China); Fan, Leqing; Wu, Jihuai [Engineering Research Center of Environment-Friendly Functional Materials, Ministry of Education, Huaqiao University, Xiamen 361021 (China)

    2015-10-15

    Highlights: • Er/N co-doped SrTiO{sub 3} was prepared by a solvothermal process at low temperature. • The co-doping induces the band gap narrowing and prominent absorbance in visible light region. • The samples show excellent catalytic activity and stability under visible light irradiation. - Abstract: Erbium–nitrogen co-doped SrTiO{sub 3} photocatalysts have been synthesized by a facile solvothermal method. The resulting samples were analyzed by FE-SEM, XRD, BET-surface area and UV–vis. The UV–vis absorption spectra of these powders indicated that erbium–nitrogen co-doped SrTiO{sub 3} possessed stronger absorption bands in the visible light region in comparison with that of pure SrTiO{sub 3}. The occurrence of the erbium–nitrogen co-doped cubic SrTiO{sub 3} induced the higher photocatalytic activities for the degradation of methyl orange (MO) under irradiation by ultraviolet light and visible light, respectively, being superior to that of pure SrTiO{sub 3} and commercial TiO{sub 2} (P-25) powders. In addition, the Er–N co-doped SrTiO{sub 3} (initial molar ratios of Sr/Er/N = 1:0.015:0.1, designated as S5) sample showed the best photocatalytic activity with the degradation rate as high as 98% after 30 min under the visible light irradiation. After five cycles, the photocatalytic activity of the S5 catalyst showed no significant decrease, which indicated that the photocatalysts were stable under visible light irradiation.

  19. Photocatalytic Destruction of Nitrogen Monoxide over La3+ and N Co-doped SrTiO3 Powders under Visible Light Irradiation

    Institute of Scientific and Technical Information of China (English)

    王金淑; 马淑云; 王国红

    2004-01-01

    Lanthanum and nitrogen co-doped SrTiO3 was prepared by a mechanochemical reaction using SrTiO3, urea and La2O3 as the raw materials. The samples were characterized by X-ray diffraction, X-ray photoelectron spectrometer, transmission electron microscopy, and nitrogen adsorption-desorption isotherm measurements. Lanthanum doping could increase the doping content of nitrogen in the sample. The sample prepared with 0.2 mol% La2O3, 22 mol% urea and 77.8 mol% SrTiO3 by mechanochemical reaction, which has nearly the same nitrogen and lanthanum doping fractions, exhibited high photocatalytic activities. Under the irradiation of light with wavelength larger than 400, and 290 nm, the photocatalytic activity of nitrogen and lanthanum co-doped SrTiO3 were 2.6 and 2 times greater than that of pure SrTiO3.

  20. Effective visible light-active nitrogen and samarium co-doped BiVO{sub 4} for the degradation of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min; Niu, Chao [College of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110165 (China); Liu, Jun, E-mail: minwang62@msn.com [Shenyang Military General Hospital, Shenyang 110016 (China); Wang, Qianwu; Yang, Changxiu; Zheng, Haoyan [College of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110165 (China)

    2015-11-05

    Nitrogen and samarium co-doped BiVO{sub 4} (N–xSm–BiVO{sub 4}) nanoparticles were synthesized using a sol–gel method with a corn stem template. The physicochemical properties of the resultant N–xSm–BiVO{sub 4} particles were characterized using various methods: XPS, XRD, SEM, BET, and UV–Vis DRS analyses. The visible-light photocatalytic activity was successfully demonstrated by degrading a model dye, namely, methyl orange. The dopant content was optimized, and the nitrogen and samarium co-doped BiVO{sub 4} extended the light absorption spectrum toward the visible region, significantly enhancing the photodegradation of the model dye. The Sm and N co-doped BiVO{sub 4} exhibited the highest photocatalytic activity compared to materials with a single dopant or no dopant. The significantly enhanced photocatalytic activity of the N–Sm co-doped BiVO{sub 4} under visible-light irradiation can be attributed to the synergistic effects of the nitrogen and samarium. - Highlights: • The N–Sm codoped BiVO{sub 4} were synthesized using a sol–gel method with a corn stem template. • The N and Sm codoped BiVO{sub 4} has excellent photocatalytic activity of methyl orange degradation. • The maximum activity was observed when the molar ratio of Sm/Bi was 1.0. • The high photocatalytic activity was caused by the synergistic effects between N doping and Sm doping.

  1. Enhanced photocatalytic degradation of dye under visible light on mesoporous microspheres by defects in manganese- and nitrogen-co-doped TiO2

    Science.gov (United States)

    Feng, Lu; Jiang, Heng; Zou, Mingming; Xiong, Fengqiang; Ganeshraja, Ayyakannu Sundaram; Pervaiz, Erum; Liu, Yinan; Zou, Shunying; Yang, Minghui

    2016-09-01

    Manganese- and nitrogen-co-doped mesoporous TiO2 microsphere photocatalysts are prepared by a simple sol-gel method with controllable sizes in the range of 400-500 nm and high surface area of 112 m2 g-1. Manganous acetate is the Mn source, and ammonia gas is the nitrogen source used. The dopants are found to be uniformly distributed in the TiO2 matrix. Interestingly, in (Mn,N)-co-doped TiO2, we observe an effective indirect band gap of 2.58 eV. (Mn,N)-co-doped mesoporous TiO2 microspheres show higher photocatalytic activity than Mn-TiO2 microspheres under visible light irradiation. Among the samples reported in this work, 0.2 at.% Mn doping and 500 °C 2-h nitriding condition give the highest photocatalytic activity. The observed photocatalytic activity in the (Mn,N)-co-doped TiO2 is attributed to the contribution from improved absorption due to trap levels of Mn, oxygen vacancies and N doping.

  2. Nitrogen and sulfur co-doped carbon dots for highly selective and sensitive detection of Hg (II) ions.

    Science.gov (United States)

    Li, Libo; Yu, Bin; You, Tianyan

    2015-12-15

    Nitrogen and sulfur co-doped carbon dots (N,S/C-dots) with high fluorescence quantum yields (FLQY, 25%) was successfully synthesized by a one-step microwave-assisted method. In comparison with nitrogen doped C-dots (N/C-dots) prepared using the same method, the resulting N,S/C-dots featured small particle size, uniform surface state, insensitive FL properties to excitation wavelengths and environmental conditions, negligible cytotoxicity and excellent biocompatibility. Simultaneous doping of N and S effectively promoted electron-transfer and coordination interaction between N,S/C-dots and Hg(2+). Thus, when used as fluorescence probe for Hg(2+) label-free detection, the resulting N,S/C-dots showed good detection sensitivity and ion selectivity. The limit of detection was 2 μM; among 15 metal ions investigated, only Fe(3+) showed interference to the Hg(2+) detection. Fortunately, this interference could be effectively shielded using a chelating agent sodium hexametaphoshpate. The applicability of N,S/C-dots as fluorescence probe for Hg(2+) detection in lake water and tap water was demonstrated. Finally, based on its favorable features of negligible cytotoxicity and excellent biocompatibility, the N,S/C-dots were successfully applied to probe Hg(2+) in living cells, which broaden its application in biological system.

  3. TiO2 nanoparticles co-doped with silver and nitrogen for antibacterial application.

    Science.gov (United States)

    Yuan, Yali; Ding, Jianqiang; Xu, Jinsheng; Deng, Jian; Guo, Jianbo

    2010-08-01

    We have prepared a series of TiO2 nanoparticles for antibacterial applications. These TiO2 nanoparticles were prepared by the hydrolysis precipitation method with Ti(OBu)4, silver nitrate and ammonia. Crystal structure, particle size, interfacial structure and UV-visible light response of the prepared nanoparticles were characterized by X-ray diffraction measurements (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRs). The XRD spectra showed that all samples were anatase structure calcined at 450 degrees C for 3 hours. The Ag doping made the peak of diffraction wider. The results of TEM showed that the nanoparticles of TiO2, N-TiO2 and 1% Ag-N-TiO2 were all spherical in shape and well distributed with a mean size of 19.8 nm, 39.2 nm and 20.7 nm, respectively. N doping caused the nanoparticle size to increase, while, when the doped amount of Ag+ increased, the TiO2 particle size decreased. The FTIR revealed that Ag and N doping of TiO2 appeared to have strong absorption by -OH group and showed the characteristic absorption band of NH4+ and Ag. The UV-Vis-DRs indicated that the absorption band of Ag-N co-doped TiO2 had red shift and that the optical absorption response (between 400 nm and 700 nm) had obvious enhancement. The antibacterial properties of nanoparticles were investigated by agar diffusion method toward Escherichia coli and Bacillus subtilis. The results indicated that both Ag- and N-doped TiO2 could increase the antibacterial properties of TiO2 nanoparticles under fluorescent light irradiation. A 1% Ag-N-TiO2 had the highest antibacterial activity with a clear antibacterial circle of 33.0 mm toward Escherichia coli and 22.8 mm toward Bacillus subtilis after cultivation for 24 hours.

  4. Computational investigation of the co-doping effect of sulphur and nitrogen on the electronics of CsTaWO6

    Directory of Open Access Journals (Sweden)

    Liuxie Liu

    2017-03-01

    Full Text Available CsTaWO6 is a typical AMWO6-type compound and the photocatalysis of the pure and doped phases has been extensively studied experimentally. In this work, the electronic structures of sulphur (S and nitrogen (N co-doped CsTaWO6 have been studied in the framework of density functional theory, in particular the S/N co-doping effect has been investigated. It is found that, (i S/N co-dopants prefer to be separated; (ii middle-gap states are introduced by N and S-dopant at the edges of valence band and conduction band; and (iii Co-doping not only narrows the band gap, but also promotes the separation of photo-excited electrons and holes. Feature (iii has been identified as a key reason why S/N co-doped CsTaWO6 is more efficient in photocatalytic water-splitting. A general doping strategy has been further suggested: co-dopants which can dominate the frontier states and favour to be separated can offer excellent photocatalysis performance.

  5. Facile preparation of nitrogen/sulfur co-doped and hierarchical porous graphene hydrogel for high-performance electrochemical capacitor

    Science.gov (United States)

    Li, Jinhui; Zhang, Guoping; Fu, Chaopeng; Deng, Libo; Sun, Rong; Wong, Ching-Ping

    2017-03-01

    Nitrogen/sulfur co-doped and hierarchical porous graphene hydrogels (DHGHs) are prepared by facile self-assembly process. The results show that the pH values of preparation process significantly affect the microstructures and electrochemical properties of DHGHs and the mechanism has been discussed. The as-prepared DHGHs can be directly used as binder-free electrodes to assemble full-cell supercapacitor devices. It is surprising that the DHGHs prepared at basic condition (DHGH-12) delivers a specific capacitance of 251 F g-1 (0.5 A g-1). Moreover, the DHGH-12 shows rectangular cyclic voltammetry shape at a high scan rate of 3000 mV s-1 and symmetrical galvanostatic charge/discharge curves at 100 A g-1 which exhibits a specific capacitance of 136.5 F g-1, a high energy density of 4.74 Wh kg-1 and high power density of 25.47 kW kg-1. Additionally, DHGH-12 presents superior cycling stability (96.8% retention after 2000 cycles at 20 A g-1) in 6 M KOH solution. Therefore, the novel DHGHs can be considered as promising candidate for high energy density supercapacitors at high rates.

  6. Nickel cobaltite nanosheets strongly anchored on boron and nitrogen co-doped graphene for high-performance asymmetric supercapacitors

    Science.gov (United States)

    Jiao, Xinyan; Xia, Xifeng; Liu, Peng; Lei, Wu; Ouyang, Yu; Hao, Qingli

    2017-08-01

    Strongly coupled boron and nitrogen co-doped graphene (BN-G) hybrids with nickel cobaltite (NiCo2O4) nanosheets (NCO/BN-G) were fabricated by a facile soft-chemical method for asymmetric supercapacitors with high-performance. The strong interaction between BN-G and NiCo2O4 nanosheets are explored by various techniques. The effect of heteroatom doping on electrochemical properties of the hybrids is systematically investigated. The strong synergistic effect between NiCo2O4 and BN-G leads to a specific capacitance of 106.5 mA h g-1 at the current density of 0.5 A g-1 and capacitance retention of 96.8% after 10 000 cycles at 5 A g-1, much better than those of the pure NiCo2O4 and its hybrid with N-doped graphene. Moreover, an asymmetric supercapacitor device, assembled with NCO/BN-G and activated carbon (NCO/BN-G//AC), exhibits a maximum energy density of 45.6 Wh kg-1 and an excellent cycling stability. The improved electrochemical performance of the NCO/BN-G hybrid is attributed to the good conductivity of BN-G and the synergistic effect between NiCo2O4 nanosheets and BN-G combined together through a plane-to-plane contact mode.

  7. CuO nanoparticles supported on nitrogen and sulfur co-doped graphene nanocomposites for non-enzymatic glucose sensing

    Science.gov (United States)

    Li, Meixia; Guo, Qingbin; Xie, Juan; Li, Yongde; Feng, Yapeng

    2017-01-01

    Developing highly active catalysts to promote the electrocatalytic glucose oxidation (EGO) is a crucial demand for non-enzymatic glucose sensing. Herein, we reported the use of nitrogen and sulfur co-doped graphene (NSG) as a novel support material for anchoring CuO nanoparticles and obtained CuO/NSG was employed as an efficient EGO catalyst for non-enzymatic glucose sensing. The results showed that the NSG endowed the CuO/NSG with large surface area, increased structural defects, improved conductivity, and strong covalent coupling between NSG and CuO. Owing to the significant contribution of NSG and the synergistic effect of NSG and CuO, the CuO/NSG exhibited a remarkably higher EGO activity than CuO and CuO/reduced graphene oxide. The CuO/NSG-based sensor displayed excellent glucose sensing performances with a considerably low detection limit of 0.07 μM. These findings elucidate that the NSG is a promising support material for non-enzymatic glucose detection.

  8. Oxygen and nitrogen co-doped porous carbon nanosheets derived from Perilla frutescens for high volumetric performance supercapacitors

    Science.gov (United States)

    Liu, Bei; Liu, Yijiang; Chen, Hongbiao; Yang, Mei; Li, Huaming

    2017-02-01

    Biomass-derived O/N-co-doped porous carbons have become the most competitive electrode materials for supercapacitors because of their renewability and sustainability. We herein present a simple approach to fabricate O/N-co-doped porous carbon nanosheets by the direct pyrolysis of Perilla frutescens (PF) leaves. Under optimum pyrolysis temperature (700 °C), the PF leaf-derived carbon nanosheets (PFC-700) having O, N contents of 18.76 at.% and 1.70 at.%, respectively, exhibit a hierarchical pore structure with a moderate BET surface area (655 m2 g-1) and a relatively low pore volume (0.44 cm3 g-1). Such O/N-co-doped porous carbon nanosheets display both high gravimetric capacitance (270 F g-1 at 0.5 A g-1) and high volumetric capacitance (287 F cm-3 at 0.5 A g-1). In addition, the PFC-700-based symmetric supercapacitor offers a high volumetric energy density (14.8 Wh L-1 at 490 W L-1) as well as a high stability (about 96.1% of capacitance retention after 10000 cycles at 2 A g-1).

  9. Enhanced photocatalytic activity of (La, N) co-doped TiO2 by TiCl4 sol-gel autoigniting synthesis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    (La, N) co-doped TiO2 photocatalysts were synthesized using TiCl4 sol-gel autoigniting synthesis (SAS) starting from a plished in the formation of TiO2 nanocrystals. The prepared samples were characterized by using X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the separation of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalytic activity of (La, N) co-doped titania by SAS was discussed in detail.

  10. Synthesis, Characterization, and Tribological Evaluation of TiO2-Reinforced Boron and Nitrogen co-Doped Reduced Graphene Oxide Based Hybrid Nanomaterials as Efficient Antiwear Lubricant Additives.

    Science.gov (United States)

    Jaiswal, Vinay; Kalyani; Umrao, Sima; Rastogi, Rashmi B; Kumar, Rajesh; Srivastava, Anchal

    2016-05-11

    The microwave-synthesized reduced graphene oxide (MRG), boron-doped reduced graphene oxide (B-MRG), nitrogen-doped reduced graphene oxide (N-MRG), boron-nitrogen-co-doped reduced graphene oxide (B-N-MRG), and TiO2-reinforced B-N-MRG (TiO2-B-N-MRG) nanomaterials have been synthesized and characterized by various state-of-the-art techniques, like Raman spectroscopy, powder X-ray diffraction, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Furthermore, the tribological properties of prepared nanomaterials as antiwear additives in neutral paraffin oil have been evaluated using a four-ball machine at an optimized additive concentration (0.15% w/v). The tribological parameters, like mean wear scar diameter, coefficient of friction, and wear rates, revealed that these nanomaterials have potential to be developed as environmentally friendly sulfated-ash-, phosphorus-, and sulfur-free antiwear lubricant additives. The friction- and wear-reducing behavior of MRG increased upon successive doping of nitrogen, boron, and both nitrogen and boron. Among these additives, B-N-co-doped MRG shows superior tribological behavior in paraffin base oil. Besides this, the load-carrying properties of B-N-co-doped MRG have significantly improved after its reinforcement with TiO2 nanoparticles. A comparative study of the surface morphology of a lubricated track in the presence of various additives has been assessed by SEM and contact-mode atomic force microscopy. The X-ray photoelectron spectroscopy studies have proved that the excellent lubrication properties of TiO2-B-N-MRG are due to the in situ formation of a tribofilm composed of boron nitride, adsorbed graphene layers, and tribosintered TiO2 nanoparticles during the tribocontact. Being sulfur-, halogen-, and phosphorus-free, these graphene-based nanomaterials act as green antiwear additives, protecting interacting

  11. Synthesis of Nitrogen-doped Titania by Solvothermal Reactions in Alcohols

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nitrogen-doped titania nanoparticles were obtained by the homogeneous precipitation in hexamethylenetetraminetitanium trichloride-alcohol aqueous solutions at 90 ℃ followed by heating at 190 ℃. Anatase, rutile and brookite were obtained, where the crystallite size, specific surface area and color greatly changed as 5~50 nm, 20~200 m2/g and light gray to yellow, depending on the solvent and pH. The products after calcination were yellow, indicating doping with nitrogen ion. All colored titania showed photocatalytic activity under visible light irradiation for the oxidative decomposition of nitrogen monoxide in air. Especially, the nanoparticles of anatase type nitrogen-doped titania obtained using methanol aqueous solution showed excellent photocatalytic activity.

  12. Algae biomass as a precursor for synthesis of nitrogen-and sulfur-co-doped carbon dots: A better probe in Arabidopsis guard cells and root tissues.

    Science.gov (United States)

    Zhang, Che; Xiao, Yumei; Ma, Yongqiang; Li, Baoming; Liu, Zhidan; Lu, Cheng; Liu, Xue; Wei, Yao; Zhu, Zhangbing; Zhang, Yuanhui

    2017-09-01

    The challenge of controlling algal blooms and reusing algal biomass remain unsolved worldwide. We introduce a facile method to reuse Nannochloropsis biocrude oil (NBO) for the synthesis of nitrogen and sulfur co-doped carbon dots (N-S-C-dots). N-S-C-dots can pass through the heavily thickened wall of mature Arabidopsis thaliana (A. thaliana) guard cells because of high solubility and excellent biocompatibility. N-S-C-dots exhibit multicolor luminescence and could effectively reduce the interference of autofluorescence in plant cells by changing filters. Bioimaging of root tissues reveals that 2 major factors affect the transmission of N-S-C-dots: high osmotic pressure and intensity of cellular metabolism. This study highlights the potential application of CDs for bioimaging in plant cells and demonstrates the significance of investigating the reuse of algal biomass. Copyright © 2017. Published by Elsevier B.V.

  13. Isoelectronic co-doping

    Science.gov (United States)

    Mascarenhas, Angelo

    2004-11-09

    Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  14. Enhanced photocatalytic degradation properties of nitrogen-doped titania nanotube arrays

    Institute of Scientific and Technical Information of China (English)

    DONG Lin; CAO Guo-xi; MA Ying; JIA Xiao-lin; YE Guo-tian; GUAN Shao-kang

    2009-01-01

    Nitrogen-doped TiO_2 nanotubes array were synthesized to improve the photocatalytic efficiency by annealing the anodized titania nanotubes with ammonia at 500 ℃.Detailed structural analysis revealed that the nitrogen-doped titania nanotubes are of highly ordered structure,and exhibit a decreased phase transformation temperature compared with those that are not doped,as evidenced by the decrease in full width at half maximum (FWHM) of the (110) peak of rutile phase and the occurrence of the typical Raman peaks of rutile phase at 196,235,442,610 cm~(-1).According to the photocatalytic degradation of methyl orange under visible light irradiation,the nitrogen-doped TiO_2 nanotubes exhibit enhanced photocatalytic efficiency compared with their non-doped nanotubes,which might be a result of either the nitrogen doping induced band gap narrowing or the synergistic effect produced by both nitrogen and fluorine dopants.

  15. Mechanochemical Synthesis of Visible-light Induced Photocatalyst with Nitrogen and Carbon Doping

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nitrogen and/or carbon doped titania photocatalysts were prepared by a novel mechanochemical method. The prepared powders possessed two absorption edges around 400 and 540 nm wavelengths and showed excellent photocatalytic ability for nitrogen monoxide oxidation under visible light irradiation. Under the irradiation of visible light of wavelength >510 nm, 37% of nitrogen monoxide could be continuously removed by the carbon and nitrogen co-doped titania prepared by planetary ball milling of P-25 titania-10% hexamethylenetetramine mixture followed by calcination in air at 400 ℃.

  16. Electro spraying of titania for nitrogen oxide abatement

    NARCIS (Netherlands)

    Ursem, W.N.J.; Marijnissen, J.C.; Roos, R.A.; Kelder, E.M.

    2010-01-01

    The invention provides a method for the production of a titania coating (80) on a surface (101) of an object (100) comprising electro spraying a titanium comprising liquid (15) to the surface (101) of the object (100) to provide a titanium comprising layer (85); and heating thetitanium comprising la

  17. Synthesis, characterization and degradation of Bisphenol A using Pr, N co-doped TiO 2 with highly visible light activity

    Science.gov (United States)

    Yang, Juan; Dai, Jun; Li, Jiantong

    2011-08-01

    Praseodymium and nitrogen co-doped titania (Pr/N-TiO 2) photocatalysts, which could degrade Bisphenol A (BPA) under visible light irradiation, were prepared by the modified sol-gel process. Tetrabutyl titanate, urea and praseodymium nitrate were used as the sources of titanium, nitrogen and praseodymium, respectively. The resulting materials were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis absorbance spectroscopy, X-ray photoelectron spectroscopy (XPS), N 2 adsorption-desorption isotherm and Fourier transform infrared spectra (FTIR). It was found that Pr doping inhibited the growth of crystalline size and the transformation from anatase to rutile. The degradation of BPA under visible light illumination was taken as probe reaction to evaluate the photo-activity of the co-doped photocatalyst. In our experiments, the optimal dopant amount of Pr was 1.2 mol% and the calcination temperature was 500 °C for the best photocatalytic activity. Pr/N-TiO 2 samples exhibited enhanced visible-light photocatalytic activity compared to N-TiO 2, undoped TiO 2 and commercial P25. The nitrogen atoms were incorporated into the crystal of titania and could narrow the band gap energy. Pr doping could slow the radiative recombination of photogenerated electrons and holes in TiO 2. The improvement of photocatalytic activity was ascribed to the synergistic effects of nitrogen and Pr co-doping.

  18. Boron/nitrogen co-doped helically unzipped multiwalled carbon nanotubes as efficient electrocatalyst for oxygen reduction.

    Science.gov (United States)

    Zehtab Yazdi, Alireza; Fei, Huilong; Ye, Ruquan; Wang, Gunuk; Tour, James; Sundararaj, Uttandaraman

    2015-04-15

    Bamboo structured nitrogen doped multiwalled carbon nanotubes have been helically unzipped, and nitrogen doped graphene oxide nanoribbons (CNx-GONRs) with a multifaceted microstructure have been obtained. CNx-GONRs have then been codoped with nitrogen and boron by simultaneous thermal annealing in ammonia and boron oxide atmospheres, respectively. The effects of the codoping time and temperature on the concentration of the dopants and their functional groups have been extensively investigated. X-ray photoelectron spectroscopy results indicate that pyridinic and BC3 are the main nitrogen and boron functional groups, respectively, in the codoped samples. The oxygen reduction reaction (ORR) properties of the samples have been measured in an alkaline electrolyte and compared with the state-of-the-art Pt/C (20%) electrocatalyst. The results show that the nitrogen/boron codoped graphene nanoribbons with helically unzipped structures (CNx/CBx-GNRs) can compete with the Pt/C (20%) electrocatalyst in all of the key ORR properties: onset potential, exchange current density, four electron pathway selectivity, kinetic current density, and stability. The development of such graphene nanoribbon-based electrocatalyst could be a harbinger of precious metal-free carbon-based nanomaterials for ORR applications.

  19. Low-cost adsorbent derived and in situ nitrogen/iron co-doped carbon as efficient oxygen reduction catalyst in microbial fuel cells.

    Science.gov (United States)

    Cao, Chun; Wei, Liling; Su, Min; Wang, Gang; Shen, Jianquan

    2016-08-01

    A novel low-cost adsorbent derived and in situ nitrogen/iron co-doped carbon (N/Fe-C) with three-dimensional porous structure is employed as efficient oxygen reduction catalyst in microbial fuel cells (MFCs). The electrochemical active area is significantly improved to 617.19m(2)g(-1) in N/Fe-C by Fe-doping. And N/Fe-C (4.21at.% N, 0.11at.% Fe) exhibits excellent electrocatalytic activity with the oxygen reduction potential of -0.07V (vs. Ag/AgCl) which is comparable to commercial Pt/C. In MFCs tests, the maximum power density and output voltage with N/Fe-C are enhanced to 745mWm(-2) and 562mV (external resistance 1kΩ), which are 11% and 0.72% higher than Pt/C (0.5mgPtcm(-2)), respectively. Besides, the long-term stability of N/Fe-C retains better for more than one week. Moreover, the charge transfer resistance (Rct) values are recorded by the impedance measurements, and the low Rct of N/Fe-C is also result in better catalytic activity.

  20. Preparation, characterization and visible light photocatalytic activity of silver, nitrogen co-doped TiO2 photocatalyst

    Science.gov (United States)

    Khan, Matiullah; Ramin Gul, Sahar; Li, Jing; Cao, Wenbin; Mamalis, Athanasios G.

    2015-06-01

    TiO2 photocatalyst codoped with Silver (Ag) and Nitrogen (N) with different Ag doping concentrations is successfully synthesized by hydrothermal method. The as-synthesized samples are characterized through x-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-vis. absorption spectra and x-ray photoelectron spectroscopy (XPS). The photocatalytic response is evaluated by the photodegradation of methylene blue under visible light irradiations. All synthesized samples are composed of pure anatase phase with good crystallinity. The absorption edge of codoped TiO2 is shifted towards visible light region. X-ray photoelectron spectroscopy confirmed the existence of silver and nitrogen in the codoped samples. All the codoped samples demonstrated improved photocatalytic activity compared to pure TiO2. Among the different codoped samples, the one with silver doping concentration of 4 at. % exhibited the highest photoactivity.

  1. Supercapacitance of nitrogen-sulfur-oxygen co-doped 3D hierarchical porous carbon in aqueous and organic electrolyte

    Science.gov (United States)

    Yang, Wang; Yang, Wu; Song, Ailing; Gao, Lijun; Su, Li; Shao, Guangjie

    2017-08-01

    This work report the synthesis of porous carbon with hierarchical pore structure and uniform nitrogen-sulfur-oxygen doping. The favorable pore structure (micro-, meso-, and macro-pores) is beneficial to ion adsorption and transportation, and the doping heteroatoms can introduce electrochemical active sites which contribute to additional pseudocapacitance. Therefore, the carbon material shows good electrochemical performance when employed as supercapacitor electrode. High specific capacitance (367 F g-1 at 0.3 A g-1), good rate performance and stable cycling characteristics are obtained in 6 M KOH. In addition, when tested in 1 M H2SO4, a higher specific capacitance (382 F g-1 at 0.3 A g-1) is delivered. Furthermore, the assembled symmetric cell yields a maximum specific energy of 35.3 W h kg-1 in 1 M TEABF4/AN, significantly improving the specific energy of carbon-based supercapacitors.

  2. Visible light photocatalytic degradation of 4-chlorophenol using vanadium and nitrogen co-doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Jaiswal, R.; Kothari, D. C. [Department of Physics, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai 400 098 (India); Patel, N.; Miotello, A. [Dipartimento di Fisica, Universita degli Studi di Trento, I-38123 Povo ( Trento) (Italy)

    2013-02-05

    Vanadium and Nitrogen were codoped in TiO{sub 2} photocatalyst by Sol-gel method to utilize visible light more efficiently for photocatalytic reactions. A noticeable shift of absorption edge to visible light region was obtained for the singly-doped namely V-TiO{sub 2}, N-TiO{sub 2} and codoped V-N-TiO{sub 2} samples in comparison with undoped TiO{sub 2}, with smallest band gap obtained with codoped-TiO{sub 2}. The photocatalytic activities for all TiO{sub 2} photocatalysts were tested by 4-chlorophenol (organic pollutant) degradation under visible light irradiation. It was found that codoped TiO{sub 2} exhibits the best photocatalytic activity, which could be attributed to the synergistic effect produced by V and N dopants.

  3. One-step hydrothermal method to prepare nitrogen and lanthanum co-doped TiO{sub 2} nanocrystals with exposed {0 0 1} facets and study on their photocatalytic activities in visible light

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Lian; Yang, Xiaofang; He, Jie; He, Yi; Wang, Dongsheng, E-mail: wangdongshengrcees@126.com

    2015-07-15

    Highlights: • (0 0 1) dominated TiO{sub 2} nanosheets co-doped with N and La is synthesized. • N,La–TiO{sub 2} nanosheets shows higher visible light photocatalytic activity than N,La–TiO{sub 2} nanoparticles. • N and La co-doping could produce a synergistic effect. • N and La co-doping could increase BET surface area. - Abstract: The photocatalytic activity of TiO{sub 2} can be mainly improved from three approaches: (1) enhancing the separation efficiency of photoelectrons and holes, (2) enhancing surface energy, and (3) increasing availability of visible light. Here, we report a one-step method to obtain nitrogen and lanthanum co-doped TiO{sub 2} nanosheets with dominant {0 0 1} facets through a hydrothermal process, using TBOT, triethylamine and LaCl{sub 3}·nH{sub 2}O as precursor and sources of N, La respectively in HF–HNO{sub 3} mixed aqueous solution, and the samples were characterized by XRD, SEM, TEM, XPS, UV-DRS and BET analyses. The XRD and XPS results confirmed that N was doped into the lattice of anatase TiO{sub 2}, while La was not. N acts as an O–Ti–N structure or interstitial N and La exists as LaF{sub 3} in TiO{sub 2} nanosheets. The SEM and TEM results show that the percentage of {0 0 1} facets in the as-synthesized N,La–TiO{sub 2} nanosheets is estimated to be about 75% on average at R{sub F} = 1.0. N,La–TiO{sub 2} nanosheets can absorb visible light due to the red shift in the absorption edges, and compared with N–TiO{sub 2} nanosheets, N and La co-doping can further strengthen the absorption of visible light. N,La–TiO{sub 2} nanosheets exhibited higher photocatalytic activity for photodegradation of Rh B under visible light than pure TiO{sub 2}, N–TiO{sub 2}, La–TiO{sub 2} nanosheets and N,La–TiO{sub 2} nanoparticles. N and La co-doping could produce a synergistic effect. The N doping narrowed the band gap of TiO{sub 2}, while the La doping could improve the separation efficiency of photoelectrons and holes. In

  4. Detection of Trace Heavy Metals Ions by Arrays of Titania Nanotubes Annealed in Nitrogen

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhi-man; XIAO Peng; CAO Guo-zhong

    2009-01-01

    Redox response of trace heavy metals ions(THMIs) has better performance on highly ordered vertically oriented titania nanotube arrays(TNA) annealed in nitrogen. Experimental data showed that different THMIs possess different reaction peak shapes and charge and discharge capacities. Therefore, the TNA will become an important tool used for environmental protection and facilitating the rapid determination of THMIs. THMIs of 5×10~(-4) mol/L concentration were measured at a scan rate of 100 mV/s. The analytical utility of TNA is demonstrated in a neutral 0.5 mol/L Na_2SO_4 solution. The results sufficiently show that titania nanotube arrays electrodes(TNAE) will be used to measure THMIs.

  5. Nitrogen and sulfur co-doped carbon with three-dimensional ordered macroporosity: An efficient metal-free oxygen reduction catalyst derived from ionic liquid

    Science.gov (United States)

    Wu, Hui; Shi, Liang; Lei, Jiaheng; Liu, Dan; Qu, Deyu; Xie, Zhizhong; Du, Xiaodi; Yang, Peng; Hu, Xiaosong; Li, Junsheng; Tang, Haolin

    2016-08-01

    The development of efficient and durable catalyst for oxygen reduction reaction (ORR) is critical for the practical application of proton exchange membrane fuel cell (PEMFC). A novel imidazole based ionic liquid is synthesized in this study and used subsequently for the preparation of a N and S co-doped metal-free catalyst with three dimensional ordered microstructure. The catalyst prepared at 1100 °C showed improved ORR catalytic performance and stability compared to commercial Pt/C catalyst. We demonstrate that the high graphitic N content and high degree of graphitization of the synthesized catalyst is responsible for its superb ORR activity. Our results suggest that the N and S co-doped metal-free catalyst reported here is a promising alternative to traditional ORR catalyst based on noble metal. Furthermore, the current study also demonstrate that importance of morphology engineering in the development of high performance ORR catalyst.

  6. Controlled Phase Changes of Titania Using Nitrogen Plasma

    Science.gov (United States)

    Trejo-Tzab, R.; Caballero-Espada, Liliana; Quintana, P.; Ávila-Ortega, Alejandro; Medina-Esquivel, R. A.

    2017-01-01

    In this work, the development of a new crystallization technique is reported, using nitrogen plasma (AC) to obtain nanostructured anatase and rutile from amorphous titanium oxide (TiO2). This methodology increases throughput and minimizes thermal effects. Nanostructured amorphous TiO2 was obtained by the sol-gel method and subsequently subjected to AC treatment, at a controlled pressure, applying different powers and treatment times in order to obtain phase changes. The obtained samples were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The results show the crystallization in parallel with anatase and rutile phases with a proportion that is directly related to the applied power in the plasma and the treatment time. This technique allows us to obtain smaller crystals in comparison with those of classic thermal methodologies. It is also demonstrated that the application of plasma represents a novel and innovative method to obtain phase polymorphic changes in titanium oxide without needing to apply prolonged heat treatments at high temperatures and can therefore be taken into consideration as a technique with low energy costs, in comparison with conventional heat treatments.

  7. Phosphorus, and nitrogen co-doped carbon dots as a fluorescent probe for real-time measurement of reactive oxygen and nitrogen species inside macrophages.

    Science.gov (United States)

    Gong, Yunqian; Yu, Bin; Yang, Wen; Zhang, Xiaoling

    2016-05-15

    Phosphorus and nitrogen doped carbon dots (PN-CDs) were conveniently prepared by carbonization of adenosine-5'-triphosphate using a hydrothermal treatment. The PN-CDs with P/C atomic ratio of ca. 9.2/100 emit blue luminescence with high quantum yields of up to 23.5%. The PN-CDs were used as a novel sensing platform for live cell imaging of reactive oxygen species (ROS) and reactive nitrogen species (RNS), including ClO(-), ONOO(-), and NO in macrophages. The nanosensor design is based on our new finding that the strong fluorescence of the PN-CDs can be sensitively and selectively quenched by ROS and RNS both in vitro and in vivo. These results reveal that the PN-CDs can serve as a sensitive sensor for rapid imaging of ROS and RNS signaling with high selectivity and contrast.

  8. Sulfur and Nitrogen co-doped graphene quantum dot decorated ZnO nanorod/polymer hybrid flexible device for photosensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Hmar, Jehova Jire L.; Majumder, Tanmoy; Dhar, Saurab; Mondal, Suvra Prakash, E-mail: suvraphy@gmail.com

    2016-08-01

    S and N co-doped graphene quantum dots (S,N-GQDs) have been synthesized by a hydrothermal process. S,N-GQDs are made up of 1–5 monolayer of graphene with average diameter 13.3 nm. The absorption peaks at 336 and 621 nm, are attributed to n → Π{sup ⁎} transitions of electrons in C=O and S=O bonds, respectively. S,N-GQDs are highly luminescent and showed excitation dependent emission behaviors. Hybrid photosensing device has been fabricated with S,N-GQD sensitized ZnO nanorods and a conjugated polymer poly(3-hexylthiophene) (P3HT). S,N-GQD decorated ZnO nanorod demonstrated higher photoresponse compared to pristine ZnO nanorod based device. S,N-GQD/ZnO nanorod hybrid device showed superior incident photon to electron conversion efficiency (IPCE), photoresponsivity and detectivity compared to the control samples. The flexibility study of the samples has been monitored by measuring current-voltage characteristics at different bending angles. - Highlights: • S and N co-doped graphene quantum dots (S,N-GQDs) were synthesized. • ZnO nanorods were grown on ITO coated flexible PET substrates. • S,N-GQDs were attached with ZnO nanorods and used as a green sensitizer. • Photosensing properties of S,N-GQD/ZnO and P3HT polymer hybrid device was studied.

  9. A new approach to the preparation of nitrogen-doped titania visible light photocatalyst

    KAUST Repository

    Kachina, Anna

    2012-02-28

    A new simple method is described, allowing introduction of nitrogen into the TiO 2 lattice at low temperatures. The technique is based on the introduction of oxophilic molecules, such as CCl 4, into the reaction mixture. The treatment of titanium dioxide powders by NH 3-CCl 4 mixtures leads to highly dispersed N-doped TiO 2. As compared to bare TiO 2 or to the same oxide treated with sole NH 3, the solids treated with NH 3-CCl 4 mixtures showed a stronger red shift in optical absorption and enhanced photocatalytic activity under visible light, as demonstrated for two reactions of formic acid oxidation and photocatalytic production of hydrogen from methanol. The nitridation temperature can be significantly decreased by introducing CCl 4, because of a favorable change of the reaction thermodynamics. Not only can higher specific surface area of materials be obtained as a result of avoiding sintering but a higher amount of nitrogen is introduced in a position beneficial for the enhanced catalytic activity. The X-ray photoelectron spectroscopy study demonstrated increased surface concentration of nitrogen having N 1s binding energy near 399 eV. As established by ESR, the nature of paramagnetic species generated by treatments is strongly dependent on the titania polymorph variety and crystallinity as well as on the treatment conditions, but in all cases the major part of introduced nitrogen remains ESR-silent. © 2012 American Chemical Society.

  10. Extremely fast dark adsorption rate of carbon and nitrogen co-doped TiO2 prepared by a relatively fast, facile and low-cost microwave method

    Science.gov (United States)

    Du, Chun; Zhou, Jiangshan; Li, Fangzhou; Li, Wei; Wang, Yinzhen; He, Qinyu

    2016-07-01

    A facile and low-cost microwave method was used to prepare C and N co-doped TiO2 in just 8 min. The prepared samples were thoroughly characterized and were found to have favourable features such as surface adsorption of pollutants and photocatalysis. The rapid decomposition of CH5N3HCl under microwave irradiation led to mesopores and surface roughness in the as-prepared particles, resulting in large surface adsorption of pollutant and good photodegradation. The best sample is the one with the ratio of TiO2/CH2N3HCl at 3:1, which adsorbed 86.3 % of a methylene orange (MO) solution (20 mg L-1) in 10 min.

  11. Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

    Science.gov (United States)

    Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

    2016-02-01

    This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.

  12. Preparation of fine, uniform nitrogen- and sulfur-modified TiO2 nanoparticles from titania nanotubes

    Directory of Open Access Journals (Sweden)

    Mathieu Grandcolas and Jinhua Ye

    2010-01-01

    Full Text Available TiO2 nanoparticles modified with nitrogen and sulfur were prepared from titania nanotubes by a facile wet chemistry method. The samples synthesized with different thiourea/TiO2 ratios showed a uniform nanoparticle size distribution centred at approximately 10 nm with a developed specific surface area of 246 m2 g-1. These modified nanosized photocatalysts exhibited higher photocatalytic activity for the degradation of gaseous isopropanol than unmodified titania nanotubes under visible illumination. This could be attributed to the synergistic effects of a large specific surface area, strong absorption in the visible region, a redshift in the adsorption edge, and surface adsorption modification induced by nitrogen and sulfur compounds.

  13. Degradation of Dyes over Carbon, Cobalt Co-Doped Mesoporous Nano Titania with Anatase Crystalline Structure (C,Co-MTiO2)%具有介孔结构的纳米锐钛矿型C,Co-MTiO2降解染料的研究

    Institute of Scientific and Technical Information of China (English)

    姚文华; 秦云

    2013-01-01

    为了提高催化剂对太阳光的充分吸收和利用,采用模板技术合成了C,Co共掺杂的具有介孔结构的纳米锐钛矿型TiO2(C,Co-MTiO2).采用N2-物理吸附和解吸附、X-射线衍射、高分辨电子显微镜、UV-Vis对材料进行表征.结果表明,该材料热稳定性好,比表面积高,是具有较大介孔孔径的锐钛矿型TiO2.在夏季太阳光照射下光催化降解亚甲基蓝、甲基紫、曙红Y和甲基橙4种有机染料,与商品化的P-25TiO2相比,C,Co-MTiO2有很好的催化活性.该催化剂的高效光催化活性可能与其锐钛矿晶体结构、高比表面积、纳米尺寸、介孔孔道、碳和钴的协同效应有关.%In order to improve absorption and utilization of solar light,carbon,cobalt co-doped mesoporous nano titania with anatase crystalline structure(C,Co-MTiO2) was prepared using templating method.The catalyst was characterized by techniques like N2 physisorption,X-ray diffraction (XRD),HRTEM,UV-Vis.The characterization results indicated that the mesoporous titania with anatase crystalline structure exhibited highly thermal stability,high specific surface area and large pore size.The C,Co-MTiO2 was used for the solar photocatalytic degradation of methylene blue,methyl violet,eosin Y and methyl orange.It was found that the catalyst exhibited an excellent activity of photocatalytic degradation of dyes under solar light irradiation in summer,compared to commercial Degussa P-25 TiO2.The enhanced photocatalytic activity of C,Co-MTiO2 catalyst may be attributed to the synergistic effects of anatase crystalline structure,nano-size,mesoporous channels,high specific surface area,carbon and cobalt.

  14. Hierarchical nitrogen and cobalt co-doped TiO{sub 2} prepared by an interface-controlled self-aggregation process

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shishuai; Li, Qiang; Hou, Chengcheng; Feng, Xiaodong; Guan, Zisheng, E-mail: zishengguan@163.com

    2013-10-25

    Highlights: •N–Co-codoped TiO{sub 2} was prepared by hydrothermal method at vapor–liquid interface. •Hierarchical N–Co-codoped TiO{sub 2} was synthesized. •Growth mechanism of N–Co-codoped TiO{sub 2} was discussed. •Ferromagnetism was found on the titanate N–Co-codoped TiO{sub 2} at room temperature. •Light absorption edge of N–Co-codoped TiO{sub 2} was shifted to visible light region. -- Abstract: Hierarchical N and Co co-doped TiO{sub 2} (NCT) self-aggregates were prepared by the interfacial self-aggregation in an autoclave, where a mixed Ti(SO{sub 4}){sub 2} and Co(NO{sub 3}){sub 2} solution reacted with polyacrylate-controlled-releasing ammonia at the vapor–liquid interface. The SEM images show that the typical hierarchical NCT self-aggregates were composed of perpendicular nanosheets on the top, granule aggregates in the middle, and flower-like nanosheets at the bottom. A possible mechanism of their formation has been proposed on the basis of a series of experiments. We found that the morphology and crystal structure of the NCT self-aggregates can be controlled by adjusting reaction temperature, reaction time, and the amount of ammonia solution. The demonstration of hysteresis loops in the magnetization curves indicates that the NCT self-aggregate samples prepared at 150 °C were ferromagnetic at room temperature. The absorption spectra of the samples prepared at 150 °C showed evident absorption in the visible region. These NCT self-aggregates may be potentially useful in photoelectrochemical and magneto-electronic applications.

  15. Enhancing the photoelectric conversion of dye-sensitized solar cell via nitrogen-doped nanocrystalline titania electrode.

    Science.gov (United States)

    Cheng, Ping; Lan, Tian; Yang, Haijun; Wang, Wanjun; Wu, Haixia; Deng, Changsheng; Dai, Xiaming; Guo, Shouwu

    2010-11-01

    A high efficient dye-sensitized solar cell (DSC) was fabricated using nitrogen-doped nanocrystalline titania(TiO2) photoanode. X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRD), zeta potentials, nitrogen adsorption-desorption and elemental analysis experiments were employed to characterize the nitrogen-doped nanocrystalline TiO2 photoanode. An obvious enhancement of the optical absorption in the range of 380-550 nm was observed for nitrogen-doped TiO2, which was attributed to both the substitutional N and the chemisorbed N2 molecules. A conversion efficiency of 9.04% was obtained on the DSC based on nitrogen-doped TiO2 photoanode annealed in a flow of NH3 at 550 degrees C, with an increase of 15.6% improvement in comparison with pure TiO2 (7.82%). The mechanism for the enhanced photovoltaic performance was discussed.

  16. A facile method to synthesize nitrogen and fluorine co-doped TiO{sub 2} nanoparticles by pyrolysis of (NH{sub 4}){sub 2}TiF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Chen Daimei; Jiang Zhongyi; Geng Jiaqing; Zhu Juhong; Yang Dong, E-mail: dyangdong@hotmail.co [Tianjin University, Key Laboratory for Green Chemical Technology, School of Chemical Engineering and Technology (China)

    2009-02-15

    The nitrogen and fluorine co-doped TiO{sub 2} (N-F-TiO{sub 2}) nanoparticles of anatase crystalline structure were prepared by a facile method of (NH{sub 4}){sub 2}TiF{sub 6} pyrolysis, and characterized by thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy etc. With the increase of calcination temperature, (NH{sub 4}){sub 2}TiF{sub 6} decomposed into TiOF{sub 2} and NH{sub 4}TiOF{sub 3} at first, and then formed anatase-type TiO{sub 2} with thin sheet morphology. H{sub 3}BO{sub 3} as oxygen source can promote the formation of anatase TiO{sub 2}, but decrease the F content in the N-F-TiO{sub 2} materials due to the formation of volatile BF{sub 3} during the precursor decomposition. The photocatalytic activity of the obtained N-F-TiO{sub 2} samples was evaluated by the methylene blue degradation under visible light, and all the samples exhibited much higher photocatalytic activity than P25. Moreover, the merits and disadvantages of this proposed method to prepare doped TiO{sub 2} are discussed.

  17. A brief review of co-doping

    Science.gov (United States)

    Zhang, Jingzhao; Tse, Kinfai; Wong, Manhoi; Zhang, Yiou; Zhu, Junyi

    2016-12-01

    Dopants and defects are important in semiconductor and magnetic devices. Strategies for controlling doping and defects have been the focus of semiconductor physics research during the past decades and remain critical even today. Co-doping is a promising strategy that can be used for effectively tuning the dopant populations, electronic properties, and magnetic properties. It can enhance the solubility of dopants and improve the stability of desired defects. During the past 20 years, significant experimental and theoretical efforts have been devoted to studying the characteristics of co-doping. In this article, we first review the historical development of co-doping. Then, we review a variety of research performed on co-doping, based on the compensating nature of co-dopants. Finally, we review the effects of contamination and surfactants that can explain the general mechanisms of co-doping.

  18. A simple preparation method and characterization of B and N co-doped TiO2 nanotube arrays with enhanced photoelectrochemical performance

    Science.gov (United States)

    Georgieva, J.; Valova, E.; Armyanov, S.; Tatchev, D.; Sotiropoulos, S.; Avramova, I.; Dimitrova, N.; Hubin, A.; Steenhaut, O.

    2017-08-01

    Highly ordered TiO2 nanotube arrays (TNTA) have attracted much attention due to the excellent photocatalytic, optical and electrical properties. However, their absorption range is limited to ultraviolet (UV) spectrum only due to the wide band gap (3.2 eV). One of the strategies to overcome this problem is doping with boron and nitrogen. They are produced via titanium sheet anodization and subsequent electrochemical treatment of titania in an electrolyte containing boric acid. The as-prepared B-TNTA are annealed in N2 atmosphere at 500 °C for 2 h to obtain B,N-TNTA. The samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The B,N-TNTA consist of uniform and well aligned nanotubes with an average inner diameter of 80-100 nm and a length not exceeding 1 μm. The photocurrent response measurements of undoped TNTA, N-doped and B,N-co-doped samples are performed under UV and visible light (Vis) illumination and a comparison is made. The obtained results show that the B,N-doping leads to remarkable photocurrent enhancement and better photocatalytic activity for methyl orange (MO) degradation due to the synergistic effects of B,N-co-doping and lower electron-hole recombination rates.

  19. Biomimetic layer-by-layer deposition assisted synthesis of Cu, N co-doped TiO2 nanosheets with enhanced visible light photocatalytic performance.

    Science.gov (United States)

    Wang, Xiaobo; Yan, Yong; Hao, Bo; Chen, Ge

    2014-10-07

    In this paper, a Cu, N co-doped TiO2 nanosheet with increased visible light photocatalytic activity was successfully synthesized using a biomimetic layer-by-layer deposition process. The polymer, branched-polyethyleneimine (b-PEI) was used as an induction agent for the hydrolysis of titanium bis(ammonium lactato)-dihydroxide (Ti-BALDH) as well as for a nitrogen resource, and the graphene oxide (GO) was used as a two-dimensional nano-template. The positively charged b-PEI will bind to the negatively charged GO and titania. In a typical layer-by-layer deposition process, GO nanosheets are exposed in an alternating fashion to aqueous b-PEI, CuCl2 and Ti-BALDH solutions, thus, making the layer-by-layer deposition of a conformal b-PEI/Cu-Ti-O coating on the GO. Subsequent b-PEI and GO pyrolysis at 550 °C under air yielded Cu, N co-doped TiO2 nanosheets. The materials obtained were comprehensively investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, Raman spectra, photoluminescence spectra and electron paramagnetic resonance. The Cu, N co-doped TiO2 nanosheets showed obviously enhanced photocatalytic activity which was evaluated by degradation of methylene blue under visible light irradiation. This research might provide some new insights for the "green synthesis" of the simultaneous doping of two kinds of foreign atoms into TiO2 with controlled morphology and photocatalytic properties.

  20. Probing the Effects of Templating on the UV and Visible Light Photocatalytic Activity of Porous Nitrogen-Modified Titania Monoliths for Dye Removal.

    Science.gov (United States)

    Nursam, Natalita M; Wang, Xingdong; Tan, Jeannie Z Y; Caruso, Rachel A

    2016-07-13

    Porous nitrogen-modified titania (N-titania) monoliths with tailored morphologies were prepared using phase separation and agarose gel templating techniques. The doping and templating process were simultaneously carried out in a one-pot step using alcohol amine-assisted sol-gel chemistry. The amount of polymer used in the monoliths that were prepared using phase separation was shown to affect both the physical and optical properties: higher poly(ethylene glycol) content increased the specific surface area, porosity, and visible light absorption of the final materials. For the agarose-templated monoliths, the infiltration conditions affected the monolith morphology. A porous monolith with high surface area and the least shrinkage was obtained when the N containing alkoxide precursor was infiltrated into the agarose scaffolds at 60 °C. The effect of the diverse porous morphologies on the photocatalytic activity of N-titania was studied for the decomposition of methylene blue (MB) under visible and UV light irradiation. The highest visible light activity was achieved by the agarose-templated N-titania monolith, in part due to higher N incorporation. This sample also showed better UV activity, partly because of the higher specific surface area (up to 112 m(2) g(-1)) compared to the phase separation-induced monoliths (up to 103 m(2) g(-1)). Overall, agarose-templated, porous N-titania monoliths provided better features for effectively removing the MB contaminant.

  1. Cumulative effect of transition metals on nitrogen and fluorine co-doped graphite nanofibers: an efficient and highly durable non-precious metal catalyst for the oxygen reduction reaction.

    Science.gov (United States)

    Peera, S Gouse; Arunchander, A; Sahu, A K

    2016-08-14

    Nitrogen and fluorine co-doped graphite nanofibers (N/F-GNF) and their cumulative effect with Fe and Co have been developed as an alternative non-precious metal catalyst for efficient oxygen reduction reaction (ORR) in acidic media. The synergistic effect between the doped hetero atoms and the co-ordinated Fe and Co towards ORR activity and durability of the catalyst is deeply investigated. A high ORR onset potential comparable with commercial Pt/C catalyst is observed with the Fe-Co/NF-GNF catalyst, which indicates that this catalyst is a potential alternative to Pt/C. A fivefold increase in mass activity is achieved by the Fe-Co/NF-GNF catalyst compared to the simple N/F-GNF catalyst, which endorses the significant role of transition metal atoms in enhancing ORR activity. The advanced Fe-Co/NF-GNF catalyst also exhibits complete tolerance to CH3OH and CO. The Fe-Co/NF-GNF catalyst also exhibits excellent durability towards the ORR with only a 10 mV negative shift in its half wave potential after a 10 000 repeated potential cycling test, whereas in the case of a commercial Pt/C catalyst there was an ∼110 mV negative shift under similar environmental conditions. More stringent corrosive test cycles were also performed by maintaining the cell as high as 1.4 V with a later decrease to 0.6 V vs. RHE for 300 cycles, which showed the excellent durability of the Fe-Co/NF-GNF catalyst in comparison with the Pt/C catalyst. XPS analysis of the Fe-Co/NF-GNF catalyst presents the ORR active chemical states of N (pyridinic-N and graphitic-N) and F (semi-ionic-F) and the co-ordinated sites of Fe and Co species with the dopants. The excellent performance and durability of the Fe-Co/NF-GNF catalyst is due to the synergistic effect between the hetero atoms dopants (N and F) and strong co-ordinating bonds of M-N-C, which protect the graphene layers around the metallic species and greatly mitigates the leaching of Co and Fe during the long term cycling test. The high activity

  2. Nitrogen-modified nano-titania: True phase composition, microstructure and visible-light induced photocatalytic NOx abatement

    Science.gov (United States)

    Tobaldi, D. M.; Pullar, R. C.; Gualtieri, A. F.; Otero-Irurueta, G.; Singh, M. K.; Seabra, M. P.; Labrincha, J. A.

    2015-11-01

    Titanium dioxide (TiO2) is a popular photocatalyst used for many environmental and anti-pollution applications, but it normally operates under UV light, exploiting ∼5% of the solar spectrum. Nitrification of titania to form N-doped TiO2 has been explored as a way to increase its photocatalytic activity under visible light, and anionic doping is a promising method to enable TiO2 to harvest visible-light by changing its photo-absorption properties. In this paper, we explore the insertion of nitrogen into the TiO2 lattice using our green sol-gel nanosynthesis method, used to create 10 nm TiO2 NPs. Two parallel routes were studied to produce nitrogen-modified TiO2 nanoparticles (NPs), using HNO3+NH3 (acid-precipitated base-peptised) and NH4OH (totally base catalysed) as nitrogen sources. These NPs were thermally treated between 450 and 800 °C. Their true phase composition (crystalline and amorphous phases), as well as their micro-/nanostructure (crystalline domain shape, size and size distribution, edge and screw dislocation density) was fully characterised through advanced X-ray methods (Rietveld-reference intensity ratio, RIR, and whole powder pattern modelling, WPPM). As pollutants, nitrogen oxides (NOx) are of particular concern for human health, so the photocatalytic activity of the NPs was assessed by monitoring NOx abatement, using both solar and white-light (indoor artificial lighting), simulating outdoor and indoor environments, respectively. Results showed that the onset of the anatase-to-rutile phase transformation (ART) occurred at temperatures above 450 °C, and NPs heated to 450 °C possessed excellent photocatalytic activity (PCA) under visible white-light (indoor artificial lighting), with a PCA double than that of the standard P25 TiO2 NPs. However, higher thermal treatment temperatures were found to be detrimental for visible-light photocatalytic activity, due to the effects of four simultaneous occurrences: (i) loss of OH groups and water adsorbed

  3. Mussel-inspired one-pot synthesis of transition metal and nitrogen co-doped carbon (M/N-C) as efficient oxygen catalysts for Zn-air batteries

    Science.gov (United States)

    Li, Bing; Chen, Ye; Ge, Xiaoming; Chai, Jianwei; Zhang, Xiao; Hor, T. S. Andy; Du, Guojun; Liu, Zhaolin; Zhang, Hua; Zong, Yun

    2016-02-01

    Transition metal and nitrogen co-doping into carbon is an effective approach to promote the catalytic activities towards the oxygen reduction reaction (ORR) and/or oxygen evolution reaction (OER) in the resultant electrocatalysts, M/N-C. The preparation of such catalysts, however, is often complicated and in low yield. Herein we report a robust approach for easy synthesis of M/N-C hybrids in high yield, which includes a mussel-inspired polymerization reaction at room temperature and a subsequent carbonization process. With the introduction of selected transition metal salts into an aqueous solution of dopamine (DA), the obtained mixture self-polymerizes to form metal-containing polydopamine (M-PDA) composites, e.g. Co-PDA, Ni-PDA and Fe-PDA. Upon carbonization at elevated temperatures, these metal-containing composites were converted into M/N-C, i.e. Co-PDA-C, Ni-PDA-C and Fe-PDA-C, respectively, whose morphologies, chemical compositions, and electrochemical performances were fully studied. Enhanced ORR activities were found in all the obtained hybrids, with Co-PDA-C standing out as the most promising catalyst with excellent stability and catalytic activities towards both ORR and OER. This was further proven in Zn-air batteries (ZnABs) in terms of discharge voltage stability and cycling performance. At a discharge-charge current density of 2 mA cm-2 and 1 h per cycle, the Co-PDA-C based ZnABs were able to steadily cycle up to 500 cycles with only a small increase in the discharge-charge voltage gap which notably outperformed Pt/C; at a discharge current density of 5 mA cm-2, the battery continuously discharged for more than 540 h with the discharge voltage above 1 V and a voltage drop rate of merely 0.37 mV h-1. With the simplicity and scalability of the synthetic approach and remarkable battery performances, the Co-PDA-C hybrid catalyst is anticipated to play an important role in practical ZnABs.Transition metal and nitrogen co-doping into carbon is an effective

  4. Cobalt and sulfur co-doped nano-size TiO2 for photodegradation of various dyes and phenol

    KAUST Repository

    Siddiqa, Asima

    2015-11-01

    Various compositions of cobalt and sulfur co-doped titania nano-photocatalyst are synthesized via sol–gel method. A number of techniques including X-ray diffraction (XRD), ultraviolet–visible (UV–Vis), Rutherford backscattering spectrometry (RBS), thermal gravimetric analysis (TGA), Raman, N2 sorption, electron microscopy are used to examine composition, crystalline phase, morphology, distribution of dopants, surface area and optical properties of synthesized materials. The synthesized materials consisted of quasispherical nanoparticles of anatase phase exhibiting a high surface area and homogeneous distribution of dopants. Cobalt and sulfur co-doped titania demonstrated remarkable structural and optical properties leading to an efficient photocatalytic activity for degradation of dyes and phenol under visible light irradiations. Moreover, the effect of dye concentration, catalyst dose and pH on photodegradation behavior of environmental pollutants and recyclability of the catalyst is also examined to optimize the activity of nano-photocatalyst and gain a better understanding of the process.

  5. Cobalt and sulfur co-doped nano-size TiO2 for photodegradation of various dyes and phenol.

    Science.gov (United States)

    Siddiqa, Asima; Masih, Dilshad; Anjum, Dalaver; Siddiq, Muhammad

    2015-11-01

    Various compositions of cobalt and sulfur co-doped titania nano-photocatalyst are synthesized via sol-gel method. A number of techniques including X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Rutherford backscattering spectrometry (RBS), thermal gravimetric analysis (TGA), Raman, N2 sorption, electron microscopy are used to examine composition, crystalline phase, morphology, distribution of dopants, surface area and optical properties of synthesized materials. The synthesized materials consisted of quasispherical nanoparticles of anatase phase exhibiting a high surface area and homogeneous distribution of dopants. Cobalt and sulfur co-doped titania demonstrated remarkable structural and optical properties leading to an efficient photocatalytic activity for degradation of dyes and phenol under visible light irradiations. Moreover, the effect of dye concentration, catalyst dose and pH on photodegradation behavior of environmental pollutants and recyclability of the catalyst is also examined to optimize the activity of nano-photocatalyst and gain a better understanding of the process.

  6. Synthesis and characterization of thermally stable Sm,N co-doped TiO2 with highly visible light activity.

    Science.gov (United States)

    Ma, Yunfei; Zhang, Jinlong; Tian, Baozhu; Chen, Feng; Wang, Lingzhi

    2010-10-15

    Samarium and nitrogen co-doped titania (Sm/N-TiO(2)) was successfully prepared via coprecipitation method. The resulting materials were characterized by X-ray diffraction (XRD), N(2) physical adsorption, UV-vis absorbance spectroscopy, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared (FTIR) spectra. Experimental results indicated that samarium doping inhibited the growth of crystalline size and the transformation from anatase to rutile phase. The photocatalytic activities of the samples were evaluated for degradation of salicylic acid under visible light irradiation. It was found that the Sm/N-TiO(2) samples presented much higher photocatalytic activity than N-TiO(2) and pure TiO(2) under visible light irradiation. This could be attributed to the appropriate crystallite size, more efficient separation of electrons and holes on Sm/N-TiO(2). In our experiments, the optimal dopant amount of samarium was 1.5% for the maximum photocatalytic degradation and the sample calcined at 400 degrees C showed the best reactivity.

  7. Synthesis and characterization of thermally stable Sm,N co-doped TiO{sub 2} with highly visible light activity

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yunfei [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Zhang Jinlong, E-mail: jlzhang@ecust.edu.cn [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001 (China); Tian Baozhu; Chen, Feng; Wang Lingzhi [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)

    2010-10-15

    Samarium and nitrogen co-doped titania (Sm/N-TiO{sub 2}) was successfully prepared via coprecipitation method. The resulting materials were characterized by X-ray diffraction (XRD), N{sub 2} physical adsorption, UV-vis absorbance spectroscopy, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared (FTIR) spectra. Experimental results indicated that samarium doping inhibited the growth of crystalline size and the transformation from anatase to rutile phase. The photocatalytic activities of the samples were evaluated for degradation of salicylic acid under visible light irradiation. It was found that the Sm/N-TiO{sub 2} samples presented much higher photocatalytic activity than N-TiO{sub 2} and pure TiO{sub 2} under visible light irradiation. This could be attributed to the appropriate crystallite size, more efficient separation of electrons and holes on Sm/N-TiO{sub 2}. In our experiments, the optimal dopant amount of samarium was 1.5% for the maximum photocatalytic degradation and the sample calcined at 400 deg. C showed the best reactivity.

  8. Preparation and characterization of titania catalyst co-doped with boron, nitrogen, and cerium%B、N和Ce共掺杂TiO2光催化剂的制备及表征

    Institute of Scientific and Technical Information of China (English)

    张鹏会; 李艳春; 王九思

    2015-01-01

    以尿素、硼酸和硝酸铈分别作为氮、硼和铈源,采用溶胶-凝胶法制备出B,N和Ce共掺杂TiO2光催化剂,并用XRD、XPS、FT-IR和SEM等对其进行了表征.以酸性大红染料为污染物,考察其光催化活性.结果表明,所制备的光催化剂均为锐钛矿;B和N元素进入TiO2的晶格,形成了O-Ti-N和B-Ti-O键,而Ce以氧化物(Ce2O3)形式分散于TiO2的表面,抑制了电子-空穴对复合,提高光量子效率,增强了共掺杂TiO2光催化活性.另外,B-N-Ce-TiO2催化剂重复使用10次后,其对大红染料的降解率仍可以达到95%以上.

  9. Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

    Directory of Open Access Journals (Sweden)

    Chun-Hung Huang

    2012-01-01

    Full Text Available A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities of NOx photodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the total NOx removal under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O, which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

  10. Tuning the near-gap electronic structure of Cu2O by anion-cation co-doping for enhanced solar energy conversion

    Science.gov (United States)

    Si, Yuan; Yang, Hao-Ming; Wu, Hong-Yu; Huang, Wei-Qing; Yang, Ke; Peng, Ping; Huang, Gui-Fang

    2017-01-01

    Doping is an effective strategy to tune the electronic properties of semiconductors, but some side effects caused by mono-doping degrade the specific performance of matrixes. As a model system to minimize photoproduced electron-hole pairs recombination by anion-cation co-doping, we investigate the electronic structures and optical properties of (Fe+N) co-doped Cu2O using the first-principles calculations. Compared to the case of mono-doping, the FeCuNO (a Fe (N) atom substituting a Cu (O) atom) co-doping reduces the energy cost of doping as a consequence of the charge compensation between the iron and nitrogen impurities, which eliminates the isolated levels (induced by mono-dopant) in the band gap. Interestingly, it is found that the contributions of different host atoms (Cu and O) away from anion (N) and cation (Fe) dopants to the variation of near band gap electronic structure of the co-doped Cu2O are different. Moreover, co-doping reduces the band gap and increases the visible-light absorption of Cu2O. Both band gap reduction and low recombination rate are critical elements for efficient light-to-current conversion in co-doped semiconductor photocatalysts. These findings raise the prospect of using co-doped Cu2O with specifically engineered electronic properties in a variety of solar applications.

  11. Co-doping as a tool for tuning the optical properties of singlewalled carbon nanotubes: A first principles study

    Science.gov (United States)

    Sharma, Deepa; Jaggi, Neena

    2017-07-01

    This paper presents a first principles study on the effect of co-doping on various optical spectra of a zigzag single-walled carbon nanotube (SWCNT). Optical spectra of a pristine SWCNT, SWCNT co-doped with Aluminum (Al) & Phosphorus (P) and another one co-doped with Al, P and Nitrogen (N) have been calculated using density functional theory (DFT).The theory has been implemented using the Cambridge sequential total energy package (CASTEP) code available as a userfriendly module with the software 'Material Studio'. Polarized and unpolarized light as well as light through polycrystalline media have been considered. The dependence of various spectra on the status of incident light presents a clear evidence of anisotropicity in the optical properties. Analysis of the simulated spectra involves calculation and comparison of different optical properties like dielectric function, reflectivity, refractive index, conductivity and loss function for the pristine and co-doped SWCNTs. Noticeable variations are observed in the optical properties on simultaneously doping the SWCNT with Al and P and then further introducing N atom into the structure so that it can be concluded that co-doping (simultaneous doping with different combinations of dopants) can be evolved as a novel and effective tool for tailoring the optical properties of SWCNTs as per the requirements while designing an optical device. It will prove to be highly significant for effective designing of SWCNT based sensitive optical devices for a variety of technological applications.

  12. Water disinfection through photoactive modified titania.

    Science.gov (United States)

    Sethi, Diptipriya; Pal, Ajoy; Sakthivel, Ramasamy; Pandey, Sony; Dash, Tapan; Das, Trupti; Kumar, Rohit

    2014-01-05

    TiO(2), N-TiO(2) and S-TiO(2) samples have been prepared by various chemical methods. These samples were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Laser Raman spectrometer, UV-Visible spectrophotometer, field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). X-ray powder diffraction study reveals that all three samples are single anatase phase of titania and the crystallinity of titania decreases with sulphur doping whereas nitrogen doping does not affect it. UV-Visible (diffuse) reflectance spectra shows that doping of titania with nitrogen and sulphur shift the absorption edge of titania from ultraviolet to visible region. XPS study confirms that both nitrogen and sulphur are well doped in the titania lattice. It is observed that nitrogen occupies at both substitutional and interstitial position in the lattice of titania. FE-SEM and TEM studies demonstrate that the particles are below 50nm range. It is found that S and N doping of titania increased its water disinfection property in the order TiO(2)UV-Visible light irradiation.

  13. Nitrogen-modified nano-titania: True phase composition, microstructure and visible-light induced photocatalytic NO{sub x} abatement

    Energy Technology Data Exchange (ETDEWEB)

    Tobaldi, D.M., E-mail: david.tobaldi@ua.pt [Department of Materials and Ceramic Engineering / CICECO−Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Pullar, R.C. [Department of Materials and Ceramic Engineering / CICECO−Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Gualtieri, A.F. [Dipartimento di Scienze Chimiche e Geologiche, Università degli studi di Modena e Reggio Emilia, I-41121 Modena (Italy); Otero-Irurueta, G.; Singh, M.K. [Center for Mechanical Technology and Automation – TEMA, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Seabra, M.P.; Labrincha, J.A. [Department of Materials and Ceramic Engineering / CICECO−Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal)

    2015-11-15

    Titanium dioxide (TiO{sub 2}) is a popular photocatalyst used for many environmental and anti-pollution applications, but it normally operates under UV light, exploiting ∼5% of the solar spectrum. Nitrification of titania to form N-doped TiO{sub 2} has been explored as a way to increase its photocatalytic activity under visible light, and anionic doping is a promising method to enable TiO{sub 2} to harvest visible-light by changing its photo-absorption properties. In this paper, we explore the insertion of nitrogen into the TiO{sub 2} lattice using our green sol–gel nanosynthesis method, used to create 10 nm TiO{sub 2} NPs. Two parallel routes were studied to produce nitrogen-modified TiO{sub 2} nanoparticles (NPs), using HNO{sub 3}+NH{sub 3} (acid-precipitated base-peptised) and NH{sub 4}OH (totally base catalysed) as nitrogen sources. These NPs were thermally treated between 450 and 800 °C. Their true phase composition (crystalline and amorphous phases), as well as their micro-/nanostructure (crystalline domain shape, size and size distribution, edge and screw dislocation density) was fully characterised through advanced X-ray methods (Rietveld-reference intensity ratio, RIR, and whole powder pattern modelling, WPPM). As pollutants, nitrogen oxides (NO{sub x}) are of particular concern for human health, so the photocatalytic activity of the NPs was assessed by monitoring NO{sub x} abatement, using both solar and white-light (indoor artificial lighting), simulating outdoor and indoor environments, respectively. Results showed that the onset of the anatase-to-rutile phase transformation (ART) occurred at temperatures above 450 °C, and NPs heated to 450 °C possessed excellent photocatalytic activity (PCA) under visible white-light (indoor artificial lighting), with a PCA double than that of the standard P25 TiO{sub 2} NPs. However, higher thermal treatment temperatures were found to be detrimental for visible-light photocatalytic activity, due to the effects

  14. Structural Formation and Photocatalytic Activity of Magnetron Sputtered Titania and Doped-Titania Coatings

    Directory of Open Access Journals (Sweden)

    Peter J. Kelly

    2014-10-01

    Full Text Available Titania and doped-titania coatings can be deposited by a wide range of techniques; this paper will concentrate on magnetron sputtering techniques, including “conventional” reactive co-sputtering from multiple metal targets and the recently introduced high power impulse magnetron sputtering (HiPIMS. The latter has been shown to deliver a relatively low thermal flux to the substrate, whilst still allowing the direct deposition of crystalline titania coatings and, therefore, offers the potential to deposit photocatalytically active titania coatings directly onto thermally sensitive substrates. The deposition of coatings via these techniques will be discussed, as will the characterisation of the coatings by XRD, SEM, EDX, optical spectroscopy, etc. The assessment of photocatalytic activity and photoactivity through the decomposition of an organic dye (methylene blue, the inactivation of E. coli microorganisms and the measurement of water contact angles will be described. The impact of different deposition technologies, doping and co-doping strategies on coating structure and activity will be also considered.

  15. Encapsulation of Fe3O4 Nanoparticles into N, S co-Doped Graphene Sheets with Greatly Enhanced Electrochemical Performance

    Science.gov (United States)

    Yang, Zunxian; Qian, Kun; Lv, Jun; Yan, Wenhuan; Liu, Jiahui; Ai, Jingwei; Zhang, Yuxiang; Guo, Tailiang; Zhou, Xiongtu; Xu, Sheng; Guo, Zaiping

    2016-01-01

    Particular N, S co-doped graphene/Fe3O4 hybrids have been successfully synthesized by the combination of a simple hydrothermal process and a subsequent carbonization heat treatment. The nanostructures exhibit a unique composite architecture, with uniformly dispersed Fe3O4 nanoparticles and N, S co-doped graphene encapsulant. The particular porous characteristics with many meso/micro holes/pores, the highly conductive N, S co-doped graphene, as well as the encapsulating N, S co-doped graphene with the high-level nitrogen and sulfur doping, lead to excellent electrochemical performance of the electrode. The N-S-G/Fe3O4 composite electrode exhibits a high initial reversible capacity of 1362.2 mAhg−1, a high reversible specific capacity of 1055.20 mAhg−1 after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 556.69 mAhg−1 when cycled at the current density of 1000 mAg−1, indicating that the N-S-G/Fe3O4 composite is a promising anode candidate for Li-ion batteries. PMID:27296103

  16. Encapsulation of Fe3O4 Nanoparticles into N, S co-Doped Graphene Sheets with Greatly Enhanced Electrochemical Performance

    Science.gov (United States)

    Yang, Zunxian; Qian, Kun; Lv, Jun; Yan, Wenhuan; Liu, Jiahui; Ai, Jingwei; Zhang, Yuxiang; Guo, Tailiang; Zhou, Xiongtu; Xu, Sheng; Guo, Zaiping

    2016-06-01

    Particular N, S co-doped graphene/Fe3O4 hybrids have been successfully synthesized by the combination of a simple hydrothermal process and a subsequent carbonization heat treatment. The nanostructures exhibit a unique composite architecture, with uniformly dispersed Fe3O4 nanoparticles and N, S co-doped graphene encapsulant. The particular porous characteristics with many meso/micro holes/pores, the highly conductive N, S co-doped graphene, as well as the encapsulating N, S co-doped graphene with the high-level nitrogen and sulfur doping, lead to excellent electrochemical performance of the electrode. The N-S-G/Fe3O4 composite electrode exhibits a high initial reversible capacity of 1362.2 mAhg‑1, a high reversible specific capacity of 1055.20 mAhg‑1 after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 556.69 mAhg‑1 when cycled at the current density of 1000 mAg‑1, indicating that the N-S-G/Fe3O4 composite is a promising anode candidate for Li-ion batteries.

  17. Experimental Studies on Doped and Co-Doped ZnO Thin Films Prepared by RF Diode Sputtering

    OpenAIRE

    2009-01-01

    Our research on the growing and characterizing of p-type ZnO thin films, prepared by radio frequency (RF) diode sputtering, mono-doped with nitrogen, and co-doped with aluminium and nitrogen, is a response of the need from p-type ZnO thin films for device applications. The dopants determine the conductivity type of the film and its physical properties. We obtained p-type ZnO thin films by RF diode sputtering and using a nitrogen dopant source. The novelty in our approach is in the use of a pl...

  18. Absence of dipolar ordering in Co doped CuO

    Science.gov (United States)

    Chaudhary, N. Vijay Prakash; Murthy, J. Krishna; Venimadhav, A.

    2016-12-01

    Polycrystalline CuO samples with Co doping were prepared by solid state method with flowing oxygen condition and examined their structural and multiferroic properties. Structural studies have confirmed single phase monoclinic crystal structure of all samples, however, in Co doped samples a decrease in volume with an increase in monoclinic distortion is found. For pristine sample, temperature dependent magnetization has confirmed two antiferromagnetic (AFM) transitions at 213 K and 230 K and frequency independent dielectric peaks at these AFM transitions suggesting the ferroelectric nature. Magnetization of the Co doped samples has showed a marginal increase in ordering temperature of the high-temperature AFM transition and decrease in low temperature AFM ordering temperature. Further, doped samples have shown giant dielectric constant with no signature of ferroelectricity. The X-ray photoelectric spectroscopy study has revealed multiple valance states for both Co and Cu in the doped samples that simultaneously explain the giant dielectric constant and suppression of ferroelectric order.

  19. Cellular attachment and differentiation on titania nanotubes exposed to air- or nitrogen-based non-thermal atmospheric pressure plasma.

    Science.gov (United States)

    Seo, Hye Yeon; Kwon, Jae-Sung; Choi, Yu-Ri; Kim, Kwang-Mahn; Choi, Eun Ha; Kim, Kyoung-Nam

    2014-01-01

    The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ), elicited from one of two different gas sources (nitrogen and air), to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in cellular activity

  20. Cellular attachment and differentiation on titania nanotubes exposed to air- or nitrogen-based non-thermal atmospheric pressure plasma.

    Directory of Open Access Journals (Sweden)

    Hye Yeon Seo

    Full Text Available The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ, elicited from one of two different gas sources (nitrogen and air, to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in

  1. First-principles calculation of nitrogen-tungsten codoping effects on the band structure of anatase-titania

    OpenAIRE

    2009-01-01

    The electronic properties and photocatalytic activity of nitrogen (N) and/or tungsten (W)-doped anatase are calculated using density functional theory. For N-doping, isolated N 2p states above the top of the valence band are responsible for experimentally observed redshifts in the optical absorption edge. For W-doping, W 5d states below the conduction band lead to band gap narrowing; the transition energy is reduced by 0.2 eV. Addition of W to the N-doped system yields significant band gap na...

  2. Photoluminescence properties of Co-doped ZnO nanocrystals

    DEFF Research Database (Denmark)

    Lommens, P.; Smet, P.F.; De Mello Donega, C.

    2006-01-01

    We performed photoluminescence experiments on colloidal, Co -doped ZnO nanocrystals in order to study the electronic properties of Co in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co dopant. The spectral posit...

  3. Photocatalytic degradation of coking wastewater by nanocrystalline (Fe,N) co-doped TiO2 powders

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The yellowish nitrogen and iron co-doped nanocrystalline titanium dioxide ((Fe,N) co-doped TiO2) powders have been prepared by hydrothermal method using TiOSO4 and CO(NH2)2 as starting materials.The grain size of the synthesized powders was estimated as 11 nm by Scherrer’s method.The UV-Vis diffuse reflectance spectra indicated that the light absorption edge of the powders was red-shifted up to 605 nm.And the doped TiO2 powders exhibited good photocatalytic activities during the photo-degradation of coking wastewater under sunshine irradiation.The biotreatability of the coking wasterwater after photocatalytic degradation was improved greatly and it is more suitable to be further treated by biochemical method.

  4. Up-conversion luminescence in Yb(3+)-Er(3+)/Tm(3+) co-doped Al2O3-TiO2 nano-composites.

    Science.gov (United States)

    Mokoena, Teboho Patrick; Linganiso, Ella Cebisa; Kumar, Vinod; Swart, Hendrik C; Cho, So-Hye; Ntwaeaborwa, Odireleng Martin

    2017-06-15

    The sol gel method was used to prepare rare-earths (Yb(3+)-Er(3+) and Yb(3+)-Tm(3+)) co-doped Al2O3-TiO2 nano-composite powder phosphors and their up-conversion luminescence properties were investigated. Mixed oxides of titania (TiO2) rutile phase and an early stage crystallization of alumina (Al2O3) phase were confirmed from the X-ray diffraction data with the average crystallite size of ∼36nm. The rutile phase TiO2 was further confirmed by selected area diffraction analysis of the composites. Microscopy analysis showed interesting rod-like morphologies with rough surfaces indicating that a spherulitic growth process took place during the crystal growth. Photoluminescence characterization of the phosphors was carried out under near infra-red excitation at 980nm and the prominent emission bands were observed in the visible region at 523, 548 and 658nm for the Yb(3+)-Er(3+) co-doped systems. Emission in bands extending from the visible to near infra-red regions were observed at 480, 650, 693 and 800nm for the Yb(3+)-Tm(3+) co-doped systems. These upconverted emissions and energy transfer mechanisms taking place are discussed in detail.

  5. Magnetic properties of gadolinium and carbon co-doped gallium nitride

    Science.gov (United States)

    Syed Kaleemullah, N.; Ramsubramanian, S.; Mohankumar, R.; Munawar Basha, S.; Rajagopalan, M.; Kumar, J.

    2017-01-01

    Investigations have been carried out to study the ferromagnetic properties of Gadolinium (Gd) Carbon (C) co-doped wurtzite Gallium Nitride (GaN) using full-potential linear augmented plane wave (FP-LAPW) method within the density functional theory. The system shows half-metallic nature when single Gd is substituted in Ga36N36 supercell. The presence of carbon in GaN supercell is found to generate weak magnetic moment (Ms) in the neighbouring atoms. When Carbon is codoped in the Gd-GaN, it increased the total magnetic moment of the system (Mtot). The cause of ferromagnetism in the Gd and C co-doped GaN has been explained by Zener's p-d exchange mechanism. The role of defects in the magnetic property of this system is also investigated. The results indicate the gallium vacancy influences the magnetic moment of the Gd and C codoped GaN more than the nitrogen vacancy. The presence of holes is effective than electrons in achieving the ferromagnetism in the considered system.

  6. 一步合成硫、氮共掺杂的碳量子点及其在Fe3+检测中的应用%One-step Synthesis of Sulfur-and Nitrogen-co-doped Carbon Quantum Dots for Fe(Ⅲ) Detection

    Institute of Scientific and Technical Information of China (English)

    张文宇; 常青; 周雨锋; 魏志佳; 李凯凯; 胡胜亮

    2016-01-01

    碳量子点的光致发光性质不仅决定于尺寸还依赖于它的表面态,因此通过在碳量子点表面掺杂或嫁接不同元素与基团有望调节它的荧光发射行为。为了研究多种元素掺杂对碳量子点发光性质的影响,本文以对氨基苯磺酸为原料,通过水热法一步合成了氮、硫共掺杂的碳量子点。实验结果表明:制备的碳量子点尺寸分布均匀,氮、硫分别以氨基和磺酸基团的形式存在于碳量子点的表面。与已有的报道不同,碳量子点展现出了非激发波长依赖的蓝光发射行为,三价铁离子可有效猝灭其荧光,铁离子浓度在0~10-3 mol·L-1范围内与碳量子点的荧光猝灭程度呈现良好的线性关系,检出限约为10-7 mol·L-1。制备的碳量子点对三价铁离子具有高选择性、高灵敏性以及较好的抗干扰能力,能作为三价铁离子检测的传感器。%Not only do the photoluminescence ( PL) properties of carbon quantum dots ( CQDs) de-pend on their sizes, but also rely on their surface states. Accordingly, the PL behaviors of CQDs could be tuned by doping and/or grafting heteroatoms and groups. In this work, sulfur-and nitrogen-co-doped carbon quantum dots ( SN-CQDs) were firstly synthesized by one-step hydrothermal meth-od using p-aminobenzenesulfonicacid as carbon source. Experimental results indicate that the ob-tained SN-CQDs have a uniform size and are modified by amine and sulphonic acid groups at their surface. Unlike previous reports, the SN-CQDs show the excitation-wavelength-independent photolu-minescence behavior and their fluorescence can be quenched by Fe3+ ions. There is a good linear relationship between the Fe3+ concentrations within 0-10 -3 mol·L-1 and the fluorescence quench-ing rates of SN-CQDs. The detecting limit for Fe3+ ions is about 10 -7 mol·L-1 . The obtained SN-CQDs have the ability of high selectivity, high sensitivity and good anti-jamming capability to ferric

  7. Comparative study of titania nanoparticles and nanotubes as antibacterial agents

    Science.gov (United States)

    Jing, Zhihong; Guo, Daojun; Wang, Weihua; Zhang, Shufang; Qi, Wei; Ling, Baoping

    2011-09-01

    Anatase titania nanoparticles with a high surface area (about 587.7 m 2/g) were synthesized by sol-gel method using isobutyl alcohol as solvent, and then anatase titania nanotubes with needlelike shape, which had diameters of about 5 nm and wall thickness of about 1 nm, could be obtained by microwave process using the above titania nanoparticles as precursors. Both titania nanoparticles and nanotubes were characterized through X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, photoluminescence spectroscopy and nitrogen adsorption-desorption isotherm technique. The antibacterial activities of both titania nanoparticles and nanotubes against Escherichia coli ( E. coli) were developed by quantification and qualitative ways, e.g. microcalorimetric method and disk diffusion method. At the same time, their antibacterial activities against E. coli were also investigated in dark and under UV irradiation. As a result, both the titania nanoparticles and nanotubes had good antibacterial activities against E. coli due to their low inhibitory concentration and large diameter of antibacterial circle. In addition, the titania nanoparticles displayed higher antibacterial activities than those of the titania nanotubes under UV irradiation, though they presented similar antibacterial activities in dark. The differences in antibacterial activities between titania nanoparticles and nanotubes might be attributed to the changes of their microstructure in our works.

  8. Yellow luminescence of co-doped gadolinium oxyhydroxide

    Institute of Scientific and Technical Information of China (English)

    Hiroaki Samata; Shungo Imanaka; Masashi Hanioka; Tadashi C Ozawa

    2015-01-01

    Crystals of co-doped gadolinium oxyhydroxide (GdOOH), Gd0.98Eu0.02−xTbxOOH and Gd1−y−zDyyBizOOH, were synthe-sized by a flux method. The color coordinates in the Commission Internationale de I’Eclairage (CIE) chromaticity diagram of Gd0.98Eu0.02−xTbxOOH, obtained under 254 nm irradiation, shifted along a straight line with the changing values ofxto include the yellow region. The CIE coordinates of Dy3+ doped in GdOOH were located in the yellow region, while the emission intensity of Dy3+ under 286 nm irradiation increased by more than 40 times when co-doped with Bi3+.

  9. Photocatalysis Activity and Physicochemical Structure of Titanium Dioxide Co-doped with N and B

    Institute of Scientific and Technical Information of China (English)

    YAN Gui-Yang; ZHENG Liu-Ping; LIN Shen; YE Jin-Hua

    2008-01-01

    Titanium dioxide co-doped with N and B was prepared by sol-gel method. The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible light. Its physicochemical properties were characterized by means of UV-Vis DRS, XRD, FT-IR, and XPS. The results indicated that N-B-TiO2 has good activity to the photodegradation of MB. Its decolourizing rate of methylene blue solution goes up to 98.4% under the visible light irradiation with 5 h. The doping nitrogen forms N-Ti-O and boron primarily existing in oxide appears in the N-B-TiO2 sample. They response for visible light of TiO2 was also exploited.

  10. Co-doped sodium chloride crystals exposed to different irradiation temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Morales, A. [Unidad Profesional Interdisciplinaria de Ingenieria y Tecnologias Avanzadas, IPN, Av. Instituto Politecnico Nacional 2580, Col. La Laguna Ticoman, 07340 Mexico D.F., Mexico and Unidad de Irradiacion y Segurid (Mexico); Cruz-Zaragoza, E.; Furetta, C. [Unidad de Irradiacion y Seguridad Radiologica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F (Mexico); Kitis, G. [Nuclear Physics Laboratory, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Flores J, C.; Hernandez A, J.; Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP. 20-364, 01000 Mexico D.F (Mexico)

    2013-07-03

    Monocrystals of NaCl:XCl{sub 2}:MnCl{sub 2}(X = Ca,Cd) at four different concentrations have been analyzed. The crystals were exposed to different irradiation temperature, such as at room temperature (RT), solid water (SW), dry ice (DI) and liquid nitrogen (LN). The samples were irradiated with photon from {sup 60}Co irradiators. The co-doped sodium chloride crystals show a complex structure of glow curves that can be related to different distribution of traps. The linearity response was analyzed with the F(D) index. The F(D) value was less than unity indicating a sub-linear response was obtained from the TL response on the function of the dose. The glow curves were deconvoluted by using the CGCD program based on the first, second and general order kinetics.

  11. Significant enhancement in the photocatalytic activity of N, W co-doped TiO2 nanomaterials for promising environmental applications.

    Science.gov (United States)

    Thind, Sapanbir S; Wu, Guosheng; Tian, Min; Chen, Aicheng

    2012-11-30

    In this work, a mesoporous N, W co-doped TiO(2) photocatalyst was synthesized via a one-step solution combustion method, which utilized urea as the nitrogen source and sodium tungstate as the tungsten source. The photocatalytic activity of the N, W co-doped TiO(2) photocatalyst was significantly enhanced by a facile UV pretreatment approach and was evaluated by measuring the rate of photodegradation of Rhodamine B under both UV and visible (λ > 420) light. Following the UV pretreatment, the UV photocatalytic activity of the N, W co-doped TiO(2) was doubled. In terms of visible light activity, the UV pretreatment resulted in an extraordinary >12 fold improvement. In order to gain insight into this substantial enhancement, the N, W co-doped TiO(2) photocatalysts were studied using x-ray diffraction, transmission electron microscopy, N(2) physisorption, UV-vis absorbance spectroscopy and x-ray photoelectron spectroscopy prior to and following the UV pretreatment. Our experimental results have revealed that this significant augmentation of photocatalytic activity may be attributed to several synergetic factors, including increase of the specific surface area, reduction of the band gap energy and the removal of carbon impurities.

  12. Visible light-responded C, N and S co-doped anatase TiO{sub 2} for photocatalytic reduction of Cr(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Lei, X.F., E-mail: leixuefei69@163.com [School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China); Institute of Metallurgical Resource and Environmental Engineering, Northeastern University, Shenyang 110819 (China); Liaoning Key Laboratory of Metallurgical Resource Recycling Science, Shenyang 110819 (China); Liaoning Engineering and Technology Research Center of Boron Resource, Comprehensive, Utilization, Shenyang 110819 (China); Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological, Utilization, Technology and Boron Materials, Shenyang 110819 (China); Xue, X.X.; Yang, H. [Institute of Metallurgical Resource and Environmental Engineering, Northeastern University, Shenyang 110819 (China); Liaoning Key Laboratory of Metallurgical Resource Recycling Science, Shenyang 110819 (China); Liaoning Engineering and Technology Research Center of Boron Resource, Comprehensive, Utilization, Shenyang 110819 (China); Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological, Utilization, Technology and Boron Materials, Shenyang 110819 (China); Chen, C.; Li, X.; Pei, J.X.; Niu, M.C.; Yang, Y.T.; Gao, X.Y. [School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China)

    2015-10-15

    The (C, N and S) co-doped TiO{sub 2} (TH-TiO{sub 2}) samples were synthesized by a sol-gel method calcined at 500 °C, employing butyl titanate as the titanium source and thiourea as the dopant. The structures of TH-TiO{sub 2} samples were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), photoluminescence (PL) spectroscopy, Thermo gravimetry and differential thermal analysis (TG-DTA), Scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherms. The photocatalytic activities were checked through the photocatalytic reduction of Cr(VI) as a model compound under visible light irradiation. The results showed that the thiourea content played an important role on the microstructure and photocatalytic activity of the samples. According to XPS results, (C, N and S) atoms were successfully co-doped into the nanostructures of TH-TiO{sub 2} samples. TH-TiO{sub 2} samples with thiourea: Ti molar ratio of 1.5 exhibits higher photocatalytic activity than that of the other samples under visible light irradiation, which can be attributed to the synergic effect of the pure anatase structure, the higher light absorption characteristics in visible regions, separation efficiency of electron–hole pairs, the specific surface area and the optimum (C, N and S) content. - Graphical abstract: (C, N and S) co-doped TiO{sub 2} samples show good photocatalytic activity for Cr (VI) reduction under visible light irradiation. - Highlights: • (C, N and S) co-doping in TH-TiO{sub 2} samples can promote the formation of the pure anatase structure. • (C, N and S) atoms were successfully co-doped into the nanostructures of TH-TiO{sub 2} samples. • The band gap energy of TH-TiO{sub 2} samples reduced after (C, N and S) co-doping. • (C, N and S) co-doped TiO{sub 2} samples were effective for the photocatalytic reduction of Cr(VI) under visible light

  13. Controlled fabrication of oriented co-doped ZnO clustered nanoassemblies.

    Science.gov (United States)

    Barick, K C; Aslam, M; Dravid, Vinayak P; Bahadur, D

    2010-09-01

    Clustered nanoassemblies of Mn doped ZnO and co-doped ZnO (Mn, Sn co-doped ZnO; Mn, Sb co-doped ZnO; and Mn, Bi co-doped ZnO) were prepared by refluxing their respective precursors in diethylene glycol medium. The co-doping elements, Sn, Sb and Bi exist in multi oxidation states by forming Zn-O-M (M=Sb, Bi and Sn) bonds in hexagonal wurtzite nanostructure. The analyses of detailed structural characterization performed by XRD, X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), show that co-doping ions are successfully incorporated into the ZnO nanostructure and do not appear as precipitates or secondary phases. HRTEM analysis also confirmed the oriented attachment of nanocrystals as well as their defect structures. The formation/activation of higher amount of intrinsic host defects, for instance, oxygen vacancies in co-doped ZnO as compared to Mn doped ZnO sample is evident from Raman spectra. The doped and co-doped samples exhibit ferromagnetic like behavior at room temperature presumably due to the presence of defects. Specifically, it has been observed that the incorporation of dopant and co-dopants into ZnO structure can modulate the local electronic structure due to the formation/activation of defects and hence, cause significant changes in their structural, vibrational, optical and magnetic properties.

  14. Superconductivity in Co-doped SmFeAsO

    Energy Technology Data Exchange (ETDEWEB)

    Qi Yanpeng; Gao Zhaoshun; Wang Lei; Wang Dongliang; Zhang Xianping; Ma Yanwei [Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, PO Box 2703, Beijing 100190 (China)], E-mail: ywma@mail.iee.ac.cn

    2008-11-15

    Here we report the synthesis and characterizations of SmFe{sub 1-x}Co{sub x}AsO (x = 0.10, 0.15) for the first time. The parent compound SmFeAsO itself is not superconducting but shows an antiferromagnetic order near 150 K, which must be suppressed by doping before superconductivity emerges. With Co doping in the FeAs planes, antiferromagnetic order is destroyed and superconductivity occurs at 15.2 K. Similar to LaFe{sub 1-x}Co{sub x}AsO, the SmFe{sub 1-x}Co{sub x}AsO system appears to tolerate considerable disorder in the FeAs planes. This result is important, suggesting a different mechanism for cuprate superconductors compared to the iron-based arsenide ones.

  15. Effect of calcination temperature on the structure and visible-light photocatalytic activities of (N, S and C) co-doped TiO2 nano-materials

    Science.gov (United States)

    Lei, X. F.; Xue, X. X.; Yang, H.; Chen, C.; Li, X.; Niu, M. C.; Gao, X. Y.; Yang, Y. T.

    2015-03-01

    The (N, S and C) co-doped TiO2 samples (NSC-TiO2) were synthesized by the sol-gel method combining with the high energy ball milling method calcined at the different temperature (400-700 °C), employing butyl titanate as the titanium source and thiourea as the doping agent. The structures of NSC-TiO2 samples were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), X-ray photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption isotherms. The photocatalytic activities were checked through the photocatalytic reduction of Cr(VI) as a model compound under visible light irradiation. The results showed that the (N, S and C) co-doping and the calcination temperature played important role on the microstructure and photocatalytic activity of the samples. According to XPS spectra, sulfur was mainly attributed to the Tisbnd Osbnd S bond; nitrogen was ascribed to the Tisbnd Osbnd N and Tisbnd N bonds; carbon was assigned to the Tisbnd Osbnd C bond in the NSC-TiO2 samples. (N, S and C) co-doped TiO2 samples calcinated at 500 °C exhibits higher photocatalytic activity than that of the other samples under visible light irradiation, which can be attributed to the synergic effect of its enhancing crystallization of anatase and (N, S and C) co-doping.

  16. Effect of oxygen vacancy defect on the magnetic properties of Co-doped ZnO

    Institute of Scientific and Technical Information of China (English)

    Weng Zhen-Zhen; Zhang Jian-Min; Huang Zhi-Gao; Lin Wen-Xiong

    2011-01-01

    The influence of oxygen vacancy on the magnetism of Co-doped ZnO has been investigated by the first-principles calculations. It is suggested that oxygen vacancy and its location play crucial roles on the magnetic properties of Co-doped ZnO. The exchange coupling mechanism should account for the magnetism in Co-doped ZnO with oxygen vacancy and the oxygen vacancy is likely to be close to the Co atom. The oxygen vacancy (doping electrons) might be available for carrier mediation but is localized with a certain length and can strengthen the ferromagnetic exchange interaction between Co atoms.

  17. Dynamics of iron-acceptor-pair formation in co-doped silicon

    Energy Technology Data Exchange (ETDEWEB)

    Bartel, T.; Gibaja, F.; Graf, O.; Gross, D.; Kaes, M.; Heuer, M.; Kirscht, F. [Calisolar GmbH, Magnusstrasse 11, 12489 Berlin (Germany); Möller, C. [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany); TU Ilmenau, Institut für Physik, Weimarer Str. 32, 98693 Ilmenau (Germany); Lauer, K. [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany)

    2013-11-11

    The pairing dynamics of interstitial iron and dopants in silicon co-doped with phosphorous and several acceptor types are presented. The classical picture of iron-acceptor pairing dynamics is expanded to include the thermalization of iron between different dopants. The thermalization is quantitatively described using Boltzmann statistics and different iron-acceptor binding energies. The proper understanding of the pairing dynamics of iron in co-doped silicon will provide additional information on the electronic properties of iron-acceptor pairs and may become an analytical method to quantify and differentiate acceptors in co-doped silicon.

  18. Photocatalytic activity of La, Y Co-doped TiO2 nanoparticles synthesized by ultrasonic assisted sol-gel method.

    Science.gov (United States)

    Gao, Hongtao; Liu, Wenchao; Lu, Bing; Liu, Fangfang

    2012-05-01

    Bare TiO2 (T), La-doped TiO2 (LT), Y-doped TiO2 (YT), La, Y co-doped TiO2 (LYT) were successfully prepared by facile ultrasonic assisted sol-gel synthesis using Ti(OC4H9)4 as the precursor. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectra (DRS), and X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic activities of anatase samples, with the average particle diameters ranging from 14 nm to 21 nm, were evaluated for photodegradation of methyl orange (MO). The XPS results indicated that Y atoms were incorporated into titania lattice, while La atoms existed on the crystal surface. Due to doping, the optical absorption edges of LT, YT, and LYT shifted to the visible light region by 21 nm, 29 nm and 35 nm, respectively. The photocatalytic performances of the doped samples, such as LT, YT and LYT, were much higher than that of bare TiO2 under UV-visible light irradiation. And the photoreactivity efficiency of the LYT was the highest. It indicated that a strong La-Y synergistic interaction appeared to play a decisive role in driving the excellent photocatalytic performance of titania.

  19. Phosphorus/sulfur Co-doped porous carbon with enhanced specific capacitance for supercapacitor and improved catalytic activity for oxygen reduction reaction

    Science.gov (United States)

    Zhou, Yao; Ma, Ruguang; Candelaria, Stephanie L.; Wang, Jiacheng; Liu, Qian; Uchaker, Evan; Li, Pengxi; Chen, Yongfang; Cao, Guozhong

    2016-05-01

    Phosphorus (P)/sulfur (S) co-doped porous carbon derived from resorcinol and furaldehyde are synthesized through one-step sol-gel processing with the addition of phosphorus pentasulfide as P and S source followed with freeze-drying and pyrolysis in nitrogen. The P/S co-doping strategy facilitates the pore size widening both in micropore and mesopore regions, together with the positive effect on the degree of graphitization of porous carbon through elimination of amorphous carbon through the formation and evaporation of carbon disulfide. As an electrode for supercapacitor application, P/S co-doped porous carbon demonstrates 43.5% improvement on specific capacitance of the single electrode compared to pristine porous carbon in organic electrolyte at a current of 0.5 mA due to the P-induced pseudocapacitive reactions. As for electrocatalytic use, promoted electrocatalytic activity and high resistance to crossover effects of oxygen reduction reaction (ORR) in alkaline media are observed after the introduction of P and S into porous carbon. After air activation, the specific capacitance of the single electrode of sample PS-pC reaches up to 103.5 F g-1 and an improved oxygen reduction current density.

  20. Preparation and Characterization of Mn/N Co-Doped TiO2 Loaded on Wood-Based Activated Carbon Fiber and Its Visible Light Photodegradation

    Directory of Open Access Journals (Sweden)

    Xiaojun Ma

    2015-09-01

    Full Text Available Using MnSO4·H2O as manganese source and urea as nitrogen source, Mn/N co-doped TiO2 loaded on wood-based activated carbon fiber (Mn/Ti-N-WACF was prepared by sol–gel method. Mn/Ti-N-WACF with different Mn doping contents was characterized by scanning electron microscopy, X-ray diffraction (XRD and X-ray photoelectron spectroscopies (XPS, and ultraviolet-visible spectrophotometer. Results showed that the loading rate of TiO2 in Mn/Ti-N-WACF was improved by Mn/N co-doping. After calcination at 450 °C, the degree of crystallinity of TiO2 was reduced due to Mn/N co-doption in the resulting Mn/Ti-N-WACF samples, but the TiO2 crystal phase was not changed. XPS spectra revealed that some Ti4+ ions from the TiO2 lattice of Mn/Ti-N-WACF system were substituted by doped Mn. Moreover, new bonds formed within N–Ti–N and Ti–N–O because of the doped N that substituted some oxygen atoms in the TiO2 lattice. Notably, the degradation rate of methylene blue for Mn/Ti-N-WACF was improved because of the co-doped Mn/N under visible-light irradiation.

  1. Enhanced photocatalytic activity and stability of nano-scaled TiO{sub 2} co-doped with N and Fe

    Energy Technology Data Exchange (ETDEWEB)

    Hu Shaozheng, E-mail: hushaozheng001@163.com [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China); Li Fayun; Fan Zhiping [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China); Chang, Chein-Chi [Department of Chemical Engineering, Bioengineering, and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, MD 21250 (United States); Department of Engineering and Technical Services, D. C. Water and Sewer Authority, Washington, DC 20032 (United States)

    2011-10-15

    Titanium dioxide (TiO{sub 2}) nanoparticles co-doped with N and Fe were prepared via modified sol-gel process. The products were characterized by transmission electron microscopy (TEM), N{sub 2} adsorption, X-ray diffraction (XRD), Raman spectroscopy, UV-vis spectroscopy, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). It is shown that the prepared TiO{sub 2} particles were less than 10 nm with narrow particle size distribution. The addition of MCM-41 caused the formation of Ti-O-Si bond which fixed the TiO{sub 2} on MCM-41 surface, thus restricted the agglomeration and growth of TiO{sub 2} particles. The photocatalytic performance in the degradation of methylene blue showed that N, Fe co-doped TiO{sub 2} exhibited much higher photocatalytic activity than doped sample with nitrogen or Fe{sup 3+} alone under both UV and visible light. N, Fe co-doping decreased the loss of doping N during the degradation reaction, thus increased the photocatalytic stability. It was also found that the nitridation time had significant influence on the photocatalytic activity of prepared TiO{sub 2} catalysts.

  2. Electrochemical Properties for Co-Doped Pyrite with High Conductivity

    Directory of Open Access Journals (Sweden)

    Yongchao Liu

    2015-09-01

    Full Text Available In this paper, the hydrothermal method was adopted to synthesize nanostructure Co-doped pyrite (FeS2. The structural properties and morphology of the synthesized materials were characterized using X-ray diffraction (XRD and scanning electron microscopy (SEM, respectively. Co in the crystal lattice of FeS2 could change the growth rate of different crystal planes of the crystal particles, which resulted in various polyhedrons with clear faces and sharp outlines. In addition, the electrochemical performance of the doping pyrite in Li/FeS2 batteries was evaluated using the galvanostatic discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. The results showed that the discharge capacity of the doped material (801.8 mAh·g−1 with a doping ratio of 7% was significantly higher than that of the original FeS2 (574.6 mAh·g−1 because of the enhanced conductivity. Therefore, the doping method is potentially effective for improving the electrochemical performance of FeS2.

  3. Effect of shallow donors on Curie–Weiss temperature of Co-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shuxia, E-mail: gsx0391@sina.com [Department of Physics, Jiaozuo Teachers College, Jiaozuo 454001 (China); Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Li, Jiwu [Department of Physics, Jiaozuo Teachers College, Jiaozuo 454001 (China); Du, Zuliang [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China)

    2014-12-15

    Co-doped ZnO and Al, Co co-doped ZnO polycrystalline powders were synthesized by co-precipitation method. The magnetization curves measured at 2 K show no hysteresis neither remanence for all samples. ZnO:Co grown at low temperature has a positive Curie–Weiss temperature Θ, and ZnO:Co grown at high temperature has a negative Θ. But Al-doped ZnO:Co grown at high temperature has a positive Θ. Positive Curie–Weiss temperature Θ was considered to have relation to the presence of shallow donors in the samples. - Highlights: • Co-doped ZnO and Al, Co co-doped ZnO polycrystalline powders were synthesized. • No hysteresis is observed for all samples. • The Curie–Weiss temperature Θ changes its sign by Al doping. • Positive Θ should be related to shallow donors.

  4. Co-doping of hydroxyapatite with zinc and fluoride improves mechanical and biological properties of hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Idil Uysal

    2014-08-01

    Full Text Available Hydroxyapatite (HA co-doped with Zn2+ and F− ions was synthesized by precipitation method for the first time in this study. FTIR spectroscopy revealed Zn2+ and F− ions incorporation into HA structure. Co-doping of Zn2+ and F− ions decreased unit cell volume of HA and decreased grain sizes. Zn2+ or 5 mol% F− addition into HA significantly improved its density. Microhardness was increased with Zn2+ addition and further increase was detected with F− co-doping. Zn2+ and F− co-doped samples had higher fracture toughness than pure HA. Zn2+ incorporation to the structure resulted in an increase in cell proliferation and ALP activity of cells, and further increase was observed with 1 mol% F− addition. With superior mechanical properties and biological response 2Zn1F is a good candidate for biomedical applications.

  5. Co-doping of hydroxyapatite with zinc and fluoride improves mechanical and biological properties of hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    Idil Uysal; Feride Severcana; Aysen Tezcanera; Zafer Evisa

    2014-01-01

    Hydroxyapatite (HA) co-doped with Zn2+ and F- ions was synthesized by precipitation method for the first time in this study. FTIR spectroscopy revealed Zn2+ and F- ions incorporation into HA structure. Co-doping of Zn2 + and F- ions decreased unit cell volume of HA and decreased grain sizes. Zn2+ or 5 mol% F- addition into HA significantly improved its density. Microhardness was increased with Zn2 + addition and further increase was detected with F- co-doping. Zn2+ and F- co-doped samples had higher fracture toughness than pure HA. Zn2+incorporation to the structure resulted in an increase in cell proliferation and ALP activity of cells, and further increase was observed with 1 mol%F- addition. With superior mechanical properties and biological response 2Zn1F is a good candidate for biomedical applications.

  6. Synthesis, characterization and photocatalytic reactions of phosphated mesoporous titania

    Indian Academy of Sciences (India)

    Pallabi Goswami; Jatindra Nath Ganguli

    2012-10-01

    Mesoporous titania nanoparticles with a well-definedmesostructure was prepared by hydrothermal process, using nonionic triblock copolymer P123 as surfactant template, modified with phosphoric acid and followed by calcination at 600°C. The sol–gel titania was modified by in situ phosphorylation using phosphoric acid and thereby incorporating phosphorous directly into the framework of TiO2. The resulting materials were characterized by XRD, SEM, TEM, nitrogen adsorption, TGA and DRS. It was found that the structural and optical properties of titania samples are strongly influenced by their phosphate modification. In case of calcined samples a positive effect on the specific surface area for the in situ phosphated sample was found. Mesoporous structure of phosphated titania did not collapse even after calcination at 600°C. The enhanced photocatalytic activity of the synthesized phosphate nanomaterials were evaluated through a study of the decomposition of fluorescein under UV light excitation and compared with undoped titania nanomaterial as well as with commercial titania.

  7. Titanium complex formation of organic ligands in titania gels.

    Science.gov (United States)

    Nishikiori, Hiromasa; Todoroki, Kenta; Setiawan, Rudi Agus; Teshima, Katsuya; Fujii, Tsuneo; Satozono, Hiroshi

    2015-01-27

    Thin films of organic ligand-dispersing titania gels were prepared from titanium alkoxide sols containing ligand molecules by steam treatment without heating. The formation of the ligand-titanium complex and the photoinduced electron transfer process in the systems were investigated by photoelectrochemical measurements. The complex was formed between the 8-hydroxyquinoline (HQ) and titanium species, such as the titanium ion, on the titania nanoparticle surface through the oxygen and nitrogen atoms of the quinolate. A photocurrent was observed in the electrodes containing the complex due to the electron injection from the LUMO of the complex into the titania conduction band. A bidentate ligand, 2,3-dihydroxynaphthalene (DHN), formed the complex on the titania surface through dehydration between its two hydroxyl groups of DHN and two TiOH groups of the titania. The electron injection from the HOMO of DHN to the titania conduction band was observed during light irradiation. This direct electron injection was more effective than the two-step electron injection.

  8. First-principles study on electronic and magnetic properties of N mono-doped and (N, Co) co-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Abbad, A., E-mail: am.ben@voila.fr [Laboratory of Material Valorisation, Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Bentounes, H.A. [Signals and Systems Laboratory (LSS), Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Benstaali, W. [Laboratory of Material Valorisation, Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Belaidi, A. [Automatic and Systems Analysis Laboratory (LAAS), ENSET, Oran 31000 (Algeria)

    2013-01-15

    Using first principles calculations based on the density functional theory and local spin density approximation, we predict magnetic and electronic properties of N mono-doped and (N-Co) co-doped ZnO for different dopants concentration. The results show that ZnO doped with N concentration of 12.5% is p-type, semi-metallic and ferromagnetic due to the strong hybridization effect between N 2p and O 2p states, with a total magnetic moment of 1 {mu}{sub B} mainly arises from N 2p orbitals. Nevertheless we find a deep and narrow acceptor level, resulting in large acceptor ionization energy of ZnO (N). With increasing N concentration to 25% we find that the impurity energy level is shallow and shifts downward to the direction of low energy, consequentially, the acceptor binding energy is reduced. (N-Co) co-doped ZnO with a concentration of 12.5% for the two dopants is p-type and half-metallic with an important magnetic moment of 3.98 {mu}{sub B}, due to Co 3d and N 2p states. - Highlights: Black-Right-Pointing-Pointer The electronic and magnetic properties of N mono-doped and (N-Co) co-doped ZnO have been investigated. Black-Right-Pointing-Pointer ZnO doped with 12.5% of Nitrogen is p-type and semi-metallic. Black-Right-Pointing-Pointer N-doping can enhance electronic conductivity of N-doped ZnO. Black-Right-Pointing-Pointer We find narrow N-impurity band for N-doped ZnO. Black-Right-Pointing-Pointer The co-doping of Co donors with N-acceptors causes an important change from semi-metallic material to half-metallic one.

  9. Structural, magnetic and electronic structure properties of Co doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Shalendra, E-mail: shailuphy@gmail.com [Institute of Basic Sciences, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Song, T.K., E-mail: tksong@changwon.ac.kr [School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Gautam, Sanjeev; Chae, K.H. [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Kim, S.S.; Jang, K.W. [Institute of Basic Sciences, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of)

    2015-06-15

    Highlights: • XRD and HR-TEM results show the single phase nature of Co doped ZnO nanoparticles. • XMCD and dc magnetization results indicate the RT-FM in Co doped ZnO nanoparticles. • Co L{sub 3,2} NEXAFS spectra infer that Co ions are in 2+ valence state. • O K edge NEXAFS spectra show that O vacancy increases with Co doping in ZnO. - Abstract: We reported structural, magnetic and electronic structure studies of Co doped ZnO nanoparticles. Doping of Co ions in ZnO host matrix has been studied and confirmed using various methods; such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersed X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, magnetic hysteresis loop measurements and X-ray magnetic circular dichroism (XMCD). From the XRD and HR-TEM results, it is observed that Co doped ZnO nanoparticles have single phase nature with wurtzite structure and exclude the possibility of secondary phase formation. FE-SEM and TEM micrographs show that pure and Co doped nanoparticles are nearly spherical in shape. O K edge NEXAFS spectra indicate that O vacancies increase with Co doping. The Co L{sub 3,2} edge NEXAFS spectra revealed that Co ions are in 2+ valence state. DC magnetization hysteresis loops and XMCD results clearly showed the intrinsic origin of temperature ferromagnetism in Co doped ZnO nanoparticles.

  10. Enhanced performance of dye-sensitized solar cells aided by Sr,Cr co-doped TiO2 xerogel films made of uniform spheres.

    Science.gov (United States)

    Bakhshayesh, A M; Bakhshayesh, N

    2015-12-15

    One-pot preparation of Sr,Cr co-doped TiO2 xerogel film for boosting the short circuit current density of dye-sensitized solar cells (DSCs) is reported. The 2.5-μm-diameter spheres are assembled from 60nm nanoparticles by a modified sol-gel method. X-ray photoelectron spectroscopy (XPS) shows that Sr(2+) and Cr(3+) ions to be well incorporated into the titania crystal lattice without forming specific strontium and chromium compositions. The crystallite size, phase composition, and band structure of the particles depend on the dopants concentration. Isolated energy levels near valence band as a result of the transition ion (i.e., Cr) introduction, in conjunction with the local lattice distortions owing to the alkaline earth ion (i.e., Sr) insertion, improves the photocatalytic activity of the prepared TiO2 spheres, enhancing the short circuit current density of the cells. The DSC co-doped with 0.075 at.% Sr and 2.5 at.% Cr (i.e., S7C25 solar cell) showed the highest power conversion efficiency of 7.89% and short circuit current density of 18.58mA/cm(2) thanks to lower charge transfer resistance (2.35Ωcm(2)), lower electron transit time (1.26ms), and higher electron diffusion coefficient (17.1×10(4)cm(2)S(-1)) compared to the other cells, demonstrated by electrochemical impedance spectroscopy (EIS). The concept of simultaneously introduction of alkaline earth ions and transition ions into TiO2 lattice will open up a new insight into the fabrication of high performance DSCs.

  11. Effect of Co doping on structural, optical, magnetic and dielectric properties of Bi2Fe4O9

    Science.gov (United States)

    Mohapatra, S. R.; Sahu, B.; Kaushik, S. D.; Singh, A. K.

    2015-06-01

    Polycrystalline Bi2Fe4O9 and 2% Co doped Bi2Fe4O9 were prepared by solid state reaction route. X-ray diffraction (XRD) result reveals that there is no change in the crystal structure due to Co doping and the compound has orthorhombic structure. UV-visible spectroscopy confirms the decrease in band gap due Co doping. Zero field cooled magnetization measurement at 100 Oe magnetic field shows substantial decrease in the magnetic transition temperature. Room temperature frequency dependent dielectric permittivity at 1V DC bias shows ˜10% increase in Co doped sample with respect to pure Bi2Fe4O9.

  12. Characterization of Co-doped birnessites and application for removal of lead and arsenite

    Energy Technology Data Exchange (ETDEWEB)

    Yin Hui; Feng Xionghan; Qiu Guohong; Tan Wenfeng [Key Laboratory of Subtropical Agriculture Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, No. 1 Nanhu Shizishan Street, Wuhan, 430070 (China); Liu Fan, E-mail: liufan@mail.hzau.edu.cn [Key Laboratory of Subtropical Agriculture Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, No. 1 Nanhu Shizishan Street, Wuhan, 430070 (China)

    2011-04-15

    Nanostructured Co-doped birnessites were successfully synthesized, and their application for the removal of Pb{sup 2+} and As(III) from aquatic systems was investigated. Powder X-ray diffraction, chemical analysis, nitrogen physical adsorption, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structure, chemical composition, micromorphologies and surface properties of the birnessites. Doping cobalt into the layer of birnessite had little effect on its crystal structure and micromorphology. Both chemical and XPS analyses showed that the manganese average oxidation state (Mn AOS) decreased after cobalt doping. The Co dopant existed mainly in the form of Co(III)OOH in the birnessite structure. Part of the doped Co{sup 3+} substituted for Mn{sup 4+}, resulting in the gain of negative charge of the layer and an increase in the content of the hydroxyl group, which accounted for the improved Pb{sup 2+} adsorption capacity. The maximum capacity of Pb{sup 2+} adsorption on HB, CoB5, CoB10 and CoB20 was 2538 mmol kg{sup -1}, 2798 mmol kg{sup -1}, 2932 mmol kg{sup -1} and 3146 mmol kg{sup -1}, respectively. The total As(III) removal from solution was 94.30% for CoB5 and 100% for both CoB10 and CoB20, compared to 92.03% for undoped HB, by oxidation, adsorption and fixation, simultaneously.

  13. Band gap tuning and room temperature ferromagnetism in Co doped Zinc stannate nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sumithra, S., E-mail: ssmithra@gmail.com; Victor Jaya, N.

    2016-07-15

    The effect of Co doping on structural, optical and magnetic behavior of pure and Co doped Zinc stannate (ZTO) nanostructures was investigated. Pure and Co (1%, 3% & 5%) doped Zn{sub 2}SnO{sub 4} compounds were prepared through simple precipitation route. Formation of cubic inverse spinel structure and metal oxide vibrations of the samples were investigated using XRD and FTIR. Co doping influences the crystallite size producing micro strain in ZTO lattice. Poly dispersed rod like shape of the particles was examined by FESEM. Elemental composition of prepared samples was identified by EDAX analysis. Optical Absorption spectra shows significant red shift on increasing the dopant concentration which indicates the reduction in optical band gap. Visible luminescence observed from photoluminescence studies confirms the presence of oxygen vacancies and trap sites in the lattice. Magnetization analysis reveals the enhanced ferromagnetic behavior in all Co doped ZTO samples. The amplified ferromagnetic ordering in Co doped ZTO compounds has been explained in terms of defects serving as free spin polarized prophetic carriers.

  14. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sreelekha, N.; Subramanyam, K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Department of Physics, Raghu Engineering College, Visakhapatnam, Andrapradesh 531162 (India); Amaranatha Reddy, D. [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609735 (Korea, Republic of); Murali, G. [Department of BIN Fusion Technology & Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk (Korea, Republic of); Ramu, S. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Rahul Varma, K. [Department of Mechanical Engineering, University of California, Berkeley (United States); Vijayalakshmi, R.P., E-mail: vijayaraguru@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2016-08-15

    Highlights: • Cu{sub 1−x}Co{sub x}S nanoparticles were synthesized via chemical co-precipitation method. • Structural, band gap, magnetization and photocatalysis studies were carried out. • All the doped samples exhibited intrinsic room temperature ferromagnetism. • Effect of magnetic properties on photocatalytic activity was analyzed. • CuS:Co nanoparticles may find applications in photocatalytic and spintronic devices. - Abstract: Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV–vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  15. Characterization of co-doped (In, N): ZnO by indigenous thermopower measurement system

    Science.gov (United States)

    Kedia, Sanjay Kumar; Singh, Anil; Chaudhary, Sujeet

    2016-05-01

    The thermopower measurement of (In, N) co-doped ZnO thin films have been carried out using indigenous high and low temperature thermopower measurement system. The compact thermopower measurement system has been designed, developed, tested in house. The sensitivity and accuracy of indigenous thermopower system have been investigated by measuring thermopower of standard samples like Cu, Ni, Sb etc. It has been also investigated by the comparison of carrier concentration using Hall Effect and Thermopower measurement of these (In, N) co-doped ZnO thin films. The constant temperature gradient between hot and cold junction has been maintained by using the temperature controller. The room temperature and low temperature Seebeck coefficient measurements were performed on these co-doped ZnO samples. A series of experiments have been performed to detect the p-type conductivity in co-doped ZnO thin films, particularly at low temperature. The negative Seebeck coefficient observed down to 40 K established the n-type behavior in these co-doped samples.

  16. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    Science.gov (United States)

    Sreelekha, N.; Subramanyam, K.; Amaranatha Reddy, D.; Murali, G.; Ramu, S.; Rahul Varma, K.; Vijayalakshmi, R. P.

    2016-08-01

    Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV-vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  17. Comparative study on beryllium and magnesium as a co-doping element for ZnO:N

    Science.gov (United States)

    Yu-Quan, Su; Ming-Ming, Chen; Long-Xing, Su; Yuan, Zhu; Zi-Kang, Tang

    2016-06-01

    Stable nitrogen doping is an important issue in p-type ZnO research for device applications. In this paper, beryllium and magnesium are systematically compared as a dopant in ZnO to reveal their nitrogen-stabilizing ability. Secondary ion mass spectrum shows that Be and Mg can both enhance the stability of nitrogen in ZnO while Be has a better performance. Zn 2p and O 1s electron binding energies change in both MgZnO and BeZnO thin films. Donor-acceptor luminescence is observed in the BeZnO samples. We conclude that Be is a better co-doping element than Mg for p-type ZnO:N. Project supported by the National Key Basic Research Program of China (Grant No. 2011CB302000), the National Natural Science Foundation of China (Grant Nos. 51232009 and 51202299), the Fundamental Research Funds for the Central Universities, China (Grant No. 11lgpy16), the Natural Science Foundation for Jiangsu Provincial Higher Education, Institutions of China (Grant No. 15KJB510005), and the Talent Fund of Jiangsu University, China (Grant No. 15JDG042).

  18. Study on Synthesis and Photocatalytic Activity of Porous Titania Nanotubes

    Directory of Open Access Journals (Sweden)

    Huang Liu

    2016-01-01

    Full Text Available Using the common natural cellulose substance (filter paper and triblock copolymer (Pluronic P123 micelles as dual templates, porous titania nanotubes with enhanced photocatalytic activity have been successfully synthesized through sol-gel methods. Firstly, P123 micelles were adsorbed onto the surfaces of cellulose nanofibers of filter paper, followed by hydrolysis and condensation of tetrabutyl titanate around these micelles to form titania layer. After calcination to remove the organic templates, hierarchical titania nanotubes with pores in the walls were obtained. The sample was characterized by X-ray diffraction pattern (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, nitrogen adsorption/desorption, Fourier Transform Infrared Spectroscopy (FT-IR, Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS, and X-ray photoelectron spectroscopy (XPS. As compared with commercial P25 catalyst, the porous titania nanotubes prepared by this method displayed significantly enhanced photocatalytic activity for degrading methyl orange under UV irradiation. Within 10 minutes, the porous titania nanotubes are able to degrade over 70% of the original MO, while the value for the commercial Degussa P25 is only about 33%.

  19. Performance Study of CdS/Co-Doped-CdSe Quantum Dot Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Xiaoping Zou

    2014-01-01

    Full Text Available In order to optimize the charge transfer path in quantum dot sensitized solar cells (QDSCs, we employed successive ionic layer adsorption and reaction method to dope CdSe with Co for fabricating CdS/Co-doped-CdSe QDSCs constructed with CdS/Co-doped-CdSe deposited on mesoscopic TiO2 film as photoanode, Pt counter electrode, and sulfide/polysulfide electrolyte. After Co doping, the bandgap of CdSe quantum dot decreases, and the conduction band and valence band all improve, forming a cascade energy level which is more conducive to charge transport inside the solar cell and reducing the recombination of electron-hole thus improving the photocurrent and ultimately improving the power conversion efficiency. This work has not been found in the literature.

  20. C, N co-doped TiO2/TiC0.7N0.3 composite coatings prepared from TiC0.7N0.3 powder using ball milling followed by oxidation

    Science.gov (United States)

    Hao, Liang; Wang, Zhenwei; Zheng, Yaoqing; Li, Qianqian; Guan, Sujun; Zhao, Qian; Cheng, Lijun; Lu, Yun; Liu, Jizi

    2017-01-01

    Ball milling followed by heat oxidation was used to prepared C, N co-doped TiO2 coatings on the surfaces of Al2O3 balls from TiC0.7N0.3 powder. The as-prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrophotometer (UV-vis). The results show that continuous TiC0.7N0.3 coatings were formed after ball milling. C, N co-doped TiO2/TiC0.7N0.3 composite coatings were prepared after the direct oxidization of TiC0.7N0.3 coatings in the atmosphere. However, TiO2 was hardly formed in the surface layer of TiC0.7N0.3 coatings within a depth less than 10 nm during the heat oxidation of TiC0.7N0.3 coatings in carbon powder. Meanwhile, the photocatalytic activity evaluation of these coatings was conducted under the irradiation of UV and visible light. All the coatings showed photocatalytic activity in the degradation of MB no matter under the irradiation of UV or visible light. The C, N co-doped TiO2/TiC0.7N0.3 composite coatings showed the most excellent performance. The enhancement under visible light irradiation should attribute to the co-doping of carbon and nitrogen, which enhances the absorption of visible light. The improvement of photocatalytic activity under UV irradiation should attribute to the synergistic effect of C, N co-doping, the formation of rutile-anatase mixed phases and the TiO2/TiC0.7N0.3 composite microstructure.

  1. Superhydrophilicity-assisted preparation of transparent and visible light activated N-doped titania film.

    Science.gov (United States)

    Xu, Qing Chi; Wellia, Diana V; Amal, Rose; Liao, Dai Wei; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

    2010-07-01

    A novel and environmental friendly method was developed to prepare transparent, uniform, crack-free and visible light activated nitrogen doped (N-doped) titania thin films without the use of organic Ti precursors and organic solvents. The N-doped titania films were prepared from heating aqueous peroxotitanate thin films deposited uniformly on superhydrophilic uncoated glass substrates. The pure glass substrates were superhydrophilic after being heated at 500 degrees C for 1 h. Nitrogen concentrations in the titania films were adjusted by changing the amount of ammonia solution. The optimal photocatalytic activity of the N-doped titania films was about 14 times higher than that of a commercial self-cleaning glass under the same visible light illumination. The current reported preparative technique is generally applicable for the preparation of other thin films.

  2. Superhydrophilicity-assisted preparation of transparent and visible light activated N-doped titania film

    Science.gov (United States)

    Xu, Qing Chi; Wellia, Diana V.; Amal, Rose; Liao, Dai Wei; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

    2010-07-01

    A novel and environmental friendly method was developed to prepare transparent, uniform, crack-free and visible light activated nitrogen doped (N-doped) titania thin films without the use of organic Ti precursors and organic solvents. The N-doped titania films were prepared from heating aqueous peroxotitanate thin films deposited uniformly on superhydrophilic uncoated glass substrates. The pure glass substrates were superhydrophilic after being heated at 500 °C for 1 h. Nitrogen concentrations in the titania films were adjusted by changing the amount of ammonia solution. The optimal photocatalytic activity of the N-doped titania films was about 14 times higher than that of a commercial self-cleaning glass under the same visible light illumination. The current reported preparative technique is generally applicable for the preparation of other thin films.

  3. Structural and optical properties of Co-doped NiO films prepared by SILAR method

    Science.gov (United States)

    Taşköprü, T.; Bayansal, F.; Şahin, B.; Zor, M.

    2015-01-01

    In this study, transparent thin films of un-doped and Co-doped nickel oxide were deposited onto microscopic glass substrates using the successive ionic layer adsorption and reaction (SILAR) method. The effect of cobalt doping on structural, morphological and optical properties was investigated. XRD studies reveal that all the films are polycrystalline with cubic structure and exhibit (1 1 1) and (2 2 2) preferential orientations. Co is well incorporated in the host lattice without altering the structure. All films retain high transparency throughout the visible spectral regime. No significant shift in Raman spectra was observed due to the Co doping.

  4. Ferromagnetism from Co-Doped ZnO Nanocantilevers above Room Temperature

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shao-Min; WANG Peng; LI Sheng; ZHANG Bin; GONG He-Chun; DU Zu-Liang

    2008-01-01

    @@ At low temperature (400° C), chemical vapour deposition (CVD) is employed to make comb-like Co-doped ZnO nanocantilever arrays (NAs). The magnetization curves of the as-synthesized Co-doped ZnO NAs indicate the existence of above-room-temperature ferromagnetism (ARTFM) (Curie temperature, Tc > 300 K) whereas un-doped ZnO NAs does not. The corresponding ferromagnetic source mechanism is discussed, in which defects play an important role due to the strong green light emission.

  5. Enhanced magnetic and dielectric behavior in Co doped BiFeO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarti, Kaushik; Sarkar, Babusona; Ashok, Vishal Dev [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India); Chaudhuri, Sheli Sinha [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700032 (India); De, S.K., E-mail: msskd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India)

    2015-05-01

    Magnetic and dielectric properties of Co doped BiFeO{sub 3} (BFO) nanoparticles (13 nm) have been investigated. The dopant Co{sup 2+} converts spherical morphology to cubic nanostructures. The significant changes in temperature dependence of magnetization may be due to magnetic disorder phase induced by divalent Co. The substitution of Fe by Co disrupts cycloidal spin structure of BFO and improves the ferromagnetic property. Enhancement of the saturation magnetization and coercivity by about 10 times in doped BFO are due to changes in morphology. High dielectric constant of about 670 and low loss at room temperature show Co doped BFO as promising material for multifunctional devices.

  6. Preparation and photocatalytic activity of B, Y co-doped nanosized TiO_2 catalyst

    Institute of Scientific and Technical Information of China (English)

    石中亮; 刘富梅; 姚淑华

    2010-01-01

    The catalysts of un-doped, single-doped and co-doped titanium dioxide (TiO2) powders were prepared by sol-gel method with Ti(OC4H9)4 as a raw material. The photocatalytic decomposition of phenol in aqueous solution under UV light was used as a probe reaction to evaluate their photocatalytic activities. The effects of B, Y co-doping on the crystallite sizes, crystal pattern, surface composition, and optical property of the catalyst were investigated by thermogravimetric differential thermal analysis, X-ray d...

  7. Effect of Co doping concentration on structural properties and optical parameters of Co-doped ZnO thin films by sol-gel dip-coating method.

    Science.gov (United States)

    Nam, Giwoong; Yoon, Hyunsik; Kim, Byunggu; Lee, Dong-Yul; Kim, Jong Su; Leem, Jae-Young

    2014-11-01

    The structural and optical properties of Co-doped ZnO thin films prepared by a sol-gel dip-coating method were investigated. X-ray diffraction analysis showed that the thin films were grown with a c-axis preferred orientation. The position of the (002) peak was almost the same in all samples, irrespective of the Co concentration. It is thus clear that Co doping had little effect on the position of the (002) peak. To confirm that Co2+ was substituted for Zn2+ in the wurtzite structure, optical measurements were conducted at room temperature by a UV-visible spectrometer. Three absorption peaks are apparent in the Co-doped ZnO thin films that do not appear for the undoped ZnO thin film. As the Co concentration was increased, absorption related to characteristic Co2+ transitions increased because three absorption band intensities and the area underneath the absorption wells between 500 and 700 nm increased with increasing Co concentration. The optical band gap and static dielectric constant decreased and the Urbach energy and extinction coefficient increased with increasing Co concentration.

  8. Synthesis and polymorphic control for visible light active titania nanoparticles

    Science.gov (United States)

    Kaewgun, Sujaree

    Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases. Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties of polymorphic brookite TiO2 by minimizing the lattice defects and narrowing band gap of titania by nitrogen and/or carbon chromophone, and to investigate the deactivation, reusability, and regeneration of the VLA titania in order to design better titania catalysts for organic compound degradation applications. In order to study the influence of hydroxyl content on photocatalytic activities (PCAs) of polymorphic titania nanoparticles, the WACS samples were post-treated by a Solvent-based Ambient Condition Sol (SACS) process in sec-butanol (sec-BuOH). All samples were characterized for phase composition, surface area, hydroxyl contamination, and particle morphology by x-ray diffraction, N2 physisorption, FT-IR, solid state 1H NMR and scanning electron microscopy, and then compared to a commercial titania, Degussa P25. Evaluation of methyl orange (MO) degradation under UV irradiation results showed that the lower lattice hydroxyl content in SACS titania enhanced the PCA. As-prepared titania and SACS samples, which have similar surface areas and crystallinity, were compared in order to prove that the superior PCA came from the reduction in the lattice hydroxyl content. To enhance PCA and VLA properties of WACS, an alternative high boiling point polar solvent, N-methylpyrrolidone (NMP), was utilized in the

  9. A facile one-step electrochemical strategy of doping iron, nitrogen, and fluorine into titania nanotube arrays with enhanced visible light photoactivity

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Zulin; Dai, Zhangyan [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China); Bai, Xue, E-mail: baixue10@tsinghua.org.cn [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China); Ye, Zhengfang [Key Laboratory of Water and Sediment Sciences of the Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871 (China); Gu, Haixin; Huang, Xin [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China)

    2015-08-15

    Highlights: • Fe, N, F tri-doped TiO{sub 2} was prepared by a facile one-step electrochemical method. • Fe, N, F tri-doping resulted in a synergetic effect for the enhanced photoactivity. • The formation of N 2p near the valence band contributed to visible light absorption. • Doping fluorine and Fe{sup 3+} ions reduced the recombination of photogenerated e{sup −}–h{sup +}. • The synergistic effect in Fe, N, F tri-doping was confirmed by XPS and FTIR. - Abstract: Highly ordered iron, nitrogen, and fluorine tri-doped TiO{sub 2} (Fe, (N, F)-TiO{sub 2}) nanotube arrays were successfully synthesized by a facile one-step electrochemical method in an NH{sub 4}F electrolyte containing Fe ions. The morphology, structure, composition, and photoelectrochemical property of the as-prepared nanotube arrays were characterized by various methods. The photoactivities of the samples were evaluated by the degradation of phenol in an aqueous solution under visible light. Tri-doped TiO{sub 2} showed higher photoactivities than undoped TiO{sub 2} under visible light. The optimum Fe{sup 3+} doping amount at 0.005 M exhibited the highest photoactivity and exceeded that of undoped TiO{sub 2} by a factor of 20 times under visible light. The formation of N 2p level near the valence band (VB) contributed to visible light absorption. Doping fluorine and appropriate Fe{sup 3+} ions reduced the photogenerated electrons–holes recombination rate and enhanced visible light photoactivity. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results indicated the presence of synergistic effects in Fe, N, and F tri-doped TiO{sub 2}, which enhanced visible light photoactivity. The Fe, (N, F)-TiO{sub 2} photocatalyst exhibited high stability.

  10. Sulfur impregnated N, P co-doped hierarchical porous carbon as cathode for high performance Li-S batteries

    Science.gov (United States)

    Cai, Junjie; Wu, Chun; Zhu, Ying; Zhang, Kaili; Shen, Pei Kang

    2017-02-01

    A nitrogen and phosphorus co-doped hierarchical porous carbon (N, P-HPC) were fabricated by simply pyrolysis of polyaniline aerogels in the presence of phytic acid and subsequently activation treatment by KOH. The as-prepared N, P-HPC with a highly interconnected network structure and possesses a large surface area and pore volume is very favor in the impregnation of sulfur. Moreover, simultaneously introduced nitrogen and phosphorous into the carbon could create more active sites than the mono-doped carbons, the synergistic effects of dual activation of carbon atoms induced stronger chemical adsorption ability. Benefiting from the advantages of suitable hierarchical porosity, high conductivity, fast ion transportation, physical and chemical adsorption of the N, P-HPC, the Sulfur/N, P-HPC composite exhibits high initial discharge capacity of 1116 mAh g-1 at 0.1 C (1 C = 1675 mA g-1, based on sulfur content) and high rate capability of 550 mAh g-1 at 2C, as well as excellent long term cycling stability at a current rate of 1 C with only 0.058% capacity decay per cycle for over 500 cycles. Such a high capacity and stability suggests that the novel cathode have alluring prospect for Li-S batteries.

  11. Influence of defects on electrical properties of electrodeposited co-doped ZnO nanocoatings

    Science.gov (United States)

    Simimol, A.; Anappara, Aji A.; Barshilia, Harish C.

    2017-01-01

    We present a systematic investigation of the electrical properties of undoped and Co-doped ZnO nanostructures at room temperature as an extensive study of the role of defects in ZnO. The ZnO nanostructures were fabricated by the electrodeposition method at low bath temperature (80 °C) and the Co concentration was varied from 0.01 to 0.2 mM. Electrical properties of the undoped and Co-doped ZnO nanostructures were studied in detail. The carrier concentration increases while the mobility reduces with increase in Co-concentration. The resistivity increases with an increase in Co-concentration and the reason is correlated with the defects in ZnO. In order to understand more details of the role of defects in the present I-V characteristic behavior of the Co-doped ZnO, high temperature vacuum annealing of ZnO sample was carried out. Electrical, optical and magnetic properties of the high temperature vacuum annealed ZnO were studied in detail. Photoluminescence spectroscopy (PL) results revealed more information of the defect levels which act as scattering centers for the carriers. Co-doping as well as annealing at high temperature in vacuum environment tunes the defects in ZnO and which influence the optical, magnetic and electrical behavior of the ZnO nanostructures.

  12. Re-dispersible Li+ and Eu3+ co-doped CdS nanoparticles: Luminescence studies

    Indian Academy of Sciences (India)

    N S Gajbhiye; Raghumani Singh Ninghoujam; Asar Ahmed; D K Panda; S S Umare; S J Sharma

    2008-02-01

    Re-dispersible CdS, 5 at.% Eu3+-doped CdS, 2 at.% Li+ and 5 at.% Eu3+ co-doped CdS nanoparticles in organic solvent are prepared by urea hydrolysis in ethylene glycol medium at a low temperature of 170°C. CdS nanoparticles have spherical shape with a diameter of ∼ 80 nm. The asymmetric ratio (21) of the integrated intensities of the electrical dipole transition to the magnetic dipole transition for 5 at.% Eu3+-doped CdS is found to be 3.8 and this ratio is significantly decreased for 2 at.% Li+ and 5 at.% Eu3+ co-doped CdS (21 = 2.6). It establishes that the symmetry environment of Eu3+ ion is more favored by Li-doping. Extra peak at 550 nm (green emission) could be seen for 2 and 5 at.% Eu3+ co-doped CdS. Also, the significant energy transfer from host CdS to Eu3+ is found for 5 at.% Eu3+-doped CdS compared to that for 2 at.% Li+ and 5 at.% Eu3+ co-doped CdS.

  13. Wideband Erbium-Ytterbium Co-Doped Phosphate Glass Waveguide Amplifier

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new '(?)' type of wideband erbium-ytterbium co-doped phosphate glass waveguide amplifier integrated with medium thin film filter is proposed, Average gain about 15.5dB between 1530nm and 1570nm with gain difference of below 2 dB is obtained.

  14. High Co-doping promotes the transition of birnessite layer symmetry from orthogonal to hexagonal

    NARCIS (Netherlands)

    Yin, H.; Liu, Y.; Koopal, L.K.; Feng, X.; Chu, S.; Zhu, M.; Lui, F.

    2015-01-01

    Despite its presence in limited amounts, birnessite has a wide spread distribution and is often highly enriched in trace metals such as Co in diverse geological environments. This study investigated the effects of Co doping on the layer structure and properties of birnessites synthesized through the

  15. Ferromagnetism at room temperature in Co-doped KNbO{sub 3} bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Astudillo, A., E-mail: jaastudillo@unicauca.edu.co [Low Temperature Laboratory, Department of Physics, University of Cauca, Calle 5 No. 4-70, Popayán (Colombia); Izquierdo, J.L. [Universidad Nacional de Colombia, Campus Medellín, Departamento de Física, Laboratorio de Materiales Cerámicos y Vítreos, A.A. 568, Medellín (Colombia); Gómez, A. [Universidad Nacional de Colombia, Campus Medellín, Facultad de Minas, Laboratorio de Caracterización de Materiales, A.A. 568, Medellín (Colombia); Bolaños, G. [Low Temperature Laboratory, Department of Physics, University of Cauca, Calle 5 No. 4-70, Popayán (Colombia); Morán, O. [Universidad Nacional de Colombia, Campus Medellín, Departamento de Física, Laboratorio de Materiales Cerámicos y Vítreos, A.A. 568, Medellín (Colombia)

    2015-01-01

    In this work, polycrystalline KNb{sub 1−x}Co{sub x}O{sub 3} (x=0, 0.05 and 0.1) samples were synthesized through standard solid-state reaction, and their structural and magnetic properties were carefully studied. The X-ray powder diffraction (XRD) patterns show reflections of a pure orthorhombic structure (space group Bmm2) with lattice parameters being very close to those reported in the literature. The most important point here is that all the samples ended up being single-phase with no affectation by impurities or segregates. The XRD peaks of Co-doped samples are broadened and shifted to the right side as compared to those of the pristine compound (x=0) suggesting effective substitution of Nb by Co ions. The Co-doped samples exhibit ferromagnetic properties at room temperature, which contrasts starkly with the paramagnetic behavior exhibited by the undoped sample. Interactions between bound magnetic polarons are considered as a possible scenario to explain the appearance of the ferromagnetic signal in the Co-doped samples. - Highlights: • Polycrystalline KNb{sub 1−x}Co{sub x}O{sub 3} (x=0, 0.05 and 0.1) is synthesized by physical route. • XRD patterns show reflections of a pure orthorhombic structure. • No affectation by impurities or segregates is verified by XRD analysis. • The Co-doped samples exhibit ferromagnetic properties at room temperature.

  16. (Al, Er) co-doped ZnO nanoparticles for photodegradation of rhodamine blue

    Science.gov (United States)

    Ghomri, R.; Shaikh, M. Nasiruzzaman; Ahmed, M. I.; Bououdina, M.; Ghers, M.

    2016-10-01

    Pure and co-doped (Al, Er) ZnO nanoparticles (NPs) have been synthesized by hydrothermal method using (Zn, Er and Al) nitrates. X-ray diffraction patterns reveal the formation of single phase of ZnO würtzite-type structure. The crystallite size for pure ZnO is in the order of 26.5 nm which decreases up to the range 14.2-22.0 nm after (Al, Er) co-doping. SEM micrographs show that the specimen is composed of regular spherical particles in the nanoscale regime with homogeneous size distribution and high tendency to agglomeration. FTIR spectra exhibit absorption lines located at wavenumbers corresponding to vibration modes between the constituent atoms. Raman spectra recorded under excitation ( λ exc = 632.8 nm) reveal peaks related to modes of transverse and longitudinal optical phonons of the würtzite ZnO structure. The energy band gap E g of ZnO:(Al, Er) NPs ranges in 3.264-3.251 eV. The photocatalytic activity of pure and co-doped (Al, Er) ZnO NPs was evaluated by the photodegradation of rhodamine blue under an irradiation of wavelength 554 nm. It is found that a photodegradation rate above 90 % could be achieved for a period of time of 40 min for pure ZnO and 120 min for (Al, Er) co-doped ZnO. A photodegradation mechanism is proposed.

  17. Preparation, characterization and photoluminescent studies of Cr and Nd co-doped Ce:YAG compounds

    Energy Technology Data Exchange (ETDEWEB)

    Naik, S.R. [Department of Chemistry, Goa University, Goa 403206 (India); Shripathi, T. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452017 (India); Salker, A.V., E-mail: sal_arun@rediffmail.com [Department of Chemistry, Goa University, Goa 403206 (India)

    2015-05-15

    Sol–gel autocombustion as an efficient method in the preparation of monophasic Cr and Nd co-doped Ce:YAG compounds has been demonstrated. A reduction in the formation temperature to 1000 °C as compared to the classical ceramic method has been effectively shown. Monophasic formation of the compounds has been confirmed from the X-ray diffraction study which is equally supported by the Raman spectroscopy. The TEM analysis confirms the formation of submicron sized particles (around 100 nm) which are equally supported by SEM micrographs revealing the granular morphology for the compounds. Photoluminescence (excitation) studies carried out for the compounds at 468, 341 and 685 nm display excellent emission intensity for the compounds with similar emission pattern pointing towards a common emission centre in all the three cases. Decrease in Ce{sup 3+} emission intensity for the Cr and Nd co-doped Ce:YAG is observed. Energy transfer mechanism is suggested for the lowering of emission intensity confirming the activity of Ce{sup 3+} as a sensitizer. - Highlights: • Nd and Cr co-doped Ce:YAG are prepared by the sol–gel autocombustion. • Monophasic preparation proves the method to be efficient. • Formation of particles around 100 nm is confirmed from TEM. • Singly doped Ce:YAG exhibits maximum emission intensity. • Energy transfer between ions in excited state is in co-doped samples.

  18. Transient Dynamics of Fluoride-Based High Concentration Erbium/Cerium Co-Doped Fiber Amplifier

    Institute of Scientific and Technical Information of China (English)

    S. S-H. Yam; Y. Akasaka; Y. Kubota; R. Huang; D. L. Harris; J. Pan

    2003-01-01

    We designed and evaluated a fluoride-based high concentration erbium/ cerium co-doped fiber amplifier. It is suitable for Metropolitan Area Networks due to faster transient, flatter (unfiltered) gain, smaller footprint and gain excursion than its silica-based counterpart.

  19. Strain-dependent electronic and magnetic of Co-doped monolayer of WSe2

    Science.gov (United States)

    Wu, Ninghua; Zhao, Xu; Wang, Tianxing

    2016-10-01

    We perform first-principles calculation to investigate electronic and magnetic properties of Co-doped WSe2 monolayer with strains from -10% to 10%. We find that Co can induce magnetic moment about 0.894 μB, the Co-doped WSe2 monolayer is a magnetic semiconductor material without strain. The doped system shows half-metallic properties under tensile strain, and the largest half-metal gap is 0.147 eV at 8% strain. The magnetic moment (0.894 μB) increases slightly from 0% to 6%, and jumps into about 3 μB at 8% and 10%, which presents high-spin state configurations. When we applied compressive strain, the doped system shows a half-metallic feature at -2% strain, and the magnetic moment jumps into 1.623 μB at -4% strain, almost two times as the original moment 0.894 μB at 0% strain. The magnetic moment vanishes at -7% strain. The Co-doped WSe2 can endure strain from -6% to 10%. Strain changes the redistribution of charges and magnetic moment. Our calculation results show that the Co-doped WSe2 monolayer can transform from magnetic semiconductor to half-metallic material under strain.

  20. Nitrogen

    Science.gov (United States)

    Apodaca, Lori E.

    2013-01-01

    The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

  1. Highly luminescent N, S- Co-doped carbon dots and their direct use as mercury(II) sensor

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu [Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Department of Advanced Organic Materials Science and Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Kim, Sung-Hoon, E-mail: shokim@knu.ac.kr [Department of Advanced Organic Materials Science and Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Feng, Liang, E-mail: fengl@dicp.ac.cn [Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2015-08-26

    Heteroatom doping has been proven as an efficient way to improve the fluorescent efficiency of carbon dots. Co-doping with heteroatoms may introduce more active sites to carbon dots, which would broaden applications of CDs in sensing. In this work, highly luminescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized through a facile one-step microwave assisted method by using citric acid and rubeanic acid as carbon, nitrogen, and sulfur sources. The well-isolated NSCDs not only exhibit an enhanced fluorescent efficiency with a relatively high quantum yield up to 17.6%, but also show potential use as a multi-sensing platform based on their fluorescence “on-off-on” and color changing behaviors. The NSCDs can be directly used for the selective determination of mercury cations without any functionalization. The detection limit is approximately calculated as 0.18 μM and linear range is 0–20 μM. The sensing mechanism is proposed as coordination reaction induced by oligomers upon the carbon core. Furthermore, in the presence of cyanide anions, the fluorescence shows linear recovery associated with the concentration of cyanide, indicating its potential usage for the detection of cyanide ion. The optimized pH range for such fluorescence “on-off-on” sensing system is investigated as pH 6–8, suggesting potential applications in bio-sensing and imaging area. In addition, by adding hydrosulfide anion to NSCDs@Hg{sup 2+} complex, a notable color change could be clearly observed due to the formation of fuscous HgS. In application, a handy test paper for direct and rapid detection of Hg{sup 2+} is manufactured for the evaluation of usage of NSCDs in the real circumstance. - Highlights: • NSCDs were synthesized by using citric acid and rubeanic acid. • NSCDs exhibited an enhanced fluorescent efficiency with high QY up to 17.6%. • NSCDs presented good sensing performance to mercury ions. • NSCDs showed potential use as a multi-sensing platform.

  2. Influence of Co doping on combined photocatalytic and antibacterial activity of ZnO nanoparticles

    Science.gov (United States)

    Anandan, M.; Dinesh, S.; Krishnakumar, N.; Balamurugan, K.

    2016-11-01

    The present work aims to investigate the structural, optical, photocatalyst and antibacterial properties of bare and cobalt doped ZnO nanoparticles (NPs) with different concentrations Zn1-x Co x O (x = 0, 0.03, 0.06 and 0.09) synthesized by co-precipitation method. The XRD patterns confirmed that all samples of cobalt doped ZnO nanostructures revealed the formation of single phase having hexagonal wurtzite structure with crystallite size in the range of 31-41 nm. Further, the decreasing trend in lattice parameters and grain sizes were also seen with increasing doping concentrations which confirms the incorporation of Co ions into the ZnO lattice. This result was further supported by the FT-IR data. HR-TEM images demonstrated the distinct hexagonal like morphology with small agglomeration. The UV-visible absorption spectra exhibits red shift with increase in Co doping concentration in ZnO while corresponding bandgap energy of cobalt doped ZnO NPs decreased with increased Co doping concentration. PL spectra showed a weak UV and visible emission band which may be ascribed to the reduction in oxygen vacancy and defects by cobalt doping. XPS and EDX spectral results confirm the composition and the purity of Co doped ZnO NPs. Furthermore, the Co doped ZnO NPs were found to exhibit lesser photocatalytic activity for the degradation of methyl green dye under UV light illumination in comparison with the bare ZnO NPs. Moreover, anti-bacterial studies reveals that the Co doped ZnO NPs possess more antibacterial effect against gram positive Basillus subtills and gram negative Klebsiella pneumoniae bacterial strains than the bare ZnO NPs.

  3. Synergistic effects of F and Fe in co-doped TiO2 nanoparticles

    Science.gov (United States)

    Zhang, Yufei; Shen, Huiyuan; Liu, Yanhua

    2016-03-01

    TiO2 photocatalysts co-doped with F and Fe were synthesized by a sol-gel method. Synergistic effects of F and Fe in the co-doped TiO2 were verified by NH3 decomposition, X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV-Vis) absorption spectroscopy, and was analyzed by the simulation based on the density functional theory (DFT). The results from NH3 decomposition confirmed that the cooperation of F and Fe broadened the optical response of TiO2 to visible light region and also enhanced the photocatalytic activity of TiO2 under ultraviolet light. XRD patterns, SEM and HRTEM images showed that the co-doped samples were nanometric anatase with an average particle size of 25 nm. Co-doping with F and Fe inhibited the grain growth of TiO2 from anatase to rutile and resulted in a larger lattice defect. XPS analysis exhibited that the doped F and Fe atoms were into the TiO2 lattice. UV-Vis absorption spectra showed that its optical absorption edge was moved up to approximately 617 nm and its ultraviolet absorption was also enhanced. The DFT results indicated that the cooperation of Fe 3d and O 2p orbits narrowed the band gap of TiO2 and F 2p orbit widened the upper valence bands. The synergistic electron density around F and Fe in co-doped TiO2 was capable to enhance the photo-chemical stability of TiO2.

  4. The influence of oxygen and nitrogen doping on GeSbTe phase-change optical recording media properties

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrov, D.; Shieh, H.-P.D

    2004-03-15

    Nitrogen and oxygen doped and co-doped GeSbTe (GST) films for phase-change optical recording are investigated. It is found that the crystallization temperature increased as well as the crystalline microstructure refined by doping. The carrier-to-noise ratio (CNR) and erasability of phase-change optical disks are improved being up to 52 and 35 dB, respectively, by using an appropriate nitrogen doping or co-doping concentration in the recording layer. Optical disks with co-doped recording layer are found to be superior in the recording characteristics then the single doped recording layer disks.

  5. Solvothermal Synthesis of Visible Light Responsive Titania Nanocrystals at Moderate Temperature

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Visible light responsive nitrogen-doped titania nanocrystals were prepared by "Homogeneous Precipitation-Solvothermal Process" in TiCl3-hexamethylenetetramine (C6Hi2N4) mixed solution. The phase composition, crystallinity, microstructure and specific surface area of titania greatly changed depending on pH,solvent and temperature. The titania powders prepared in TiCl3-hexamethylenetetramine aqueous solutions at pH 1~6 and 190℃ for 2 h consisted of single phase of brookite and that prepared at pH 9 was single phase of rutile. On the other hand, the sample prepared in the presence of methanol at pH 9 consisted of single phase of anatase. All titania powders prepared in the present study were yellow and showed excellent visible light absorption property and photocatalytic ability for NO destruction under irradiation of the visible light (λ>510nm). The photocatalytic activity of the sample possessing similar specific surface area was in the order anatase > brookite > rutile. The photocatalytic activity of nitrogen doped titania under irradiation of visible light (λ>510 nm) slightly decreased with increasing calcination temperature up to 600℃ and then greatly decreased at 800 C. The visible light responsive photocatalytic activity of rutile titania nanoparticles could be improved by forming nanocomposite with layered tetratitanate possessing high specific surface area via a delamination-reassembly process of K2Ti4O9 combined with planetary ball-milling.

  6. Hemocompatibility of titania nanotube arrays.

    Science.gov (United States)

    Smith, Barbara S; Yoriya, Sorachon; Grissom, Laura; Grimes, Craig A; Popat, Ketul C

    2010-11-01

    Hemocompatibility is a key consideration for the long-term success of blood contacting biomaterials; hence, there is a critical need to understand the physiological response elicited from blood/nano-biomaterial interactions. In this study, we have investigated the adsorption of key blood serum proteins, in vitro adhesion and activation of platelets, and clotting kinetics of whole blood on titania nanotube arrays. Previous studies have demonstrated improved mesenchymal stem cell functionality, osteoblast phenotypic behavior, localized drug delivery, and the production of endothelial cell ECM on titania nanotube arrays. Furthermore, these titania nanotube arrays have elicited minimal levels of monocyte activation and cytokine secretion, thus exhibiting a very low degree of immunogenicity. Titania nanotube arrays were fabricated using anodization technique and the surface morphology was examined through scanning electron microscopy (SEM). The crystalline phases were identified using glancing angled X-ray diffraction (GAXRD). Nanoindentation and scratch tests were used to characterize the mechanical properties of titania nanotube arrays. The adsorption of key blood proteins (albumin, fibrinogen, and immunoglobulin-g) was evaluated using a micro-BCA assay and X-ray photoelectron spectroscopy (XPS). The adhesion and activation of platelets was investigated using live-cell staining, MTT assay, and SEM. Whole blood clotting kinetics was evaluated by measuring the free hemoglobin concentration, and SEM was used to visualize the clot formation. Our results indicate increased blood serum protein adsorption, platelet adhesion and activation, and whole blood clotting kinetics on titania nanotube arrays.

  7. Enhanced photo-catalytic activity of Sr and Ag co-doped TiO2 nanoparticles for the degradation of Direct Green-6 and Reactive Blue-160 under UV & visible light.

    Science.gov (United States)

    Naraginti, Saraschandra; Thejaswini, T V L; Prabhakaran, D; Sivakumar, A; Satyanarayana, V S V; Arun Prasad, A S

    2015-10-05

    This work is focused on sol-gel synthesis of silver and strontium co-doped TiO2 nanoparticles and their utilization as photo-catalysts in degradation of two textile dyes. Effect of pH, intensity of light, amount of photo-catalyst, concentration of dye, sensitizers, etc., were studied to optimize conditions for obtaining enhanced photo-catalytic activity of synthesized nanoparticles. XRD, BET, HR-TEM, EDAX and UV-Vis (diffused reflectance mode) techniques were used to characterize the nanoparticles. Interestingly, band gap of Sr and Ag co-doped TiO2 nanoparticles showed considerable narrowing (2.6 eV) when compared to Ag doped TiO2 (2.7 eV) and undoped TiO2 (3.17 eV) nanoparticles. Incorporation of Ag and Sr in the lattice of TiO2 could bring isolated energy levels near conduction and valence bands thus narrowing band gap. The XRD analysis shows that both Ag and Sr nanoparticles are finely dispersed on the surface of titania framework, without disturbing its crystalline structure. TEM images indicate that representative grain sizes of Ag-doped TiO2 & Sr and Ag co-doped TiO2 nanoparticles are in the range of 8-20 nm and 11-25 nm, respectively. Effective degradation of Direct Green-6 (DG-6) and Reactive Blue-160 (RB-160) under UV and visible light has been achieved using the photo-catalysts. Sr and Ag co-doped TiO2 photo-catalysts showed higher catalytic activity during degradation process in visible region when compared to Ag-doped and undoped TiO2 nanoparticles which could be attributed to the interactive effect caused by band gap narrowing and enhancement in charge separation. For confirming degradation of the dyes, total organic carbon (TOC) content was monitored periodically. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Novel Approach for the Synthesis of Nanocrystalline Anatase Titania and Their Photovoltaic Application

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available High surface area titania with crystalline anatase walls has been synthesized using ordered large mesoporous carbon as a template. The pore structure of mesoporous carbon is infiltrated with titanium tetraisopropoxide solution at room temperature and the mixture is subjected to heat treatment at 550oC in presence of air to complete removal of the template. The prepared crystalline anatase frameworks are characterized by XRD, N2 adsorption and HR-TEM. The nitrogen adsorption-desorption analysis of the prepared anatase titania particles exhibits BET specific surface area of 28 m2/g. The dye-sensitized solar cells performance of this anatase titania material has been tested and energy conversion efficiency of 3.0% is achieved under AM 1.5 sunlight. This work reports a new approach for fabrication of nanocrystalline anatase titania by simple hard templating technique for the first time and their applications for dye-sensitized solar cell.

  9. Anomalous enhancement of the thermoelectric figure of merit by V co-doping of Nb-SrTiO3

    KAUST Repository

    Ozdogan, K.

    2012-05-10

    The effect of V co-doping of Nb-SrTiO3 is studied by full-potential density functional theory. We obtain a stronger increase of the carrier density for V than for Nbdopants. While in Nb-SrTiO3 a high carrier density counteracts a high thermoelectric figure of merit, the trend is inverted by V co-doping. The mechanism leading to this behavior is explained in terms of a local spin-polarization introduced by the V ions. Our results indicate that magnetic co-doping can be a prominent tool for improving the thermoelectric figure of merit.

  10. Boron, bismuth co-doping of gallium arsenide and other compounds for photonic and heterojunction bipolar transistor devices

    Energy Technology Data Exchange (ETDEWEB)

    Mascarenhas, Angelo

    2017-08-01

    Isoelectronic co-doping of semiconductor compounds and alloys with acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. For example, Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, B and Bi, to customize solar cells, and other semiconductor devices. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  11. Boron, bismuth co-doping of gallium arsenide and other compounds for photonic and heterojunction bipolar transistor devices

    Science.gov (United States)

    Mascarenhas, Angelo

    2015-07-07

    Isoelectronic co-doping of semiconductor compounds and alloys with acceptors and deep donors is sued to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. For example, Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, B and Bi, to customize solar cells, and other semiconductor devices. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  12. Facile and controllable synthesis of N/P co-doped graphene for high-performance supercapacitors

    Science.gov (United States)

    Xia, Kaisheng; Huang, Zhiyuan; Zheng, Lin; Han, Bo; Gao, Qiang; Zhou, Chenggang; Wang, Hongquan; Wu, Jinping

    2017-10-01

    Improving the energy density of carbon-based supercapacitors is one of the most urgent demands for developing high-power energy supplies, which in general requires delicate engineering of the carbon composition and textures. By pre-functionalization of graphene nanosheets and successive one-step (NH4)3PO4 activation, we prepared a type of nitrogen and phosphorus co-doped graphene (NPG) with high specific surface areas, hierarchical pore structures as well as tunable N and P contents. The as-obtained NPG shows high specific capacitances of 219 F g-1 (123 F cm-3) at 0.25 A g-1 and 175 F g-1 (98 F cm-3) at 10 A g-1, respectively. Accordingly, the NPG-based symmetrical supercapacitor device, working at a potential window of 1.3 V, could deliver an enhanced energy density of 8.2 Wh kg-1 (4.6 Wh L-1) at a power density of 162 W kg-1 (91 W L-1), which still retains 6.7 Wh kg-1 at 6.5 kW kg-1. In particular, under a current density of 5 A g-1, the device endows an 86% capacitance retention of initial after 20,000 cycles, displaying superior cycle stability. Our results imply the feasibility of NPG as a promising candidate for high-performance supercapacitors.

  13. Enhanced electrical activation in In-implanted Ge by C co-doping

    Energy Technology Data Exchange (ETDEWEB)

    Feng, R., E-mail: ruixing.feng@anu.edu.au; Kremer, F.; Mirzaei, S.; Medling, S. A.; Ridgway, M. C. [Department of Electronic Materials Engineering, Australian National University, Canberra ACT 0200 (Australia); Sprouster, D. J. [Nuclear Science and Technology Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Decoster, S.; Pereira, L. M. C. [KU Leuven, Instituut voor Kern-en Stralingsfysica, 3001 Leuven (Belgium); Glover, C. J. [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia); Russo, S. P. [Applied Physics, School Applied Sciences, RMIT University, Melbourne 3001 (Australia)

    2015-11-23

    At high dopant concentrations in Ge, electrically activating all implanted dopants is a major obstacle in the fulfillment of high-performance Ge-channel complementary metal oxide semiconductor devices. In this letter, we demonstrate a significant increase in the electrically-active dopant fraction in In-implanted Ge by co-doping with the isovalent element C. Electrical measurements have been correlated with x-ray absorption spectroscopy and transmission electron microscopy results in addition to density functional theory simulations. With C + In co-doping, the electrically active fraction was doubled and tripled at In concentrations of 0.2 and 0.7 at. %, respectively. This marked improvement was the result of C-In pair formation such that In-induced strain in the Ge lattice was reduced while the precipitation of In and the formation of In-V clusters were both suppressed.

  14. First Principles Study of Electronic and Magnetic Properties of Co-Doped Armchair Graphene Nanoribbons

    Directory of Open Access Journals (Sweden)

    Biao Li

    2015-01-01

    Full Text Available Using the first principles calculations, we have studied the atomic and electronic structures of single Co atom incorporated with divacancy in armchair graphene nanoribbon (AGNR. Our calculated results show that the Co atom embedded in AGNR gives rise to significant impacts on the band structures and the FM spin configuration is the ground state. The presence of the Co doping could introduce magnetic properties. The calculated results revealed the arising of spin gapless semiconductor characteristics with doping near the edge in both ferromagnetic (FM and antiferromagnetic (AFM magnetic configurations, suggesting the robustness for potential application of spintronics. Moreover, the electronic structures of the Co-doped AGNRs are strongly dependent on the doping sites and the edge configurations.

  15. Long Lasting Phosphorescence in Eu2+ and Ce3+ Co-Doped Strontium Borate Glasses

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2+ and Ce3+. The methods of photoluminescence, thermoluminescence and phosphorescence were used to study the samples, and possible mechanism was suggested. The co-doping of Ce3+ ions poisoned the phosphorescence emission of Eu2+ because of the competition to obtain the trapped electron. The phosphorescence of Ce3+ in the sample decays more quickly than that of Eu2+, which is suggested for the reason that the emission energy of Ce3+ is higher or the distance between Ce3+ and electron traps of the glasses is longer.

  16. Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: Optical and electrochemical properties

    Science.gov (United States)

    Romeiro, Fernanda C.; Marinho, Juliane Z.; Lemos, Samantha C. S.; de Moura, Ana P.; Freire, Poliana G.; da Silva, Luis F.; Longo, Elson; Munoz, Rodrigo A. A.; Lima, Renata C.

    2015-10-01

    We report for the first time a rapid preparation of Zn1-2xCoxNixO nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green-orange-red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra. Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni co-doped ZnO samples when compared to pure ZnO.

  17. Co-doping of Potassium and Bromine in Carbon Nanotubes: A Density Functional Theory Study

    Institute of Scientific and Technical Information of China (English)

    XIAO Yong; YAN xiao-Hong; DING Jian-Wen

    2007-01-01

    We investigate the co-doping of potassium and bromine in singlewalled carbon nanotubes (SWCNTs)and doublewalled carbon nanotubes(DWCNTs)based on density functional theory.In the co-doped(6,O)SWCNTs,the 4s electron of potassium is transferred to nanotube and Br,leading to the n-type feature of SWCNTs.When potassium is intercalated into inner tube and bromine is put on outer tube,the positive and negative charges reside on the outer and inner tubes of the(7.0)@(16,0)DWCNT,respectively.It is expected that DWCNTs would be an ideal candidate for p-n junction and diode applications.

  18. Electronic structure, magnetic and superconducting properties of co-doped iron-arsenide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Rosner, Helge; Schnelle, Walter; Nicklas, Michael; Leithe-Jasper, Andreas [MPI CPfS Dresden (Germany); Weikert, Franziska [Los Alamos National Laboratory, New Mexico (United States); HLD Dresden Rossendorf (Germany); Wosnitza, Joachim [HLD Dresden Rossendorf (Germany)

    2013-07-01

    We present a joint experimental and theoretical study of co-doped iron-arsenide superconductors of the 122 family A{sub 1-x}K{sub x}Fe{sub 2-y}T{sub y}As{sub 2} (A = Ba,Sr,Eu; T = Co,Ru,Rh). In these systems, the co-doping enables the separation of different parameters - like electron count, disorder or the specific geometry of the FeAs layer - with respect to the position of the respective compounds in the general 122 phase diagram. For a series of compounds, we investigate the relevance of the different parameters for the magnetic, thermodynamic and superconducting properties. Our experimental investigations are supported by density functional electronic structure calculations applying different approximations for doping and disorder.

  19. Nuclear magnetic resonance study of pure and Ni/Co doped LiFeAs

    Energy Technology Data Exchange (ETDEWEB)

    Grafe, Hans-Joachim; Baek, Seung-Ho; Hammerath, Franziska; Graefe, Uwe; Utz, Yannic; Harnagea, L.; Nacke, Claudia; Aswartham, Saicharan; Wurmehl, Sabine; Buechner, Bernd [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung, Dresden (Germany)

    2011-07-01

    We present Nuclear Magnetic and Nuclear Quadrupole Resonance (NMR/NQR) measurements on pure, Ni and Co doped LiFeAs single crystals. The parent compound LiFeAs exhibits unconventional superconductivity with a transition temperature of about 17 K. Unlike other Fe based superconductors, where superconductivity is induced or stabilized by Co or Ni doping, replacement of Fe by these elements leads to a suppression of the superconducting transition temperature in LiFeAs. In case of Ni doping, a bulk magnetic order is induced below about 160 K. In contrast, for Co doping, the superconducting transition temperature is only reduced, but no magnetic order is observed. We discuss the nature and the origin of this magnetic order and its relation to unconventional superconductivity in pure LiFeAs.

  20. Enhancement of carrier mobility in thin Ge layer by Sn co-doping

    Science.gov (United States)

    Prucnal, S.; Liu, F.; Berencén, Y.; Vines, L.; Bischoff, L.; Grenzer, J.; Andric, S.; Tiagulskyi, S.; Pyszniak, K.; Turek, M.; Drozdziel, A.; Helm, M.; Zhou, S.; Skorupa, W.

    2016-10-01

    We present the development, optimization and fabrication of high carrier mobility materials based on GeOI wafers co-doped with Sn and P. The Ge thin films were fabricated using plasma-enhanced chemical vapour deposition followed by ion implantation and explosive solid phase epitaxy, which is induced by millisecond flash lamp annealing. The influence of the recrystallization mechanism and co-doping of Sn on the carrier distribution and carrier mobility both in n-type and p-type GeOI wafers is discussed in detail. This finding significantly contributes to the state-of-the-art of high carrier mobility-GeOI wafers since the results are comparable with GeOI commercial wafers fabricated by epitaxial layer transfer or SmartCut technology.

  1. Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: Optical and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Romeiro, Fernanda C.; Marinho, Juliane Z.; Lemos, Samantha C.S. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Moura, Ana P. de [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Freire, Poliana G. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Silva, Luis F. da; Longo, Elson [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Munoz, Rodrigo A.A. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Lima, Renata C., E-mail: rclima@iqufu.ufu.br [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil)

    2015-10-15

    We report for the first time a rapid preparation of Zn{sub 1−2x}Co{sub x}Ni{sub x}O nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green–orange–red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra. Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni co-doped ZnO samples when compared to pure ZnO. - Graphical abstract: Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: optical and electrochemical properties. Co, Ni co-doped ZnO hexagonal nanoparticles with optical and electrocatalytic properties were successfully prepared for the first time using a microwave hydrothermal method at mild conditions. - Highlights: • Co{sup 2+} and Ni{sup 2+} into ZnO lattice obtained a mild and environmentally friendly process. • The heating method strongly influences in the growth and shape of the particles. • Short-range defects generated by the ions insertion affects the photoluminescence. • Doped ZnO nanoparticles improve the electrocatalytic properties of pure oxide.

  2. Cr-N CO-DOPED ZnO NANOPARTICLES: SYNTHESIS ...

    African Journals Online (AJOL)

    BCSE

    Here we report the synthesis of CrN co-doped ZnO for the first time. ... detoxification of organic dye effluents have taken an increasingly important ... the transition pH range 1.2-2.8, 7.8-9.8 is red to yellow and yellow to blue, respectively. ... 0.1 g of the photocatalyst was dispersed in 50 mL of deionized .... 54 cm-1 are due.

  3. Influence of the chromium and ytterbium co-doping on the photoluminescence of zinc selenide crystals

    Institute of Scientific and Technical Information of China (English)

    I Radevici

    2014-01-01

    The luminescent properties of ZnSe, ZnSe:Cr (0.05 at.%Cr), ZnSe:Yb (0.03 at.%Yb) and ZnSe:Cr:Yb (0.05 at.%Cr, 0.05 at.%Yb) crystals, doped during the growth process by the chemical vapor transport method, were studied within the temperature in-terval of 6-300 K. At the 6 K temperature in the visible spectral range 2 bands were observed:a band in the excitonic spectral region and a band of self-activated luminescence. It was shown that co-doping of zinc selenide crystals with the chromium and ytterbium led to the combination of the impurities influence on the photoluminescent properties. At the liquid helium temperature in the middle in-frared range of the spectra of the ytterbium and chromium co-doped crystal a band with the maximum localized at 1.7 µm was ob-served, which was overlapped with a complex band in the middle-IR spectral range, characteristic for the chromium doped ZnSe crys-tals. On the basis of obtained data an interaction mechanism of the chromium and ytterbium co-doping impurities was proposed. Guided by the existent model of the ytterbium ion incorporation in the selenide sublattice of the ZnSe crystals, an assumption about stabilization of single charged chromium ions in the zinc sublattice crystal nodes, by means of formation of the local charge compen-sating clusters, was made. It was assumed that the resonant energy transfer from one chromium ion to another, which led to the con-centration quenching of the IR emission in the ZnSe:Cr PL spectra, would lead to the broadening of the IR emission in the spectra of ytterbium and chromium co-doped zinc selenide crystals.

  4. Structural, optical and magnetic properties of pulsed laser deposited Co-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Karzazi, O., E-mail: ouiame_karzazi@hotmail.fr [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); LPS, Physics Department, Faculty of Sciences, BP 1796, Fes (Morocco); Sekhar, K.C. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); El Amiri, A. [LPTA, Université Hassan II-Casablanca, Faculté des Sciences, B.P. 5366, Maârif (Morocco); Hlil, E.K. [Institut Néel, CNRS, Université J. Fourier, BP 166, 38042 Grenoble (France); Conde, O. [Departamento de Física, Faculdade de Ciências, Universidade de Lisboa and CeFEMA, Campo Grande, 1749-016 Lisboa (Portugal); Levichev, S. [Research Institute for Chemistry, Nizhni Novgorod State University, 603950 Nizhni Novgorod (Russian Federation); Agostinho Moreira, J. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007, Porto (Portugal); Chahboun, A. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); FST Tanger, Physics Department, BP 416, Tangier (Morocco); Almeida, A. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007, Porto (Portugal); Gomes, M.J.M. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2015-12-01

    Zn{sub 1−x}Co{sub x}O films with different Co concentrations (with x=0.00, 0.10, 0.15, and 0.30) were grown by pulsed laser deposition (PLD) technique. The structural and optical properties of the films were investigated by grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy and photoluminescence (PL). The magnetic properties were measured by conventional magnetometry using a SQUID and simulated by ab-initio calculations using Korring–Khon–Rostoker (KKR) method combined with coherent potential approximation (CPA). The effect of Co-doping on the GIXRD and Raman peaks positions, shape and intensity is discussed. PL studies demonstrate that Co-doping induces a decrease of the bandgap energy and quenching of the UV emission. They also suggest the presence of Zn interstitials when x≥0.15. The 10% Co-doped ZnO film shows ferromagnetism at 390 K with a spontaneous magnetic moment ≈4×10{sup −5} emu and coercive field ≈0.17 kOe. The origin of ferromagnetism is explained based on the calculations using KKR method. - Highlights: • Zn{sub 1−x}Co{sub x}O films (x=0.00, 0.10, 0.15, and 0.30) were grown by (PLD) technique. • Zn{sub 0.9}Co{sub 0.1}O film shows ferromagnetism above room temperature. • The origin of ferromagnetism behavior is attributed to the p-d hybridization. • Co-doping induces a decrease of the bandgap energy of the films.

  5. AC conductivity and dielectric properties of Co-doped TiO 2

    Science.gov (United States)

    Okutan, Mustafa; Basaran, Engin; Bakan, Halil I.; Yakuphanoglu, Fahrettin

    2005-07-01

    The alternating current (AC) conductivity and dielectric properties of the Co-doped TiO 2 were investigated. The temperature dependence of AC conductivity and the parameter s, is reasonably well interpreted by the correlated barrier hopping (CBH) model. The activation energy ( E), and the density of states at Fermi level, N( EF) were determined. The dielectric constant decreases with frequency at low frequencies and increases at high frequencies.

  6. AC conductivity and dielectric properties of Co-doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Okutan, Mustafa [Department of Physics, Gebze Institute of Technology, P.O. Box 141, 41400 Gebze (Turkey)]. E-mail: mustafa@gyte.edu.tr; Basaran, Engin [Department of Physics, Gebze Institute of Technology, P.O. Box 141, 41400 Gebze (Turkey); Bakan, Halil I. [TUBITAK-MAM, Materials and Chemical Research Institute, 41470 Gebze (Turkey); Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Arts and Science, Firat University, 23169 Elazig (Turkey)

    2005-07-15

    The alternating current (AC) conductivity and dielectric properties of the Co-doped TiO{sub 2} were investigated. The temperature dependence of AC conductivity and the parameter s, is reasonably well interpreted by the correlated barrier hopping (CBH) model. The activation energy (E), and the density of states at Fermi level, N(E {sub F}) were determined. The dielectric constant decreases with frequency at low frequencies and increases at high frequencies.

  7. Sb/Mn co-doped oxyfluoride silicate glasses for potential applications in photosynthesis

    OpenAIRE

    Zhu, Chaofeng; ZHANG, XIANGHUA; Ma, Hongli

    2016-01-01

    International audience; A series of Sb/Mn co-doped oxyfluoride silicate glasses were prepared via the melt-quenching method to explore red luminescent materials for potential applications in photosynthesis of green plants, and these glasses are investigated by means of luminescence decay curves, absorption, emission, and excitation spectra. We find that the as-prepared glasses are transparent in the visible region and can emit strong red light under ultraviolet, purple, and green light excita...

  8. Enhanced photocatalytic activity of Co doped ZnO nanodisks and nanorods prepared by a facile wet chemical method.

    Science.gov (United States)

    Kuriakose, Sini; Satpati, Biswarup; Mohapatra, Satyabrata

    2014-07-07

    Cobalt doped ZnO nanodisks and nanorods were synthesized by a facile wet chemical method and well characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy, photoluminescence spectroscopy, Raman spectroscopy and UV-visible absorption spectroscopy. The photocatalytic activities were evaluated for sunlight driven degradation of an aqueous methylene blue (MB) solution. The results showed that Co doped ZnO nanodisks and nanorods exhibit highly enhanced photocatalytic activity, as compared to pure ZnO nanodisks and nanorods. The enhanced photocatalytic activities of Co doped ZnO nanostructures were attributed to the combined effects of enhanced surface area of ZnO nanodisks and improved charge separation efficiency due to optimal Co doping which inhibit recombination of photogenerated charge carriers. The possible mechanism for the enhanced photocatalytic activity of Co doped ZnO nanostructures is tentatively proposed.

  9. Synthesis and characterization of Co-doped zinc oxide nanorods prepared by ultrasonic spray pyrolysis and hydrothermal methods

    Science.gov (United States)

    Febrianti, Y.; Putri, N. A.; Sugihartono, I.; Fauzia, V.; Handoko, D.

    2017-07-01

    ZnO nanorods was synthesized by using ultrasonic spray pyrolysis deposition process and grown by hydrothermal method on a glass substrate. The influences of varying Co doping in structural, morphological and optical properties were investigated by X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), and UV-Visible (UV-Vis) spectrometry, respectively. All the nanorods exhibit polycrystalline wurtzite structure with smaller crystalline size on the Co-doped nanorods. The nanorods also show no orientation alignment and random particle size. Interestingly, the nanorods with 3 wt.% Co doped shows high absorbance at UV and visible region indicating that optical properties of the ZnO nanorods have been modified by Co doping.

  10. Structural, optical and dielectric property of Co doped Bi{sub 2}Fe{sub 4}O{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Swain, Smita, E-mail: singhanil@nitrkl.ac.in; Mohapatra, S. R., E-mail: singhanil@nitrkl.ac.in; Sahoo, B., E-mail: singhanil@nitrkl.ac.in; Singh, A. K., E-mail: singhanil@nitrkl.ac.in [Department of Physics, National Institute of Technology, Rourkela -769008, Odisha (India)

    2014-04-24

    Multiferroic Bi{sub 2}Fe{sub 4}O{sub 9} and Co doped Bi{sub 2}Fe{sub 4}O{sub 9} are prepared by solid state route reaction method using bismuth oxide(Bi{sub 2}O{sub 3}), iron oxide(Fe{sub 2}O{sub 3}) and cobalt oxide (Co{sub 3}O{sub 4}). Their structural optical and dielectric properties are studied and compared. X-ray diffraction (XRD) results confirm that there is no change in crystal structure due to Co doping. From dielectric constant measurement we conclude that dielectric constant increases due to Co doping. UV-Visible plot shows due to Co doping bang gap energy increases.

  11. Defect mediated magnetic interaction and high Tc ferromagnetism in Co doped ZnO nanoparticles.

    Science.gov (United States)

    Pal, Bappaditya; Giri, P K

    2011-10-01

    Structural, optical and magnetic studies have been carried out for the Co-doped ZnO nanoparticles (NPs). ZnO NPs are doped with 3% and 5% Co using ball milling and ferromagnetism (FM) is studied at room temperature and above. A high Curie temperature (Tc) has been observed from the Co doped ZnO NPs. X-ray diffraction and high resolution transmission electron microscopy analysis confirm the absence of metallic Co clusters or any other phase different from würtzite-type ZnO. UV-visible absorption and photoluminescence studies on the doped samples show change in band structure and oxygen vacancy defects, respectively. Micro-Raman studies of doped samples shows defect related additional strong bands at 547 and 574 cm(-1) confirming the presence of oxygen vacancy defects in ZnO lattice. The field dependence of magnetization (M-H curve) measured at room temperature exhibits the clear M-H loop with saturation magnetization and coercive field of the order of 4-6 emu/g and 260 G, respectively. Temperature dependence of magnetization measurement shows sharp ferromagnetic to paramagnetic transition with a high Tc = 791 K for 3% Co doped ZnO NPs. Ferromagnetic ordering is interpreted in terms of overlapping of polarons mediated through oxygen vacancy defects based on the bound magnetic polaron (BMP) model. We show that the observed FM data fits well with the BMP model involving localised carriers and magnetic cations.

  12. Luminescence Properties of Sm3+/Eu3+ Co-Doped ZnO Quantum Dots.

    Science.gov (United States)

    Liu, Fengyi; Li, Hong; Hu, Yajing; Na, Jin; Mou, Yun; Yang, Kun; Ye, Zuhu; Li, Mingyue; Xie, Ya-Hong

    2016-04-01

    In order to improve luminescence properties of semiconductor ZnO quantum dots (QDs), Sm3+/Eu3+ co-doped ZnO QDs have been controllably synthesized by sol-gel method in this paper. ZnO QDs have a spherical shape with mean diameter at about 5-6 nm, which was characterized by high-resolution transmission electron microscopy (HRTEM). ZnO QDs have hexagonal wurtzite structure with parts of Sm3+ and Eu3+ incorporated into the lattice, which was demonstrated by X-ray Diffraction (XRD). Luminescence properties at room temperature (RT) of different amount of Sm3+ and 2 mol% Eu3+ doped ZnO QDs were examined in-depth by optical spectra. In contrast to the Pr3+/Eu3+ co-doped fluorescent performance researched in our previous study, the photoluminescence (PL) spectra indicates the unique luminescence properties of Sm3+/Eu3+ co-doped ZnO QDs. In addition, fluorescence lifetimes were obtained to illustrate the luminous mechanism.

  13. Co-doped branched ZnO nanowires for ultraselective and sensitive detection of xylene.

    Science.gov (United States)

    Woo, Hyung-Sik; Kwak, Chang-Hoon; Chung, Jae-Ho; Lee, Jong-Heun

    2014-12-24

    Co-doped branched ZnO nanowires were prepared by multistep vapor-phase reactions for the ultraselective and sensitive detection of p-xylene. Highly crystalline ZnO NWs were transformed into CoO NWs by thermal evaporation of CoCl2 powder at 700 °C. The Co-doped ZnO branches were grown subsequently by thermal evaporation of Zn metal powder at 500 °C using CoO NWs as catalyst. The response (resistance ratio) of the Co-doped branched ZnO NW network sensor to 5 ppm p-xylene at 400 °C was 19.55, which was significantly higher than those to 5 ppm toluene, C2H5OH, and other interference gases. The sensitive and selective detection of p-xylene, particularly distinguishing among benzene, toluene, and xylene with lower cross-responses to C2H5OH, can be attributed to the tuned catalytic activity of Co components, which induces preferential dissociation of p-xylene into more active species, as well as the increase of chemiresistive variation due to the abundant formation of Schottky barriers between the branches.

  14. Improved Methane Sensing Properties of Co-Doped SnO2 Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    Weigen Chen

    2013-01-01

    Full Text Available Co-doped SnO2 nanofibers were successfully synthesized via electrospinning method, and Co-doped SnO2 nanospheres were also prepared with traditional hydrothermal synthesis route for comparison. The synthesized SnO2 nanostructures were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectra. Planar-type chemical gas sensors were fabricated and their sensing properties to methane were investigated in detail. Gas sensors based on these two samples demonstrate the highest CH4 sensing response at an operating temperature of 300°C. Compared with traditional SnO2 nanospheres, the nanofiber sensor shows obviously enhanced gas response, higher saturated detection concentration, and quicker response-recovery time to methane. Moreover, good stability, prominent reproducibility, and excellent selectivity are also observed based on the nanofibers. These results demonstrate the potential application of Co-doped SnO2 nanofibers for fabricating high performance methane sensors.

  15. Synthesis and characterization of Ce, Cu co-doped ZnS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Harish, G.S.; Sreedhara Reddy, P., E-mail: psreddy4@gmail.com

    2015-09-15

    Ce, Cu co-doped ZnS nanoparticles were prepared at room temperature using a chemical co-precipitation method. The prepared nanoparticles were characterized by X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and high resolution Raman spectroscopic techniques. Transmission electron microscopy (TEM) and X-ray diffraction studies showed that the diameter of the particles was around 2–3 nm. Broadened XRD peaks revealed the formation of nanoparticles with a face centered cubic (fcc) structure. DRS studies confirmed that the band gap increased with an increase in the dopant concentration. The Raman spectra of undoped and Ce, Cu ions co-doped ZnS nanoparticles showed longitudinal optical mode and transverse optical mode. Compared with the Raman modes (276 and 351 cm{sup −1}) of undoped ZnS nanoparticles, the Raman modes of Ce, Cu co- doped ZnS nanoparticles were slightly shifted towards lower frequency. PL spectra of the samples showed remarkable enhancement in the intensity upon doping.

  16. Preparation and photocatalytic activity of nonmetal Co-doped titanium dioxide photocatalyst

    Science.gov (United States)

    Sun, Xiaogang; Xing, Jun; Qiu, Jingping

    2016-06-01

    A series of boron and sulfur co-doped titanium dioxide (TiO2) photocatalysts were prepared by a sol-gel method using boric acid, thiourea and tetrabutyl titanate [Ti(OC4H9)4] as precursors. The photoabsorbance of as-prepared photocatalysts was measured by UV-Vis diffuse reflectance spectroscopy (DRS), and its microstructure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption measurements. The prepared photocatalysts consisted of the anatase phase mainly in the form of spherical particles. The photocatalytic performance was studied by photodegradation of methyl blue (MB) in water under UV and visible light irradiation. The calcination temperature and the codoping content influenced the photoactivity. The synergistic effect of boron and sulfur co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of codoped TiO2 was also confirmed, the photocatalytic activity of TiO2 remained above 91% of that of the fresh sample after being used four times. It was shown that the co-doped TiO2 could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants.

  17. Visible upconversion in Er3+/Yb3+ co-doped LaAlO3 phosphors

    Science.gov (United States)

    Singh, Vijay; Rai, V. K.; Singh, N.; Pathak, M. S.; Rathaiah, M.; Venkatramu, V.; Patel, Rahul V.; Singh, Pramod K.; Dhoble, S. J.

    2017-01-01

    The Er3+ doped and Er3+/Yb3+ co-doped LaAlO3 phosphors have been synthesized by the combustion method and characterized their structural, morphological, elemental, vibrational and optical properties. The optical absorption and upconversion properties of the synthesized phosphors have been studied. Upon co-doping Yb3+ ions into Er3+:LaAlO3, the blue, green and red upconversion emissions of Er3+ ions have been enhanced about 20, 54 and 22 times, under 978 nm laser excitation. The observed upconversion emissions could be due to excited state absorption in Er3+:LaAlO3, whereas energy transfer is dominant mechanism in Er3+/Yb3+:LaAlO3 phosphors. The tuning in the color emitted from the synthesized phosphors towards the green region has been found due to incorporation of the Yb3+ ions. With increase in the pump power, the color emitted from the co-doped phosphor is not tuned significantly, showing its applicability in making the green display devices.

  18. Charge transport in conducting polyaniline co-doped with sulfosalicylic acid and dodecylbenzoyl sulfonic acid

    Institute of Scientific and Technical Information of China (English)

    MA Li; YAN Jun; GAN Meng-Yu; HE Ling; LI Jian-Feng

    2009-01-01

    We prepared conducting polyaniline (PAn) co-doped with sulfosalicylic acid (SSA) and dodecylbenzoyl sulfonic acid (DBSA) in micro-emulsive polymerization, and studied its charge transport behaviors based on the measurement of its electrical conductivity in the temperature range between 203 K and 298 K. The conductivity was found to increase with temperature, similar to the case in semiconductors. Analyzing the experimental data with three models, namely the charge-energy-limited-tunneling model, Kivelson model and the three-dimensional variable range hopping (3D-VRH) model demonstrated that these models all describe well the charge transport behaviors of PAn co-doped with SSA and DBSA within the mentioned temperature range. From calculation with the 3D-VRH model, the hopping distance of the conducting PAn is obviously larger than its localization length. The PAn doped with SSA and DBSA enjoys desirable crystallinity due to the co-doping of two functional sulfonic acids. The macroscopic conductivity may correspond to three-dimensional transport in the network of the bundles, and the metallic islands may be attributed to quasi-one-dimensional bundles.

  19. Color tunable ZnO nanorods by Eu and Tb co-doping for optoelectronic applications

    Science.gov (United States)

    Pal, Partha P.; Manam, J.

    2014-07-01

    Eu/Tb co-doped ZnO nanorods were prepared by co-precipitation method and the effect of Eu-Tb co-doping was studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), UV-Vis-NIR diffuse reflectance (DR) and photoluminescence (PL) spectroscopy. The XRD pattern shows typical peak pattern for pure hexagonal wurtzite structure to match with the JCPDS data. The samples are found to be consisting of nanorods of diameter 20-30 nm as revealed by the TEM image. The FTIR pattern confirms the formation of the compounds. The DR study was carried to show the variation of absorption edge and the variation in band gap values, which showed the crystal size effect in the co-doped sample of different rare-earth ratios. The room temperature PL study shows bright emission spectra for the samples with different rare-earth ratios. It shows a very good energy transfer from Tb to Eu ions. The energy transfer mechanism and color tunability were discussed thoroughly.

  20. Preparation and photoluminescence enhancement of Li+ and Eu3+ co-doped YPO4 hollow microspheres

    Institute of Scientific and Technical Information of China (English)

    ZHAG Lixin; JIU Hongfang; FU Yuehua; SUN Yixin; WANG Yuanzhong

    2013-01-01

    Li+ and Eu3+ co-doped YPO4 hollow microspheres were successfully synthesized by a sacrificial template method using polystyrene (PS) as template.Techniques of X-ray diffraction (XRD),scanning electron microscopy (SEM),as well as transmission electron microscopy (TEM) were employed to characterize the as-synthesized sample.Furthermore,the photoluminescence (PL)characterization of the Li+ and Eu3+ co-doped YPO4 microsphere was carried out and the effects of the doping concentration of Li+ and Eu3+ active center concentration as well as calcination temperature on the PL properties were studied in detail.The results showed that the incorporation of Li+ ions into the YPO4∶Eu3+ lattice could induce a remarkable improvement of the PL intensity.The highest emission intensity was observed with the compound of 5%Li+ and 5%Eu3+ co-doped YPO4,whose brightness was increased by a factor of more than 2.2 in comparison with that of the YPOa:5%Eu3+.

  1. Novel trichromatic phosphor Co-doped with Eu, Tb in SiO2 gel matrix

    Institute of Scientific and Technical Information of China (English)

    HU XiaoYun; FAN Jun; LI Ting; ZHANG DeKai; BAI JinTao; REN ZhaoYu; HOU Xun

    2007-01-01

    The Eu, Tb co-doped SiO2 matrix tricolor fluorescence system was prepared by sol-gel technique. Red emission at 618 nm, green emission at 543 nm and blue emission at 350-500 nm were observed in the PL spectra of the sample, indicating that Eu3+, Eu2+ and Tb3+ ions coexisted in the matrix. In the co-doped sample, the blue emission of Eu2+ was much stronger than that of the sample single doped with Eu, which implied that the electron transfer between Eu3+ and Tb3+ maybe happened in the SiO2 matrix. The influences of the annealing temperature and Tb concentration on the PL spectra of the samples were investigated. The optimal doped concentration of Tb was determined to be 0.2% and the optimal annealing temperature 850℃. Annealed at 600℃, Tb3+ had a sensitizing effect on Eu3+ in the SiO2 matrix, and the emission intensity of Eu3+ in the Eu, Tb co-doped sample was more than four times that of the single doped sample, which could be attributed to the energy transfer from Tb3+ to Eu3+.

  2. Microstructural analysis and thermoelectric properties of Sn-Al co-doped ZnO ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hoemke, Joshua, E-mail: jhoemke@sigma.t.u-tokyo.ac.jp; Tochigi, Eita; Shibata, Naoya; Ikuhara, Yuichi [Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Khan, Atta Ullah; Mori, Takao [National Institute of Materials Science (NIMS) 1-1 Namiki, Tsukuba 305-0044 (Japan); Yoshida, Hidehiro; Sakka, Yoshio [National Institute of Materials Science (NIMS), 1–2–1 Sengen, Tsukuba, 305–0047 (Japan)

    2016-08-26

    Sn-Al co-doped polycrystalline ZnO ceramics were prepared by sintering in air. Phase and microstructure analysis was performed by X-ray diffraction and SEM-EDS and thermoelectric properties were measured. XRD analysis showed a ZnO primary phase as well as secondary phase peaks due to the formation of a Zn{sub 2}SnO{sub 4} spinel phase or SnO{sub 2}(ZnO:Sn-Al){sub m} intergrowth phase. SEM analysis revealed a dense microstructure with a small number of nanometric pores, consistent with the measured density of 5.48 g/cm{sup 3}. An activated electrical conductivity characteristic of a semiconducting material was observed as well as a negative Seebeck coefficient with both values increasing in absolute value from RT to 730 °C. The power factor had a maximum value of 3.73×10{sup −4} W m{sup −1} K{sup −2} at 730 °C. Thermal conductivity measurements showed a significant reduction over the measured temperature range compared to undoped ZnO. This could be attributed to grain size reduction, the formation of a nanoscale secondary phase or a reduction in crystallinity caused by Sn-Al co-doping. A maximum ZT of 0.06 was obtained at 750 °C for the Sn-Al co-doped ZnO ceramics.

  3. Catalytic wet air oxidation of phenol over Co-doped Fe3O4 nanoparticles

    Science.gov (United States)

    Song, Xu Chun; Zheng, Yi Fan; Yin, Hao Yong

    2013-08-01

    The Fe3O4 nanoparticles doped with cobalt ions have been successfully synthesized by the co-precipitation process. The X-ray diffraction, inductively coupled plasma, scanning electron microscopy, and transmission electron microscopy were used to characterize the as-prepared nanoparticles. The results show that the phase structure of the nanoparticles is spinel structure of pure Fe3O4 with the particle size ranging from 40 to 50 nm. The Co-doping concentration can be controlled by changing the atomic ratio of the stock materials. The catalytic activity of the Co-doped Fe3O4 was further investigated by decomposing the phenol in liquid phase. The results show that cobalt ions doping can improve the catalytic efficiency of Fe3O4 nanoparticles in phenol degradation with catalytic reaction fitting the first-order kinetics. According to the estimated reaction rate of Co-doped Fe3O4 nanoparticles at different temperatures, the activation energy was calculated to be 45.63 kJ/mol.

  4. Physical mechanism of resistance switching in the co-doped RRAM

    Science.gov (United States)

    Yang, Jin; Dai, Yuehua; Lu, Shibin; Jiang, Xianwei; Wang, Feifei; Chen, Junning

    2017-01-01

    The physical mechanism of the resistance switching for RRAM with co-doped defects (Ag and oxygen vacancy) is studied based on the first principle calculations and the simulation tool VASP. The interaction energy, formation energy and density of states of Ag and oxygen vacancy defect (VO) are calculated. The calculated results reveal that the co-doped system is more stable than the system only doped either Ag or VO defect and the impurity energy levels in the band gap are contributed by Ag and VO defects. The obtained partial charge density confirmed further that the clusters are obvious in the direction of Ag to Hf ions, which means that it is Ag but VO plays a role of conductive paths. For the formation mechanism, the modified electron affinity and the partial charge density difference are calculated. The results show that the ability of electron donors of Ag is stronger than VO In conclusion, the conductivity of the physical mechanism of resistance switching in the co-doped system mainly depends on the doped Ag. Project supported by the National Natural Science Foundation of China (No. 61376106), the Research Foundation of Education Bureau of Anhui Province, China (Nos. KJ2015A276, KJ2016A574, KJ2014A208), and the Special Foundation for Young Scientists of Hefei Normal University (No. 2015rcjj02).

  5. Observation of low field microwave absorption in co-doped ZnO system

    Science.gov (United States)

    Mahule, Tebogo S.; Srinivasu, Vijaya V.; Das, Jayashree

    2016-10-01

    Room temperature low field microwave absorption (LFMA) in magnetic materials find application in microwave absorbers and low field sensors. However not all the magnetic materials show LFMA and the phenomenon is not fully understood. We report on the observation of low field microwave absorption (LFMA) or the non-resonant microwave absorption (NRMA) in the transition metal (TM) co-doped ZnO samples of the composition Zn1-x(TM:TM)xO synthesized by solid state reaction technique. LFMA peaks and hysteresis matches very well with that of the magnetization hysteresis loop and the anisotropy fields at room temperature similar to the reports in the literature for other magnetic systems. However we show through our careful experiments that such a correlation between LFMA and the magnetization does not survive at low temperatures and particularly at 10 K the LFMA hysteresis collapses in our TM co-doped ZnO system; whereas the magnetization hysteresis loop becomes very big and anisotropy field becomes bigger in the range of kOe. We interpret the LFMA as field dependent surface impedance or eddy current losses, in terms of a possible role of anomalous hall resistivity that follows magnetization and the ordinary hall resistivity that only follows the applied field. We then argue that LFMA accordingly follows magnetization or applied field when AHE or OHE dominates respectively. Also we confirm the absence of LFMA signals in the rare earth co-doped ZnO system.

  6. Nanoscale α-MnS crystallites grown on N-S co-doped rGO as a long-life and high-capacity anode material of Li-ion batteries

    Science.gov (United States)

    Liu, Boli; Liu, Zhengjiao; Li, Dan; Guo, Pengqian; Liu, Dequan; Shang, Xiaonan; Lv, Mingzhi; He, Deyan

    2017-09-01

    The rock-salt structural manganous sulfide (α-MnS) is of higher lithium storage capacity. To improve the cyclability of α-MnS anode in lithium-ion batteries, we prepared a composite of α-MnS nanocrystallites grown on nitrogen and sulfur co-doped reduced graphene oxide (rGO) honeycomb framework. N and S atoms have been co-doped into rGO along with the growth of the α-MnS nanocystallites by a one-pot hydrothermal synthesis using thiourea as dopant and reactant. The typical α-MnS/Nsbnd S co-doped rGO (NSG) composite electrode exhibits a reversible capacity as high as 763.5 mAh g-1 after 100 cycles at 100 mA g-1, and a reversible capacity of 576.7 mAh g-1 even after 2000 cycles at 1000 mA g-1. More importantly, the α-MnS/NSG composite electrodes show superior cycle performance at asymmetric discharge/charge current densities. The excellent electrochemical performance can be attributed to that the α-MnS nanocrystallites shorten lithium ion transmission distance, N-S co-doping improves the electronic conductivity of rGO, and the formation of chemical bonds combination between α-MnS and NSG enhances the electrode structural stability and the electron transport. In addition, more stable architecture of NSG-supported ultrafine α-MnS particles is formed upon cycling, which greatly enhances the electrical contact and further improves the electrochemical performance.

  7. Titania Deposition on PMR-15

    Science.gov (United States)

    Meador, Mary B.; Sutter, James K.; Pizem, Hillel; Gershevitz, Olga; Goffer, Yossi; Frimer, Aryeh A.; Sukenik, Chaim N.; Sampathkumaran, Uma; Milhet, Xavier; McIlwain, Alan

    2005-01-01

    The formation, degree of crystallinity and adherence of dense titania (TiO2) thin film coatings on a high-temperature polyimide resin (PMR-15) can be influenced by the chemical composition of the polymer surface. Furthermore, solution deposition conditions can be adjusted to provide additional control over the morphology and crystallinity of the titania films. Recipes for solution-based titania deposition that used a slowly-hydrolyzing titanium fluoride salt in the presence of boric acid as a fluoride scavenger allowed growth of films up to 750 nm thick in 22 h. By adjusting solution pH and temperature, either amorphous titania or oriented crystalline anatase films could be formed. Surface sulfonate groups enhance the adhesion of solution-deposited oxide thin film coatings. While most sulfonation procedures severely damaged the PMR-15 surface, the use of chlorosulfonic acid followed by hydrolysis of the installed chlorosulfonyl groups provided effective surface sulfonation without significant surface damage. In some cases, the oxide deposition solution caused partial hydrolysis of the polymer surface, which itself was sufficient to allow adhesion of the titania film through chelation of titanium ions by exposed benzoic acid groups on the polymer surface.

  8. Photocatalytic Degradation of Dicofol and Pyrethrum with Boric and Cerous Co-doped TiO2 under Light Irradiation

    Institute of Scientific and Technical Information of China (English)

    GONG Lifen; ZOU Jing; ZENG Jinbin; CHEN Wenfeng; CHEN Xi; WANG Xiaoru

    2009-01-01

    Boric and cerous co-doped nano titanium dioxide (B/Ce co-doped TiO2) was synthesized using a sol-gel tech-nique, which involved the hydrolyzation of tetrabutyl titanate with the addition of boric acid and cerous nitrate. The B/Ce co-doped TiO2 was employed for the photocatalytic degradation of dicofol, cyfluthrin and fenvalerate under light irradiation. XRD, TEM, Fr-IR and UV-Vis DRS methods were used to characterize the crystalline structure. Experimental results showed that only the anatase signal phase was found for B/Ce co-doped TiO2, but multiplicate phases, including anatase, rutile and less brookite phases, were identified both in the pure TiO2 nanoparticles and Ce-doped TiO2 nanoparticles. The band gap value of B/Ce co-doped nano TiO2 was narrower than that of undoped nano TiO2. Compared to undoped TiO2, a stronger absorption in the range of 420 to 850 nm was found for B/Ce co-doped nano TiO2, which presented a higher photocatalytic activity in the degradation of dicofol, cyfluthrin and fenvalerate than both Ce doped nano TiO2 and pure nano TiO2 under the same light irradiation.

  9. Structural and electronic properties study on B-N co-doped (4,3) carbon nanotubes through first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuechao; Shi, Jianhao; Zhao, Tong [Department of Materials Physics and Chemistry, Kunming University of Science & Technology, Kunming, Yunnan 650093 (China); Wan, Rundong, E-mail: rdwan@kmust.edu.cn [Department of Materials Physics and Chemistry, Kunming University of Science & Technology, Kunming, Yunnan 650093 (China); Leng, Chongyan [Department of Materials Physics and Chemistry, Kunming University of Science & Technology, Kunming, Yunnan 650093 (China); Lei, Ying [Department of Metallurgical Engineering, Anhui University of Technology, Maanshan, Anhui 243002 (China)

    2016-06-01

    Abstracts: We carry out theoretical studies for both the pristine and boron-nitrogen co-doped (4,3) single-walled carbon nanotubes (SWCNTs). We first acquire the optimized geometries using a pure functional. We then obtain the electronic structures with a relatively accurate hybrid functional. We systematically study four different patterns for doping along different chain directions. Our calculated results reveal that the energy band splits, and many new states appear in the gap after doping. The band gap gradually decreases with the increasing number of dopants, while it begins to expand when the doping concentration is larger. Through projected density of states analyses, we find that the individual atoms make different contribution to the valence states, gap region states, and conduction states. These findings are expected to provide some reliable theoretical supports with the following research on the modification of carbon nanotubes.

  10. Thermoelectric performance of intermetallic FeGa{sub 3} with Co doping

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandran, B.; Syu, K.Z. [Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan (China); Kuo, Y.K., E-mail: ykkuo@mail.ndhu.edu.tw [Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan (China); Gippius, A.A. [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Shevelkov, A.V.; Verchenko, V.Yu. [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Lue, C.S. [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2014-09-01

    Highlights: • From the resistivity study of Fe{sub 1−x}Co{sub x}Ga{sub 3} (0.005 ⩽ x ⩽ 0.5), the metallic behavior is observed for the compounds with Co content of x ⩾ 0.125. • The Seebeck coefficient of these compounds has contribution from both diffusion thermoelectric power and phonon-drag effect. • A reduction in Seebeck coefficient with Co doping is observed, due to the modification in band gap and density of states at the Fermi level. • Low-temperature lattice thermal conductivity of FeGa{sub 3} is suppressed significantly by Co doping due to the phonon-point-defect scattering. • The maximum ZT value of ∼0.05 is achieved for Fe{sub 0.95}Co{sub 0.05}Ga{sub 3} at 400 K, ten times higher than that of the parent FeGa{sub 3}. - Abstract: Investigation on temperature-dependent electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) of intermetallic Fe{sub 1−x}Co{sub x}Ga{sub 3} (0.005 ⩽ x ⩽ 0.5) compounds are carried out to probe their thermoelectric performance. From resistivity study, it is observed that increase in number of valence electrons introduced by Co doping leads to a change from semiconducting to metallic behavior, which occurs between x = 0.05 and 0.125. The characteristics of the Seebeck coefficient show a substantial decrease with the Co doping, due to the modifications in the band gap and the Fermi-level density of states. Analyses of thermal conductivity of the Co doped FeGa{sub 3} compounds reveal that thermal transport is essentially due to the lattice phonons. It is also noticed that the low-temperature peak in the lattice thermal conductivity of these compounds is reduced significantly with the increase in Co content, attributing to the enhanced scattering of phonons by point-defects. The value of the figure-of-merit, ZT = (S{sup 2}/ρκ)T, is estimated for all compounds, and the maximum room-temperature ZT value of about 0.02 was achieved for Fe{sub 0.95}Co{sub 0.05}Ga{sub 3}, and

  11. Structure and photoluminescence of TiO{sub 2} nanocrystals doped and co-doped with N and rare earths (Y{sup 3+}, Pr{sup 3+})

    Energy Technology Data Exchange (ETDEWEB)

    Ricci, P.C., E-mail: carlo.ricci@dsf.unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, 09042 Monserrato (Italy); Carbonaro, C.M.; Geddo Lehmann, A.; Congiu, F.; Puxeddu, B. [Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, 09042 Monserrato (Italy); Cappelletti, G.; Spadavecchia, F. [Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano (Italy)

    2013-06-05

    Highlights: ► We studied singly and co-doped N, Y and Pr:TiO{sub 2} nanoparticles. ► A mixed anatase-brookite phase with average dimension lower than 10 nm was revealed. ► The nature of defects in the TiO{sub 2} structures depends on the doping elements. ► Bulk and surface defects are related to nitrogen in the TiO{sub 2} matrix. ► Y{sup 3+} ion acts as a surface stabilizer, Pr{sup 3+} generates surface recombination centers. -- Abstract: The structural and optical properties of sol–gel synthesized TiO{sub 2} nanoparticles doped and co-doped with N and rare earth ions (Y{sup 3+} and Pr{sup 3+}) are presented. Crystal structures, phase composition, and crystallite sizes are analyzed by powder X-ray diffraction and Raman spectroscopy. The analysis of intragap excited photoluminescence indicates the formation of radiative recombinations related to different defect centers in the TiO{sub 2} structure, generated by the presence of doping elements. In particular we assign the formation of bulk and surface defects to the presence of nitrogen in the TiO{sub 2} matrix, whereas we observe different effects on the defective TiO{sub 2} structure related to the two rare earths: the presence of Y{sup 3+} ion acts as a stabilizer of the TiO{sub 2} surface whereas the presence of Pr{sup 3+} generates surface recombination centers.

  12. A comparative investigation on structure and multiferroic properties of bismuth ferrite thin films by multielement co-doping

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guohua; Tan, Guoqiang, E-mail: tan3114@163.com; Luo, Yangyang; Liu, Wenlong; Xia, Ao; Ren, Huijun

    2014-12-15

    Highlights: • Multielement (Tb, Cr and Mn) co-doped BiFeO{sub 3} films were fabricated by CSD method. • Multielement co-doping induces a structural transition. • It is found effective to stabilize the valence of Fe ions at +3 by the strategy. • The co-doping at A/B-sites gives rise to the superior multiferroic properties. - Abstract: (Tb, Cr and Mn) multielement co-doped BiFeO{sub 3} (BTFCMO) thin films were prepared by the chemical solution deposition method on fluorine doped tin oxide (FTO) substrates. X-ray diffraction, Rietveld refinement and Raman analyses revealed that a phase transition from rhombohedral to triclinic structure occurs in the multielement co-doped BiFeO{sub 3} films. It is found that the doping is conducive to stabilizing the valence of Fe ions and reducing leakage current. In addition, the highly enhanced ferroelectric properties with a huge remanent polarization (2P{sub r}) of 239.6 μC/cm{sup 2} and a low coercive field (2E{sub c}) of 615.6 kV/cm are ascribed to the well film texture, the structure transition and the reduced leakage current by the co-doping. Moreover, the structure transition is the dominant factor resulting in the significant enhancement observed in magnetization (M{sub s} ∼ 10.5 emu/cm{sup 3}), owing to the collapse of the space-modulated spin structure. In this contribution, these results demonstrate that the multielement co-doping is in favor of the enhanced multiferroic properties of the BFO films for possible multifunctional applications.

  13. N, S co-doped carbon dots with orange luminescence synthesized through polymerization and carbonization reaction of amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Ya-Wen [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma, De-Kun, E-mail: dkma@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Wang, Wei; Chen, Jing-Jing; Zhou, Lin; Zheng, Yi-Zhou [Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027 (China); Yu, Kang, E-mail: yukang62@126.com [Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027 (China); Huang, Shao-Ming, E-mail: smhuang@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China)

    2015-07-01

    Graphical abstract: N, S co-doped CDs with orange luminescence were synthesized through one-pot polymerization and carbonization reactions under hydrothermal conditions, using two different amino acids as raw materials. - Highlights: • N, S co-doped CDs were synthesized by one-pot carbonization reactions, using two different amino acids as raw materials. • The as-obtained N, S co-doped CDs showed unique orange fluorescence under excitation at room temperature. • The products could be applied in the imaging of peritoneal macrophages of mice without any functionalization. - Abstract: For practical application, it is highly desirable to obtain carbon dots (CDs) through environmentally benign synthetic route, using green raw materials. On the other hand, at present, most of CDs reported in the literature showed blue, green and yellow emission. Therefore it is still necessary to develop new strategy to obtain CDs with longer wavelength emission in order to expand their application range. Toward this end, in this study, N, S co-doped CDs were synthesized through one-pot condensation polymerization and carbonization reactions under hydrothermal conditions, using two different amino acids as raw materials. Taking the reaction of L-serine with L-cystine as an example, the as-obtained products were characterized by various techniques such as transmission electron microscopy, elemental analysis, Fourier-transform infrared spectrum, X-ray photoelectron spectra, and so on. Interestingly, N, S co-doped CDs displayed unique orange emission at room temperature. The possible photoluminescence mechanism of N, S co-doped CDs was proposed. Furthermore, the as-synthesized N, S co-doped CDs were directly applied in the imaging of peritoneal macrophages of mice.

  14. Europium and potassium co-doped strontium metaborate single crystals grown by the Czochralski method

    Science.gov (United States)

    Głowacki, Michał; Solarz, Piotr; Ryba-Romanowski, Witold; Martín, Inocencio R.; Diduszko, Ryszard; Berkowski, Marek

    2017-01-01

    Strontium metaborate (SrB2O4) is a suitable material for use as a matrix for luminescent dopant ions. Similarity of ionic radii of strontium and divalent europium makes it an excellent host for Eu dopant. This paper reports on the Czochralski growth and spectroscopic study of SrB2O4 single crystals doped with europium and co-doped with europium and potassium. Based on recorded luminescence spectra it was found that both Eu3+ and Eu2+ ions occur in this host. Trivalent europium ions give rise to a narrow-band long-lived red luminescence that is not affected by incorporation of potassium ions. Divalent europium ions emit a UV-blue luminescence, consisting of a large spectral band centered at ca 430 nm. In the absence of potassium ions the decay of this luminescence deviates slightly from a single exponential time dependence with a mean lifetime value of 2.0 ns. In potassium-co-doped sample a strong deviation from a single exponential decay was observed for longer stages of decay, beginning at ca 2.5 ns. This phenomenon was attributed to dissimilarity of relaxation rates of a fraction of europium ions distributed in different lattice sites that are distorted by the presence of big potassium ions. By co-doping the host with alkali ions one can influence the oxidation state of europium ions thereby enhancing the emission of trivalent europium ions. It was concluded that the material under study is a promising phosphor for visible light emission applications.

  15. Superconductivity in fluorine and yttrium co-doped SmFeAsO

    Science.gov (United States)

    Lai, K. T.; Kwong, F. L.; Ng, Dickon H. L.

    2012-05-01

    Polycrystalline fluorine and yttrium co-doped SmFeAsO samples are synthesized by solid state sintering and their physical properties are studied. The lattice parameters of the Sm1-yYyFeAsO0.8F0.2 samples decrease with the increasing y due to the smaller Y ions and the stiffness of the Y-O bond. The maximum critical temperature Tc of the samples is at y = 0.05. This may be due to the fact that the strong interaction between Sm and Fe of the Fe-As bond is being re-disturbed by the doped Y ions.

  16. Structural, chemical and magnetic properties of secondary phases in Co-doped ZnO

    DEFF Research Database (Denmark)

    Ney, A; Kovács, András; Ney, V;

    2011-01-01

    , chemical and magnetic properties of Co-doped ZnO samples. It can be established on a quantitative basis that the superparamagnetic (SPM) behavior observed by integral superconducting quantum interference device magnetometry is not an intrinsic property of the material but stems from precipitations...... of metallic Co. Their presence is revealed by TEM as well as XAS. Annealing procedures for these SPM samples were also studied, and the observed changes in the magnetic properties found to be due to a chemical reduction or oxidation of the metallic Co species....

  17. Ionic conductivity of co-doped Sc2O3-ZrO2 ceramics

    DEFF Research Database (Denmark)

    Omar, Shobit; bin Najib, Waqas; Chen, Weiwu

    2012-01-01

    The oxide ionic conductivity of Sc0.18Zr0.82O1.91 doped with 0.5 mol.% of both Yb2O3 and In2O3 is evaluated at various temperatures in air. Among various co-doped compositions, In0.02Sc0.18Zr0.80O1.90 exhibits the highest grain ionic conductivity followed by Yb0.02Sc0.18Zr0.80O1.90 at 500°C. Howe...

  18. Enhanced Luminescent Properties in Tm3+/Dy3+ Co-doped Transparent Phosphate Glass Ceramic

    Directory of Open Access Journals (Sweden)

    Yao L. Q.

    2016-01-01

    Full Text Available Novel Tm3+/Dy3+ co-doped phosphate glass and glass ceramic samples for white light emitting diodes were prepared by melt quenching method. Under 353 nm excitation, the colors of the luminescence of the glass and glass ceramic samples are white. The CIE chromaticity coordinates (0.338, 0.328 of the emission from the glass ceramic is close to the standard white-light illumination (0.333, 0.333. Compared to the glass, the fluorescence intensity in the glass ceramic is greatly enhanced.

  19. Ferromagnetism in Co-doped (La,Sr)TiO3

    Energy Technology Data Exchange (ETDEWEB)

    Fix, T.; Liberati, M.; Aubriet, H.; Sahonta, S.-L.; Bali, R.; Becker, C.; Ruch, D.; MacManus-Driscoll, J.L.; Arenholz, E.; Blamire, M.G.

    2009-04-21

    The origin of ferromagnetism in Co-doped (La,Sr)TiO{sub 3} epitaxial thin films is discussed. While the as-grown samples are not ferromagnetic at room temperature or at 10 K, ferromagnetism at room temperature appears after annealing the films in reducing conditions and disappears after annealing in oxidizing conditions. Magnetic measurements, x-ray absorption spectroscopy, x-ray photoemission spectroscopy and transmission electron microscopy experiments indicate that within the resolution of the instruments the activation of the ferromagnetism is not due to the presence of pure Co.

  20. Co-doping with antimony to control phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-02-15

    In germanium, phosphorous and antimony diffuse quickly and as such their transport must be controlled in order to design efficient n-typed doped regions. Here, density functional theory based calculations are used to predict the influence of double donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy were formed. These clusters are energetically stable and can lead to the formation of even larger clusters involving a number of donor atoms around a vacancy, thereby affecting the properties of devices.

  1. Co-doping effects on luminescence and scintillation properties of Ce doped Lu{sub 3}Al{sub 5}O{sub 12} scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, Kei, E-mail: kamada@imr.tohoku.ac.jp [Tohoku University, New Industry Creation Hatchery Center, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); C& A Corporation, T-Biz, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Nikl, Martin [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Kurosawa, Shunsuke [Tohoku University, New Industry Creation Hatchery Center, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Tohoku University Institute for Material Reseach, 2-1-1 Katahira Aoba-ku, Sendai 980-8577, Miyagi (Japan); Beitlerova, Alena [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Nagura, Aya [Tohoku University Institute for Material Reseach, 2-1-1 Katahira Aoba-ku, Sendai 980-8577, Miyagi (Japan); Shoji, Yasuhiro [C& A Corporation, T-Biz, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Tohoku University Institute for Material Reseach, 2-1-1 Katahira Aoba-ku, Sendai 980-8577, Miyagi (Japan); Pejchal, Jan [Tohoku University, New Industry Creation Hatchery Center, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Ohashi, Yuji [Tohoku University Institute for Material Reseach, 2-1-1 Katahira Aoba-ku, Sendai 980-8577, Miyagi (Japan); Yokota, Yuui [Tohoku University, New Industry Creation Hatchery Center, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Yoshikawa, Akira [Tohoku University, New Industry Creation Hatchery Center, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); C& A Corporation, T-Biz, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Tohoku University Institute for Material Reseach, 2-1-1 Katahira Aoba-ku, Sendai 980-8577, Miyagi (Japan)

    2015-05-11

    The Mg, Ca, Sr and Ba 200 ppm co-doped Ce:Lu{sub 3}Al{sub 5}O{sub 12} single crystals were prepared by micro pulling down method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of the co-doping. The scintillation decays were accelerated by both Mg and Ca co-dopants. The Mg co-doped samples showed the fastest decay and the highest light yield among the co-doped samples.

  2. Thermally and optically stimulated radiative processes in Eu and Y co-doped LiCaAlF{sub 6} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Kentaro, E-mail: ken-fukuda@tokuyama.co.jp [Tokuyama Corporation, 1-1 Mikage-cho, Shunan-shi, Yamaguchi 745-8648 (Japan); Yanagida, Takayuki; Fujimoto, Yutaka [Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu, Kitakyushu, Fukuoka 808-0196 (Japan)

    2015-06-01

    Yttrium co-doping was attempted to enhance dosimeter performance of Eu doped LiCaAlF{sub 6} crystal. Eu doped and Eu, Y co-doped LiCaAlF{sub 6} were prepared by the micro-pulling-down technique, and their dosimeter characteristics such as optically stimulated luminescence (OSL) and thermally stimulated luminescence (TSL) were investigated. By yttrium co-doping, emission intensities of OSL and TSL were enhanced by some orders of magnitude. In contrast, scintillation characteristics of yttrium co-doped crystal such as intensity of prompt luminescence induced by X-ray and light yield under neutron irradiation were degraded.

  3. Co-doping effects on luminescence and scintillation properties of Ce doped (Lu,Gd)3(Ga,Al)5O12 scintillator

    Science.gov (United States)

    Yamaguchi, Hiroaki; Kamada, Kei; Kurosawa, Shunsuke; Pejchal, Jan; Shoji, Yasuhiro; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira

    2016-11-01

    Mg co-doping effects on scintillation properties of Ce:Lu1Gd2(Ga,Al)5O12 (LGGAG) were investigated. Mg 200 ppm co-doped Ce:LGGAG single crystals were prepared by micro pulling down method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Mg co-doping. Ce4+ charge transfer absorption was observed below 300 nm in Mg,Ce:LGGAG which is in good agreement with previous reports. The scintillation decay times were accelerated by Mg co-doping.

  4. First principles study on the spin dependent electronic behavior of Co doped ZnO structures joining the Al electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Caliskan, S., E-mail: scaliskan@fatih.edu.tr; Guner, S.

    2015-01-15

    Highlights: • An atomic configuration joining the electrodes can govern spin resolved transport. • Co position and concentration in ZnO have a crucial effect on electronic behavior. • It is possible to obtain high spin polarization in Al–Co doped ZnO–Al systems. • Al–Co doped ZnO–Al device structures reveal Schottky-like contact at the interface. - Abstract: Employing first principles, Co doped ZnO systems between the Al electrodes were investigated through the Density Functional Theory combined with Non Equilibrium Green’s Function Formalism. Electronic transport properties of these systems, in the presence of spin property, were revealed using substitutional Co atoms in a supercell. Spin resolved electronic behavior was observed to be crucially governed by atomic configuration, defined by doping position and concentration, of the system joining the electrodes. Using this feature, one can manipulate both the electronic transport and magnetic properties of an Al–Co doped ZnO–Al device structure. A nonlinearity was exhibited in current–voltage characteristics for Co doped ZnO systems attached to the Al electrodes, which implies a Schottky-like contact at the interface. The induced magnetic moment and spin polarization in the system, yielding the spin dependent transport, were elucidated.

  5. The effect of CO-doped on the room-temperature ferromagnetism of CeO{sub 2} nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Xu, H.F, E-mail: xuhaifeng@ahsztc.edu.cn [School of Mechanical and Electronic Engineering, Suzhou University, Suzhou 234000 (China); Li, H [School of Information Engineering, Suzhou University, Suzhou 234000 (China)

    2015-03-01

    Co-doped CeO{sub 2} nanorods of 10–20 nm in diameter and 200–600 nm or more in length have been synthesized by a simple co-precipitation method. The results of XRD and SADE analysis indicate that the as-synthesized CeO{sub 2} samples have the fluorite structure. X-ray photoelectron spectroscopy and Raman spectra show that Ce{sup 4+} and Ce{sup 3+} ions coexist at the surface of non-doped CeO{sub 2} nanorods. The magnetic measurements indicated that Co-doped CeO{sub 2} nanorods exhibit stronger ferromagnetism at room temperature, and while increasing the amount of Co ions, the ferromagnetism increase more, which can be associated with the presence of Ce{sup 3+} and Co{sup 2+}. - Highlights: • Co-doped CeO{sub 2} nanorods are synthesized by a simple hydrothermal method. • The synthesized Co-doped CeO{sub 2} nanorods show excellent RTFM. • The controllable morphology and RTFM should make the Co-doped CeO{sub 2} nanorods excellent candidates for applications in related areas.

  6. Tailoring Imprinted Titania Nanoparticles for Purines Recognition

    Directory of Open Access Journals (Sweden)

    Adnan Mujahid

    2015-01-01

    Full Text Available Molecular imprinted titania nanoparticles were developed for selective recognition of purines, for example, guanine and its final oxidation product uric acid. Titania nanoparticles were prepared by hydrolysis of titanium butoxide as precursor in the presence of pattern molecules. The morphology of synthesized nanoparticles is evaluated by SEM images. Recognition characteristics of imprinted titania nanoparticles are studied by exposing them to standard solution of guanine and uric acid, respectively. The resultant change in their concentration is determined by UV/Vis analysis that indicated imprinted titania nanoparticles possess high affinity for print molecules. In both cases, nonimprinted titania is taken as control to observe nonspecific binding interactions. Cross sensitivity studies suggested that imprinted titania is at least five times more selective for binding print molecules than competing analyte thus indicating its potential for bioassay of purines.

  7. YellowupconversionluminescenceinHo3+/Yb3+co-dopedGd2Mo3O9phosphor

    Institute of Scientific and Technical Information of China (English)

    孙家跃; 薛兵; 孙广超; 崔殿鹏

    2013-01-01

    The strong yellow upconversion (UC) light emission was observed in Ho3+/Yb3+co-doped Gd2Mo3O9 phosphor under the excitation of 980 nm diode laser. The phosphors were synthesized by the traditional solid-state reaction method. The structures of the samples were characterized by X-ray diffraction (XRD). Under 980 nm excitation, Ho3+/Yb3+co-doped Gd2Mo3O9 exhibited strong yellow UC emission based on the green emission near 541 nm generated by 5F4,5S2→5I8 transition and the strong red emission around 660 nm generated by 5F5→5I8 transition, which assigned to the intra-4f transitions of Ho3+ions. The doping concentrations of Ho3+and Yb3+were determined to be 0.01 mol Ho3+and 0.2 mol Yb3+for the strongest yellow emission. Then the dependence of UC emis-sion intensity on excitation power density showed that the green and red UC emissions were involved in two-photon process. The possible UC mechanisms for the strong yellow emission were also investigated. The result indicated that this material was a promis-ing candidate for the application in the yellow display field.

  8. Broadband near-infrared emission from Tm3+/Er3+ co-doped nanostructured glass ceramics

    Science.gov (United States)

    Chen, Daqin; Wang, Yuansheng; Bao, Feng; Yu, Yunlong

    2007-06-01

    Transparent SiO2-Al2O3-NaF-YF3 glass ceramics co-doped with Er3+ and Tm3+ were prepared by melt quenching and subsequent heating. X-ray diffraction and transmission electron microscopy experiments revealed that β-YF3 nanocrystals incorporated with Er3+ and Tm3+ were precipitated homogeneously among the oxide glass matrix. An integrated broad near-infrared emission band in the wavelength region of 1300-1700 nm, consisting of Tm3+ emissions around 1472 nm (H34→F34) and 1626 nm (F34→H36), and Er3+ emission around 1543 nm (I413/2→I415/2), was obtained under 792 nm laser excitation. The full width at half maximum of this integrated band increased with the increasing of [Tm]/[Er] ratio, and it reached as large as 175 nm for the 0.1 mol% Er3+ and 0.8 mol% Tm3+ co-doped sample. The energy transfers between Er3+ and Tm3+ were proposed to play an important role in tailoring the emission bandwidth of the sample.

  9. Photocatalytic decomposition of perfluorooctanoic acid by iron and niobium co-doped titanium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Renan Estrellan, Carl, E-mail: estrellan.c.ac@m.titech.ac.jp [Department of International Development Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Salim, Chris; Hinode, Hirofumi [Department of International Development Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2010-07-15

    The photocatalytic decomposition of perfluorooctanoic acid (PFOA) in aqueous solution using Fe and Nb co-doped TiO{sub 2} (Fe:Nb-TiO{sub 2}) prepared by sol-gel method was investigated. The photocatalytic activity of Fe:Nb-TiO{sub 2} towards PFOA degradation was compared to that of pure TiO{sub 2} synthesized using the same method, and that of the commercially available TiO{sub 2} photocatalyst, Aeroxide TiO{sub 2} P25 (AO-TiO{sub 2} P25). The photocatalysts were characterized by XRD, DRS, BET-N{sub 2} adsorption isotherm, and SEM-EDX techniques and the data were correlated to the photocatalytic activity. Fe:Nb-TiO{sub 2} showed the highest activity compared to the undoped TiO{sub 2} and the commercially available TiO{sub 2}. Such activity was attributable to the effects of co-doping both on the physico-chemical properties and surface interfacial charge transfer mechanisms. Perfluorocarboxylic acids (PFCAs) with shorter carbon chain length and fluoride ions were identified as photocatalytic reaction intermediates and products.

  10. Electronic and optical properties study on Fesbnd B co-doped anatase TiO2

    Science.gov (United States)

    Li, Xuechao; Shi, Jianhao; Chen, Hao; Wan, Rundong; Leng, Chongyan; Lei, Ying

    2016-09-01

    We investigate the density of states and optical properties for Fe, 2B and (Fe, 2B) doped TiO2 with DFT calculations. The calculated results reveal mono-doping introduces midgap states which are half-occupied and easy to become the recombination centers of charge carriers, thus inhibiting the enhancement of photocatalystic activity. The coupling of 2p-3d states in the (Fe, 2B) compensated co-doped TiO2 makes gap states couple with the valence bands edge, thus greatly causing the band gap narrowing and higher visible light absorption. Moreover, the gap states cannot become recombination centers of the photoexcited carriers, thus promoting the separation of electron-hole pairs, prolonging the lifetime of carriers. The analysis of electron density indicates more electrons from Fe transfer to adjacent B, realizing the charge compensation and forming a stronger Fesbnd B bond. Therefore, the (Fe, 2B) compensated co-doped TiO2 exhibits the higher visible-light photocatalystic activity than those of pure and solely doped TiO2.

  11. Enhanced stability of Eu in GaN nanoparticles: Effects of Si co-doping

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Prabhsharan [Dr. Vijay Kumar Foundation, 1969 Sector 4, Gurgaon 122001, Haryana (India); Department of Physics, Guru Nanak Dev University, Amritsar 143005, Punjab (India); Sekhon, S. S. [Department of Physics, Guru Nanak Dev University, Amritsar 143005, Punjab (India); Department of Physics, The University of the West Indies, St. Augustine (Trinidad and Tobago); Zavada, J. M. [Department of Electrical and Computer Engineering, NYU Polytechnic School of Engineering, Brooklyn, New York 11201 (United States); Kumar, Vijay [Dr. Vijay Kumar Foundation, 1969 Sector 4, Gurgaon 122001, Haryana (India); Center for Informatics, School of Natural Sciences, Shiv Nadar University, NH91, Tehsil Dadri, Gautam Buddha Nagar 201314, Uttar Pradesh (India)

    2015-06-14

    Ab initio calculations on Eu doped (GaN){sub n} (n = 12, 13, and 32) nanoparticles show that Eu doping in nanoparticles is favorable compared with bulk GaN as a large fraction of atoms lie on the surface where strain can be released compared with bulk where often Eu doping is associated with a N vacancy. Co-doping of Si further facilitates Eu doping as strain from an oversized Eu atom and an undersized Si atom is compensated. These results along with low symmetry sites in nanoparticles make them attractive for developing strongly luminescent nanomaterials. The atomic and electronic structures are discussed using generalized gradient approximation (GGA) for the exchange-correlation energy as well as GGA + U formalism. In all cases of Eu (Eu + Si) doping, the magnetic moments are localized on the Eu site with a large value of 6μ{sub B} (7μ{sub B}). Our results suggest that co-doping can be a very useful way to achieve rare-earth doping in different hosts for optoelectronic materials.

  12. Co-doping effects of Gd and Ag on YBCO films derived by metalorganic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Meijuan; Liu, Zhiyong; Bai, Chuanyi; Guo, Yanqun; Lu, Yuming; Fan, Feng; Cai, Chuanbing, E-mail: cbcai@t.shu.edu.cn

    2015-12-15

    Highlights: • MOD was employed to fabricate (YGd)BaCuO films together with Ag addition for the first time. • Better connectivity of grains was obtained by Ag addition. • Pyrolysis rate and surface morphology were able to be improved by Ag addition. • Gd substitution and relevant ion defects are emerged in the studied (YGd)BaCuO films. • Better c-axis orientation, superior surface microstructure and improved superconducting performance are obtained by co-doping of Gd and Ag. - Abstract: Y{sub 1–x}Gd{sub x}Ba{sub 2}Cu{sub 3}O{sub 7–δ}-Ag (x = 0, 0.25, 0.5, 0.75, 1) thin films were prepared on oxide buffered Hastelloy substrates by low fluorine metalorganic depostion (MOD) process. The effects of co-doping of Ag and Gd on the microstructures and superconducting properties of YBCO thin films are investigated with respect to improvement on texture and superconducting performance in case of optimized doping content. It is found that optimum addition of Ag and Gd may lead to better c-axis orientation, superior surface microstructure and finally give rise to much improvement of superconducting performance.

  13. Tricolor white emitting phosphor co-doped with Eu, Dy in SiO2 matrix

    Institute of Scientific and Technical Information of China (English)

    HU XiaoYun; FAN Jun; ZHANG DeKai; MA YiPing; BAI JinTao; REN ZhaoYu; HOU Xun

    2008-01-01

    A Eu, Dy co-doped SiO2 matrix, white emitting phosphor was prepared by the sol-gel technique. Strong red, green and blue emissions located at 618 nm, 573 nm and 400-550 nm were observed under UV laser excitation at room temperature. Such techniques as FT-IR and TGA-DSC were used to measure the microstructure of the luminescent material. The influence of the preparation techniques on the lu-minescence property of the Eu, Dy co-doped SiO2 matrix, such as anneal temperature, anneal time, dried atmosphere and the components of the matrix, was systematically studied, and the luminescence mechanism was interpreted. The red emission is the strongest when annealed at 750℃. However, blue emission appears when annealed at 700℃ and is the intensest at 900℃. For the samples dried in vac-uum, Eu3+ is more easily deoxidized to Eu2+ at lower temperatures, because the samples dried in the air compared with that dried in vacuum need higher temperature to form network structures. Only the SA and SAB matrix annealed at 850℃ had blue emission in the four matrices (SA, SAB, SB, S) xerogel and the emission in the SAB matrix was stronger than that in the SA matrix. This may be due to the eutectic phase formed by the oxide boron, alkaline oxide and alumina in the SAB matrix, which constructs network structures and stabilizes the emission center and enhances the blue emission.

  14. Investigation of Co-doped PZT films deposited by rf-magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Felicia Gheorghiu

    2014-09-01

    Full Text Available The focus of the present paper is to describe the preparation procedure and to investigate the microstructural characteristics and the electrical properties of Co-doped PZT films deposited by rf-sputtering by using a “mixture” target system onto Au-electroded Al2O3 ceramic substrates. The X-ray diffraction patterns of the Co-doped PZT thin films as a function of the annealing temperature confirmed the formation of pure perovskite phase started with temperatures of 600 °C, but a perfect crystallization was achieved at a temperature of ∼700 °C. The microstructures strongly depend on the thermal treatment temperature and indicated a discontinuous surface without large pores and with a bimodal grain size distribution. The XPS analysis demonstrated that the dopant element is present mainly in its Co2+ state. The macroscopic P(E hysteresis loops were recorded in different locations of the films surface and demonstrated ferroelectric behaviour with a resistive leakage contribution.

  15. A one-pot method to prepare N-doped titania hollow spheres with high photocatalytic activity under visible light

    Science.gov (United States)

    Ao, Yanhui; Xu, Jingjing; Zhang, Songhe; Fu, Degang

    2010-02-01

    N-doped titania hollow spheres (NTHS) were prepared by a one-pot hydrothermal method using urea as precursor of nitrogen. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectrum (DRS). The photocatalytic activity of as-prepared titania hollow spheres was determined by degradation of Reactive Brilliant Red dye X-3B (C.I. reactive red 2) under visible light irradiation, and was compared to non-doped titania hollow spheres and commercial P25 titania. Results indicated that the as-prepared NTHS showed highest photocatalytic activity.

  16. W/Mo co-doped BiVO4 for photocatalytic treatment of polymer-containing wastewater in oilfield

    Science.gov (United States)

    Zhou, Ying; Li, Wei; Wan, Wenchao; Zhang, Ruiyang; Lin, Yuanhua

    2015-06-01

    Polymer flooding is an effective way to enhance oil recovery (EOR). However, the treatment of the oily wastewater becomes an urgent issue. Photocatalysis is a promising approach for this purpose. In this report, W/Mo co-doped BiVO4 particles are synthesized by hydrothermal method. W/Mo co-doping could promote an effective separation of photogenerated carriers reflecting from the 6 times higher photocurrent density compared to pure BiVO4. The photodegradation of partially hydrolyzed polyacrylamide (HPAM) over 0.5 at.% W and 1.5 at.% Mo co-doped BiVO4 is 43% under UV-vis light irradiation for 3 h, which is much higher than that of pure BiVO4 (18%).

  17. Fabrication and photoelectric properties of Er3+ and Yb3+ co-doped ZnO films

    Science.gov (United States)

    Feng, Wei; Wang, Xiangfu; Meng, Lan; Yan, Xiaohong

    2016-01-01

    In this paper, the Er3+ and Yb3+ co-doped ZnO films deposited by a novel thermal decomposition method under different annealing temperature process have been reported. The effects of annealing temperature on the morphology and properties of the films are systematically studied. The resulting spectra demonstrate that the Er3+ and Yb3+ co-doped ZnO films possessed the property of up-conversion, converting IR light into visible light that can be absorbed by amorphous silicon solar cell. After all, inner photoelectric effect of the Er3+ and Yb3+ co-doped ZnO films in the amorphous as a light scattering layer are also found with an infrared 980 nm laser as excitation source.

  18. Enhanced dopant solubility and visible-light absorption in Cr-N co-doped TiO2 nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Chiodi, Dr Mirco [University of Brescia (UNIBS); Cheney, Christine [ORNL; Vilmercati, Paolo [ORNL; Cavaliere, Emanuele [University of Brescia (UNIBS); Mannella, Norman [ORNL; Gavioli, Luca [University of Brescia (UNIBS); Weitering, Harm H [ORNL

    2012-01-01

    A major obstacle toward employing TiO2 as an efficient photoactive material is related to its large optical band gap, strongly limiting visible light absorption. Substitutional doping with both donors and acceptors (co-doping) potentially leads to a significant band gap reduction, but the effectiveness of the co-doping approach remains limited by the low solubility of dopants inside TiO2. Here we show that nanostructured Cr and N co-doped TiO2 thin films can be obtained by Supersonic Cluster Beam Deposition (SCBD) with a high concentration of dopants and a strongly reduced band gap. Complementary spectroscopic investigations show that doping effectively occurs into substitutional lattice sites, inducing dopant levels in the gap that are remarkably delocalized. The high surface-to-volume ratio, typical of SCBD nanostructured films, likely facilitates the dopant incorporation. The present results indicate that SCBD films are highly promising photoactive nanophase materials.

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

    Science.gov (United States)

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

    2016-10-01

    In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO2 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 TiO2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase JSC of the surface while slightly decreasing VOC compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

  20. The effect of K-na co-doping on the formation and particle size of Bi-2212 phase

    Science.gov (United States)

    Kır, M. Ebru; Özkurt, Berdan; Aytekin, M. Ersin

    2016-06-01

    Superconducting K-Na co-doped Bi2Sr2KxCa1Cu1.75Na0.25Oy (x=0, 0.05, 0.1 and 0.25) ceramics are prepared by a solid-state reaction method. It is clearly determined from XRD data that the characteristic peaks of Bi-2212 phase are observed in all samples. The resistivity measurements show that Tc (onset) values is gradually increasing as K content is increased. It is also found that K-Na co-doping influence the grain sizes for Bi-2212 phase significantly. The critical current densities as a function of magnetic field have been calculated from M-H hysteresis loops of samples according to Bean's critical model, indicating that K-Na co-doping cause higher Jc values than the pure ones.

  1. Structural, morphological, optical, and magnetic properties of Gd-doped and (Gd, Mn) co-doped ZnO nanoparticles

    Science.gov (United States)

    Poornaprakash, B.; Chalapathi, U.; Babu, S.; Park, Si-Hyun

    2017-09-01

    Undoped, Gd doped, and (Gd, Mn) co-doped ZnO nanoparticles were fabricated via a hydrothermal method and their structural, morphological, optical, and magnetic properties were examined. X-ray diffraction and Raman spectroscopy studies confirmed that the Gd and Mn ions successfully entered the ZnO hexagonal lattice as substitute ions without changing the internal structure of the lattice. Morphology studies revealed that the synthesized nanoparticles were monodisperse and closely hexagonal shaped. The reflectance spectra showed a red shift of the absorption edge in both doped and co-doped samples. The diamagnetic ZnO sample was altered into a ferromagnetic material when doped with Gd ions, but this behavior was suppressed when Mn ions were co-doped into the matrix.

  2. Preparation of nanoporous titania spherical nanoparticles

    Science.gov (United States)

    Shiba, Kota; Sato, Soh; Matsushita, Takayuki; Ogawa, Makoto

    2013-03-01

    Preparation of nanoporous titania particles from well-defined titania-octadecylamine (titania-ODA) hybrid spherical particles with 450 nm in size, which were prepared by the method reported previously (Chem. Commun., 2009, pp. 6851-6853 [39]; RSC Adv., 2012, vol. 2, pp. 1343-1349 [40]), was studied. ODA was removed by solvent extraction with acidic ethanol to obtain nanoporous titania particles and subsequent calcination led to the formation of nanoporous titania particles with the nanopore size ranging from 2 to 4 nm depending on the calcination temperature. The as-synthesized titania was amorphous and was transformed into anatase (at around 300 °C) and rutile (at around 600 °C) by the heat treatment. The phase transition behavior was discussed in comparison with that of as-synthesized titania-ODA particles without ODA removal. Spherical particles of titania-ODA hybrids with 70 nm in size were also transformed into nanoporous titania particles composed of anatase crystallites by the washing and calcination at 500 °C for 1 h.

  3. Novel band gap-tunable K–Na co-doped graphitic carbon nitride prepared by molten salt method

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiannan [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China); School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun 113001 (China); Ma, Lin [School of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001 (China); Wang, Haoying; Zhao, Yanfeng [School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun 113001 (China); Zhang, Jian [School of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001 (China); Hu, Shaozheng, E-mail: hushaozhenglnpu@163.com [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China)

    2015-03-30

    Graphical abstract: K and Na ions co-doped into g-C{sub 3}N{sub 4} crystal lattice can tune the position of CB and VB potentials, influence the structural and optical properties, and thus improve the photocatalytic degradation and mineralization ability. - Highlights: • K, Na co-doped g-C{sub 3}N{sub 4} was prepared in KCl/NaCl molten salt system. • The structural and optical properties of g-C{sub 3}N{sub 4} were greatly influenced by co-doping. • The position of VB and CB can be tuned by controlling the weight ratio of eutectic salts to melamine. • Co-doped g-C{sub 3}N{sub 4} showed outstanding photodegradation ability, mineralization ability, and catalytic stability. - Abstract: Novel band gap-tunable K–Na co-doped graphitic carbon nitride was prepared by molten salt method using melamine, KCl, and NaCl as precursor. X-ray diffraction (XRD), N{sub 2} adsorption, Scanning electron microscope (SEM), UV–vis spectroscopy, Photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The CB and VB potentials of graphitic carbon nitride could be tuned from −1.09 and +1.55 eV to −0.29 and +2.25 eV by controlling the weight ratio of eutectic salts to melamine. Besides, ions doping inhibited the crystal growth of graphitic carbon nitride, enhanced the surface area, and increased the separation rate of photogenerated electrons and holes. The visible-light-driven Rhodamine B (RhB) photodegradation and mineralization performances were significantly improved after K–Na co-doping.

  4. Titania-alumina aerogel materials for degradation of rhodamine B dye: Impact of particle size of titania

    Science.gov (United States)

    Shrestha, Sunav

    Disposal of pollutants, mainly organic dyes from textile industries are the primary sources of water pollution in developing countries, and often leading to scarcity of clean water. These dyes can undergo further oxidation and form several toxic compounds, which possess threat to the water ecosystem. It is therefore necessary to remove these organics from effluents for a clean environment. Among the various methods, Advanced Oxidation Processes (AOPs) called heterogeneous photocatalysis is considered as an effective method for the removal of organics from water sources. In this regard, a set of titania-alumina (TiO2-Al2O3) mixed oxide materials were prepared by supercritical drying method and investigated towards the degradation of a model pollutant, rhodamine B (RhB). The physico-chemical properties of the synthesized materials were studied in detail using several techniques that include powder X-ray diffraction, nitrogen physisorption, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS). The Electrospray ionization-Mass spectroscopic (ESI-MS) studies were also carried out to confirm the degradation of the RhB by identifying its intermediate products. The results indicate that the particle size of the photoactive species, titania, was the key factor for effective photocatalytic degradation of the RhB dye over the titania-alumina mixed oxide materials.

  5. Analysis of structure origin and luminescence properties of Yb(3+)-Er(3+) co-doped fluorophosphate glass.

    Science.gov (United States)

    Chen, Fangze; Jing, Xufeng; Wei, Tao; Wang, Fengchao; Tian, Ying; Xu, Shiqing

    2014-08-14

    The near infrared luminescence properties of Yb(3+)-Er(3+) co-doped fluorophosphate glasses have been investigated. The various effects on structure and 1.53 μm emission were analyzed as a function of Yb(3+) concentration. The energy transfer mechanism was proposed. High measured lifetime (10.75 ms), large effective full widths at half maximum (73.71 nm) and large gain per unit length (62.8 × 10(-)(24)cm(2)s) have been achieved in prepared glass. The present glass co-doped with 6mol% YbF3 and 2 mol% ErF3 showed magnificent luminescence properties for telecommunication application.

  6. Highly luminescent S, N co-doped graphene quantum dots with broad visible absorption bands for visible light photocatalysts

    Science.gov (United States)

    Qu, Dan; Zheng, Min; Du, Peng; Zhou, Yue; Zhang, Ligong; Li, Di; Tan, Huaqiao; Zhao, Zhao; Xie, Zhigang; Sun, Zaicheng

    2013-11-01

    A facile hydrothermal synthesis route to N and S, N co-doped graphene quantum dots (GQDs) was developed by using citric acid as the C source and urea or thiourea as N and S sources. Both N and S, N doped GQDs showed high quantum yield (78% and 71%), excitation independent under excitation of 340-400 nm and single exponential decay under UV excitation. A broad absorption band in the visible region appeared in S, N co-doped GQDs due to doping with sulfur, which alters the surface state of GQDs. However, S, N co-doped GQDs show different color emission under excitation of 420-520 nm due to their absorption in the visible region. The excellent photocatalytic performance of the S, N co-doped GQD/TiO2 composites was demonstrated by degradation of rhodamine B under visible light. The apparent rate of S, N:GQD/TiO2 is 3 and 10 times higher than that of N:GQD/TiO2 and P25 TiO2 under visible light irradiation, respectively.A facile hydrothermal synthesis route to N and S, N co-doped graphene quantum dots (GQDs) was developed by using citric acid as the C source and urea or thiourea as N and S sources. Both N and S, N doped GQDs showed high quantum yield (78% and 71%), excitation independent under excitation of 340-400 nm and single exponential decay under UV excitation. A broad absorption band in the visible region appeared in S, N co-doped GQDs due to doping with sulfur, which alters the surface state of GQDs. However, S, N co-doped GQDs show different color emission under excitation of 420-520 nm due to their absorption in the visible region. The excellent photocatalytic performance of the S, N co-doped GQD/TiO2 composites was demonstrated by degradation of rhodamine B under visible light. The apparent rate of S, N:GQD/TiO2 is 3 and 10 times higher than that of N:GQD/TiO2 and P25 TiO2 under visible light irradiation, respectively. Electronic supplementary information (ESI) available: More XPS and UV-Vis spectra. See DOI: 10.1039/c3nr04402e

  7. Room-temperature ferromagnetism in Co-doped ZnO thin films prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Belghazi, Y. [Laboratoire de Physique des Materiaux, Faculte des Sciences, B.P. 1014, Rabat (Morocco); IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Schmerber, G. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Colis, S. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Rehspringer, J.L. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Berrada, A. [Laboratoire de Physique des Materiaux, Faculte des Sciences, B.P. 1014, Rabat (Morocco); Dinia, A. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France)]. E-mail: aziz.dinia@ipcms.u-strasbg.fr

    2007-03-15

    We report on room-temperature ferromagnetism in Co-doped ZnO thin films grown onto Si(100) and SiO{sub 2} substrates using the spin-coating technique. X-ray diffraction measurements show that the films have the wurtzite structure with a preferential orientation along the c-axis. UV-Visible spectroscopy has shown that the Co{sup 2+} ions are substituted to Zn{sup 2+} ions in ZnO matrix. The analysis of the magnetization measurements indicates that the observed ferromagnetism in ZnO and Co-doped ZnO films is extrinsic and can be due to a pollution.

  8. Effects on the optical properties and conductivity of Ag-N co-doped ZnO

    Science.gov (United States)

    Xu, Zhenchao; Hou, Qingyu; Qu, Lingfeng

    2017-01-01

    Nowadays, the studies of the effects on the optical bandgap, absorption spectrum, and electrical properties of Ag-N co-doped ZnO have been extensively investigated. However, Ag and N atoms in doped systems are randomly doped, and the asymmetric structure of ZnO is yet to be explored. In this paper, the geometric structure, stability, density of states, absorption spectra and conductivity of pure and Ag-N co-doped Zn1‑xAgxO1‑xNx(x=0.03125, 0.0417 and 0.0625) in different orientations are calculated by using plane-wave ultrasoft pseudopotential on the basis of density functional theory with GGA+U method. Results show that the volume, equivalent total energy and formation energy of the doped system increase as the concentration of Ag-N co-doped Zn1‑xAgxO1‑xNx increases at the same doping mode. The doped systems also become unstable, and difficulty in doping. At the same concentration of Ag-N co-doped Zn1‑xAgxO1‑xNx, the systems with Ag-N along the c-axis orientation is unstable, and doping is difficult. The optical bandgap of Ag-N co-doped systems is narrower than that of the pure ZnO. At the same doping mode, the optical bandgap of the systems with Ag-N perpendicular to the c-axis orientation becomes narrow as the concentration of Ag-N co-doped Zn1‑xAgxO1‑xNx increases. The absorption spectra of the doped systems exhibit a red shift, and this red shift becomes increasingly significant as the concentration of Ag-N co-doped Zn1‑xAgxO1‑xNx increases. Under the same condition, the relative hole concentrations of the doped systems increases, the hole effective mass in valence band maximum decreases, the hole mobility decreases, the ionization energy decreases, Bohr radius increases, the conductance increases and the conductivity become better. Our results may be used as a basis for the designing and preparation of new optical and electrical materials for Ag-N co-doped ZnO applied in low temperature end of temperature difference battery.

  9. Structural, Optical, and Magnetic Properties of Co Doped CdTe Alloy Powders Prepared by Solid-State Reaction Method

    Directory of Open Access Journals (Sweden)

    M. Rigana Begam

    2013-01-01

    Full Text Available Co doped CdTe powder samples were prepared by solid-state reaction method. In the present work effect of Co doping on structural, optical, and magnetic properties has been studied. X-ray diffraction studies confirm zinc blend structure for all the samples. The lattice parameter showed linear increase with the increase in Co content. The elemental constituents were characterized by EDAX. Optical studies showed the increase in band gap with increase in Co level. The samples were diluted magnetic semiconductors and exhibited clear hysteresis loop showing room temperature ferromagnetism as confirmed by vibrating sample magnetometer.

  10. Direct Sensitization Up-conversion Mechanism in Er3+∶Yb3+ Co-doped Fluoride Materials

    Institute of Scientific and Technical Information of China (English)

    肖思国; 阳效良; 刘政威; 佘仲明; 陈春先

    2002-01-01

    Up-conversion luminescence have been studied on Yb3+-Er3+ co-doped fluoride samples. Two infrared lasers with wavelength of 930 nm and 858 nm are carefully chosen as excitation sources. The experimental results suggest direct cooperation sensitization up-conversion rather than two-step sensitization up-conversion is responsible for the increased population of 2H11/2 (Er3+) and thus the increased green emission in the region 514~574 nm in Yb3+-Er3+ co-doped system.

  11. Luminescence properties of Ce{sup 3+} and Tb{sup 3+} co-doped SiO{sub x}N{sub y} thin films: Prospects for color tunability in silicon-based hosts

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez, J. M., E-mail: joan-manel.ramirez@u-psud.fr; Ruiz-Caridad, A.; Estradé, S.; Peiró, F.; Garrido, B. [MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Wojcik, J.; Mascher, P. [Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, 1280 Main St. W, Hamilton, Ontario L8S4L7 (Canada); Gutierrez, A. M.; Sanchís, P. [Nanophotonics Technology Center, Universitat Politècnica València, 46022 Valencia (Spain)

    2016-03-21

    In this work, the role of the nitrogen content, the annealing temperature, and the sample morphology on the luminescence properties of Ce{sup 3+} and Tb{sup 3+} co-doped SiO{sub x}N{sub y} thin films has been investigated. An increasing nitrogen atomic percentage has been incorporated in the host matrix by gradually replacing oxygen with nitrogen during fabrication while maintaining the Si content unaltered, obtaining a sequential variation in the film composition from nearly stoichiometric SiO{sub 2} to SiO{sub x}N{sub y}. The study of rare earth doped single layers has allowed us to identify the parameters that yield an optimum optical performance from Ce{sup 3+} and Tb{sup 3+} ions. Ce{sup 3+} ions proved to be highly sensitive to the annealing temperature and the nitrogen content, showing strong PL emission for relatively low nitrogen contents (from 0 to 20%) and moderate annealing temperatures (800–1000 °C) or under high temperature annealing (1180 °C). Tb{sup 3+} ions, on the other hand, displayed a mild dependence on those film parameters. Rare earth co-doping has also been investigated by comparing the luminescence properties of three different approaches: (i) a Ce{sup 3+} and Tb{sup 3+} co-doped SiO{sub x}N{sub y} single layer, (ii) a bilayer composed of two SiO{sub x}N{sub y} single layers doped with either Ce{sup 3+} or Tb{sup 3+} ions, and (iii) a multilayer composed of a series of either Tb{sup 3+} or Ce{sup 3+}-doped SiO{sub x}N{sub y} thin films with interleaved SiO{sub 2} spacers. Bright green emission and efficient energy transfer from either Ce{sup 3+} ions or Ce silicates to Tb{sup 3+} ions has been observed in the co-doped single layer as a consequence of the strong ion-ion interaction. On the other hand, independent luminescence from Ce{sup 3+} and Tb{sup 3+} ions has been observed in the Ce{sup 3+} and Tb{sup 3+} co-doped bilayer and multilayer, providing a good scenario to develop light emitting devices with wide color tunability by

  12. Investigation on Mg and Sc co-doped Ceria electrolyte for IT-SOFC

    Directory of Open Access Journals (Sweden)

    P.Ravi Chandran

    2014-07-01

    Full Text Available Nanocrystalline form of pure ceria (CeO2 and metal (Mg or Sc doped ceria was attempted for 10 mol %. Also, Mg and Sc co-doped ceria with Ce1-x(Mg0.5Sc0.5xO2 (x=0-0.24 was prepared as an electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs by co-precipitation method. The synthesized different compositions of pure and doped nanocrystalline powders were then subjected to powder X-ray diffraction (XRD for phase and structural identification. All the nanocrystalline samples were found to be ceria based solid solutions of fluorite type structures. A.C. impedance spectroscopy measurements in the frequency range of 50Hz to 5MHz was carried out to study the grain, grain boundary and ionic conductivity of doped ceria samples in the temperature range of 400-600oC. The sample Ce0.84(Mg0.5Sc0.50.16O2 composition showed highest ionic conductivity i.e., 1.923 x 10-2 S/cm at 500oC. Its morphology and composition was investigated using scanning electron microscopic analysis (SEM and energy dispersive X-ray spectrometry (EDS and conductivity behavior was compared with those of pure ceria and singly doped ceria electrolytes namely Ce0.9Mg0.1O2 and Ce0.9Sc0.1O2. The impedance analysis reveals that the sample Ce0.9Mg0.1O2 was found to have higher ionic conductivity compared to Ce0.9Sc0.1O2 in the temperature range of 400–600°C. The co-doped ceria showed a much higher conductivity in air at 500oC in comparison to that of singly doped ceria. Therefore, these co-doped ceria are also the more ideal electrolyte materials for IT-SOFCs. Nyquist plot shows the major contributions were due to the grain boundary resistance contributions which accounts for the higher ionic conductivity in case of the dopants. These dopant effect on the ceria is discussed in detail.

  13. Study on the effects of Ga-2N high co-doping and preferred orientation on the stability, bandgap and absorption spectrum of ZnO

    Science.gov (United States)

    Hou, Qing-Yu; Li, Wen-Cai; Qu, Ling-Feng; Zhao, Chun-Wang

    2017-06-01

    Currently, the stability and visible light properties of Ga-2N co-doped ZnO systems have been studied extensively by experimental analysis and theoretical calculations. However, previous theoretical calculations arbitrarily assigned Ga- and 2N-doped sites in ZnO. In addition, the most stable and possible doping orientations of doped systems have not been fully and systematically considered. Therefore, in this paper, the electron structure and absorption spectra of the unit cells of doped and pure systems were calculated by first-principles plane-wave ultrasoft pseudopotential with the GGA+U method. Calculations were performed for pure ZnO, Ga-2N supercells heavily co-doped with Zn1-xGaxO1-yNy (x = 0.03125 - 0.0625, y = 0.0625 - 0.125) under different co-doping orientations and conditions, and the Zn16GaN2O14 interstitial model. The results indicated that under different orientations and constant Ga-2N co-doping concentrations, the systems co-doped with Ga-N atoms vertically oriented to the c-axis and with another N atom located in the nearest-neighboring site exhibited higher stability over the others, thus lowering formation energy and facilitating doping. Moreover, Ga-interstitial- and 2N-co-doped ZnO systems easily formed chemical compounds. Increasing co-doping concentration while the co-doping method remained constant decreased doped system volume and lowered formation energies. Meantime, co-doped systems were more stable and doping was facilitated. The bandgap was also narrower and red shifting of the absorption spectrum was more significant. These results agreed with previously reported experimental results. In addition, the absorption spectra of Ga-interstitial- and 2N-co-doped ZnO both blue shifted in the UV region compared with that of the pure ZnO system.

  14. Influence of Input Pulse Durations on Properties of Er3+/Yb3+ Co-doped DCFA

    Institute of Scientific and Technical Information of China (English)

    ZHAN Sheng-bao; ZHAO Shang-hong; SHI Lei; XU Jie; ZHAO Xiao-ming

    2006-01-01

    Based on propagation-rate equations,the influence of different input pulse durations on the properties of Er3+/Yb3+ co-doped double-clad fiber amplifier at dynamic equilibrium was analyzed. The change characteristic of output power sag with pulse duration and repetition rate was shown. Whether single or multi-channel input pulses are amplified,the shorter the input pulse duration is,the smaller the power sags of output pulse will be. At low repetition rate,upper gain values(Gupper) of gain swing are almost the same for different input pulse durations,which tend to the small signal gain,but lower gain value(Glower) of short input pulse is larger than that of long input pulse. At high repetition rate,lower gain value(Glower) approaches to upper gain value(Gupper).

  15. Local fields in Co and Mn Co-doped ZnO

    Science.gov (United States)

    Sato, W.; Kano, Y.; Suzuki, T.; Nakagawa, M.; Kobayashi, Y.

    2016-12-01

    The magnetic properties of ZnO co-doped with 5 at. % Co and 5 at. % Mn(Zn0.90Co0.05Mn0.05O) synthesized by a solid-state reaction were investigated by means of 57Co emission Mössbauer spectroscopy. The majority of the probe ions (80 %) residing in defect-free substitutional Zn sites take the oxidation state of 57Fe 2+, and the others presumably form local defects taking the state of 57Fe 3+ at room temperature. Both components show doublets, and RT ferromagnetism was thus absent in the sample. For the measurement at 10 K, spectral broadening was observed, implying a possible presence of a weak magnetic component.

  16. Deposition of Co-doped TiO2 Thin Films by sol-gel method

    Science.gov (United States)

    Boutlala, A.; Bourfaa, F.; Mahtili, M.; Bouaballou, A.

    2016-03-01

    Cobalt doped TiO2 thin films have been prepared by sol-gel method onto glass substrate at room temperature. in this present work, we are interesting to study the effect of Cobalt doped TiO2 thin films.the concentration of Co was varied from 0 to 6%at .The obtained films have been annealed at 500°C for 2 hours. X-ray diffraction patterns showed that Co: TiO2 films are polycrystalline with a tetragonal anatase and orthorhombic brookite types structures. The surface morphologies of the TiO2 doped with cobalt thin films were evaluated by Atomic Force Microscopy (AFM). The optical properties were studied by mean of UV-visible and near infrared spectroscopy.The calculated optical band gap decreases from 3.30 to 2.96 eV with increasing Co doping.

  17. Aqueous synthesis and characterization of Ni, Zn co-doped CdSe QDs

    Science.gov (United States)

    Thirugnanam, N.; Govindarajan, D.

    2016-01-01

    Ni, Zn co-doped CdSe quantum dots (QDs) were synthesized by chemical precipitation method through aqueous route. The prepared QDs were characterized by X-ray diffraction (XRD) technique, UV-Vis absorption spectroscopy, photoluminescence (PL) spectroscopy and high resolution transmission electron microscopy (HRTEM). XRD technique results indicate that the prepared samples have a zinc blende cubic phase. From UV-Vis absorption spectroscopy technique, the prepared samples were blue shifted with respect to their bulk counter part due to quantum confinement effect. Among different doping ratios examined, a maximum PL emission intensity was observed for CdSe:Ni(1 %):Zn(1 %) QDs. HRTEM pictures show that the prepared QDs were in spherical shape.

  18. Synthesis, characterization and antimicrobial activity of zinc and cerium co-doped α-zirconium phosphate

    Institute of Scientific and Technical Information of China (English)

    DAI Guangjian; YU Aili; CAI Xiang; SHI Qingshan; OUYANG Yousheng; TAN Shaozao

    2012-01-01

    A series of zinc ions or/and cerium ions co-doped a-zirconium phosphate (Zn-Ce@ZrPs) were prepared.The novel Zn-Ce@ZrPs were characterized and the antibacterial activity on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were tested.The results showed that zinc ions (Zn2+) or/and cerium ions (Ce3+) were combined with ZrP,and the Ce3+ was adsorbed on the surface of ZrP through hydrogen bonds,while Zn2+ intercalated into the interlayer of ZrP.Zn-Ce@ZrPs showed excellent synergistic antibacterial activity.When Zn2+/Ce3+ atomic ratio was 0.6,the Zn-Ce@ZrP3 showed the highest synergistic antibacterial efficiency,suggesting great potential application as antibacterial agents in microbial control.

  19. Ferromagnetism in co-doped zno particles prepared by vaporization condensation in a solar image furnace

    Science.gov (United States)

    Martínez, B.; Sandiumenge, F.; Balcells, Ll.; Fontcuberta, J.; Sibieude, F.; Monty, C.

    2005-04-01

    We report on the structural and magnetic properties of Co-doped ZnO particles prepared by vaporization-condensation in the solar furnace in Odeillo. X-ray diffraction data show no traces of Co segregation or any other phase different from ZnO. High-resolution electron microscopy (HREM) and transmision electron microscopy (TEM) techniques have also been used to characterize particles. Irrespective of their composition, the shape and size of the obtained particles, as well as their magnetic properties, clearly depend on the preparation conditions. The samples prepared in vacuum exhibit hysteretic behavior with low coercivity (about 100 Oe) at T = 5 K and saturation magnetization well below that expecte for Co2+ in a tetrahedral crystal field. On the other hand, samples prepared at high pressure (70-100 Torr inside the balloon) are paramagnetic.

  20. Local distortion in Co-doped LSMO from entropy-maximized charge density distribution

    Energy Technology Data Exchange (ETDEWEB)

    Syed Ali, K.S. [Department of Physics, The Madura College, Madurai 625011 (India); Saravanan, R., E-mail: saragow@dataone.i [Department of Physics, The Madura College, Madurai 625011 (India); Pashchenko, A.V.; Pashchenko, V.P. [Galkin Donetsk Institute of Physics and Technology, National Academy of Sciences of Ukraine, Donetsk 83114 (Ukraine)

    2010-07-09

    Perovskite structure manganites La{sub 0.67}Sr{sub 0.22}Mn{sub 1.11-x}Co{sub x}O{sub 3} were prepared by the solid state reaction method. An X-ray analysis of the structure was undertaken using the Rietveld technique on the experimental powder X-ray diffraction data and, then, a charge density distribution study was undertaken, using the maximum entropy method (MEM). The charge density in the unit cell was reconstructed and the effect of Co{sup 3+} doping in the Mn-O matrix was studied. Local distortions due to Co doping were analyzed and the results are now discussed.

  1. Nickel Oxide and Nickel Co-doped Graphitic Carbon Nitride Nanocomposites and its Octylphenol Sensing Application

    KAUST Repository

    Gong, Wanyun

    2015-11-16

    Nickel oxide and nickel co-doped graphitic carbon nitride (NiO-Ni-GCN) nanocomposites were successfully prepared by thermal treatment of melamine and NiCl2 6H2O. NiO-Ni-GCN nanocomposites showed superior electrochemical catalytic activity for the oxidation of octylphenol to pure GCN. A detection method of octylphenol in environmental water samples was developed based at NiO-Ni-GCN nanocomposites modified electrode under infrared light irradiation. Differential pulse voltammetry was used as the analytic technique of octylphenol, exhibiting stable and specific concentration-dependent oxidation signal in the presence of octylphenol in the range of 10nM to 1μM and 1μM to 50μM, with a detection limit of 3.3nM (3S/N). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Hydrothermal synthesis and characterization of fluorine & manganese co-doped PZT based cuboidal shaped powder

    Science.gov (United States)

    Nawaz, H.; Shuaib, M.; Saleem, M.; Rauf, A.; Aleem, A.

    2016-08-01

    Cuboidal shaped PZT powder particles based composition Pb0.89(Ba, Sr)0.11(Zr0.52Ti0.48)O3 co- doped with 1 mol% manganese and 2 mol% fluorine was prepared through hydrothermal route. 200-250nm size cuboidal particles were observed under FE-SEM. XRD technique revealed that the perovskite type ceramic structure has a dominant rhombohedral phase. The resultant powder particles were then spray dried, uniaxially pressed and sintered at different temperatures to achieve maximum theoretical density. 98% density was obtained in the pellets at a sintering temperature of 1190°C with an average grain size of 1-3um. The electrical properties of sintered samples were also measured before and after poling to evaluate the effect of dopants on piezoelectric properties.

  3. Structural, chemical and magnetic properties of secondary phases in Co-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Ney, A; Ney, V; Ye, S; Ollefs, K; Kammermeier, T [Fakultaet fuer Physik and CeNIDE, Universitaet Duisburg-Essen, Lotharstrasse 1, D-47057 Duisburg (Germany); Kovacs, A; Dunin-Borkowski, R E [Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kgs Lyngby (Denmark); Wilhelm, F; Rogalev, A, E-mail: andreas.ney@uni-due.de [European Synchrotron Radiation Facility (ESRF), 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex (France)

    2011-10-15

    We have utilized a comprehensive set of experimental techniques such as transmission electron microscopy (TEM) and synchrotron-based x-ray absorption spectroscopy (XAS) and the respective x-ray linear dichroism and x-ray magnetic circular dichroism to characterize the correlation of structural, chemical and magnetic properties of Co-doped ZnO samples. It can be established on a quantitative basis that the superparamagnetic (SPM) behavior observed by integral superconducting quantum interference device magnetometry is not an intrinsic property of the material but stems from precipitations of metallic Co. Their presence is revealed by TEM as well as XAS. Annealing procedures for these SPM samples were also studied, and the observed changes in the magnetic properties found to be due to a chemical reduction or oxidation of the metallic Co species. (paper)

  4. Phase diagram of F- and Co-doped CeFeAsO

    Energy Technology Data Exchange (ETDEWEB)

    Vakaliuk, Oleksii; Wurmehl, Sabine; Malbrich, Christine; Bruening, Eva; Grafe, Hans-Joachim; Hess, Christian; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstr. 20, 01069 Dresden (Germany)

    2013-07-01

    We carried out an experimental systematic electronic resistivity investigation of CeFeAsO system in a wide Co-doping range (0-0.12) and compare it to F-doped (0-0.10) CeFeAsO. The resistivity of the pristine compound: i) exhibits a pronounced peak at approximately 150 K, followed by a steep decrease and ii) an inflection point which are clear signatures of the tetragonal to orthorhombic structural transition, and the antiferromagnetic spin density wave transition, respectively. iii) At low temperature the resistivity shows a kink-like anomaly due to ordering of Ce magnetic moments. Upon doping these anomalies shifts to lower temperature, and become suppressed and broadened. From these observations we construct the magnetic/superconducting phase diagrams for both compounds. Furthermore, NMR/NQR studies reveal a new type of microscopic order in the underdoped normal state regime.

  5. Crystallization studies on rare-earth co-doped fluorozirconate-based glasses.

    Science.gov (United States)

    Paßlick, C; Johnson, J A; Schweizer, S

    2013-07-01

    This work focuses on the structural changes of barium chloride (BaCl2) nanoparticles in fluorochlorozirconate-based glass ceramics when doped with two different luminescent activators, in this case rare-earth (RE) ions, and thermally processed using a differential scanning calorimeter. In a first step, only europium in its divalent and trivalent oxidation states, Eu(2+) and Eu(3+), is investigated, which shows no significant influence on the crystallization of hexagonal phase BaCl2. However, higher amounts of Eu(2+) increase the activation energy of the phase transition to an orthorhombic crystal structure. In a second step, nucleation and nanocrystal growth are influenced by changing the structural environment of the glasses by co-doping with Eu(2+) and trivalent Gd(3+), Nd(3+), Yb(3+), or Tb(3+), due to the different atomic radii and electro-negativity of the co-dopants.

  6. Cooperative energy transfer in Tm3+ and Yb3+ co-doped phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    XU Bo; YANG Bin; ZHANG Yuepin; XIA Haiping; WANG Jinhao

    2013-01-01

    An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated,which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+to Yb3+ ions.Judd-Ofelt (J-O) theory was used to calculate the intensity parameters (Ω2,Ω4,Ω6),the radiative transition rates (Ar),and radiative transition lifetime (τrad) of Tm3+.Based on Inokuti-Hirayama's model,the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system.Quantum efficiency related to Yb3+concentration was calculated,and the maximum QE efficiency reached 169.8%.

  7. EPR investigation of pure and Co-doped ZnO oriented nanocrystals

    Science.gov (United States)

    Savoyant, A.; Alnoor, H.; Bertaina, S.; Nur, O.; Willander, M.

    2017-01-01

    Pure and cobalt-doped zinc oxide aligned nanorods have been grown by the low-temperature (90 °C) aqueous chemical method on amorphous ZnO seed layer, deposited on a sapphire substrate. High crystallinity of these objects is demonstrated by the electron paramagnetic resonance investigation at liquid helium temperature. The successful incorporation of Co2+ ions in substitution of Zn2+ ones in the ZnO matrix has also been confirmed. A drastic reduction of intrinsic ZnO nanorods core defects is observed in the Co-doped samples, which enhances the structural quality of the NRs. The quantification of substitutional Co2+ ions in the ZnO matrix is achieved by comparison with a reference sample. The findings in this study indicate the potential of using the low-temperature aqueous chemical approach for synthesizing material for spintronics applications.

  8. Direct Synthesis of Co-doped Graphene on Dielectric Substrates Using Solid Carbon Sources

    Institute of Scientific and Technical Information of China (English)

    Qi Wang; Pingping Zhang; Qiqi Zhuo; Xiaoxin Lv; Jiwei Wang; Xuhui Sun

    2015-01-01

    Direct synthesis of high-quality doped graphene on dielectric substrates without transfer is highly desired for simplified device processing in electronic applications. However, graphene synthesis directly on substrates suitable for device applications, though highly demanded, remains unattainable and challenging. Here, a simple and transfer-free synthesis of high-quality doped graphene on the dielectric substrate has been developed using a thin Cu layer as the top catalyst and polycyclic aromatic hydrocarbons as both carbon precursors and doping sources. N-doped and N, F-co-doped graphene have been achieved using TPB and F16CuPc as solid carbon sources, respectively. The growth conditions were systematically optimized and the as-grown doped graphene were well characterized. The growth strategy provides a controllable transfer-free route for high-quality doped graphene synthesis, which will facilitate the practical applications of graphene.

  9. Synthesis of Pyridinic-Rich N, S Co-doped Carbon Quantum Dots as Effective Enzyme Mimics

    Science.gov (United States)

    Liu, Teng; Cui, Zhi-wei; Zhou, Jun; Wang, Ying; Zou, Zhi-gang

    2017-05-01

    N and S co-doped carbon quantum dots (N, S-CQDs) with high N- and S-doping level were synthesized by microwave solid-phase pyrolysis within 50 s. Owing to the dominant pyridinic N injection into the conjugated framework, both high enzyme mimics catalytic activity and photoluminescence quantum yield are achieved simultaneously.

  10. Synthesis of Co-Doped CdS Nanocrystals by Direct Thermolysis of Cadmium and Cobalt Thiolate Clusters

    Directory of Open Access Journals (Sweden)

    Jianing Zhao

    2015-01-01

    Full Text Available Co-doped CdS (Co:CdS nanocrystals with controllable morphology (quantum dots and nanorods were easily synthesized by direct thermolysis of (Me4N2[Co4(SC6H510] and (Me4N4[S4Cd10(SPh16] under different precursor concentration, in virtue of the ions exchange of molecular clusters. The Co:CdS quantum dots were produced under low precursor concentration, and the Co:CdS nanorods could be obtained under higher precursor concentration. The Co-doping effect on the structure, growth process, and property of CdS nanocrystals was also investigated. The results indicated that the Co-doping was favorable for the formation of the nanorod structures for a short reaction time. In addition, the Co-doping in the CdS lattice resulted in the ferromagnetic property of the Co:CdS quantum dots at room temperature. Moreover, compared with the CdS quantum dots, the Co:CdS quantum dots exhibited obvious quantum confinement effect and photoluminescence emission with slightly red-shift.

  11. Photocatalytic Activity of Nanosized TiO2 Enhanced by co-doping with Fe3+ and Nd3+ Ions

    Institute of Scientific and Technical Information of China (English)

    Fu Pingfeng; Zhao Zhuo; Wang Jingxin

    2007-01-01

    In this study, nanosized TiO2 co-doped with Fe3+ and Nd3+ ions was synthesized via a sol-gel method. The metallic ion doped TiO2 was thoroughly characterized with XRD and UV-vis, and the photocatalytic activity was evaluated by degrading methylene blue (MB) solution. The results indicated that TiO2 crystalline size was reduced and phase transformation of anatase to rutile was suppressed as the content of doped Nd3+ ion increased in the co-doped TiO2. The UV-vis spectra of co-doped TiO2 seemed to simply overlay two spectra of single metal doped TiO2, and had significantly increased absorbance in the ranges of 400~500 nm, 565~600 nm and 730~765 nm as compared to pure TiO2. The photocatalytic activity of co-doped TiO2 was obviously enhanced, and raised about 30% compared to that of pure TiO2 as doped Nd3+ content was 0.15% and Fe3+ content was 0.05%, respectively. The enhanced catalytic activity was attributed to a synergistic effect of two doped ions, where doped Fe3+ ion inhibited the recombination of photogenerated electron and hole, and Nd3+ ion brought more surface carboxyl to promote the degradation reaction.

  12. Pr and Cr co-doped BiFeO3 nanotubes: an advance multiferroic oxide material

    Directory of Open Access Journals (Sweden)

    Mandal Kalyan

    2013-01-01

    Full Text Available Arrays of single phase pure and Pr-Cr co-doped BiFeO3 (BFO nanotubes (NTs with compositions BiFeO3 and Bi0.9Pr0.1Fe0.9Cr0.1O3 have been synthesized using Anodic Aluminium Oxide (AAO template (pore diameter ~250 nm by wet chemical liquid phase deposition technique. All the NTs show ferromagnetic nature at room temperature (RT. Better magnetic properties are observed in the co-doped BFO NTs with the value of saturation magnetization (MS ~49 memu/g, magnetization at the remanence (MR ~12 memu/g and coercive field (HC ~103 Oe. Increase of ferromagnetic signature in the co-doped BFO NTs is believed to be due to the collapse of the space-modulated spin structure. Significant increase in the dielectric characteristics in co-doped BFO NTs suggests lowering of leakage current due to the reduction of the oxygen vacancies in the structure. Strong Magnetodielectric effect (MD, expressed by [εr(H-εr(0]/εr(0 is observed in doped BFO NTs, where the increase of the dielectric constant is noticeable with the increase in the applied magnetic field. The codoped BFO NTs show noticeable increase in MD effect at a lower field (1-2 kOe.

  13. Exploring the dielectric behavior of Co doped ZnO nanoparticles synthesized by wet chemical route using impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arshad, Mohd, E-mail: arshad_632000@yahoo.com [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Aligarh Muslim University, Aligarh (India); Ahmed, Arham S. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Aligarh Muslim University, Aligarh (India); Azam, Ameer [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Aligarh Muslim University, Aligarh (India); Center of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Naqvi, A.H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Aligarh Muslim University, Aligarh (India)

    2013-11-15

    Highlights: •Co doped ZnO nanoparticles were synthesized using wet chemical route. •Particle size and lattice parameters decreased with Co doping. •Dominance of grain boundary contribution was observed in doped samples. •Dielectric constant and loss tangent reduced with Co doping. -- Abstract: In the present investigation, we report the synthesis of Co doped ZnO nanoparticles by wet chemical method with dopant content varying from 0% to 5%. The structural and dielectric properties of the samples were studied. Crystallite sizes were calculated from the X-ray diffraction (XRD) patterns, which were found to decrease with the increase in Co content. The XRD analysis also ensures that ZnO has a hexagonal (wurtzite) crystal structure and Co{sup 2+} ions were successfully incorporated into the lattice sites of Zn{sup 2+} ions. Dielectric constant was found to decrease with frequency and dopant concentration. Loss tangent results show the decrease in the hopping frequency of charge carriers between metal ions with doping.

  14. Amorphous titania/carbon composite electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Vaughey, John T.; Jansen, Andrew; Joyce, Christopher D.

    2017-05-09

    An isolated salt comprising a compound of formula (H.sub.2X)(TiO(Y).sub.2) or a hydrate thereof, wherein X is 1,4-diazabicyclo[2.2.2]octane (DABCO), and Y is oxalate anion (C.sub.2O.sub.4.sup.-2), when heated in an oxygen-containing atmosphere at a temperature in the range of at least about 275.degree. C. to less than about 400.degree. C., decomposes to form an amorphous titania/carbon composite material comprising about 40 to about 50 percent by weight titania and about 50 to about 60 percent by weight of a carbonaceous material coating the titania. Heating the composite material at a temperature of about 400 to 500.degree. C. crystallizes the titania component to anatase. The titania materials of the invention are useful as components of the cathode or anode of a lithium or lithium ion electrochemical cell.

  15. Temperature dependence anomalous dielectric relaxation in Co doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Sajid Ali; Nisar, Ambreen; Fatma, Bushara [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh 202 002 (India); Khan, Wasi, E-mail: wasiamu@gmail.com [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh 202 002 (India); Chaman, M. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh 202 002 (India); Mewat Engg. College (Wakf) Mewat, Haryana (India); Azam, Ameer [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh 202 002 (India); Centre of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Naqvi, A.H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh 202 002 (India)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► We prepared Co doped ZnO by facile gel-combustion method. ► Studied temperature dependent dielectric properties in detail. ► Relaxation time shifts toward the higher temperature as increase in Co content. ► SEM analysis shows formation and agglomeration of nanoparticles. ► Dielectric constants, loss and ac conductivity increases with rise in temperature. ► The dielectric constant, loss and ac conductivity decreases as Co ion increases. -- Abstract: We have reported temperature and frequency dependence of dielectric behavior of nanocrystalline Zn{sub 1−x}Co{sub x}O (x = 0.0, 0.01, 0.05 and 0.1) samples prepared by gel-combustion method. The synthesized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and LCR-meter, respectively. The XRD analysis reveals that ZnO has a hexagonal (wurtzite) crystal structure. The morphology and size of the nanoparticles (∼10–25 nm) were observed by SEM for 5% Co doped ZnO sample. In dielectric properties, complex permittivity (ε{sup *} = ε′ − jε″), loss tangent (tan δ) and ac conductivity (σ{sub ac}) in the frequency range 75 kHz to 5 MHz were analyzed with temperature range 150–400 °C. The experimental results indicate that ε′, ε″, tan δ and σ{sub ac} decreases with increase in frequency and temperature. The transition temperature as obtained in dispersion curve of dielectric constant shifts toward higher temperature with increase Co content.

  16. Multimodal emissions from Tb3+/Yb3+ co-doped lithium borate glass: Upconversion, downshifting and quantum cutting

    Science.gov (United States)

    Bahadur, A.; Yadav, R. S.; Yadav, R. V.; Rai, S. B.

    2017-02-01

    This paper reports the optical properties of Tb3+/Yb3+ co-doped lithium borate (LB) glass prepared by melt quench method. The absorption spectrum of the Yb3+ doped LB glass contains intense NIR band centered at 976 nm due to 2F7/2→2F5/2 transition. The emission spectra of the prepared glasses have been monitored on excitation with 266, 355 and 976 nm. The Yb3+ doped glass emits a broad NIR band centered at 976 nm whereas the Tb3+ doped glass gives off visible bands on excitations with 266 and 355 nm. When the Tb3+ and Yb3+ ions are co-doped together, the emission intensity in the visible region decreases whereas it increases in the NIR region significantly. The increase in the emission intensity in the NIR region is due to efficient cooperative energy transfer (CET) from Tb3+ to Yb3+ ions. The quantum cutting efficiency for Tb3+/Yb3+ co-doped glass has been calculated and compared for 266 and 355 nm excitations. The quantum cutting efficiency is larger for 355 nm excitation (137%). The Tb3+/Yb3+ co-doped LB glass also emits upconverted visible bands on excitation with 976 nm. The mechanisms involved in the energy transfer have been discussed using schematic energy level diagram. The Tb3+/Yb3+ co-doped LB glass may be used in the optical devices and in solar cell for solar spectral conversion and behaves as a multi-modal photo-luminescent material.

  17. Effect of co-doping on luminescence of LiCaAlF{sub 6}:Eu phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Rahangdale, S.R.; Palikundwar, U.A. [Department of Physics, Nagpur University, Nagpur 440033 (India); Wankhede, S.P. [Department of Physics, K.D.K. College of Engineering, Nagpur (India); Dhabekar, Bhushan; Kadam, Sonal [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre (BARC), Mumbai 400085 (India); Moharil, S.V., E-mail: svmoharil@yahoo.com [Department of Physics, Nagpur University, Nagpur 440033 (India)

    2015-11-15

    Abstracts: LiCaAlF{sub 6} is a versatile host material. Applications of this host as scintillation detector and solid state laser have been reported quite frequently. Thermoluminescence studies on LiCaAlF{sub 6}:Eu have also been reported. They are, however, not consistent. The glow curve structure depends on the synthesis route. At least two glow peaks are observed, around 180 °C and 240 °C. Effects of co-doping on the glow curve are reported. Co-doping with Y (0.5 mol%) suppresses the 240 °C peak and increases the intensity of 180 °C peak nearly 3 fold and shifts it to slightly higher temperature of 190 °C. Co-doping with La (0.8 mol%), on the other hand, removes 180 °C peak and intense peak at 240 °C can be observed. Thus co-doping produces a relatively simple glow curve with only one dominant peak. LiCaAlF{sub 6}:Eu phosphor also shows intense optically stimulated luminescence (OSL). The OSL sensitivity of LiCaAlF{sub 6}:Eu codoped with Y is about 7 times that of commercially available Al{sub 2}O{sub 3}:C. Other OSL properties useful for dosimetry applications are also reported in this paper. - Highlights: • Precipitation synthesis of LiCaAlF{sub 6}:Eu, Yttrium co-doping simplifies glow curve. • TL sensitivity is 3 times that of CaSO{sub 4}:Dy. • OSL sensitivity is 7 times that of Al{sub 2}O{sub 3}:C (Landauer). • Linear OSL response in the range 3 mGy to 1 kGy. • Negligible fading over 40 days.

  18. Co-co-doping Effect on Superconducting Properties of 112-Type Ca0.8La0.2FeAs2 Single Crystals

    Science.gov (United States)

    Xing, Xiangzhuo; Zhou, Wei; Xu, Baozhang; Li, Na; Sun, Yiran; Zhang, Yufeng; Shi, Zhixiang

    2015-07-01

    We systematically investigated the Co-co-doping effects in Ca0.8La0.2FeAs2 superconductors. The superconducting transition temperature (Tc) decreases almost linearly with increasing Co content. Simultaneously, it is found that the (Ca,La)112 phase is so sensitive to the Co doping level that chemical phase separation becomes more and more apparent as a result of formation of the (Ca,La)122 phase. The maximum Co doping level for 112 phase seems very low, indicating a quite cruel growth condition for 112 compared with other IBSs.

  19. Effect of Peptization on Densification and Phase-Transformation Behavior of Sol–Gel-Derived Nanostructured Titania

    NARCIS (Netherlands)

    Kumar, Krishnankutty-Nair P.; Kumar, Jalajakumari; Keizer, Klaas

    1994-01-01

    Porosity reduction, packing, pore-size distribution, and anatase to rutile phase transformation behavior of nanostructured titania ceramics prepared from both peptized and unpeptized sols were studied and compared using XRD, DSC, and nitrogen-gas physisorption techniques. Precursor gels prepared fro

  20. N and Al co-doping as a way to p-type ZnO without post-growth annealing

    Science.gov (United States)

    Snigurenko, Dymitr; Guziewicz, Elzbieta; Krajewski, Tomasz A.; Jakiela, Rafal; Syryanyy, Yevgen; Kopalko, Krzysztof; Paszkowicz, Wojciech

    2016-12-01

    We demonstrate experimental results on p-type ZnO films grown by atomic layer deposition (ALD) and co-doped with aluminum and nitrogen (ANZO). The films were obtained at low temperature (100 °C) with different N to Al ratio and show conductivity type, which depends on the N and Al content. We applied the x-ray photoelectron spectroscopy in order to get insight into a chemical nature of dopants and we found three pronounced contributions of the N1s core level which appear at binding energies of 396.1, 397.4 and around 399 eV. Based on ANZO and undoped ZnO films, both grown by the ALD technique, the ZnO homojunction was obtained in one technological process without any post-growth high temperature processing. The rectification ratio as high as 4 × 104 at ± 2 V was achieved when an ultrathin Al2O3 layer was inserted between p- and n-type ZnO and a n-type ZnO buffer layer deposited on an insulating Si substrate was applied.

  1. Precise size control over ultrafine rutile titania nanocrystallites in hierarchical nanotubular silica/titania hybrids with efficient photocatalytic activity.

    Science.gov (United States)

    Gu, Yuanqing; Huang, Jianguo

    2013-08-12

    Hierarchical-structured nanotubular silica/titania hybrids incorporated with particle-size-controllable ultrafine rutile titania nanocrystallites were realized by deposition of ultrathin titania sandwiched silica gel films onto each nanofiber of natural cellulose substances (e.g., common commercial filter paper) and subsequent flame burning in air. The rapid flame burning transforms the initially amorphous titania into rutile phase titania, and the silica gel films suppress the crystallite growth of rutile titania, thereby achieving nano-precise size regulation of ultrafine rutile titania nanocrystallites densely embedded in the silica films of the nanotubes. The average diameters of these nanocrystallites are adjustable in a range of approximately 3.3-16.0 nm by a crystallite size increment rate of about 2.4 nm per titania deposition cycle. The silica films transfer the electrons activated by crystalline titania and generate catalytic reactive species at the outer surface. The size-tuned ultrafine rutile titania nanocrystallites distributed in the unique hierarchical networks significantly improve the photocatalytic performance of the rutile phase titania, thereby enabling a highly efficient photocatalytic degradation of the methylene blue dye under ultraviolet light irradiation, which is even superior to the pure anatase-titania-based materials. The facile stepwise size control of the rutile titania crystallites described here opens an effective pathway for the design and preparation of fine-nanostructured rutile phase titania materials to explore potential applications.

  2. Synthesis of Cerium-Doped Titania Nanoparticles and Nanotubes.

    Science.gov (United States)

    Cao, Wei; Suzuki, Takuya; Elsayed-Ali, Hani E; Abdel-Fattah, Tarek M

    2015-03-01

    Cerium-doped titania nanoparticles and nanotubes were synthesized via hydrothermal processes. X-Ray Diffraction revealed that cerium-doped titania nanoparticles have an anatase crystal structure, while cerium-doped titania nanotubes have an H2Ti3O7-type structure. Scanning electron microscopy and high resolution transmission electron microscopy showed that both types of titania are well crystallized with relatively uniform size distribution. The photocatalytic degradation of methylthioninium chloride known as methylene blue dye was tested and both cerium-doped titania nanoparticles and nanotubes. The preliminary photocatalytic degradation of Methylene Blue data showed significantly improved visible light photocatalytic activities as compared to commercial titania powders.

  3. Effect of annealing temperature on titania nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, K., E-mail: sanjaymani367@gmail.com; Arumugam, S., E-mail: sanjaymani367@gmail.com [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli-620024 (India); Chandrasekaran, G. [Department of Physics, Pondicherry University, Pondicherry-605014 (India)

    2014-04-24

    Titania polycrystalline samples are prepared by using sol-gel route hydrolyzing a alkoxide titanium precursor under acidic conditions. The as prepared samples are treated with different calcination temperatures. The anatase phase of titania forms when treated below 600°C, above that temperature the anatase phase tends to transform into the rutile phase of titania. The experimental determination of average grain size, phase formation, lattice parameters and the crystal structures of titania samples at different calcinations is done using X-ray diffraction (XRD). Fourier Transform Infra-red Spectroscopy (FTIR), UV-vis-NIR spectroscopy and Scanning Electron Microscopy (SEM) and Energy Dispersive Analysis X-ray are used to characterize the samples to bring impact on the respective properties.

  4. Epitaxial Properties of Co-Doped ZnO Thin Films Grown by Plasma Assisted Molecular Beam Epitaxy

    Institute of Scientific and Technical Information of China (English)

    CAO Qiang; DENG Jiang-Xia; LIU Guo-Lei; CHEN Yan-Xue; YAN Shi-Shen

    2007-01-01

    High quality Co-doped ZnO thin films are grown on single crystalline Al2O3(0001) and ZnO(0001) substrates by oxygen plasma assisted molecular beam epitaxy at a relatively lower substrate temperature of 450 ℃. The epitaxial conditions are examined with in-situ reflection high energy electron diffraction (RHEED) and ex-situ high resolution x-ray diffraction (HRXRD). The epitaxial thin films are single crystal at film thickness smaller than 500nm and nominal concentration of Co dopant up to 20%. It is indicated that the Co cation is incorporated into the ZnO matrix as Co2+ substituting Zn2+ ions. Atomic force microscopy shows smooth surfaces with rms roughness of 1.9nm. Room-temperature magnetization measurements reveal that the Co-doped ZnO thin films are ferromagnetic with Curie temperatures TC above room temperature.

  5. Enhanced magnetocaloric effect in a Co-doped Heusler Mn50Ni37Co3In10 unidirectional crystal

    Science.gov (United States)

    Ren, Jian; Feng, Shutong; Fang, Yue; Zhai, Qijie; Luo, Zhiping; Zheng, Hongxing

    2016-11-01

    A high-pressure optical zone-melting technique was employed to grow a Mn-rich Heusler Mn50Ni37Co3In10 unidirectional crystal in the present study. It was found that the Co-doped Mn50Ni37Co3In10 unidirectional crystal showed a low magnetic hysteretic loss and a widened working temperature interval in the vicinity of the martensitic transformation. The inverse magnetic entropy change (∆SM) reached 7.84 Jkg-1K-1 around 237.5 K under a magnetic field change of 30 kOe, and the corresponding effective refrigeration capacity (RCeff) was about 127.2 Jkg-1. The experimental results demonstrated a high potential to develop high-performance Mn-rich Heusler Mn-Ni-In magnetocaloric materials by means of Co doping in combination with the high-pressure optical zone-melting fabrication technique.

  6. Green up-converted luminescence in (Er3+-Yb3+) co-doped LiNbO3 crystals

    Science.gov (United States)

    Stoffel, M.; Rinnert, H.; Kokanyan, E.; Demirkhanyan, G.; Demirkhanyan, H.; Aillerie, M.

    2016-07-01

    Er3+ doped and (Er3+-Yb3+) co-doped LiNbO3 (LN) crystals grown by the Czochralski method are investigated by photoluminescence spectroscopy. Green up-converted luminescence is observed in Er3+ doped LN crystals under 980 nm excitation. This is explained by an energy transfer between two neighboring Er3+ ions. In (Er3+, Yb3+) co-doped LN crystals, the intensity of the green up-converted luminescence can be further enhanced suggesting that Yb3+ ions also contribute to the up-conversion process. Time resolved photoluminescence measurements clearly demonstrate that an efficient energy transfer occurs between Yb3+ and Er3+ ions. A theoretical model taking into account the contribution of both Er3+-Er3+ pairs and Yb3+-Er3+ pairs is able to describe correctly the decay of the up-converted luminescence.

  7. Passive mode locking of a Nd:YAG laser with co-doped Nd, Cr:YAG as saturable absorber

    Institute of Scientific and Technical Information of China (English)

    Yang Lin(杨林); Feng Bao-Hua(冯宝华); Zhang Zhi-Guo(张治国); Gaebler Volker; Liu Bai-Ning(刘百宁); Eichler Hans

    2003-01-01

    We demonstrate the characteristics of relatively low saturation intensity using co-doped Nd, Cr:YAG as saturable absorber for passively mode locking the Nd:YAG laser. The difference of the saturation intensity between Q-switched and mode-locked operation in co-doped Nd, Cr:YAG was only one to two orders of magnitude, while Cr:YAG was generally reported at a difference of five orders of magnitude. More than 80% mode locking modulation depth was achieved at an incident pump power of 4.4W, corresponding to an intracavity intensity of 6 × 104W/cma2, using a 68cm long plano-concave cavity.

  8. Electronic, optical and photocatalytic behavior of Mn, N doped and co-doped TiO2: Experiment and simulation

    Science.gov (United States)

    Zhao, Ya Fei; Li, Can; Lu, Song; Liu, Ru Xi; Hu, Ji Yuan; Gong, Yin Yan; Niu, Leng Yuan

    2016-03-01

    The crystal phase structure, surface morphology, chemical states and optical properties of Mn, N mono-doped and co-doped TiO2 nanoparticles were investigated by X-ray powder diffractometry, Raman spectra, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. Meanwhile, geometry structures, formation energies, electronic and optical properties of all systems have been also analyzed by density functional theory. The results showed that the band gap values and the carrier mobility in the valence band, conduction band and impurity levels have a synergetic influence on the visible-light absorption and photocatalytic activity of the doped TiO2. The number and the carrier mobility of impurity level jointly influence the photocatalytic activity of catalyst under visible-light. Especially, the photocatalytic activity of Mn-2N co-doped TiO2 beyond three-fold than that of pure TiO2 under visible-light.

  9. Electronic Structure Magnetic Properties and Optical Properties of Co-doped AlN from First Principles

    Institute of Scientific and Technical Information of China (English)

    ZHAO Long; LU Peng-Fei; YU Zhong-Yuan; GUO Xiao-Tao; YE Han; YUAN Gui-Fang; SHEN Yue; LIU Yu-Min

    2011-01-01

    The electronic structure, magnetic properties, and optical properties of Co-doped AlN are investigated based upon the Perdew-Burke-Ernzerhof form of generalized gradient approximation within the density functional theory. The band gaps narrowing of Al1-xCoxN are found with the increase of Co concentrations. The analyses of the band structures and density of states show that Al1-xCoxN alloys exhibit a half-metallic character. Moreover, we have succeeded in demonstrating that Co doped AlN system in x = 0.125 is always antiferromagnetic, which is in good agreement with the experimental results. Besides, it is shown that the insertion of Co atom leads to redshift of the optical absorption edge.Finally, the optical constants of pure AlN and Al1-xCoxN alloy, such as loss function, refractive index and reflectivity,are discussed.

  10. The effect of CO-doped on the room-temperature ferromagnetism of CeO2 nanorods

    Science.gov (United States)

    Xu, H. F.; Li, H.

    2015-03-01

    Co-doped CeO2 nanorods of 10-20 nm in diameter and 200-600 nm or more in length have been synthesized by a simple co-precipitation method. The results of XRD and SADE analysis indicate that the as-synthesized CeO2 samples have the fluorite structure. X-ray photoelectron spectroscopy and Raman spectra show that Ce4+ and Ce3+ ions coexist at the surface of non-doped CeO2 nanorods. The magnetic measurements indicated that Co-doped CeO2 nanorods exhibit stronger ferromagnetism at room temperature, and while increasing the amount of Co ions, the ferromagnetism increase more, which can be associated with the presence of Ce3+ and Co2+.

  11. High purity green photoluminescence emission from Tb3+, Bi3+ co-doped LaGaO3 nanophosphors

    Science.gov (United States)

    Samuel, T.; Satya Kamal, Ch.; Ravipati, Srikanth; Ajayi, Babajide Patrick; Veeraiah, V.; Sudarsan, V.; Ramachandra Rao, K.

    2017-07-01

    A series of Tb3+ and Bi3+ co-doped LaGaO3 nanophosphors were synthesized by using polyol route and also characterised for their uncovering energy transfer mechanism of photoluminescence. An excellent characteristic emission of Bi3+ and Tb3+ ions was observed with an appreciable increase in photoluminescence at certain doping concentration. Energy transfer (ET) mechanism from the host lattice to Bi3+ and Tb3+ ions in the co-doped nanophosphor has been explained. The ET efficiency has been calculated and found to be 69.53%. The CIE chromaticity of the synthesized LaGaO3: Bi3+, Tb3+ nanophosphors indicates that they could be a suitable material for field emission display and LED applications.

  12. Optical Properties of Mg, Fe, Co-Doped Near-Stoichiometric LiTaO3 Single Crystals

    Directory of Open Access Journals (Sweden)

    Chung Wen Lan

    2012-01-01

    Full Text Available Mg, Fe co-doped near-stoichiometric lithium tantalite (SLT single crystals were grown by employing the zone-leveling Czochralski (ZLCz technique. The optical properties, holographic parameters, as well as the composition of the grown crystals were measured. It was found that the Li/Ta ratio decreased with the doping of Mg and Fe ions. A red shift was observed in absorption spectrum for the Mg, Fe co-doped crystals compared to the undoped and Mg-doped ones. The effect of the iron ions (Fe2+ and Fe3+ was further discussed based on the specified absorption bands. Moreover, the occupation mechanism for the defects was discussed by using the IR absorption spectrum, which was attributed to the FeTa3− defects in the highly Fe-doped crystal. In addition, the holographic parameters were also found to be improved with a higher Fe/Ta ratio in the crystals.

  13. Characterization of the new co-doped CsI microcolumnar films for high-speed radiographic imaging

    Science.gov (United States)

    Thacker, Samta C.; Gaysinskiy, Valeriy; Ovechkina, Lena E.; Miller, Stuart R.; Nagarkar, Vivek V.; Brecher, Charles; Lempicki, Alexander; Bartram, Ralph H.

    2008-03-01

    Despite its obvious advantages, well known CsI:Tl scintillator has two characteristic properties that undermine its use in clinical and high speed imaging: the presence of an afterglow component in its scintillation decay, and a hysteresis effect that causes drift in the scintillation yield after exposure to high radiation doses. We have previously reported that the addition of a second dopant, Sm 2+, to the CsI:Tl crystals, significantly suppresses both afterglow and hysteresis. Here we report on the fabrication and characterization of the Sm co-doped CsI:Tl microcolumnar films to examine if these properties are preserved in films as well. Our preliminary data suggests that the Sm co-doped CsI:Tl films significantly improve temporal response relative to their CsI:Tl counterpart, and that the newly developed films demonstrate excellent spatial resolution. Various aspects of these effects and their consequences for imaging performance are discussed in this paper.

  14. Improvement on the Luminescence Property of Y, Sb Co-doped PbWO4 Single Crystal

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of Y and Sb co-doping on the luminescence property of PbWO4 crystals has been investigated. Compared with undoped PbWO4, the transmittance and emission peak intensity of Y∶Sb∶PbWO4 crystals were obviously improved. In addition, its transmittance cutoff wavelength and emission peak shifted to the shorter one. The mechanism of effect of Y and Sb on the transmittance spectra was briefly discussed. The light yield of Y∶Sb∶PbWO4 crystals was 25p.e./MeV, which was two times of that of undoped PbWO4. Our experiments showed that Y and Sb co-doping was a selectable method to improve the luminescence property of PbWO4.

  15. Local structure analysis of diluted magnetic semiconductor Co and Al co-doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hyodo, K.; Morimoto, S.; Yamazaki, T.; Ishikawa, T.; Ichiyanagi, Y. [Department of Physics, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama, Kanagawa 240-8501 (Japan); Utsumi, J. [Engineering Department Machine Tool Division, Machinery, Equipment & Infrastructure, Mitsubishi Heavy Industries, Ltd., Ritto, Shiga 520-3080 (Japan)

    2016-02-01

    In this study, Co and Al ions co-doped ZnO nanoparticles (Zn(Al, Co)O NPs) were prepared by our original chemical preparation method. The obtained samples prepared by this method, were encapsulated in amorphous SiO{sub 2}. X-ray diffraction (XRD) results showed Zn(Al, Co)O NPs had a single-phase nature with hexagonal wurtzite structure. These particle sizes could be controlled to be approximately 30 nm. We investigate the effect that the increase in the carrier has on the magnetization by doping Al to Co-doped ZnO NPs. The local structures were qualitatively analyzed using X-ray absorption fine structure (XAFS) measurements.

  16. Theoretical study of hydrogen dissociation and diffusion on Nb and Ni co-doped Mg(0001): A synergistic effect

    Science.gov (United States)

    Chen, Ming; Cai, Zhen-Zhun; Yang, Xiao-Bao; Zhu, Min; Zhao, Yu-Jun

    2012-07-01

    The interaction of H2 with clean, Ni and Nb doped Mg(0001) surface are investigated by first-principles calculations. Individual Ni and Nb atoms within the outermost surface can reduce the dissociation barrier of the hydrogen molecule. They, however, prefers to substitute for the Mg atoms within the second layer, leading to a weaker catalytic effect for the dissociation of H2, a bottleneck for the hydriding of MgH2. Interestingly, co-doping of Ni and Nb stabilizes Ni at the first layer, and results in a significant reduction of the dissociation barrier of H2 on the Mg surface, coupled with an increase of the diffusion barrier of H. Although codoped Ni and Nb shows no remarkable advantage over single Nb here, it implies that the catalytic effect could be optimized by co-doping of "modest" transition metals with balanced barriers for dissociation of H2 and diffusion of H on Mg surfaces.

  17. Coalescence-driven magnetic order of the uncompensated antiferromagnetic Co doped ZnO

    Science.gov (United States)

    Ney, V.; Henne, B.; Lumetzberger, J.; Wilhelm, F.; Ollefs, K.; Rogalev, A.; Kovacs, A.; Kieschnick, M.; Ney, A.

    2016-12-01

    The evolution of the structural and magnetic properties of Co doped ZnO has been investigated over an unprecedented concentration range above the coalescence limit. ZnO films with Co concentrations from 20% to 60% of the cationic lattice have been grown by reactive magnetron sputtering. The wurtzite crystal structure was maintained even for these high dopant concentrations. By measuring the x-ray absorption at the near edge and the linear and circular dichroism of the films at the Zn and Co K edge, it could be shown that Co substitutes predominantly for Zn in the lattice. No indications of metallic Co have been found in the samples. At low Co concentrations, the films are paramagnetic, but with increasing Co content, the films become antiferromagnetically ordered with increasing order temperature. Uncompensated spins, coupled to the antiferromagnetic dopant configurations, lead to a vertical exchange-bias-like effect, which increases with increasing Co concentration. In parallel, the single-ion anisotropy is gradually lost.

  18. Luminescence features of dysprosium and phosphorus oxide co-doped lithium magnesium borate glass

    Science.gov (United States)

    Hashim, S.; Mhareb, M. H. A.; Ghoshal, S. K.; Alajerami, Y. S. M.; Saripan, M. I.; Bradley, D. A.

    2017-08-01

    Lithium magnesium borate (LMB) glass system co-doped with the oxides of dysprosium (Dy2O3) and phosphorus (P2O5) were synthesized using melt-quenching method. Prepared samples were characterized using various techniques to determine the effects of co-dopants concentration variation on their thermoluminescence (TL) and photoluminescence (PL) properties. TL glow curves of LMB:0.5Dy sample revealed a single prominent peak at Tm=190 °C, where TL intensity was enhanced by a factor of 2.5 with the increase of P2O5 concentration up to 1 mol%. This enhancement was accompanied by a shift in Tm towards higher temperature. Good linearity in the range of 1-100 Gy with linear correlation coefficient of 0.998 was achieved. PL spectra displayed two significant peaks centred at 481 nm and 573 nm. These attractive luminescence features of the proposed glass system may be useful for the development of radiation dosimetry.

  19. Combinatorial optimization of La, Ce-co-doped pyrosilicate phosphors as potential scintillator materials.

    Science.gov (United States)

    Wei, Qinhua; Wan, Jieqiong; Liu, Guanghui; Zhou, Zhenzhen; Yang, Hua; Wang, Jiacheng; Liu, Qian

    2015-04-13

    A combinatorial method was employed to rapidly screen the effects of La, Ce-co-doping on the luminescent properties of Gd2Si2O7 pyrosilicate using an 8 × 8 library. The candidate formulations (Gd1-x-yLax)2Si2O7:Ce2y were evaluated by luminescence pictures under ultraviolet excitation. The optimal composition was found to be (Gd0.89La0.1)2Si2O7:Ce0.02 after scaled-up preparation and detailed characterization of powder samples, which shows an excellent light output under both ultraviolet and X-ray excitation (about 5.43 times of commercial YAG:Ce powders). The XRD results indicate that the phase structure sequence is tetragonal-orthorhombic-triclinic for different calcination temperatures and doping ions. The (Gd0.89La0.1)2Si2O7:Ce0.02 powder sample also demonstrated excellent temperature stability of luminescence up to 200 °C and a short decay time of several tens of nanoseconds, suggesting that this may represent a new kind of scintillation material, such as single crystals, ceramics, glass, or phosphors.

  20. Structural, linear and nonlinear optical properties of co-doped ZnO thin films

    Science.gov (United States)

    Shaaban, E. R.; El-Hagary, M.; Moustafa, El Sayed; Hassan, H. Shokry; Ismail, Yasser A. M.; Emam-Ismail, M.; Ali, A. S.

    2016-01-01

    Different compositions of Co-doped zinc oxide [(Zn(1- x)Co x O) ( x = 0, 0.02, 0.04, 0.06, 0.08 and 0.10)] thin films were evaporated onto highly clean glass substrates by thermal evaporation technique using a modified source. The structural properties investigated by X-ray diffraction revealed hexagonal wurtzite ZnO-type structure. The crystallite size of the films was found to decrease with increasing Co content. The optical characterization of the films has been carried out using spectral transmittance and reflectance obtained in the wavelength range from 300 to 2500 nm. The refractive index has been found to increase with increasing Co content. It was further found that optical energy gap decreases from 3.28 to 3.03 eV with increasing Co content from x = 0 to x = 0.10, respectively. The dispersion of refractive index has been analyzed in terms of Wemple-DiDomenico (WDD) single-oscillator model. The oscillator parameters, the single-oscillator energy ( E o), the dispersion energy ( E d), and the static refractive index ( n 0), were determined. The nonlinear refractive index of the Zn(1- x)Co x O thin films was calculated and revealed well correlation with the linear refractive index and WDD parameters which in turn depend on the density and molar volume of the system.

  1. Aluminum- and boron-co-doped ZnO ceramics: structural, morphological and electrical characterization

    Science.gov (United States)

    Liu, Shimin; Liu, Jindong; Jiang, Weiwei; Liu, Chaoqian; Ding, Wanyu; Wang, Hualin; Wang, Nan

    2016-10-01

    Highly dense and electrically conductive aluminum- and boron-co-doped ZnO (ABZO) ceramics were prepared by traditional pressureless sintering process. Single aluminum-doped ZnO (AZO) ceramics were synthesized with similar process and characterized for comparison. The densification behavior, crystal structure, morphology, composition and electrical properties of the ceramics were studied. Results indicated that AZO ceramics with the maximum relative density of 99.01 % were obtained only at 1350 °C for 4 h, which, however, was accompanied by electrical conductivity deterioration because of the increased insulated ZnAl2O4 phase formed in ceramics. Interestingly, the ABZO ceramics reached the maximum relative density of 98.84 % at 1100 °C, which was 250 °C lower compared with that of AZO ceramics. Moreover, the electrical conductivity of ABZO ceramics improved significantly with the increased sintering temperature and increased insulated ZnAl2O4 phase, which should be ascribed to the decreased grain boundaries and the resultant reduced carrier scattering in ceramics overcoming the influence of increased ZnAl2O4 phase due to boron doping effect.

  2. Structural, electronic, and magnetic properties of Co-doped ZnO

    Institute of Scientific and Technical Information of China (English)

    Bakhtiar Ul Haq; A. Afaq; R. Ahmed; S. Naseem

    2012-01-01

    Density functional theory based calculations have been carried out to study structural,electronic,and magnetic properties of Zn1-xCoxO (x = 0,0.25,0.50,0.75) in the zinc-blende phase,and the generalized gradient approximation proposed by Wu and Cohen has been used.Our calculated lattice constants decrease while the bulk moduli increase with the increase of Co2+ concentration.The calculated spin polarized band structures show the metallic behavior of Co-doped ZnO for both the up and the down spin cases with various doping concentrations.Moreover,the electron population is found to shift from the Zn-O bond to the Co-O bond with the increase of Co2+ concentration.The total magnetic moment,the interstitial magnetic moment,the valence and the conduction band edge spin splitting energies,and the exchange constants decrease,while the local magnetic moments of Zn,Co,O,the exchange spin splitting energies,and crystal field splitting energies increase with the increase of dopant concentration.

  3. Novel erbia-yttria co-doped zirconia fluorescent thermal history sensor

    Science.gov (United States)

    Copin, E. B.; Massol, X.; Amiel, S.; Sentenac, T.; Le Maoult, Y.; Lours, P.

    2017-01-01

    Thermochromic pigments are commonly used for off-line temperature mapping on components from systems operating at a temperature higher than 1073 K. However, their temperature resolution is often limited by the discrete number of color transitions they offer. This paper investigates the potential of erbia-yttria co-doped zirconia as a florescent thermal history sensor alternative to thermochromic pigments. Samples of yttria-stabilized zirconia powder (YSZ, 8.3 mol% YO1.5) doped with 1.5 mol% ErO1.5 and synthesized by a sol-gel route are calcined for 15 minutes under isothermal conditions between 1173 and 1423 K. The effects of temperature on their crystal structure and room temperature fluorescence properties are then studied. Results show a steady increase of the crystallinity of the powders with temperature, causing a significant and permanent increase of the emission intensity and fluorescence lifetime which could be used to determine temperature with a calculated theoretical resolution lower than 1 K for intensity. The intensity ratio obtained using a temperature insensitive YSZ:Eu3+ reference phosphor is proposed as a more robust parameter regarding experimental conditions for determining thermal history. Finally, the possibilities for integrating this fluorescent marker into sol-gel deposited coatings for future practical thermal history sensing applications is also discussed.

  4. Visible light carrier generation in co-doped epitaxial titanate films

    Energy Technology Data Exchange (ETDEWEB)

    Comes, Ryan B.; Smolin, Sergey Y.; Kaspar, Tiffany C.; Gao, Ran; Apgar, Brent A.; Martin, Lane W.; Bowden, Mark E.; Baxter, Jason; Chambers, Scott A.

    2015-03-02

    Perovskite titanates such as SrTiO3 (STO) exhibit a wide range of important functional properties, including high electron mobility, ferroelectricity—which may be valuable in photovoltaic applications—and excellent photocatalytic performance. The wide optical band gap of titanates limits their use in these applications, however, making them ill-suited for integration into solar energy harvesting technologies. Our recent work has shown that by doping STO with equal concentrations of La and Cr we can enhance visible light absorption in epitaxial thin films while avoiding any compensating defects. In this work, we explore the optical properties of photoexcited carriers in these films. Using spectroscopic ellipsometry, we show that the Cr3+ dopants, which produce electronic states immediately above the top of the O 2p valence band in STO reduce the direct band gap of the material from 3.75 eV to between 2.4 and 2.7 eV depending on doping levels. Transient reflectance measurements confirm that optically generated carriers have a recombination lifetime comparable to that of STO and are in agreement with the observations from ellipsometry. Finally, through photoelectrochemical yield measurements, we show that these co-doped films exhibit enhanced visible light photocatalysis when compared to pure STO.

  5. Visible light carrier generation in co-doped epitaxial titanate films

    Energy Technology Data Exchange (ETDEWEB)

    Comes, Ryan B., E-mail: ryan.comes@pnnl.gov; Kaspar, Tiffany C.; Chambers, Scott A. [Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States); Smolin, Sergey Y.; Baxter, Jason B. [Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Gao, Ran [Department of Materials Science and Engineering, University of California-Berkeley, Berkeley, California 94720 (United States); Apgar, Brent A. [Department of Materials Science and Engineering, University of California-Berkeley, Berkeley, California 94720 (United States); Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801 (United States); Martin, Lane W. [Department of Materials Science and Engineering, University of California-Berkeley, Berkeley, California 94720 (United States); Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Bowden, Mark E. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States)

    2015-03-02

    Perovskite titanates such as SrTiO{sub 3} (STO) exhibit a wide range of important functional properties, including ferroelectricity and excellent photocatalytic performance. The wide optical band gap of titanates limits their use in these applications; however, making them ill-suited for integration into solar energy harvesting technologies. Our recent work has shown that by doping STO with equal concentrations of La and Cr, we can enhance visible light absorption in epitaxial thin films while avoiding any compensating defects. In this work, we explore the optical properties of photoexcited carriers in these films. Using spectroscopic ellipsometry, we show that the Cr{sup 3+} dopants, which produce electronic states immediately above the top of the O 2p valence band in STO reduce the direct band gap of the material from 3.75 eV to 2.4–2.7 eV depending on doping levels. Transient reflectance spectroscopy measurements are in agreement with the observations from ellipsometry and confirm that optically generated carriers are present for longer than 2 ns. Finally, through photoelectrochemical methylene blue degradation measurements, we show that these co-doped films exhibit enhanced visible light photocatalysis when compared to pure STO.

  6. Variable range hopping conduction and microstructure properties of semiconducting Co-doped TiO 2

    Science.gov (United States)

    Okutan, Mustafa; Bakan, Halil I.; Korkmaz, Kemal; Yakuphanoglu, Fahrettin

    2005-01-01

    The surface morphology, phases existing in the microstructure and conductivity behavior of Co-doped TiO2 have been investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), electrical conductivity measurements and X-ray diffraction technique. The semiconducting phase is found to obey Mott's variable range hopping mechanism of the conduction. The conduction mechanism of the ceramic shows a crossover from the, exp[-(T0/T)] law to a simply activated law, exp(-ΔE/kT). This behavior is attributed to temperature-induced transition from 3D to thermally activated behavior. The hopping conduction parameters such as the characteristic temperature ( T0), localization length ( α), hopping distance ( R), activation energy ( ΔE) and density of states at Fermi level (N(EF) have been calculated. Surface morphology shows that the ceramic has a regular surface. The SEM study indicates that there are grains which have a certain type in the microstructure. Rutile phases with different plane in microstructure were found.

  7. A first-principles study of co-doping in lanthanum bromide

    Science.gov (United States)

    Aberg, Daniel; Sadigh, Babak; Schleife, Andre; Erhart, Paul

    2015-03-01

    It was recently shown that the energy resolution of Ce-doped LaBr3 scintillator radiation detectors can be crucially improved by co-doping with Sr, Ca, or Ba. Here we outline a mechanism for this enhancement on the basis of electronic structure calculations. We show that Sr dopants create and bind to Br vacancies, resulting in stable neutral complexes. The association with Sr causes the deep vacancy level to move toward the conduction band edge. This is essential for reducing the effective carrier density available for Auger quenching during thermalization of hot carriers. Subsequent de-trapping of electrons from the complexes can activate Ce dopants that have previously captured a hole leading to luminescence. This mechanism implies an overall reduction of Auger quenching of free carriers, which is expected to improve the linearity of the photon light yield with respect to the energy of incident electron or photon. Optical properties of the Ce-Sr-vacancy triple complex are discussed and compared to experiment. Prepared by LLNL under Contract DE-AC52-07NA27344. Support from the National Nuclear Security Administration Office of Nonproliferation Research and Development (NA-22) is acknowledged.

  8. Paramagnetic behavior of Co doped TiO{sub 2} nanocrystals controlled by self-purification mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Anitha, B. [Centre for Nanoscience and Nanotechnology, University of Kerala, Kariavattom, Thiruvananthapuram 695 581 (India); Khadar, M. Abdul, E-mail: mabdulkhadar@rediffmail.com [Centre for Nanoscience and Nanotechnology, University of Kerala, Kariavattom, Thiruvananthapuram 695 581 (India); Banerjee, Alok [UGC-DAE Consortium for Scientific Research (CSR), Khandwa Road, Indore 452 001 (India)

    2016-07-15

    Doping in nanocrystals is a challenging process because of the self- purification mechanism which tends to segregate out the dopants resulting in a greater dopant concentration near the surface than at the interior of nanocrystals. In the present work nanocrystals of TiO{sub 2} doped with different atom % of Co were synthesized by peroxide gel method. XRD analysis confirmed the tetragonal anatase structure and HRTEM images showed the rod-like morphology of the samples. Raman modes of anatase phase of TiO{sub 2} along with weak intensity peaks of Co{sub 3}O{sub 4} for higher Co dopant concentrations were observed for the samples. EPR measurements revealed the presence of cobalt in +2 oxidation state in the TiO{sub 2} matrix. SQUID measurements indicated paramagnetic behavior of the Co doped TiO{sub 2} nanocrystals. The paramagnetic behavior is attributed to an increased concentration of Co{sup 2+} ions and an increased presence of Co{sub 3}O{sub 4} phase near the surface of the TiO{sub 2} nanocrystals due to self-purification mechanism. - Graphical abstract: Variation of the intensity ratios of XRD peaks as a function of atomic ratio of Co. Inset: variation of structure factor for (101) reflection as a function of atomic ratio of Co. Display Omitted - Highlights: • Co doped TiO{sub 2} nanocrystals were synthesized by peroxide gel method. • HRTEM images showed Co doped TiO{sub 2} nanocrystals to be rod-like. • EPR spectra showed +2 oxidation states for Co in the samples. • Co doped TiO{sub 2} nanocrystals showed paramagnetic behavior.

  9. Fabrication of ZnO Bi-crystals with twist boundaries using Co doped ZnO single crystals

    CERN Document Server

    Ohashi, N; Ohgaki, T; Tsurumi, T; Fukunaga, O; Haneda, H; Tanaka, J

    1999-01-01

    Zn O single crystals doped with Co were grown by using a flux method and their electrical properties were investigated by Hall effect. Then, these crystals were polished with diamond paste and bonded to form bi-crystal by hot pressing under a pressure of 10 MPa at 1000 .deg. C. The bi-crystals showed nonlinear I-V curves, and the curvature of I-V relation agreed with that for Co-doped polycrystalline ZnO.

  10. Preparation and characterization of zinc and copper co-doped WO3 nanoparticles: Application in photocatalysis and photobiology.

    Science.gov (United States)

    Mohammadi, Sanaz; Sohrabi, Maryam; Golikand, Ahmad Nozad; Fakhri, Ali

    2016-08-01

    In this study, pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles samples were prepared by precipitation and co-precipitation methods. These nanoparticles were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDX), Dynamic light scattering (DLS), UV-visible and photoluminescence (PL) spectroscopy. The synthesized pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles have smart optical properties and average sizes with 3.2, 3.12, 3.08 and 2.97eV of band-gap, 18.1, 23.2, 25.7 and 30.2nm, respectively. Photocatalytic activity of four nanoparticles was studying towards degradation of gentamicin antibiotic under ultraviolet and visible light irradiation. The result showed that Zn,Cu co-doped WO3 possessed high photocatalytic activity. The photocatalytic activity of WO3 nanoparticles could be remarkably increased by doping the Zn and Cu impurity. This can be attributed to the fact that the red shift of absorption edge and the trapping effect of the mono and co-doped WO3 nanoparticles. The research result presents a general and effective way to prepare different photocatalysts with enhanced visible and UV light-driven photocatalytic performance. Antibacterial activity of four different WO3 nanoparticles against Escherichia coli bacterium has been assessed by the agar disc method under light irradiation and dark medium. It is concluded from the present findings that WO3 nanoparticles can be used as an efficient antibacterial agent.

  11. 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.

  12. First-principle study on the effect of high Ag–2N co-doping on the conductivity of ZnO

    Indian Academy of Sciences (India)

    Wenxue Zhang; Yuxing Bai; Cheng He; Xiaolei Wu

    2015-06-01

    The geometric structure, band structure (BS) and density of state (DOS) of pure and p-type co-doping wurtzite ZnO have been investigated by the first-principle ultrasoft pseudopotential method with the generalized gradient approximation. These structures induce fully occupied defect states above the valence-band maximum of doped ZnO. The calculation results show that in the range of high doping concentration, when the co-doping concentration is more than a certain value, the conductivity decreased with the increase of co-doping concentration of Ag–2N in ZnO. Our findings suggest that co-doping of Ag–2N could efficiently enhance the N dopant solubility and is likely to yield better p-type conductivity.

  13. Effects of acceptor-donor complexes on electronic structure properties in co-doped TiO2: A first-principles study

    Science.gov (United States)

    Zhang, L.; Cai, L. L.; Yuan, X. B.; Hu, G. C.; Ren, J. F.

    2016-07-01

    We theoretically investigate the doping effects induced by impurity complexes on the electronic structures of anatase TiO2 based on the density functional theory. Mono-doping and co-doping effects are discussed separately. The results show that the impurity doping can make the band-edges shift. The induced defect levels in the band gaps by impurity doping reduce the band gap predominantly. The compensated acceptor-donor pairs in the co-doped TiO2 will improve the photoelectrochemical activity. From the calculations, it is also found that (S+Zr)-co-doped TiO2 has the ideal band gap and band edge, at the same time, the binding energy is higher than other systems, so (S+Zr)-co-doping in TiO2 is more promise in photoelectrochemical experiments.

  14. Dependences on RE of superconducting properties of transition metal co-doped (Ca, RE)FeAs2 with RE = La-Gd

    Science.gov (United States)

    Yakita, H.; Ogino, H.; Sala, A.; Okada, T.; Yamamoto, A.; Kishio, K.; Iyo, A.; Eisaki, H.; Shimoyama, J.

    2015-11-01

    Dependence of superconducting properties of (Ca, RE)(Fe, TM)As2 [(Ca, RE)112, TM: Co, Ni)] on RE elements (RE = La-Gd) was systematically investigated. Improvement of superconducting properties by Co or Ni co-doping was observed for all (Ca, RE)112, which is similar to Co-co-doped (Ca, La)112 or (Ca, Pr)112. Tc of Co-co-doped samples decreased from 38 K for RE = La to 29 K for RE = Gd with decreasing ionic radii of RE3+. However, Co-co-doped (Ca, Eu)112 showed exceptionally low Tc = 21 K probably due to the co-existence of Eu3+ and Eu2+ suggested by longer interlayer distance dFe-Fe of (Ca, Eu)112 than other (Ca, RE)112.

  15. Effect of Co doping on structural, optical, magnetic and dielectric properties of Bi{sub 2}Fe{sub 4}O{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Mohapatra, S. R.; Sahu, B.; Singh, A. K., E-mail: singhanil@nitrkl.ac.in [Department of Physics and Astronomy, National Institute of Technology, Rourkela-769008 (India); Kaushik, S. D. [UGC-DAE Consortium for Scientific Research Mumbai Centre, R-5 Shed, BARC, Mumbai-400085 (India)

    2015-06-24

    Polycrystalline Bi{sub 2}Fe{sub 4}O{sub 9} and 2% Co doped Bi{sub 2}Fe{sub 4}O{sub 9} were prepared by solid state reaction route. X-ray diffraction (XRD) result reveals that there is no change in the crystal structure due to Co doping and the compound has orthorhombic structure. UV-visible spectroscopy confirms the decrease in band gap due Co doping. Zero field cooled magnetization measurement at 100 Oe magnetic field shows substantial decrease in the magnetic transition temperature. Room temperature frequency dependent dielectric permittivity at 1V DC bias shows ∼10% increase in Co doped sample with respect to pure Bi{sub 2}Fe{sub 4}O{sub 9}.

  16. Optical and magnetic properties of Co-doped CuO flower/plates/particles-like nanostructures.

    Science.gov (United States)

    Basith, N Mohamed; Vijaya, J Judith; Kennedy, L John; Bououdina, M; Hussain, Shamima

    2014-03-01

    In this study, pure and Co-doped CuO nanostructures (0.5, 1.0, 1.5, and 2.0 at wt% of Co) were synthesized by microwave combustion method. The prepared samples were characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). Powder X-ray diffraction patterns refined by the Rietveld method indicated the formation of single-phase monoclinic structure. The surface morphology and elemental analysis of Co-doped CuO nanostructures were studied by using HR-SEM and EDX. Interestingly, the morphology was found to change considerably from nanoflowers to nanoplates then to nanoparticles with the variation of Co concentration. The optical band gap calculated using DRS was found to be 2.1 eV for pure CuO and increases up to 3.4 eV with increasing cobalt content. Photoluminescence measurements also confirm these results. The magnetic measurements indicated that the obtained nanostructures were ferromagnetic at room temperature with an optimum value of saturation magnetization at 1.0 wt.% of Co-doped CuO, i.e., 970 micro emu/g.

  17. Channeling and resonant backscattering investigations of Co doped diluted magnetic oxide films prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, V.N. E-mail: vnk@iitk.ac.in; vnk@squid.umd.edu; Shinde, S.R.; Zhao, Y.G.; Choudhary, R.J.; Ogale, S.B.; Greene, R.L.; Venkatesan, T

    2004-06-01

    We present the results of ion channeling and 3.045 MeV He{sup +} oxygen resonant backscattering along with the results of magnetic and electric characterization experiments performed on thin films of Co doped TiO{sub 2} and La{sub 0.5}Sr{sub 0.5}TiO{sub 3} oxides deposited on (0 0 1) LaAlO{sub 3} substrates using the pulsed laser deposition technique. These films exhibit Curie temperature well above 300 K and hence offer potential use for spintronic devices. In the case of Co doped TiO{sub 2} films the magnetic data have been understood in the light of channeling results, which showed non-substitutionality of Co atoms for the films deposited at 700 deg. C, and their incorporation in the matrix by either annealing at a higher temperature of 875 deg. C or deposition at this temperature. In the case of the Co doped La{sub 0.5}Sr{sub 0.5}TiO{sub 3}, the resistivity data for the films deposited at different oxygen pressures correlate well with the oxygen contents of the films obtained by resonant backscattering.

  18. Effect of Mg{sup 2+} co-doping on the scintillation performance of LuAG:Ce ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuping [Key Laboratory of Transparent Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Feng, Xiqi; Zhou, Zhiwei; Shi, Yun; Pan, Yubai [Key Laboratory of Transparent Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Nikl, Martin [Institute of Physics, ASCR, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic)

    2014-01-15

    Ce-doped Lu{sub 3}Al{sub 5}O{sub 12} optical ceramics co-doped with Mg{sup 2+} are fabricated by solid-state reaction method and further optimized by an air-annealing process. Mg{sup 2+} co-doping leads to a significant decrease of thermoluminescence intensity above room temperature and an increase of scintillation light yield (LY) value and fast component content even if the overall scintillation efficiency decreases. Scintillation LY of {proportional_to}21900 ph/MeV has been achieved with a short shaping time of 1 {mu}s, and the ratio of LY values for 1 {mu}s and 10 {mu}s shaping times was as high as 79%. The acceleration of scintillation response induced by Mg{sup 2+} co-doping and the role of Ce{sup 4+} ions in the scintillation mechanism are discussed. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. FABRICATION AND PHOTOCATALYTIC PROPERTIES OF TiO2 NANOFILMS CO-DOPED WITH Fe3+ AND Bi3+ IONS

    Science.gov (United States)

    Gao, Qiongzhi; Liu, Xin; Liu, Wei; Liu, Fang; Fang, Yueping; Zhang, Shiying; Zhou, Wuyi

    2016-12-01

    In this work, the titanium dioxide (TiO2) nanofilms co-doped with Fe3+ and Bi3+ ions were successfully fabricated by the sol-gel method with dip-coating process. Methylene blue was used as the target degradation chemical to study the photocatalytic properties affected by different doping contents of Fe3+ and Bi3+ ions. The samples were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and infrared (IR) spectroscopy. The results indicated that both pure TiO2 nanofilms and single-doped samples possessed the photocatalytic activity in degradation of methylene blue. However, when the nanofilms co-doped with Fe3+ and Bi3+ ions were fabricated at the molar ratio of 3:1 (Fe3+:Bi3+), they exhibited the best photocatalytic activity after the heat treatment at 500∘C for 2h. The wettability property test indicated that the TiO2 nanofilms co-doped with Fe3+ and Bi3+ ions in the molar ratio 3:1 owned an excellent hydrophilic property.

  20. RETRACTED: Investigation of structural, optical and electronic properties in Al-Sn co-doped ZnO thin films

    Science.gov (United States)

    Pan, Zhanchang; Tian, Xinlong; Wu, Shoukun; Yu, Xia; Li, Zhuliang; Deng, Jianfeng; Xiao, Chumin; Hu, Guanghui; Wei, Zhigang

    2013-01-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Figures 3 and 4 of this paper have also been presented as belonging to other materials in other publications. This observation is evidence of fraud and therefore it is not certain that the described research and conclusions of this paper belong to the presented images. Figures 3 and 4 of this paper can also be found in: Effect of annealing on the structures and properties of Al and F co-doped ZnO nanostructures, Materials Science in Semiconductor Processing, 2014, 17, 162-167, http://dx.doi.org/10.1016/j.mssp.2013.09.023 Highly transparent and conductive Sn/F and Al co-doped ZnO thin films prepared by sol-gel method, Journal of Alloys and Compounds, 2014,583, 32-38, http://dx.doi.org/10.1016/j.jallcom.2013.06.192 Properties of fluorine and tin co-doped ZnO thin films deposited by sol-gel method, Journal of Alloys and Compounds, 2013,576, 31-37, http://dx.doi.org/10.1016/j.jallcom.2013.04.132

  1. Effect of Ti co-doping on photoluminescence characteristics of Eu:BaAl{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, H. [Korea Research Institute of Chemical Technology, Yuseong, Daejeon 305-600 (Korea, Republic of); Bartwal, K.S., E-mail: bartwalks@yahoo.co.in [Laser Materials Development and Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2013-10-15

    Highlights: •BaAl{sub 2}O{sub 4}:Eu{sup 2+}, Ti{sup 3+}, green phosphor with varying Ti concentrations were prepared by solid-state reaction method. •Powder XRD analysis shows the prepared compositions are single phase with hexagonal structure. •High emission efficiency was observed for the Ti co-doped samples compared to the parent phosphor. •This study shows that this materials has a potential for green phosphor. -- Abstract: The effect of Ti co-doping in BaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphor material on crystalline quality, morphology and photoluminescence (PL) characteristics was investigated. The co-doped green phosphor compositions (BaAl{sub 2}O{sub 4}:Eu{sup 2+}, Ti{sup 3+}) with varying concentrations of Ti were prepared by solid-state synthesis method. These compositions were characterized for their phase, morphology and crystallinity by powder X-ray diffraction, SEM and TEM techniques. The photoluminescence properties were investigated measuring PL and decay time. Broad band UV excited luminescence was observed for BaAl{sub 2}O{sub 4}:Eu{sup 2+}, Ti{sup 3+} in the green region (λ{sub max} = 500 nm) due to transitions from 4f{sup 6} 5d{sup 1} to the 4f{sup 7} configuration of the Eu{sup 2+} ion.

  2. Effects of Li+ co-doping on properties of Eu3+ activated TiO2 anatase nanoparticles

    Science.gov (United States)

    Milićević, Bojana; Đorđević, Vesna; Vuković, Katarina; Dražić, Goran; Dramićanin, Miroslav D.

    2017-10-01

    Sol-gel technique for the synthesis of anatase TiO2 at 420 °C produces nanocrystals of 10-20 nm in size with Ti4+ in crystal volume and Ti3+ at terminal planes of the crystal. The study of Li+ co-doping effects on the structure, morphology, absorption, and luminescence of Eu3+ activated TiO2 anatase nanocrystals is presented. Pure anatase structure is achieved up to 9 at.% Li, with significant improvement in crystallinity of europium doped anatase TiO2. The Li+ co-doping reduces the unit cell volume of the crystal, induces the blue shift of the absorption edge, lengthens the lifetime of Eu3+5D0 excited state, and improves the Eu3+ emission intensity up to 37.5%. Judd-Ofelt analysis of Eu3+ emission showed enhancement of quantum efficiency from 66.4% to 98.7% when TiO2:Eu3+ was co-doped with 9 at.% of Li.

  3. Photocatalytic Activity of Lanthanum and Sulfur Co-doped TiO2 Photocatalyst under Visible Light

    Institute of Scientific and Technical Information of China (English)

    XIA Huili; ZHUANG HUISHENG; XIAO Dongchang; ZHANG Tao

    2008-01-01

    A novel lanthanum and sulfur co-doped TiO2,photocatalyst was synthesized by precipitation-dipping method,and characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM)and UV-Vis diffuse reflectance spectroscopy.Compared with the S-doped TiO2,La-doped TiO2 and the standard Degussa P25 photocatalysts,the lanthanum and sulfur co-doped TiO2 photocatalyst(the molar percentage of La is 3.O%) calcined at 450℃for 2 h showed the strongest absorption for visible light and highest activities for degradation of reactive blue 19 dye in aqueous solution under visible light(?>400 nm)irradiation.It was also discovered that the co-doping of lanthanum and sulfur hindered the aggregation and growth of TiO2 particles,and the doping of lanthanum reduced slightly the phase transition temperature of TiO2 from anatase to rutile.

  4. The effect of K-na co-doping on the formation and particle size of Bi-2212 phase

    Energy Technology Data Exchange (ETDEWEB)

    Kır, M. Ebru [Department of Physics, Faculty of Arts and Sciences, Mersin University, Çiftlikköy, 33343 Mersin (Turkey); Özkurt, Berdan, E-mail: berdanozkurt@mersin.edu.tr [Department of Physics, Faculty of Arts and Sciences, Mersin University, Çiftlikköy, 33343 Mersin (Turkey); Department of Energy Systems Engineering, Faculty of Tarsus Technology, Mersin University, Mersin (Turkey); Advanced Technology Research and Application Center, Mersin University, Yenişehir, TR-33343 Mersin (Turkey); Aytekin, M. Ersin [Advanced Technology Research and Application Center, Mersin University, Yenişehir, TR-33343 Mersin (Turkey)

    2016-06-01

    Superconducting K-Na co-doped Bi{sub 2}Sr{sub 2}K{sub x}Ca{sub 1}Cu{sub 1.75}Na{sub 0.25}O{sub y} (x=0, 0.05, 0.1 and 0.25) ceramics are prepared by a solid-state reaction method. It is clearly determined from XRD data that the characteristic peaks of Bi-2212 phase are observed in all samples. The resistivity measurements show that T{sub c} (onset) values is gradually increasing as K content is increased. It is also found that K-Na co-doping influence the grain sizes for Bi-2212 phase significantly. The critical current densities as a function of magnetic field have been calculated from M–H hysteresis loops of samples according to Bean's critical model, indicating that K-Na co-doping cause higher J{sub c} values than the pure ones.

  5. High-temperature ferromagnetism in Co-doped CeO2 synthesized by the coprecipitation technique.

    Science.gov (United States)

    Colis, S; Bouaine, A; Schmerber, G; Ulhaq-Bouillet, C; Dinia, A; Choua, S; Turek, P

    2012-05-28

    The aim of the present study is to check the influence of annealing under vacuum and a mixture of N(2)-H(2) atmosphere on the magnetic properties of polycrystalline Co-doped CeO(2) diluted magnetic oxides (DMOs) with Co concentrations of 5 at% synthesized using the coprecipitation technique. X-Ray diffraction (XRD) patterns and transmission electron microscopy (TEM) showed for all samples the expected CeO(2) cubic fluorite-type structure and that Co ions are uniformly distributed inside the samples. Room-temperature Raman and photoluminescence (PL) spectroscopies indicate an increase in the concentration of oxygen vacancies upon Co doping and further annealing. Field dependent magnetization measurements revealed a paramagnetic behavior for as-prepared Co-doped CeO(2), while a ferromagnetic behavior appears when the same samples are annealed under vacuum or N(2)-H(2) atmosphere. Temperature dependent magnetization measurements suggest that the observed ferromagnetism is due to the presence of metallic Co clusters with nanometric size and broad size distribution. These results are supported by electron paramagnetic resonance studies.

  6. Intense up-conversion luminescence in Er3+/Yb3+ co-doped CeO2 powders.

    Science.gov (United States)

    Singh, Vijay; Rathaiah, M; Venkatramu, V; Haase, Markus; Kim, S H

    2014-03-25

    The Er(3+) and Er(3+)/Yb(3+) co-doped CeO2 powders have been prepared by a urea combustion route. The structural, morphological, compositional and vibrational analysis of the Er(3+):CeO2 and Er(3+)/Yb(3+):CeO2 powders have been studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and Fourier transform infrared spectroscopy. The optical and luminescence properties of Er(3+):CeO2 and Er(3+)/Yb(3+):CeO2 powders have been studied by using laser excited spectroscopy. The effects of Yb(3+) doping on up-conversion luminescence of Er(3+) co-doped CeO2 powders were studied. The ratio of red to green intensity is decreased in Er(3+):CeO2 whereas the ratio is increased in Er(3+)/Yb(3+):CeO2 powders with increase of power. The effect of co-doping with the Yb(3+) ions on the visible luminescence of Er(3+) and the energy transfer mechanism responsible for the variation in the green and red intensity are discussed. The results indicate that these materials may be suitable for display and light emitting devices.

  7. Structural, electrical and magnetic properties of rare-earth and transition element co-doped bismuth ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Vivek, E-mail: vermavivek.neel@gmail.com

    2015-08-25

    Highlights: • Sm-doping increases the symmetry and decreases the second phase formation. • Ferromagnetic, ferroelectric and dielectric properties enhanced with doping. • M–H loops represents weak ferromagnetic (FM) behavior. • A modification in dielectric constant is observed due to doping of Mn, Co and Cr. • Saturation polarization (P{sub s}), remnant polarization (P{sub r}) and coercive field (E{sub c}) increased with doping. - Abstract: Pure and doped multiferroic samples of bismuth ferrites (BFO) were successfully synthesized by the sol–gel technique. Detailed investigations were made on the influence of (Sm and Mn, Co, Cr) co-doping on structural, electrical, ferroelectric and magnetic properties of the BFO. A structural phase transformation from rhombohedral to orthorhombic with co-doping is confirmed through XRD. It is also observed that Sm-doping increases the symmetry and decreases the second phases noticeably. Microstructure investigation using the scanning electron microscope showed a reduction of grain size with doping in BFO. Magnetic hysteresis loops showed that retentivity (Mr), coercivity (Hc) and saturation magnetization (Ms) of the doped samples were improved. Furthermore, the co-doping enhances the dielectric properties as a result of the reduction in the Fe{sup 2+} ions and oxygen vacancies. The room temperature P–E loop study shows that ferroelectric properties are strongly depend on doping.

  8. Preparation and photocatalytic activity of TiO2 nanoparticles co-doped with Fe and La

    Institute of Scientific and Technical Information of China (English)

    Zhongliang Shi; Xiaoxia Zhang; Shuhua Yao

    2011-01-01

    The catalysts of un-doped, single-doped and co-doped titanium dioxide (TiO2) nanoparticles were prepared by a sol-gel method with Ti(OC4H9)4 as a Ti source material. The photo-absorbance of the obtained nanoparticles was measured by UV-vis diffusive reflectance spectroscopy (UV-vis DRS), and the photocatalytic activity of the prepared samples under UV and visible light was estimated by measuring the degradation rate of phenol (50 mg/L) in an aqueous solution. The effect of Fe and La co-dopants on the material properties was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM)and N2 adsorption-desorption isotherm measurement. It was shown that the co-doped TiO2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions.The photocatalytic activity of TiO2 co-doped with Fe and La is markedly improved due to the synergistic actions of the two dopants.

  9. Sol-gel derived Al-Ga co-doped transparent conducting oxide ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Serrao, Felcy Jyothi, E-mail: jyothiserrao@gmail.com [Department of studies in Physics, Mangalore University, Mangalagangothri 574199 (India); Department of Physics, Karnataka Government Research centre SCEM, Mangalore, 575007 (India); Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M. [Department of studies in Physics, Mangalore University, Mangalagangothri 574199 (India)

    2016-05-23

    Transparent conducting ZnO doped with Al, Ga and co-doped Al and Ga (1:1) (AGZO) thin films were grown on glass substrates by cost effective sol-gel spin coating method. The XRD results showed that all the films are polycrystalline in nature and highly textured along the (002) plane. Enhanced grain size was observed in the case of AGZO thin films. The transmittance of all the films was more than 83% in the visible region of light. The electrical properties such as carrier concentration and mobility values are increased in case of AGZO compared to that of Al and Ga doped ZnO thin films. The minimum resistivity of 2.54 × 10{sup −3} Ω cm was observed in AGZO thin film. The co-doped AGZO thin films exhibited minimum resistivity and high optical transmittance, indicate that co-doped ZnO thin films could be used in transparent electronics mainly in display applications.

  10. Influence of Fe Buffer Layer on Co-Doped BaFe2As2 Superconducting Thin Films

    Directory of Open Access Journals (Sweden)

    C. Bonavolontà

    2015-01-01

    Full Text Available A systematic characterization of Co-doped BaFe2As2 (Ba-122 thin films has been carried out. Two samples were available, one grown on CaF2 substrate and the other on MgO with an Fe buffer layer. The goal was to investigate films’ magnetic and superconducting properties, their reciprocal interplay, and the role played by the Fe buffer layer in modifying them. Morphological characterization and Energy Dispersive X-ray analyses on the Fe-buffered sample demonstrate the presence of diffused Fe close to the Co-doped Ba-122 outer surface as well as irregular holes in the overlying superconducting film. These results account for hysteresis loops obtained with magneto-optic Kerr effect measurements and observed at both room and low temperatures. The magnetic pattern was visualized by magneto-optical imaging with an indicator film. Moreover, we investigated the onset of superconductivity through a measure of the superconducting energy gap. The latter is strictly related to the decay time of the excitation produced by an ultrashort laser pulse and has been determined in a pump-probe transient reflectivity experiment. A comparison of results relative to Co-doped Ba-122 thin films with and without Fe buffer layer is finally reported.

  11. Structural, Optical, and Magnetic Properties of Solution-Processed Co-Doped ZnS Thin Films

    Science.gov (United States)

    Goktas, A.; Mutlu, İ. H.

    2016-11-01

    Co-doped ZnS thin films have been grown on glass substrates using solution-processing and dip-coating techniques, and the impact of the Co doping level (0% to 5%) and film thickness on certain characteristics examined. X-ray diffraction study revealed that all the films possessed hexagonal crystal structure. Energy-dispersive x-ray analysis confirmed presence of Zn, Co, and S in the samples. Scanning electron microscopy showed that the film surface was homogeneous and dense with some cracks and spots. X-ray photoelectron spectroscopy confirmed introduction and integration of Co2+ ions into the ZnS thin films. Compared with undoped ZnS, optical studies indicated a reduction in optical bandgap energy ( E g) while the refractive index ( n), extinction coefficient ( k), and dielectric constants ( ɛ 1, ɛ 2) increased with film thickness ( t) and Co doping level (except for 5%). Photoluminescence spectra showed enhanced luminescence intensity as the Co concentration was increased, while the dependence on t showed an initial increase followed by a decrease. The origin of the observed low-temperature (5 K and 100 K) ferromagnetic order may be related to point defects such as zinc vacancies, zinc interstitials, and sulfide vacancies or to the grain-boundary effect.

  12. 铁、镧共掺杂纳米TiO2可见光催化性能研究%Study on the Visible Photocatalytic Performance of Fe and La Co-doped Nano-TiO2

    Institute of Scientific and Technical Information of China (English)

    郝丽萌; 傅敏; 陈盛明; 冉德超; 皮俊敏

    2012-01-01

    通过溶胶-凝胶( Sol-Gel)法制备了铁、镧共掺杂纳米TiO2,采用X线衍射仪(XRD)、X线光电子能谱(XPS)、紫外-可见分光光度计(UV-Vis)和荧光分光光度计(FL)等测试手段对样品进行表征.结果表明,500℃煅烧后的掺杂TiO2均呈锐钛矿型,平均粒径为φ6.1 nm,掺杂抑制了TiO2粒径的长大,掺杂的Fe3+、La3+能有效进入TiO2晶格.掺杂使TiO2的吸收带边红移且在可见光区的光吸收增强,样品的荧光强度越小,催化效果越好.可见光光催化降解甲基橙实验结果表明,可见光照射5h,最佳共掺杂的0.01% Fe/0.6%La-TiO2对甲基橙的降解率达40.7%.%The Fe and La co-doped nano-TiO2 has been prepared by Sol-Gel method. The sample was characterized by X-ray diffractometer(XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis)spectro-photometer and fluorescence spectrophotometer (FL). The results show that all the samples present the anatase structure and the average size of the nano-TiO2 is about 6. 1 nm after calcining at 500℃, the doping restrained the increase of grain size, the doped Fe3+ and La3+ can enter into effectively the TiO2 crystal lattice and make the absorption profile of TiO2 red-shift and increased the absorbance in visible light region. The less the fluorescence intensity of the sample was, the better the catalytic effect. The visible photocatalytic property of titania nanocrystal-line grains was evaluated by the methyl orange decomposition. The results show that the optimized Fe and La co-doped amount is approximately 0.01%Fe/0. 6%La-TiO2, The degradation rate is 40. 7% after a light exposure for 5 h.

  13. Osteoblast differentiation with titania and titania-silica-coated titanium fiber meshes.

    NARCIS (Netherlands)

    Meretoja, V.V.; Ruijter, A.E. de; Peltola, T.; Jansen, J.A.; Narhi, T.O.

    2005-01-01

    Two surface-reactive sol-gel coatings, namely titania (TiO2) and a mixture of titania and silica (TiSi), were applied to titanium fiber meshes. Differentiation of rat bone marrow stromal cells toward an osteogenic phenotype with coated and uncoated (cpTi) substrates was compared. The amount of DNA i

  14. Silica-titania composite aerogel photocatalysts by chemical liquid deposition of titania onto nanoporous silica scaffolds.

    Science.gov (United States)

    Zu, Guoqing; Shen, Jun; Wang, Wenqin; Zou, Liping; Lian, Ya; Zhang, Zhihua

    2015-03-11

    Silica-titania composite aerogels were synthesized by chemical liquid deposition of titania onto nanoporous silica scaffolds. This novel deposition process was based on chemisorption of partially hydrolyzed titanium alkoxides from solution onto silica nanoparticle surfaces and subsequent hydrolysis and condensation to afford titania nanoparticles on the silica surface. The titania is homogeneously distributed in the silica-titania composite aerogels, and the titania content can be effectively controlled by regulating the deposition cycles. The resultant composite aerogel with 15 deposition cycles possessed a high specific surface area (SSA) of 425 m(2)/g, a small particle size of 5-14 nm, and a large pore volume and pore size of 2.41 cm(3)/g and 18.1 nm, respectively, after heat treatment at 600 °C and showed high photocatalytic activity in the photodegradation of methylene blue under UV-light irradiation. Its photocatalytic activity highly depends on the deposition cycles and heat treatment. The combination of small particle size, high SSA, and enhanced crystallinity after heat treatment at 600 °C contributes to the excellent photocatalytic property of the silica-titania composite aerogel. The higher SSAs compared to those of the reported titania aerogels (aerogels promising candidates as photocatalysts.

  15. High energy milling of zirconia-titania powders synthesized by coprecipitation; Moagem de alta energia em pos de zirconia-titania sintetizados por co-precipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cristiano M.B.; Marchi, Juliana; Lazar, Dolores R.R.; Ussui, Valter, E-mail: vussui@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    Zirconia based ceramics are known by its remarkable mechanical properties as hardness and fracture toughness and in biomedical applications are classified as bioinert. By its turn, titania ceramics has been studied due to its ability to bond directly to bone tissue, but are structurally brittle. Properties of ceramics are strongly dependent of physical and chemical characteristics of its former powders. In the present work, research done for the synthesis of zirconia-titania ceramics by the coprecipitation route are presented, emphasizing the conditioning process through a high energy milling in a atritor mill, classifying of powders in vibratory sieves and forming of cylindrical ceramic samples followed by a sintering process at 1500 deg C for 01 hour. The intermediary samples produced in the various steps of the process were characterized by scanning electronic microscope, X-ray diffraction, nitrogen gas adsorption and granulometric analysis. (author)

  16. The influence of Pr3+ co-doping on the photoluminescence and cathodoluminescence properties of SiO2:Eu3+/Tb3+

    CSIR Research Space (South Africa)

    Mhlongo, GH

    2011-07-01

    Full Text Available Tb3+-Pr3+, and Eu3+-Pr3+ ion pairs co-doped in a SiO2 matrix were prepared by a sol-gel method. Co-doping of Eu3+ and Tb3+ ions with Pr3+ in SiO2 resulted in the quenching of Eu3+ and Tb3+ emissions with increasing Pr3+ concentrations. The quenching...

  17. Bactericidal performance of visible-light responsive titania photocatalyst with silver nanostructures.

    Directory of Open Access Journals (Sweden)

    Ming-Show Wong

    Full Text Available BACKGROUND: Titania dioxide (TiO(2 photocatalyst is primarily induced by ultraviolet light irradiation. Visible-light responsive anion-doped TiO(2 photocatalysts contain higher quantum efficiency under sunlight and can be used safely in indoor settings without exposing to biohazardous ultraviolet light. The antibacterial efficiency, however, remains to be further improved. METHODOLOGY/PRINCIPAL FINDINGS: Using thermal reduction method, here we synthesized silver-nanostructures coated TiO(2 thin films that contain a high visible-light responsive antibacterial property. Among our tested titania substrates including TiO(2, carbon-doped TiO(2 [TiO(2 (C] and nitrogen-doped TiO(2 [TiO(2 (N], TiO(2 (N showed the best performance after silver coating. The synergistic antibacterial effect results approximately 5 log reductions of surviving bacteria of Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus and Acinetobacter baumannii. Scanning electron microscope analysis indicated that crystalline silver formed unique wire-like nanostructures on TiO(2 (N substrates, while formed relatively straight and thicker rod-shaped precipitates on the other two titania materials. CONCLUSION/SIGNIFICANCE: Our results suggested that proper forms of silver on various titania materials could further influence the bactericidal property.

  18. Synthesis of Mesoporous Titania with Surfactant and its Characterization

    Directory of Open Access Journals (Sweden)

    T. Benkacem

    2008-01-01

    Full Text Available A mesoporous titania was obtained by gelation from Ti-alkoxide in acidic solutions with addition of surfactant cetyltrimetylammonium bromide (CH3(CH215N(CH33Br using a sol-gel process. The effects of surfactant concentration on synthesis of mesoporous titania were studied. The structural characterisation was studied by differential thermal analysis, infrared spectroscopy, X-ray diffraction. Studies by X-ray diffraction showed that crystallisation of TiO2 powder occurs at 200°C, above 200°C we obtained a mixture of two forms-Anatase and rutile. The textural characterisation by nitrogen adsorption-desorption allowed us to observe the variation of the surface area, porous volume and pore diameters according to temperature and [CTAB]/[Ti-alkoxide] molar ratio. The analysis of the results shows that addition of surfactant residue increases considerably its pore diameters. The deposit thin layers has been realized with a sol prepared with the destabilization of colloidal solutions process. Scanning electron-spectroscopy observation for thermally treated (at 400 and 600°C samples, showed homogeneous layers without cracking.

  19. Titania-supported silver-based bimetallic nanoparticles as photocatalysts.

    Science.gov (United States)

    Barakat, M A; Al-Hutailah, R I; Hashim, M H; Qayyum, E; Kuhn, J N

    2013-06-01

    Photocatalytic process has shown recently a great potential as an environmental friendly and clean remediation technology for organic pollutants in wastewater. This work described the synthesis of silver-based bimetallic nanoparticles using colloid chemistry and the subsequent immobilization onto titania to form composite photocatalytic materials (titania-supported Ag-Pt nanoparticles). The photocatalysts were characterized by X-ray diffraction, electron microscopy, and nitrogen physisorption. The catalytic activity of the photocatalysts was evaluated by photocatalytic degradation of phenol and 2-chlorophenol (2-CP) in synthetic wastewater solutions. The photocatalytic processes were conducted in a batch photoreactor containing appropriate solutions of phenol and 2-CP with UV irradiation of 450 W. UV-visible spectrophotometer was used for analyzing the concentration of phenol and 2-CP in solutions. Parameters affecting the photocatalytic process such as the solution pH, phenol and 2-CP concentrations, and catalyst concentration were investigated. The results obtained revealed that TiO(2)-supported Ag/Pt nanoparticles showed a higher activity for UV-photocatalytic degradation of both phenol and 2-CP pollutants in the solution (as compared to the plain rutile TiO(2)). The photodegradation processes were optimized by the 0.5-g/L catalyst with a pollutant concentration of 50 mg/L for all the samples. Complete degradation for both phenol and 2-CP was achieved after 120 min.

  20. Charge defects and highly enhanced multiferroic properties in Mn and Cu co-doped BiFeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guohua; Tan, Guoqiang, E-mail: tan3114@163.com; Luo, Yangyang; Liu, Wenlong; Xia, Ao; Ren, Huijun

    2014-06-01

    Pure BiFeO{sub 3} (BFO) and Mn, Cu co-doped BiFeO{sub 3} (BFMCO) thin films were deposited on fluorine doped tin oxide (FTO) substrates by a chemical solution deposition method. Detailed investigations were made on the effects of Mn and Cu co-doping on the crystal structure, the defect chemistry, multiferroic properties of the BFO thin films. With the co-doping of Mn and Cu, a structural transition from the rhombohedral (R3c:H) to the biphasic structure (R3c:H + P1) is confirmed by XRD, Rietveld refinement and Raman analysis. X-ray photoelectron spectroscopy (XPS) analysis shows that the coexistence of Fe{sup 2+}/Fe{sup 3+} and Mn{sup 2+}/Mn{sup 3+} ions in the co-doping films are demonstrated. Meanwhile, the way of the co-doping at B-sits is conducive to suppress Fe valence state of volatility and to decrease oxygen vacancies and leakage current. It's worth noting that the co-doping can induce the superior ferroelectric properties (a huge remanent polarization, 2P{sub r} ∼ 220 μC/cm{sup 2} and a relatively low coercive field, 2E{sub c} ∼ 614 kV/cm). The introduction of Mn{sup 2+} and Cu{sup 2+} ions optimizes the magnetic properties of BFO thin films by the biphasic structure and the destruction of spin cycloid.

  1. The spectroscopic properties of Dy{sup 3+} and Eu{sup 3+} co-doped ZnWO{sub 4} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yu; Xu, Jiayue, E-mail: xujiayue@sit.edu.cn; Zhang, Zhijie, E-mail: zjzhang@sit.edu.cn; You, Mingjiang

    2014-12-05

    Highlights: • Dy{sup 3+}/Eu{sup 3+} co-doped ZnWO{sub 4} phosphors were synthesized by a hydrothermal method. • A tunable emission color was realized by adjusting the doping concentrations of Eu{sup 3+}. • The photoluminescence process in the Dy{sup 3+}/Eu{sup 3+} co-doped ZnWO{sub 4} system was described. • The Dy{sup 3+}/Eu{sup 3+} co-doped ZnWO{sub 4} phosphors have potential application in W-LEDs. - Abstract: Dy{sup 3+} and Eu{sup 3+} co-doped ZnWO{sub 4} phosphors with different doping concentrations were synthesized by a hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectra. The results showed that the doping concentrations of Eu{sup 3+} could affect the blue and yellow emission intensities of Dy{sup 3+}, and tunable emission color could be obtained by adjusting the doping concentrations of Eu{sup 3+}. Based on the excitation/emission spectra of Dy{sup 3+}/Eu{sup 3+} co-doped ZnWO{sub 4} and the energy levels of Dy{sup 3+} and Eu{sup 3+}, the photoluminescence process in the Dy{sup 3+}/Eu{sup 3+} co-doped ZnWO{sub 4} system was discussed in detail.

  2. The synergetic effect of V and Fe-co-doping in TiO2 studied from the DFT + U first-principle calculation

    Science.gov (United States)

    Liu, Baoshun; Zhao, Xiujian

    2017-03-01

    Based on the density functional theory (DFT + U), a detailed study on the energetic, electronic, and optical properties of Fe-, V-, and Fe & V-co-doping anatase and rutile TiO2 was performed The synergetic effect of Fe & V bimetal co-doping on the optical absorption was discussed on electronic level. Two kinds of co-dopants were considered, which included edge-shared and corner-shared co-doping. It was shown that Fe and V atoms prefer to replace Ti atom in the O-rich contions than in the Ti-rich conditions. Co-doping in anatase reduces the formation energies in both cases, while the formation energies for rutile cannot be decreased. The Bader charge analysis indicates the +3 of Fe atom and +4 of V atom, and the obvious electron exchange between Fe and V atom in co-doping cases can be identified, which indicates the presence of synergetic effect induced by co-doping. The cooperation of Fe & V co-dopants was also supported by the result of projected density of states and spin charge density differences, as the hybridization of Fe3d with V3d orbitals was seen within the TiO2 forbidden band. Different from single-dopant systems, the V3d-Fe3d co-interaction leads to the formation of some spin mid-gap states, which have an obvious effect on the optical absorptions.

  3. 2 inch size Czochralski growth and scintillation properties of Li+ co-doped Ce:Gd3Ga3Al2O12

    Science.gov (United States)

    Kamada, Kei; Shoji, Yasuhiro; Kochurikhin, Vladimir V.; Yoshino, Masao; Okumura, Satoshi; Yamamoto, Seiichi; Yeom, Jung Yeol; Kurosawa, Shunsuke; Yokota, Yuui; Ohashi, Yuji; Nikl, Martin; Yoshino, Masao; Yoshikawa, Akira

    2017-03-01

    The 2 inch size Li 0.15 and 1.35 mol% co-doped Ce:Gd3Al2Ga3O12 single crystals were prepared by the Czochralski (Cz) method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Li co-doping. Ce4+ CT absorption below 350 nm is clearly enhanced by Li co-doping as same as divalent ions co-doping. By 1.35 at.% Li co-doping, light yield was decrease to 88% of the Ce: GAGG standard and decay time was accelerated to 34.3ns 21.0%, 84.6ns 68.7%, 480ns 10.3%. The timing resolution measurement for a pair of 3 × 3 × 3mm3 size Li,Ce:GAGG scintillator crystals was performed using Si-PMs and the timing resolution of the 1.35 at.% Li co-doped Ce:GAGG was 218ps.

  4. Synthesis and Catalytic Applications of Non-Metal Doped Mesoporous Titania

    Directory of Open Access Journals (Sweden)

    Syed Z. Islam

    2017-03-01

    Full Text Available Mesoporous titania (mp-TiO2 has drawn tremendous attention for a diverse set of applications due to its high surface area, interfacial structure, and tunable combination of pore size, pore orientation, wall thickness, and pore connectivity. Its pore structure facilitates rapid diffusion of reactants and charge carriers to the photocatalytically active interface of TiO2. However, because the large band gap of TiO2 limits its ability to utilize visible light, non-metal doping has been extensively studied to tune the energy levels of TiO2. While first-principles calculations support the efficacy of this approach, it is challenging to efficiently introduce active non-metal dopants into the lattice of TiO2. This review surveys recent advances in the preparation of mp-TiO2 and their doping with non-metal atoms. Different doping strategies and dopant sources are discussed. Further, co-doping with combinations of non-metal dopants are discussed as strategies to reduce the band gap, improve photogenerated charge separation, and enhance visible light absorption. The improvements resulting from each doping strategy are discussed in light of potential changes in mesoporous architecture, dopant composition and chemical state, extent of band gap reduction, and improvement in photocatalytic activities. Finally, potential applications of non-metal-doped mp-TiO2 are explored in water splitting, CO2 reduction, and environmental remediation with visible light.

  5. 氮掺杂TiO_2纳米管/高岭土复合光催化剂的制备及光催化性能%Preparation and Photocatalytic Properties of Nitrogen-doped Titania Nanotubes/Kaolin Composite Photocatalysts

    Institute of Scientific and Technical Information of China (English)

    丁海辉; 王倩; 纪美茹; 赵谦; 姜廷顺

    2011-01-01

    以P25纳米TiO2为原料、尿素为氮源,通过水热法合成氮掺杂TiO2纳米管;同时以高岭土为载体,采用浸渍法制备氮掺杂TiO2纳米管/高岭土复合光催化剂。采用X射线粉末衍射、Fourier变换红外光谱、紫外-可见光谱和透射电子显微镜等表征样品的结构与形貌,并以甲基橙为模型化合物研究复合材料的光催化性能。结果表明:制备了锐钛矿和金红石混晶型的氮掺杂TiO2纳米管/高岭土复合光催化剂;在300W的中压汞灯照射60min后,复合光催化剂对甲基橙的降解率高达90.2%;样品的吸光带红移至可见光区,表明氮掺杂TiO2纳米管/高岭土复合光催化剂有望成为可见光催化剂。%Nitrogen-doped titania nanotubes(N-TNTs) were prepared by hydrothermal method using P25 as raw materials and urea as a nitrogen source.The N-TNTs/kaolin composite photocatalysts were prepared by impregnation method.Structure and morphology of resulting samples were characterized by X-ray diffraction,Fourier transform infrared spectroscopy,ultraviolet–visible spectropho-tometry,and transmission electron microscopy.Photocatalytic properties of the composite materials were tested using methyl orange as a model compound.Results show that the N-TNT/kaolin composite photocatalyst is anatase mixed with rutile.After irradiation for 60 min under a 300 W middle-pressure mercury lamp,degradation rate of methyl orange solution using N-TNT/kaolin as a catalyst can reach 90.2%.The N-TNT/kaolin sample has an evident adsorption peak in the visible range.This suggests that the N-TNT/kaolin is a promising photocatalytic material for organic pollutant degradation under the visible light.

  6. Visible-Light Degradation of Dyes and Phenols over Mesoporous Titania Prepared by Using Anthocyanin from Red Radish as Template

    Directory of Open Access Journals (Sweden)

    Zhiying Yan

    2014-01-01

    Full Text Available Heterogeneous photocatalysis is able to operate effectively to eliminate organic compounds from wastewater in the presence of semiconductor photocatalyst and a light source. Although photosensitization of titania by organic dyes is one of the conventional ways for visible-light utilization of titania, previous studies have not yet addressed the use of natural food coloring agents as templates in the synthesis of mesostructured materials, let alone the simultaneous achievement of highly crystalline mesoscopic framework and visible-light photocatalytic activity. In this work, anthocyanin, a natural pigment from red radish was directly used as template in synthesis of highly crystalline mesoporous titania. The synthesized mesoporous titania samples were characterized by a combination of various physicochemical techniques, such as XRD, SEM, HRTEM, nitrogen adsorption/desorption, and diffuse reflectance UV-Vis. The prepared mesoporous titania photocatalyst exhibited significant activity under visible-light irradiation for the degradation of dyes and phenols due to its red shift of band-gap-absorption onset and visible-light response as a result of the incorporation of surface carbon species.

  7. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yibing, E-mail: ybxie@seu.edu.cn; Zhao, Ye

    2013-12-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO{sub 2}) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity.

  8. Effects of Co doping on the metamagnetic states of the ferromagnetic fcc Fe-Co alloy.

    Science.gov (United States)

    Ortiz-Chi, Filiberto; Aguayo, Aarón; de Coss, Romeo

    2013-01-16

    The evolution of the metamagnetic states in the ferromagnetic face centered cubic (fcc) Fe(1-x)Co(x) alloy as a function of Co concentration has been studied by means of first-principles calculations. The ground state properties were obtained using the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The alloying was modeled using the virtual crystal approximation and the magnetic states were obtained from the calculations of the total energy as a function of the spin moment, using the fixed spin moment method. For ferromagnetic fcc Fe, the binding-energy curve shows metamagnetic behavior, with two minima corresponding to a small-volume, low-spin (LS) state and a large-volume, high-spin (HS) state, which are separated by a small energy (E(LS) ≲ E(HS)). The evolution of the magnetic moment, the exchange integral (J), and the binding-energy curve is analyzed in the whole range of Co concentrations (x). The magnetic moment corresponding to the HS state decreases monotonically from 2.6 μ(B)/atom in fcc Fe to 1.7 μ(B)/atom in fcc Co. In contrast, the exchange integral for the HS state shows a maximum at around x = 0.45. The thermal dependence of the lattice parameter is evaluated with a method based on statistical mechanics using the binding-energy curve as an effective potential. It is observed that the behavior of the lattice parameter with temperature is tuned by Co doping, from negative thermal expansion in fcc Fe to positive thermal expansion in fcc Co, through the modification of the energetics of the metamagnetic states.

  9. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V. [L.V. Kirensky Institute of Physics SB RAS, 660036 Krasnoyarsk (Russian Federation); Zubavichus, Y.; Veligzhanin, A. [NRC ' Kurchatov Institute,' 123182 Moscow (Russian Federation); Zaikovskiy, V. [Boreskov Institute of Catalysis, Siberian Branch of RAS, 630090 Novosibirsk (Russian Federation); Stepanov, S. [S.I. Vavilov State Optical Institute, St. Petersburg (Russian Federation); Artemenko, A. [ICMCB, UPR CNRS 9048, 33608 Pessac cedex (France); Curely, J.; Kliava, J. [LOMA, UMR 5798 Universite Bordeaux 1-CNRS, 33405 Talence cedex (France)

    2012-10-15

    A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD spectra are related to different electron transitions in Fe{sup 3+} ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by 'direct' techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the

  10. N,S-co-doped TiO2 nanophotocatalyst: synthesis, electronic structure and photocatalysis.

    Science.gov (United States)

    Sathish, M; Viswanath, R P; Gopinath, Chinnakonda S

    2009-01-01

    N,S-co-doped anatase-phase TiO2 (N,S-TiO2) nanophotocatalysts were prepared from either benzothiazoline or aminothiol with titanium isopropoxide followed by a systematic thermal decomposition. The chemical nature of S and N in N,S-TiO2 have been identified by XPS to be sulfate and NO-like, respectively. A significant band broadening and red-shift in the UV-visible absorption spectrum of N,S-TiO2 suggests a band gap reduction compared to TiO2. A maximum band-gap narrowing of 0.22 +/- 0.02 eV was observed on N,S-TiO2. Higher energy width observed on N,S-TiO, is in contrast to 0.13 eV from N-doped TiO2 indicating the sulfate-like species might play a major role in narrowing the band-gap to a higher level. It is confirmed that the oxidation of N and S to NO and SO4(2-) occurs in the final stage of preparation of N,S-TiO2, during calcination in air. It is predicted that the oxygen associated with sulfate and NO structural features could be crucial in bringing down the energy gap and red shift in optical absorption and the role of sulfur is to facilitate the above. Photocatalytic decomposition of methylene blue has been carried out on N,S-TiO2 shows higher activity than the commercial TiO2 in the visible region. However, sulfate species seems to enhance the activity of N,S-TiO2 marginally compared to N-TiO2, and possible suggestions are given to improve the same.

  11. Novel tannin-based Si, P co-doped carbon for supercapacitor applications

    Science.gov (United States)

    Ramasahayam, Sunil Kumar; Nasini, Udaya B.; Shaikh, Ali U.; Viswanathan, Tito

    2015-02-01

    Increasing environmental pollution and population compounded by a decrease in the availability of non-renewable resources and fossil fuels has propelled the need for sustainable alternate energy storage technologies particularly in the last two decades. An attempt to meet this crisis was carried out by a unique, microwave-assisted method which has enabled the generation of a novel Si, P co-doped carbon (SiPDC) for supercapacitor applications. The microwave-assisted method is useful in developing SiPDC at a rapid and economical fashion that does not employ any inert or reducing gases, but is high yielding. Varying proportions of precursor materials were utilized to generate four SiPDCs (SiPDC-1, SiPDC-2, SiPDC-3 and SiPDC-4) with varying contents of dopants as evidenced by X-ray photoelectron spectroscopic (XPS) results. Surface area and pore size analysis revealed that SiPDC-2 has a surface area of 641.51 m2 g-1, abundant micropores, mesopores and macropores which are critical for electrical double layer capacitance (EDLC). Of all the SiPDCs, SiPDC-2 exhibited highest capacitance of 276 F g-1 in 1 M H2SO4 and 244 F g-1 in 6 M KOH at a scan rate of 5 mV s-1. Galvanostatic charge-discharge studies performed in 6 M KOH establish the high capacitance of SiPDC-2. SiPDC-2 also exhibited excellent electrochemical stability in 1 M H2SO4 and 6 M KOH.

  12. Energy transfer and luminescence studies of Pr 3+ , Yb 3+ co-doped lead borate glass

    Science.gov (United States)

    Wen, Hongli; Tanner, Peter A.

    2011-09-01

    Lead borate glass samples doped with the tripositive lanthanide ions Pr 3+ and Yb 3+ were synthesized by the conventional melting-quenching method. The luminescence properties and energy transfer process from Pr 3+ to Yb 3+ were investigated. Upon ultraviolet excitation, the room temperature luminescence decay curve of a sample containing only a low concentration of Pr 3+ exhibited monoexponential decay from 1D 2 with the lifetime 37 μs, without emission from 3P 0. The room temperature Pr 3+ emission intensity decreased with the increase of Yb 3+ mole ratio in the glass. Under the excitation of 454.5 nm at 10 K, a broad red emission band centered at 605 nm, and an NIR emission band at 995 nm were observed in the co-doped lead borate glass, originating from Pr 3+ and Yb 3+ ions, respectively. The decay curves of the 1D 2 emission from Pr 3+ with addition of Yb 3+ in lead borate glass show non-monoexponential character, and are best described by a stretched exponential function. The average 1D 2 decay time decreases considerably with the addition of Yb 3+ in the glass. Decay curve fitting using a modified Inokuti-Hirayama expression indicates dipole-dipole energy transfer from Pr 3+ to Yb 3+, which is consistent with the expected cross-relaxation scheme. There is a good agreement of the estimated overall energy transfer efficiency obtained from the integrals under the normalized decay curves, or from the lifetimes fitted by the stretched exponential function, or from the average decay times.

  13. H2 evolution on Lanthanum and Carbon co-doped NaTaO3 Photocatalyst

    Directory of Open Access Journals (Sweden)

    Husni Husin

    2014-07-01

    Full Text Available We report a carbon-modify lanthanum doped sodium tantalum oxide powders (La-C-NaTaO3 by sol-gel process. The resultant materials are characterized by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The X ray diffraction of La-C-NaTaO3 show a single phases with a good crystallinity and without any impurity. The samples is exactly indexed as NaTaO3 monoclinic structure with the space group P2/m. The SEM measurements give a smaller particle size of doped NaTaO3 than pure NaTaO3. The effect of dopant on the photocatalytic activity of La-C-NaTaO3 in the photocatalytic of hydrogen generation is studied and compared with pure NaTaO3. The results show that the rate of hydrogen evolution over La-C-NaTaO3 is higher as compared to that of pure NaTaO3. The enhancement of photocatalytic activity of La-C-NaTaO3 nanocrystalline is mainly due to their capability for reducing the electron hole pair recombination. The La-C-dopant is believed to play a key role in the enhancement of photocatalytic properties of La-C-NaTaO3 crystalline.Submitted: 28th September 2013; Revised: 16th February 2014; Accepted: 28th February 2014[How to Cite: Husin, H., Mahidin, M., Zuhra, Z., Hafita, F. (2014. H2 evolution on Lanthanum and Carbon co-doped NaTaO3 Photocatalyst . Bulletin of Chemical Reaction Engineering & Catalysis, 9 (2:81-86. (doi:10.9767/bcrec.9.2.5530.81-86][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.2.5530.81-86] 

  14. 室内装饰品负载氮掺杂氧化钛的光催化性能%Photocatalytic performance of nitrogen-doped titania coated on room decorations

    Institute of Scientific and Technical Information of China (English)

    王泽清; 郭薇; 辛钢; 吴丽琼; 马廷丽

    2011-01-01

    采用钛醇盐水解法与溶胶凝胶法,以氨水、尿素、三乙胺为氮源,制备了纳米TiO2-xNx光催化剂.为了在净化室内空气的同时能够装饰环境,提出了喷涂和浸泡2种工艺将光催化剂负载于室内装饰品,并在模拟太阳光的照射下对室内污染物甲醛进行降解.XRD、UV-Vis光谱及XPS分析结果表明,在烧结温度为400℃时得到的3种TiO 2-xNx是锐钛矿相,其中以尿素为氮源的TiO2-xNx温度达到600℃时开始发生相转变,3种TiO2xNx在可见光区域的400~550 nm均出现新的吸收;以氨水、尿素和三乙胺为氮源制备的TiO2xNx的掺氮量分别为2.77%、0.29%和0.47%.以氨水为氮源制备的光催化剂,14 h降解甲醛的效率达到了95%;以三乙胺为氮源制备的光催化剂7 h降解甲醛的效率达到了96%.因此,应用喷涂法在室内装饰品上负载光催化剂降解室内污染物具有很好的应用前景.%Nanocrystalline TiO2-xNx photocatalysts were prepared by hydrolysis of titanium alkoxide and sol-gel method using aqueous ammonia, urea and triethylamine as nitrogen sources, respectively. The photocatalytic activity of TiO2-xNx coated on the ornamental flowers by spray-coating and dipping methods was evaluated through a study of the decomposition of formaldehyde under simulated solar light. The obtained photocatalysts were characterized by X-ray diffraction, UV-Vis spectrum and X-ray photoelectron spectrum. The results show that three kinds of TiO2-xNx are mainly anatase phase after calcinations at 400℃. The TiO2-xNx prepared with urea was calcined under 600℃, the phase transformation was observed. Moreover, TiO2-xNx showed a new absorption from 400 to 550 nm in the visible light region. The XPS results show that the nitrogen content of TiO2-xNx using ammonia, urea and triethylamine as nitrogen sources was 2. 77% , 0. 29% and 0.47% , respectively.The degradation rate of formaldehyde reached 96% and 95% for the photocatalysts

  15. 氮掺杂TiO2纳米管电极制备及可见光电催化活性%Fabrication of nitrogen - doped titania nanotube - like arrays electrode and its photoelectrocatalytic activity under visible light

    Institute of Scientific and Technical Information of China (English)

    鲁娜; 赵慧敏; 全燮; 于洪涛; 陈硕

    2008-01-01

    采用氮气中500℃和600℃热处理由阳极氧化法制备的TiO2纳米管阵列,制备了氮掺杂TiO2纳米管阵列电极.分别用环境扫描电镜(ESEM)、X射线光电子能谱(XPS),X射线衍射(XRD)和紫外可见漫反射吸收光谱对电极进行了表征.结果表明氮成功地掺入TiO2纳米管中.氮的引入使所制备的电极表现出可见光电催化活性,其中氮气中500℃下热处理得到的TiO2纳米管阵列电极表现出最好的可见光电催化活性.%Nitrogen -doped TiO2 nanotube -like arrays electrodes were prepared by anodic oxidation andthen followed by being treated in N2 flow at 500 and 600℃. The samples were characterized by environ-mental scanning electron microscope (ESEM), X - ray diffraction (XRD), X - ray photoelectron spec-trum (XPS) and UV - vis spectrum. The results showed successful incorporation of nitrogen into the TiO2nanotube. Enhanced photoelectrocatalytic activity in visible light region was observed owing to nitrogendoping. By comparison, the sample being treated in N2 flow at 500℃ exhibited the best photoelectrocata-lyric activity.

  16. Synthesis of Nitrogen and Sulfur Co-doped Carbon Dots from Garlic for Selective Detection of Fe3+

    Science.gov (United States)

    Sun, Chun; Zhang, Yu; Wang, Peng; Yang, Yue; Wang, Yu; Xu, Jian; Wang, Yiding; Yu, William W.

    2016-02-01

    Garlic was used as a green source to synthesize carbon dots (CDs) with a systematic study of the optical and structure properties. Ethylenediamine was added into the synthesis to improve the photoluminescence quantum yield (PL QY) of the CDs. Detailed structural and composition studies demonstrated that the content of N and the formation of C-N and C=N were critical to improve the PL QY. The as-synthesized CDs exhibited excellent stability in a wide pH range and high NaCl concentrations, rendering them applicable in complicated and harsh conditions. Quenching the fluorescence of the CDs in the presence of Fe3+ ion made these CDs a luminescent probe for selective detection of Fe3+ ion.

  17. Amorphous Si layers co-doped with B and Mn: Thin film growth and steering of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Drera, G. [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy); Mozzati, M.C. [CNISM, Dipartimento di Fisica, Università di Pavia, Via Bassi 6, 27100 Pavia (Italy); Colombi, P. [CSMT Gestione s.c.a.r.l, Via Branze 45, 25123 Brescia (Italy); Salvinelli, G.; Pagliara, S.; Visentin, D. [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy); Sangaletti, L., E-mail: sangalet@dmf.unicatt.it [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy)

    2015-09-01

    Amorphous silicon thin films co-doped with manganese (5% at.) and boron (1.8% at.) have been prepared by RF sputtering on Al{sub 2}O{sub 3} substrates held at room temperature (RT). The films, with an average thickness of about 0.9 μm, were carefully characterized by micro-Raman and X-ray photoemission spectroscopies. A ferromagnetic (FM) behavior up to RT was observed. In order to discuss and possibly rule out extrinsic effects usually related to segregations of ferromagnetic impurities in the samples, magnetization measurements were carried out on the Al{sub 2}O{sub 3} substrates, as well as on Si:B and Si:Mn films grown with the same RF sputtering system. Only the Si:B:Mn films displayed a FM behavior up to RT. Since amorphous films doped with Mn alone did not display any signature of FM ordering, boron co-doping results to be crucial for the onset of the FM behavior. The conductivity of the samples is not affected by boron doping that, therefore, does not appear to significantly contribute to a possible carrier-mediated FM interaction between Mn ions by supplying extra charges to the system. On this basis, the capability of B to hinder the quenching of the Mn 3d magnetic moments has also to be regarded as a possible role of this co-dopant in the observed magnetization. - Highlights: • We successfully deposited amorphous silicon thin films co-doped with Mn and B. • Structural, electronic, and magnetic properties have been carefully characterized. • A ferromagnetic behavior up to room temperature was detected. • The extrinsic origin of magnetism is excluded. • Boron can play a relevant role to avoid quenching of magnetic moment in Mn ions.

  18. Photocatalytic performance of magnetically separable Fe, N co-doped TiO{sub 2}-cobalt ferrite nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Gaikwad, P.N. [Department of Chemistry, Shivaji University, Kolhapur 416004 (India); Hankare, P.P., E-mail: p_hankarep@rediffmail.com [Department of Chemistry, Shivaji University, Kolhapur 416004 (India); Wandre, T.M.; Garadkar, K.M. [Department of Chemistry, Shivaji University, Kolhapur 416004 (India); Sasikala, R., E-mail: sasikala@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2016-03-15

    Graphical abstract: - Highlights: • FeN-TiO{sub 2}-cobalt ferrite shows enhanced photocatalytic activity compared to TiO{sub 2}. • Increased visible light absorption is observed for the composite catalyst. • Fe, N doped TiO{sub 2} exists as a dispersed phase on cobalt ferrite. • The composite catalyst is stable for prolonged use and magnetically separable. - Abstract: Photocatalytic activity of a magnetically separable cobalt ferrite (CoFe{sub 2}O{sub 4}, CF) coupled with Fe and N co-doped TiO{sub 2} nanocomposite was investigated for the degradation of methyl orange. TiO{sub 2} and Fe, N co-doped TiO{sub 2} existed as anatase phase of TiO{sub 2}. The presence of both anatase TiO{sub 2} and CF was indicated in the XRD pattern. The UV–visible spectra of all samples showed absorption in the visible region. The photocatalytic activity of these samples was examined in both UV and visible light. TiO{sub 2} co-doped with Fe and N exhibited the highest activity. Though the photocatalytic activity of the composite was slightly less than that of doped TiO{sub 2}, it showed improved activity compared to TiO{sub 2}. Besides, the composite has an added advantage that it is magnetically separable from the solution, which is a desired property for industrial applications. The increased photocatalytic activity is attributed to the increased optical absorption property compared to single phase TiO{sub 2}.

  19. Lanthanide–lanthanide and lanthanide–defect interactions in co-doped ceria revealed by luminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Avram, Daniel; Gheorghe, Cristina [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, RO 76900 Bucharest-Magurele (Romania); Rotaru, Codruta; Cojocaru, Bogdan; Florea, Mihaela; Parvulescu, Vasile [University of Bucharest, Department of Chemical Technology and Catalysis, 4–12 Regina Elisabeta Bvd., Bucharest (Romania); Tiseanu, Carmen, E-mail: tiseanuc@yahoo.com [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, RO 76900 Bucharest-Magurele (Romania)

    2014-12-15

    Highlights: • (Sm, Nd) and (Sm, Eu) co-doped CeO{sub 2} are investigated by luminescence spectroscopy. • Local structure at Sm sites is not changed by Nd or Eu co-dopant. • Sm is not involved in non-radiative energy transfer to Nd or Eu co-dopant. • The excitation mode of perturbed Eu centre is modified by Sm co-dopant. - Abstract: Here, we present a first study on the local structure properties, lanthanide–lanthanide and lanthanide–defect interactions in lanthanide (Sm{sup 3+}/Nd{sup 3+} and Sm{sup 3+}/Eu{sup 3+}) co-doped CeO{sub 2} nanoparticles by use of luminescence spectroscopy. By comparing the emission/excitation spectra and decays measured with the single doped and co-doped ceria, it is established that the local structure at Sm{sup 3+} sites is not affected by the presence of the Nd{sup 3+} or Eu{sup 3+} co-dopant irrespective of concentration. The results suggest that the excess of oxygen vacancies generated by the co-dopant is not associated with Sm{sup 3+}, being more probably associated with the Nd{sup 3+}/Eu{sup 3+} or/and Ce{sup 4+} cations. It is also observed that Sm{sup 3+} is not involved in significant non-radiative energy transfer to Nd{sup 3+} or Eu{sup 3+} while the relative strong shortening of Nd{sup 3+} luminescence decay with concentration is most probably related to cross-relaxation in Nd{sup 3+}–Nd{sup 3+} pairs.

  20. Luminescent properties of Ce3+/Tb3+co-doped glass ceramics containing YPO4 nanocrystals for W-LEDs

    Institute of Scientific and Technical Information of China (English)

    张志雄; 张约品; 冯治刚; 王成; 夏海平; 张新民

    2016-01-01

    Ce3+/Tb3+ co-doped transparent glass ceramics containing YPO4 nanocrystals were prepared using high temperature melt-ing method, and their structural and luminous properties were investigated. XRD analysis and TEM images confirmed the existence of YPO4 nanocrystals in glass ceramics. The transmission spectra proved that the glass ceramics specimens still maintained a high transparency. Then the excitation and emission spectra of the Ce3+ and Tb3+ single-doped and co-doped glass and glass ceramics were discussed, which proved that the glass ceramics had better luminescent properties. Under the near ultraviolet (331 nm) excitation, the broadband emission located at 385 nm was observed which was ascribed to 5d→2F5/2 and2F7/2 transition of Ce3+ ions. Several char-acteristic sharp peaks centered at 489, 543, 578 and 620 nm originated from the5D4 to7FJ (J=6, 5, 4, 3) of Tb3+ ions. The decay time of Tb3+ ions at 543 nm and the relevant energy levels of Ce3+ ions and Tb3+ ions illustrated the transfer process from Ce3+ ions to Tb3+ ions. The best CIE chromaticity coordinate of the glass ceramics specimen was calculated as (x=0.3201,y=0.3749), which was close to the NTSC standard values for white (x=0.333,y=0.333). All the results suggested that the YPO4-based Ce3+/Tb3+ co-doped glass ceramics could act as potential luminescent materials for white light-emitting diodes.

  1. Investigation on Er{sup 3+}/Ho{sup 3+} co-doped silicate glass for ~2 µm fiber lasers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xueqiang; Huang, Feifei; Cheng, Jimeng; Fan, Xiaokang; Gao, Song [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Science, Beijing 100039 (China); Zhang, Junjie [College of Materials Science and Technology, China Jiliang University, Hangzhou 310018 (China); Hu, Lili [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Chen, Danping, E-mail: dpchen2008@aliyun.com [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2015-06-15

    A stable Er{sup 3+}/Ho{sup 3+} co-doped lead silicate glass is developed. Luminescent properties are recorded under pumping with 808 and 1550 nm lasers. Energy-transfer mechanism and efficiency are analyzed. Energy-transfer efficiency from Er{sup 3+}:{sup 4}I{sub 13/2} to Ho{sup 3+}:{sup 5}I{sub 7} reaches 93.8% at 3 mol% Ho{sub 2}O{sub 3} doping concentration. Strong luminescence is detected when pumped at 1550 nm because of efficient energy transfer from Er{sup 3+}:{sup 4}I{sub 13/2} to Ho{sup 3+}:{sup 5}I{sub 7}. Peak gain coefficient at 2056 nm is detected as 1.62 cm{sup −1}. The excellent luminescent property and high stability indicate that Er{sup 3+}/Ho{sup 3+} co-doped lead silicate glass can be applied in 2 µm fiber lasers. - Highlights: • Er{sup 3+}/Ho{sup 3+} co-doped silicate glasses with high stability are prepared. • Strong luminescence is detected under pump of 1550 nm lasers owing to efficient energy transfer from Er{sup 3+} to Ho{sup 3+}. • Transfer efficiency is calculated to be 93.8% when Ho{sub 2}O{sub 3} doping concentration is up to 3 mol%. • Gain coefficient peaks at 2056 nm to be 1.62 cm{sup −1}.

  2. Investigation of Pt-Dy co-doping effects on isothermal oxidation behavior of (Co,Ni)-based alloy

    Institute of Scientific and Technical Information of China (English)

    LAN Hao; ZHANG Weigang; YANG Zhigang

    2012-01-01

    A Co32Ni21Cr8A10.6Y (wt.%) alloy with and without doping 3 wt.% platinum,or co-doping 3 wt.% platinum and 0.1 wt.% dysprosium was produced by arc melting.The hardness of both base alloy and composition-modified alloy was measured by using a Vickers hardness tester.Isothermal oxidation tests at 1000 ℃ in static air atmosphere were conducted to assess the isothermal oxidation behavior of the alloys.The microstructure and composition of the tested alloys before and after oxidation were investigated by means of X-ray diffraction (XRD),field emission-scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and back scatter detector.Results showed that platinum had significant influence on microstructure of the tested alloy by the formation of β-(Ni,Pt)Al phase.Addition of 3 wt.% platinum could slightly increase the hardness of the tested alloy.Platinum accelerated phase transformation of alumina from metastable θ-Al2O3 to stable α-Al2O3 and suppressed the consumption of β-phase.Co-doping both 3 wt.% platinum and 0.1 wt.% dysprosium induced the fastest transformation of θ- to α- alumina and the formation of a fine-grained oxide scales.The most effective reduction of oxidation rate was achieved by the Pt-Dy co-doping effects.

  3. Spectroscopic investigation of an intrinsic room temperature ferromagnetism in Co doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    N, Srinatha [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India); Angadi, Basavaraj, E-mail: brangadi@gmail.com [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India); Nair, K.G.M. [UGC-DAE-CSR, Kalpakkam Node, Kalpakkam, Kokilamedu 603 102 (India); Deshpande, Nishad G.; Shao, Y.C.; Pong, Way-Faung [Department of Physics, Tamkang University, Tamsui, Taipei 251, Taiwan (China)

    2014-08-15

    Highlights: • For the first time L-Valine was used as a fuel to synthesize Co:ZnO nanoparticles by solution combustion method. • Single phase and ferromagnetic nature were confirmed through XRD, SQUID, NEXAFS and XMCD. • Through NEXAFS and XMCD, the effect of ‘Co’ substitution at O K-edge, Co L{sub 3,2} edge, Zn L{sub 3,2} edge have been investigated. • Spectral features of NEXAFS and XMCD confirms an intrinsic RTFM by substitution of ‘Co{sup 2+}’ at ‘Zn{sup 2+}’ site and rules out the presence of secondary phases. - Abstract: Pure and Co substituted ZnO nano crystalline particles were prepared by solution combustion technique using L-Valine as a fuel. As synthesized powder samples were characterized by X-ray diffractometer and SQUID magnetometer to confirm the formation of single phase wurtzite structure and to study the bulk magnetic response of the sample, respectively. Magnetic studies show that Co doped ZnO nanoparticles exhibit ferromagnetism (FM) at room temperature (RT). Furthermore, the electronic structure and element specific magnetic properties were investigated by near-edge X-ray absorption fine structure (NEXAFS) and X-ray magnetic circular dichroism (XMCD) measurements, respectively. The effect of Co substitution on the spectral features of Co–ZnO at O K-edge, Co L{sub 3,2} edge, Zn L{sub 3,2} edge have been investigated. The spectral features of NEXAFS at Co L{sub 3,2} edge is entirely different from the spectral features of metallic clusters and other impurity phases, which rules out the presence of impurity phases. The valence state of ‘Co’ ion is found to be in +2 state. The FM nature of the sample was confirmed through XMCD spectra, which is due to the incorporation of divalent ‘Co’ ions. Hence the presented results confirm the substitution of ‘Co’ ions at ‘Zn’ site in the host lattice, which is responsible for the RTFM.

  4. The microstructure of erbium-ytterbium co-doped oxyfluoride glass-ceramic optical fibers

    Science.gov (United States)

    Augustyn, Elżbieta; Żelechower, Michał; Stróż, Danuta; Chrapoński, Jacek

    2012-04-01

    Oxyfluoride transparent glass-ceramics combine some features of glasses (easier shaping or lower than single crystals cost of fabrication) and some advantages of rare-earth doped single crystals (narrow absorption/emission lines and longer lifetimes of luminescent levels). Since the material seems to be promising candidate for efficient fiber amplifiers, the manufacturing as well as structural and optical examination of the oxyfluoride glass-ceramic fibers doped with rare-earth ions seems to be a serious challenge. In the first stage oxyfluoride glasses of the following compositions 48SiO2-11Al2O3-7Na2CO3-10CaO-10PbO-11PbF2-3ErF3 and 48SiO2-11Al2O3-7Na2CO3-10CaO-10PbO-10PbF2-3YbF3-1ErF3 (in molar%) were fabricated from high purity commercial chemicals (Sigma-Aldrich). The fabricated glass preforms were drawn into glass fibers using the mini-tower. Finally, the transparent Er3+ doped and Er3+/Yb3+ co-doped oxyfluoride glass-ceramic fibers were obtained by controlled heat treatment of glass fibers. The preceding differential thermal analysis (DTA) studies allowed estimating both the fiber drawing temperature and the controlled crystallization temperature of glass fibers. X-ray diffraction examination (XRD) at each stage of the glass-ceramic fibers fabrication confirmed the undesirable crystallization of preforms and glass fibers has been avoided. The fibers shown their mixed amorphous-crystalline microstructure with nano-crystals of size even below 10 nm distributed in the glassy host. The crystal structure of the grown nano-crystals has been determined by XRD and confirmed by electron diffraction (SAED). Results obtained by both techniques seem to be compatible: Er3FO10Si3 (monoclinic; ICSD 92512), Pb5Al3F19 (triclinic; ICSD 91325) and Er4F2O11Si3 (triclinic; ICSD 51510) against to initially expected PbF2 crystals.

  5. Photocatalytic enhancement of TiO{sub 2} by B and Zr co-doping and modulation of microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Chengxin; Gong, Yinyan, E-mail: ygong2007@gmail.com; Wu, Yitao; Liu, Jiaqi; Zhang, Zhen; Li, Can; Niu, Lengyuan, E-mail: niulengyuan@163.com

    2016-08-30

    Graphical abstract: B and Zr codoped sample was prepared by a sol–gel method, which exhibits the best photocatalytic performance on degradation of methylene blue solution under a simulated solar light source in comparison with undoped and singly doped TiO{sub 2} nanocrystals. The enhancement was tentatively attributed to: (1) The incorporation of interstitial boron dopants creates oxygen vacancies (Ov··) and reduce Ti{sup 4+} to Ti{sup 3+} to form [Ov··-Ti{sup 3+}]{sup +}, which traps the carriers and prolongs carrier lifetime; (2) Zr{sup 4+} ions replace Ti{sup 4+} ions and form impurity levels, which could improve visible light response, and (3) reduction of average crystallite size. - Highlights: • B and Zr co-doping can effectively improve the visible-light photocatalytic activity of TiO{sub 2} by more than twice. • XRD, Raman, and XPS measurements demonstrated that all the samples are anatase phase of TiO{sub 2} and Zr{sup 4+} ions replace the Ti{sup 4+} ions while the B{sup 3+} ions occupy the interstitial sites. • The incorporation of interstitial boron dopants creates oxygen vacancies (Ov··) and reduce Ti{sup 4+} to Ti{sup 3+} to form [Ov··-Ti{sup 3+}]{sup +}, which traps the carriers and prolongs carrier lifetime. • Zr{sup 4+} ions replace Ti{sup 4+} ions and form impurity levels, which could improve visible light response. • The co-doped samples are benefited from both B interstitials and Zr substitutes. - Abstract: Visible-light photodegradation test revealed that B and Zr co-doping can raise the photocatalytic ability of the undoped TiO{sub 2} by a fold. XRD crystallography and Raman phonon spectroscopy measurements suggest that the Zr{sup 4+} ions replace the Ti{sup 4+} ions while the B{sup 3+} ions occupy the interstitial sites, expanding the unit-cell volume and reducing crystallite size. The incorporation of interstitial boron dopants creates oxygen vacancies (Ov··) and reduce Ti{sup 4+} to Ti{sup 3+} to form [Ov··-Ti{sup 3

  6. Slow evaporation method and enhancement in photoluminescence properties of YPO$_4$ : Eu$^{3+}$ co-doped with Bi$_{3+}$ ions

    Indian Academy of Sciences (India)

    K A KOPARKAR; S K OMANWAR

    2016-08-01

    The series of Bi$^{3+}$ co-doped YPO$_{4}:Eu$^{3+}$ nanophosphors were successfully synthesized by the slow evaporation method. Bi$^{3+}$-doped and un-doped YPO$_4$:Eu$^{3+}$ phosphors were characterized by using powder X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Photoluminescence (PL) properties and decay time of phosphors were studied at room temperature. The YPO$_4$:Eu$^{3+}$ and Bi$^{3+}$ exhibit enhancement in PL intensity and quenched at 0.5 mol% of Bi$^{3+}$ ions.

  7. Planar waveguides formed in a new chemically stable Er3+/Yb3+ co-doped phosphate glass

    Institute of Scientific and Technical Information of China (English)

    Shilong Zhao; Baoyu Chen; Junjiang Hu; Lili Hu

    2005-01-01

    @@ A new Er3+/Yb3+ co-doped phosphate glass has been prepared, which exhibits good chemical durability and spectral properties. Planar graded index waveguides have been fabricated in the glass by Ag+-Na+ ion exchange in a mixed melt of silver nitrate and potassium nitrate. Ion exchange is carried out by varying the process parameters such as temperature, diffusion time, and molten salt compositions. The diffusion parameters, diffusion coefficients, and activation energy are determined by the guidelines of fabricated waveguides, which are determined by the input prism coupling technique.

  8. Performance comparison of bismuth/erbium co-doped optical fibre by 830 nm and 980 nm pumping

    Science.gov (United States)

    Yan, Binbin; Luo, Yanhua; Zareanborji, Amirhassan; Xiao, Gui; Peng, Gang-Ding; Wen, Jianxiang

    2016-10-01

    The performance of bismuth/erbium co-doped fibre (BEDF) by 830 nm and 980 nm pumping has been studied in detail, including the small signal absorption, pump absorption, emission, gain and excited state absorption (ESA). Based on the study, energy transition diagrams of BEDF under 830 nm or 980 nm pumping are proposed to clarify the spectroscopic properties. The results demonstrate the advantages of 830 nm pumping for BEDF over 980 nm pumping when considering the absorption, pumping efficiency, excited state absorption and optical amplification.

  9. Synthesis of La~(3+) and Nd~(3+) co-doped yttria nanopowder for transparent ceramics by oxalate precipitation method

    Institute of Scientific and Technical Information of China (English)

    王能利; 张希艳; 邱关明; 孙海鹰; 刘全生; 米晓云; 王晓春

    2010-01-01

    Polycrystalline Nd3+ and La3+ co-doped yttria nanopowder Nd3+:Y1.90La0.10O3 for transparent ceramics was synthesized by co-precipitation method using oxalate acid as the precipitant and(NH4)2SO4 as the electrical stabilizer under ultrasonic radiation.Nanopowders calcined at different temperatures were characterized with thermal gravimetric-differential thermal analysis(TG/DTA),X-ray diffraction(XRD),transmitting electron microscopy(TEM),energy dispersive spectrometry(EDS) and spectral analysis techniques.Th...

  10. Preparation and Scintillating Properties of Sol-Gel Eu3+, Tb3+ Co-Doped Lu2O3 Nanopowders

    OpenAIRE

    Joel Moreno Palmerin; Rosario Ruiz Guerrero; Margarita García Hernández; Ángel de Jesús Morales Ramírez; Antonieta García Murillo; Felipe de Jesús Carrillo Romo

    2011-01-01

    Nanocrystalline Eu3+, Tb3+ co-doped Lu2O3 powders with a maximum size of 25.5 nm were prepared by the sol-gel process, using lutetium, europium and terbium nitrates as precursors, and ethanol as a solvent. Differential thermal analysis (DTA) and infrared spectroscopy (IR) were used to study the chemical changes during the xerogel annealing. After the sol evaporation at 100 °C, the formed gel was annealed from 300 to 900 °C for 30 min under a rich O2 atmosphere, and the yielded product was ana...

  11. Low temperature magnetic and anomalous high temperature dielectric response of Dy–Ni co-doped hexagonal YMnO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Virendra [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Gaur, Anurag, E-mail: anuragdph@gmail.com [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Kumar Gaur, Umesh [Centre of Nanotechnology, Indian Institute of Technology, Roorkee 247667 (India)

    2015-06-15

    YMnO{sub 3} pristine and Dy–Ni co-doped Y{sub 1−x}Dy{sub x}Mn{sub 1−x}Ni{sub x}O{sub 3} compositions with x=0.01, 0.03 and 0.05 were synthesised by high temperature solid state route. In all synthesized samples with doping a minor phase of DyMnO{sub 3} is formed but no indication of phase transition from hexagonal to orthorhombic is observed. For 3 and 5% Dy–Ni co-doped YMnO{sub 3}, a thin coercivity is observed at 10 K due to insertion of weak ferromagnetism in these compositions. For undoped YMnO{sub 3}, crimps are observed in both FC and ZFC curves at exactly 75 K (Neel temperature), however crimps are shifted towards significantly lesser temperature after adding the dopants. For pristine and 1% Dy–Ni co-doped samples explicit bifurcation in FC–ZFC curves is observed, which is not pronounced for 3 and 5% Dy–Ni co-doped samples. Moreover, in these compositions cusps are observed only in ZFC curves at 25 and 19 K, respectively which can be considered as hallmark of weak spin glass behaviour in these compositions. Anomalous dielectric peaks are observed at 450 and 550 K for undoped YMnO{sub 3} while a distinct peak is observed at 450 K for 1% Dy–Ni co-doped sample along with the suppression of other peaks. It is proposed that relaxor behaviour of these peaks can be explained on the basis of the Maxwell–Wagner effect. - Highlights: • YMnO{sub 3} pristine and Dy–Ni co-doped Y{sub 1−x}Dy{sub x}Mn{sub 1−x}Ni{sub x}O{sub 3} compositions with x=0.01, 0.03 and 0.05 were synthesized by high temperature solid state route. • For 3 and 5 % Dy–Ni co-doped YMnO{sub 3}, a thin coercivity is observed at 10 K due to insertion of weak ferromagnetism in these compositions. • For pristine and 1 % Dy–Ni co-doped samples explicit bifurcation in FC–ZFC curves is observed, which is not pronounced for 3 and 5 % Dy–Ni co-doped samples.

  12. Corrosion protection of AISI 1018 steel using Co-doped TiO{sub 2}/polypyrrole nanocomposites in 3.5% NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Ladan, Magaji, E-mail: ladanmagaji@yahoo.com [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Department of Pure and Industrial Chemistry, Bayero University Kano (Nigeria); Basirun, Wan Jeffrey, E-mail: jeff@um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Institute of Nanotechnology and Catalysis (NanoCat), University of Malaya, Kuala Lumpur, 50603 (Malaysia); Kazi, Salim Newaz; Rahman, Fariza Abdul [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia)

    2017-05-01

    A polypyrrole nanocomposites (PPy NTCs) have been effectively synthesized in the presence of TiO{sub 2} and Co-doped TiO{sub 2} nanoparticles (NPs) by an in situ chemical oxidative polymerization. Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy revealed a tube shape structure of the PPy. The TEM results confirmed that the nanocomposite size of Co-doped TiO{sub 2}/PPy NTCs was smaller than TiO{sub 2}/PPy NTCs thereby increasing the interaction between the PPy nanotube and the AISI steel surface. The corrosion performance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements in 3.5% NaCl solution. The EIS results show that the log |Z| of AISI 1018 coated with Co-doped TiO{sub 2}/PPy NTCs and TiO{sub 2}/PPy NTCs reached about 8.2 and 6.0 respectively after 30 days of exposure in 3.5% NaCl solution. This is likely due to the increased surface area of the PPy synthesized in the presence of Co-doped TiO{sub 2} NPs. The EIS results are confirmed by the potentiodynamic polarization and open circuit potential values of the Co-doped TiO{sub 2}/PPy which indicated little changes between 1 and 30 days of exposure which confirms the protection ability of this coating. . It is evident that the presence of Co-doped TiO{sub 2} NPs can enhance the resistance against corrosion at the steel/electrolyte interface. - Highlights: • Polymerization of pyrrole monomer in the presence of Co-doped TiO{sub 2} decreases the size of the polypyrrole nanotube (PPy NT). • The corrosion protection increases with the increase in PPy NT dispersion. • The corrosion resistance of steel coated with Co-doped TiO{sub 2}/PPy NTCs is considerably higher. • TiO{sub 2}/PPy with Co doping reduces the charge transfer across the electrolyte/AISI 1018 steel interface.

  13. Highly transparent and conductive Sn/F and Al co-doped ZnO thin films prepared by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Zhanchang, E-mail: panzhanchang@163.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Luo, Junming [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Tian, Xinlong, E-mail: tianxinlong2010@163.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wu, Shoukun; Chen, Chun; Deng, Jianfeng [Huizhou King Brother Electronic Technology Co., Ltd, Huizhou 516083 (China); Xiao, Chumin [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Hu, Guanghui, E-mail: qhxy123@126.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wei, Zhigang [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China)

    2014-01-15

    Highlights: • F/Sn and Al co-doped ZnO thin films were synthesized by sol–gel method. • The co-doped nanocrystals exhibit good crystal quality. • The origin of the photoluminescence emissions was discussed. • The films showed high transmittance and low resistivity. -- Abstract: Al doped ZnO, Al–Sn co-doped ZnO and Al–F co-doped ZnO nanocrystals were successfully synthesized onto glass substrates by the sol–gel method. The structure and morphology of the films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicated that all the films were polycrystalline with a hexagonal wurtzite structure and exhibited a c-axis preferred orientation. The electrical and optical properties were also investigated by 4-point probe device and Uv–vis spectroscopy, room temperature photoluminescence (PL) and Raman spectrum (Raman), respectively. The PL and Raman results suggested that the co-doped films with a very low defect concentration and exhibit a better crystallinity than AZO thin films. The XPS study confirmed the incorporation of Al, Sn and F ions in the ZnO lattice.

  14. Effect of Mg co-doping on scintillation properties of Ce:Gd3(Ga, Al)5O12 single crystals with various Ga/Al ratios

    Science.gov (United States)

    Yoshino, Masao; Kamada, Kei; Shoji, Yasuhiro; Yamaji, Akihiro; Kurosawa, Shunsuke; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira; Chani, Valery I.

    2017-06-01

    Mg co-doped Ce1%:Gd3GaxAl5-xO12 (Ce:GAGG) crystals (x=2.4, 2.7, 3.0) were successfully grown by the Czochralski (Cz) method. Effect of Mg co-doping on the scintillation properties of Ce:GAGG was examined. This study covers measurements of solidification fraction and scintillation properties such as light yield, energy resolution and non-proportionality for each crystal. Pulse-height spectra of various gamma and X-ray sources with energies ranged from 30 keV to 662 keV were measured. Regardless of the presence/absence of Mg dopant, the non-proportionality curves with lower content of gallium in the crystal structure tend to improve. Mg co-doped Ce:GAGG samples did not show a significant difference as compared with non co-doped Ce:GAGG. Mg co-doped crystals with x=2.4 and 2.7 showed the promising scintillation properties of faster decay time and higher energy resolution than those with x=3.0.

  15. Structural, optical, and magnetic properties of polycrystalline Co-doped TiO{sub 2} synthesized by solid-state method

    Energy Technology Data Exchange (ETDEWEB)

    Bouaine, Abdelhamid, E-mail: abdelhamidfethi@yahoo.fr [Laboratoire d' Etude des Materiaux (LEM), Departement de Physique, Faculte des Sciences Exactes et des Sciences de la Nature et de la vie, Universite de Jijel, cite Oued-Aissa, B.P 98, Jijel 18000 (Algeria); Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), UMR 7504 CNRS - UdS, 23 rue du Loess, B.P. 43, 67034 Strasbourg Cedex 2 (France); Schmerber, G.; Ihiawakrim, D.; Derory, A. [Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), UMR 7504 CNRS - UdS, 23 rue du Loess, B.P. 43, 67034 Strasbourg Cedex 2 (France)

    2012-11-01

    Highlights: Black-Right-Pointing-Pointer Influence of Co doping on the TiO{sub 2} tetragonal structure. Black-Right-Pointing-Pointer Decrease of the energy band gap after doping with Co atoms. Black-Right-Pointing-Pointer Appearance of ferromagnetism in Co-doped TiO{sub 2} diluted magnetic semiconductors. - Abstract: We have used a solid-state method to synthesize polycrystalline Co-doped TiO{sub 2} diluted magnetic semiconductors (DMSs) with Co concentrations of 0, and 0.5 at.%. X-ray diffraction patterns reveal that Co doped TiO{sub 2} crystallizes in the rutile tetragonal structure with no additional peaks. Transmission electron microscopy (TEM) did not indicate the presence of magnetic parasitic phases and confirmed that Co ions are uniformly distributed inside the samples. Optical absorbance measurements showed an energy band gap which decreases after doping with the Co atoms into the TiO{sub 2} matrix. Magnetization measurements revealed a paramagnetic behavior for the as-prepared Co-doped TiO{sub 2} and a ferromagnetic behavior for the same samples after annealed under a mixture of H{sub 2}/N{sub 2} atmosphere.

  16. Influence of La{sup 3+} and Fe{sup 3+} co-doping to nano-TiO{sub 2} prepared by graded calcination

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhe [The State Key Laboratory of Heavy Oil, China University of Petroleum, Dongying, Shandong 257061 (China); Zheng, Jing-tang, E-mail: jtzheng03@163.com [The State Key Laboratory of Heavy Oil, China University of Petroleum, Dongying, Shandong 257061 (China); Wu, Ming-bo [The State Key Laboratory of Heavy Oil, China University of Petroleum, Dongying, Shandong 257061 (China)

    2012-11-25

    Highlights: Black-Right-Pointing-Pointer La{sup 3+} and Fe{sup 3+} co-doped TiO{sub 2} sample was prepared by a new process. Black-Right-Pointing-Pointer The gelatinizing time is obviously shortened. Black-Right-Pointing-Pointer The grain size of co-doped TiO{sub 2} sample is decreased. Black-Right-Pointing-Pointer The photocatalytic activity of co-doped TiO{sub 2} under visible light is improved. - Abstract: The un-doping, single-doping and co-doping TiO{sub 2} nanoparticles have been prepared through the graded calcination method with Ti(OC{sub 4}H{sub 9}){sub 4} as raw material and characterized by X-ray diffraction (XRD) and UV-vis reflection spectra. Their photocatalytic activities have been investigated by the photocatalytic oxidation of methyl orange. It is indicated that Fe{sup 3+}-doping makes the reflection profile narrow, improves photoutilization of TiO{sub 2}, and then generates more electron-hole pairs. La{sup 3+}-doping restrains the increase of grain size, leads to crystal expansion plus matrix distortion and retards the recombination of the photoexcited charge carriers. The photocatalytic activity of TiO{sub 2} co-doped with La{sup 3+} and Fe{sup 3+} is notably improved due to the cooperative actions of the two dopants.

  17. Influence of La-Mn-Al Co-Doping on Dielectric Properties and Structure of BST Thick Film

    Institute of Scientific and Technical Information of China (English)

    Mao-Yan Fan; Sheng-Lin Jiang

    2009-01-01

    A new sol-gel process is applied to fabricate the BST (BaxSr1(xTiO3) sol and nano-powder of La-Mn-Al co-doping with Ba/Sr ratio 65/35, and the BST thick film is prepared in the Pt/Ti/SiO2/Si substrate. The powder and thick film are characterized by X-ray diffraction and transmission electron microscope. The influence of La-Mn-Al co-doping on the dielectric properties and micro-structure of BST thick film is analyzed. The results show that the La, Mn, and Al ions can take an obvious restraint on the growth of BaSrTiO3 grains. The polycrystalline particles come into being during the crystallization of thick film, which may improve the uniformity and compactness of thick film. The influence of unequal-valence and doping amount on the leakage current, dielectric loss, and dielectric property are mainly discussed. The dielectric constant and dielectric loss of thick film are 1200 and 0.03, respectively, in the case of 1mol% La doping, 2mol% Mn doping, and 1mol% Al doping.

  18. Yellow laser performance of Dy$^{3+}$ in co-doped Dy,Tb:LiLuF$_4$

    CERN Document Server

    Bolognesi, Giacomo; Calonico, Davide; Costanzo, Giovanni Antonio; Levi, Filippo; Metz, Philip Werner; Kränkel, Christian; Huber, Günter; Tonelli, Mauro

    2015-01-01

    We present laser results obtained from a Dy$^{3+}$-Tb$^{3+}$ co-doped LiLuF$_{4}$ crystal, pumped by a blue emitting InGaN laser diode, aiming for the generation of a compact 578 nm source. We exploit the yellow Dy$^{3+}$ transition $^{4}$F$_{9/2}$ $\\Longrightarrow$ $^{6}$H$_{13/2}$ to generate yellow laser emission. The lifetime of the lower laser level is quenched via energy transfer to co-doped Tb$^{3+}$ ions in the fluoride crystal. We report the growth technique, spectroscopic study and room temperature continuous wave (cw) laser results in a hemispherical cavity at 574 nm and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden $^{1}$S$_{0} \\Longrightarrow ^{3}$P$_{0}$ Ytterbium clock transition, which is recommended as a secondary representation of the second in the international system (SI) of units. This paper was published in Optics Letters and is made available as an electronic reprint ...

  19. Preparation and property of spinel LiMn2O4 material by co-doping anti-electricity ions

    Institute of Scientific and Technical Information of China (English)

    XIAO Jin; ZHU Hua-li; CHEN Zhao-yong; PENG Zhong-dong; HU Guo-rong

    2006-01-01

    LiMn2-xMxO4-yFy(x=0.05; y=0.05; M=Al, Co, Cr and Mg, separately), as the cathode material, was synthesized by the method of high temperature solid-state reaction in laboratory. The results of charge-discharge test show that the properties of LiMn1.95M0.05O3.95F0.05(M= Al, Mg) are obviously superior to those of LiMn2O4. Through the condition experiments on sintering temperature, it is found that the materials present the integrate crystal structure and favorable cycle performance at 800 ℃. The research on the effects of different Mg2+ sources on the properties of LiMn2-xMgxO4-y Fy shows that, with Mg(OH)2 and LiF as the reagents respectively offering Mg2+ and F-, LiMn1.95Mg0.05O3.95F0.05 synthesized has integrate crystal structure and its capacity hardly fades. The results of cyclic voltammetry indicate that the shape of two couples of redox peaks of the material synthesized by co-doping anti-electricity ions is more integrate and symmetrical than that of pure spinel LiMn2O4, which reveals that the co-doping material possesses preferable electrochemical reversibility.

  20. Study of energy transfer and spectral downshifting in Ce, RE (RE = Nd and Yb) co-doped lanthanum phosphate

    Science.gov (United States)

    Sawala, N. S.; Omanwar, S. K.

    2017-03-01

    The phosphors LaPO4 (Lanthanum phosphate) doped with Ce(III)/Ce3+ and co-doped with Ce3+-Nd3+ and Ce3+-Yb3+ were effectively synthesized by conventional solid state reaction method. The prepared samples were characterized by powder X-ray diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infrared (NIR) and ultraviolet visible (UV-VIS) region. Additionally the luminescence time decay curves of samples were investigated to confirm energy transfer (ET) process. The Ce3+-Nd3+ ion co-doped LaPO4 phosphors can convert a photon of UV region (278 nm) into photons of NIR region (1058 nm). While Ce3+-Yb3+ ion doped LaPO4 phosphors convert photons of UV region (278 nm) into photons of NIR region (979 nm). The Ce3+ ion acts like sensitizer and Nd3+/Yb3+ ions act as activators. Both kinds of emissions are suitable for improving spectral response of solar cells.

  1. N, S co-doped-TiO2/fly ash beads composite material and visible light photocatalytic activity

    Science.gov (United States)

    Lv, Jun; Sheng, Tong; Su, Lili; Xu, Guangqing; Wang, Dongmei; Zheng, Zhixiang; Wu, Yucheng

    2013-11-01

    Using TiCl4 as the titanium source, urea as the precipitating agent, nano-TiO2/fly ash beads composite materials were prepared by hydrolysis-precipitation method. Using (NH2)2CO and (NH2)2SC as the N and S source respectively, N and S co-doped TiO2/fly ash beads composite materials were prepared by grinding them together according to a certain proportion and calcined at 500 °C for 2 h. The composite materials were characterized by SEM, EDS, XPS, and UV-vis spectrophotometer methods. The UV-vis absorption spectra results show that the absorption edge of un-doped composites is 390 nm while that of doped composites red-shifts to 500 nm. The photocatalytic activity of composite materials was evaluated by degradation of methyl orange under visible light irradiation (halogen lamp, 250 W). The results showed that after irradiation for 1 h, degradation rate of N, S co-doped-TiO2/fly ash beads composite material can reach 65%, while the degradation rate of un-doped sample and P25 were just 10% and 6%, respectively. The composite material also showed excellent recycling properties.

  2. Y/Eu co-doped TiO2:synthesis and photocatalytic activities under UV-light

    Institute of Scientific and Technical Information of China (English)

    王瑞芬; 王福明; 安胜利; 宋金玲; 张胤

    2015-01-01

    Y and Eu co-doped nano-TiO2 photocatalysts were successfully prepared via a sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectrophotometry (UV-vis), photoluminescence (PL) and Fourier transform infrared (FT-IR) spectra. Experimental results indicated that Y and Eu doping inhibited the growth of crystal-line size and the transformation from anatase to rutile phase and had the function of reducing particle reunion. At the same time, co-doping could also enhance the absorption in visible region and then narrowed the band gap. The photocatalytic activities of the samples were evaluated by the degradation of methylene blue (MB) under ultraviolet (UV) light irradiation, which showed much en-hanced photocatalytic activities over un-doped TiO2. The degradation rate of 1.5%Y/Eu-TiO2 of methylene blue was 86%, which was about 5 times of that of un-doped TiO2, and the possible reasons for the improvement of photocatalytic activities were analyzed. In this experiment, the dopant amount of rare earth was 1.5%and the ratio of Y:Eu was 2:3 for the maximum photocatalytic degrada-tion, and the sample calcined at 500 ºC showed the best reactivity. For the best samples above, the removal rate of phenol under visble light was 53%whthin 2 h.

  3. Doping levels, trap density of states and the performance of co-doped CdTe(As,Cl) photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Proskuryakov, Y.Y.; Durose, K.; Major, J.D.; Al Turkestani, M.K. [Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Barrioz, V.; Irvine, S.J.C.; Jones, E.W. [Bangor University, School of Chemistry, Bangor, Gwynedd LL57 2UW (United Kingdom)

    2009-09-15

    Doping, compensation and photovoltaic performance have been investigated in all-metal-organic vapour-phase deposition (MOCVD) grown CdTe/CdS solar cells that were co-doped with arsenic and chlorine. Although arsenic chemical concentration is in the range of 10{sup 17}-1.5 x 10{sup 19} cm{sup -3}, the maximum net acceptor concentration is only in the order of 10{sup 14} cm{sup -3}, as determined by capacitance-voltage characteristics. Admittance spectroscopy revealed shallow traps at 0.055 eV which were attributed to As{sub Te}; its compensation by Cd{sub i} is discussed. Formation of the alloy CdS{sub x}Te{sub 1-x} is linked to deep levels at E{sub V}+{proportional_to}0.55 eV and E{sub V}+{proportional_to}0.65 eV. Limits to the diffusion of photo-generated carriers were considered to be important in determining photovoltaic performance rather than carrier lifetime. Prospects for optimizing the performance of such co-doped MOCVD-grown devices are discussed. (author)

  4. Up conversion processes in yttrium-lithium-flouride crystals co-doped with erbium and ytterbium ions

    Science.gov (United States)

    Spinger, B.; Danilov, Valery P.; Prokhorov, Alexander M.; Schwan, L. O.; Schmid, D.

    2002-07-01

    We report on studies of the up-conversion process in YLiF4 single crystals co-doped with Er3+ and with Yb3+. Er3+ has a well known complicated energy level system within the 4f shell which gives rise to the up- conversion process. Yb3+ with a broad absorption band int eh regime 940 nm co-doped with Er3+ and with Yb3+ may be considered as suitable candidates for diode-laser-pumped displays and for solid state laser system int eh visible and near UV region.

  5. ZnO nanoparticles co-doped with Fe3+ and Eu3+ ions for solar assisted photocatalysis.

    Science.gov (United States)

    Yin, Dongguang; Zhang, Le; Song, Kailin; Ou, Yangjuan; Wang, Chengcheng; Liu, Bing; Wu, Minghong

    2014-08-01

    In this study, ZnO nanoparticles co-doped with Fe3+ and Eu3+ were prepared by a facile co-precipitation method. The structure and morphology of the as-prepared nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance absorption spectra, respectively. The photocatalytic activities of the prepared catalysts were evaluated by photocatalytic degradation of methyl orange in aqueous solution with solar light irradiation. The co-doped Fe3+ and Eu3+ showed a synergistic effect, which significantly increased the photocatalytic activity of ZnO. The influences of calcination time, photocatalytic reaction temperature and catalyst loading on the photocatalytic activity of the catalyst were also investigated. It was found that there were an optimum photocatalytic reaction temperature and an optimum catalyst loading for high photocatalytic efficiency, and the photocatalytic efficiency decreased with increase in calcination time. The results of this study demonstrate that the as-prepared product of Eu3+/Fe3+/ZnO is a promising photocatalyst for solar assisted degradation of organic pollutions.

  6. Energetics and magnetism of Co-doped GaN(0001) surfaces: A first-principles study

    CERN Document Server

    Qin, Zhenzhen; Chen, Guangzhao Qin Lanli

    2014-01-01

    A comprehensive first-principles study of the energetics, electronic and magnetic properties of Co-doped GaN(0001) thin films are presented and the effect of surface structure on the magnetic coupling between Co atoms is demonstrated. It is found that Co atoms prefer to substitute the surface Ga sites in different growth conditions. In particular, a CoN/GaN interface structure with Co atoms replacing the first Ga layer is preferred under N-rich and moderately Ga-rich conditions, while CoGa$_x$/GaN interface is found to be energetically stable under extremely Ga-rich conditions. It's worth noting that the AFM coupling between Co atoms is favorable in clean GaN(0001) surface, but the existence of FM would be expected to occur as Co concentration increased in Ga-bilayer GaN(0001) surface. Our study provides the theoretical understanding for experimental research on Co-doped GaN films and might promise the Co:GaN system potential applications in spin injection devices.

  7. Effect of Zr and C Co-doping on the Optical Properties and Electronic Structure of TiO_2

    Institute of Scientific and Technical Information of China (English)

    LIU Gang; LI De-Hua; ZHANG Ru

    2011-01-01

    The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functional theory (DFT) method within the generalized gradient approximation (GGA) for the exchange-correlation potential. Through the current calculations, the density of states (DOS), energy band structure and optical absorption coefficients have been obtained for TiO2 and compared with the doped TiO2, and the influence of electronic structure and optical properties caused by Zr and C co-doping has been presented qualitatively together. The results revealed that the energy band gap has been decreased owing to the doped Zr and C, whereas the optical absorption coefficients have been increased in the region of 400~800 nm and a red shift of absorption band can be found. Accordingly, photo catalytic activity of TiO2 has been enhanced. The current calculations are in good agreement with the experimental data.

  8. Luminescence studies on Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses for WLED applications

    Science.gov (United States)

    Vijayakumar, M.; Uma, V.; Arunkumar, S.; Marimuthu, K.

    2015-06-01

    Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses have been prepared and optically characterized using absorption, luminescence and decay measurements. The Nephelauxetic ratios (β), Bonding parameters (δ) and Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2, 4 and 6) were calculated to study the nature of the environment around the RE3+ ions in the prepared glasses. The yellow to blue (Y/B) intensity ratio and the chromaticity color coordinates were calculated from the luminescence measurements. The lifetimes of the 4F9/2 excited level were measured using decay curves and is found to decrease in the Dy3+:Eu3+ co-doped glass due to the occurrence of resonant energy transfer between Dy3+-Eu3+ ions and the non-exponential decay rates have been fitted with Inokuti-Hirayama (IH) model. The decay curves are well fitted for S= 6 suggesting that the interaction between active ions for the energy transfer is of dipole-dipole nature.

  9. Study on relaxation oscillation of Er~(3+)/Yb~(3+) co-doped phosphate glass optical waveguide laser

    Institute of Scientific and Technical Information of China (English)

    LIU HuaDong; ZHANG XiaoXia; WU XianLi; ZHANG Qin; LIU YongZhi

    2009-01-01

    Based on the principle and fabrication of the optical waveguide laser, and through the configuration of the energy level of Er~(3+)/Yb~(3+) co-doped system, the time-dependent rate equations are formed and then solved by Runge-Kutta algorithm. The dynamic characteristic of the waveguide laser pumped unidirec-tionally by 980 nm LD is analyzed. The curves of the relaxation oscillation are drawn, showing that the photon number and inverted population vary alternately. The attenuation characteristic of the peak power is studied. It is gained that time constant changes with pump power, length of waveguide and the reflectivity of output mirror. Furthermore, the impact of the above three parameters on the frequency and end-time of relaxation oscillation is discussed. The frequency of relaxation oscillation is propor-tional to the pump power. Under high reflectivity conditions, the length of waveguide has a weak impact on the frequency. The end-time decreases as the three parameters increase. These features and results provide a theoretical basis for designing the Er~(3+)/Yb~(3+) co-doped phosphate optical waveguide laser.

  10. Intense frequency upconversion fluorescence of Er3+/Yb3+ co-doped lithium-strontium-lead-bismuth glasses

    Institute of Scientific and Technical Information of China (English)

    Hongtao Sun; Shiqing Xu; Baoyu Chen; Shixun Dai; Shilong Zhao; Lili Hu; Zhonghong Jiang

    2005-01-01

    @@ Infrared-to-visible upconversion fluorescence of Er3+/Yb3+ co-doped lithium-strontium-lead-bismuth (LSPB) glasses for developing potential upconversion lasers has been studied under 975-nm excitation.Based on the results of energy transfer efficiency and upconversion spectra, the optimal Yb3+-Er3+ concentration ratio is found to be 5∶1. Intense green and red emissions centered at 525, 546, and 657 nm,corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2 → 4I15/2, respectively, were observed. The quadratic dependence of the 525-, 546-, and 657-nm emissions on excitation power indicates that a two-photon absorption process occurs under 975-nm excitation. The high-populated 4I11/2 level is supposed to serve as the intermediate state responsible for the upconversion processes. The intense upconversion luminescence of Er3+/Yb3+ co-doped LSPB glasses may be a potentially useful material for developing upconversion optical devices.

  11. Fluorine and boron co-doped diamond-like carbon films deposited by pulsed glow discharge plasma immersion ion processing

    CERN Document Server

    He, X M; Peters, A M; Taylor, B; Nastasi, M

    2002-01-01

    Fluorine (F) and boron (B) co-doped diamond-like carbon (FB-DLC) films were prepared on different substrates by the plasma immersion ion processing (PIIP) technique. A pulse glow discharge plasma was used for the PIIP deposition and was produced at a pressure of 1.33 Pa from acetylene (C sub 2 H sub 2), diborane (B sub 2 H sub 6), and hexafluoroethane (C sub 2 F sub 6) gas. Films of FB-DLC were deposited with different chemical compositions by varying the flow ratios of the C sub 2 H sub 2 , B sub 2 H sub 6 , and C sub 2 F sub 6 source gases. The incorporation of B sub 2 H sub 6 and C sub 2 F sub 6 into PIIP deposited DLC resulted in the formation of F-C and B-C hybridized bonding structures. The levels of the F and B concentrations effected the chemical bonding and the physical properties as was evident from the changes observed in density, hardness, stress, friction coefficient, and contact angle of water on films. Compared to B-doped or F-doped DLC films, the F and B co-doping of DLC during PIIP deposition...

  12. The origin of ferromagnetism of Co-doped TiO2 nanoparticles: Experiments and theory investigation

    Science.gov (United States)

    Zhang, Suyin; Zhou, Zhongpo; Xiong, Rui; Shi, Jing; Lu, Zhihong; Wang, Haiying

    2016-11-01

    A series of Ti1-xCoxO2-δ (x = 0.01, 0.03, 0.05, 0.07) nanoparticles were synthesized by sol-gel method. The X-ray diffraction, transmission electron microscopy, Raman analysis and X-ray photoelectron spectroscopy ruled out the signatures of Ti3+, Co-clusters or any other oxides of Co. The ferromagnetic behavior was clearly observed at room temperature in doped samples with saturation magnetization (Ms) of the order of 0.008-0.035 emu/g depending on doping concentrations. The saturation magnetization is found to be increased with the Co contents increasing from 1% to 7%. From the plot of the M-T curve, we obtain the Tc as ˜515 K for 5% Co-doped TiO2. Oxygen vacancies were detected from the photoluminescence (PL) measurement. Magnetic properties analyses and PL analyses showed that oxygen vacancies probably played a major role in ferromagnetism of the Ti1-xCoxO2 system with Co substituting for Ti. The first-principles calculation was performed to investigate the magnetic properties of Co-doped TiO2 nanoparticles. It can be found that the major magnetic moment is from the 3d electron of Co. The experiment results are consistent with the first-principles calculation. The ferromagnetism derived from the spin-split of O-2p and Co-3d electron states caused by p-d orbit hybridization.

  13. A sensitive and label-free photoelectrochemical aptasensor using Co-doped ZnO diluted magnetic semiconductor nanoparticles.

    Science.gov (United States)

    Li, Hongbo; Qiao, Yunfei; Li, Jing; Fang, Hailin; Fan, Dahe; Wang, Wei

    2016-03-15

    Co-doped ZnO diluted magnetic semiconductor as a novel photoelectric beacon was first constructed for photoelectrochemical (PEC) aptasensor of acetamiprid. The fabricated PEC sensing is based on the specific binding of acetamiprid and its aptamer, which induces the decreasement of enhanced photocurrent produced by the electron donor of quercetin. Co(2+) doping has a beneficial effect in extending the band width of light absorption of ZnO into the visible region and to promote the separation of the photoinduced carriers due to the sp-d exchange interactions existing between the band electrons and the localized d electrons of Co(2+). The fabricated aptasensor was linear with the concentration of acetamiprid in the range of 0.5-800 nmolL(-1) with the detection limit of 0.18 nmolL(-1). The presence of same concentration of other conventional pesticides did not interfere in the detection of acetamiprid and the recovery is between 96.2% and 103.7%. This novel PEC aptasensor has good performances with high sensitivity, good selectivity, low cost and portable features. The strategy of Co-doped ZnO diluted magnetic semiconductor paves a new way to improve the performances of PEC aptasensor.

  14. Efficient 2 μm emission in Nd3+/Ho3+ co-doped silicate-germanate glass pumped by common 808 nm LD

    Science.gov (United States)

    Chen, Rong; Tian, Ying; Li, Bingpeng; Huang, Feifei; Wang, Caizhi; Jing, Xufeng; Zhang, Junjie; Xu, Shiqing

    2017-03-01

    Nd3+/Ho3+ co-doped silicate-germanate glass has been synthesized by high temperature melt-quenching method. Near infrared emission centered at 2 μm has been successfully obtained by incorporating Nd3+ and Ho3+ in present glass. The Judd-Ofelt intensity parameters Ωt (t=2, 4, 6), and radiative properties of Ho3+ were calculated and discussed by using the Judd-Ofelt theory. The energy transfer processes and luminescence properties of Nd3+/Ho3+ co-doped glasses were analyzed pumped by a conventional 808 nm laser diode. Desirable spectroscopic characteristics indicates that Nd3+/Ho3+ co-doped silicate-germanate glass might be a good alternative matrix for 2 μm band mid-infrared laser.

  15. Titania nanotube array based photovoltaic cells

    Science.gov (United States)

    Yip, C. T.; Cheung, K. Y.; Djurišić, A. B.; Chan, W. K.

    2007-09-01

    It has been shown that dye sensitized solar cells (DSSCs) based on porous titanium dioxide (titania) layers have efficiencies exceeding 10%. Although porous structure has the advantage of large surface area for light harvesting, electron transport through the random nanoparticle network forming a porous film results in electron mobilities which are two orders of magnitude lower compared to the single crystal materials. Therefore, considerable efforts have been made to fabricate DSSC based on one dimensional nanostructures, such as nanowires or nanotubes. Titania nanotube arrays are typically made by anodization of titanium, followed by annealing to improve crystallinity. In this work, we investigated the influence of annealing temperature and annealing atmosphere on the crystal structure, the electron transport, and the solar cell performance of titania nanotube arrays. The titania nanotube arrays were prepared from electrochemically anodized titanium foils and their morphology and crystal structure were characterized by scanning electron microscopy and transmission electron microscopy. The crystal phases and the compositions of nanotube arrays were further investigated by X-ray diffraction for different annealing temperatures and X-ray photoelectron spectroscopy for different annealing atmospheres. For optimal annealing conditions, the short circuit current density of 4.27 mA/cm2 and power conversion efficiency of 1.30% could be achieved under AM 1.5 simulated solar irradiation for 2 μm long nanotubes.

  16. Titania nanotube arrays: Interfaces for implantable devices

    Science.gov (United States)

    Smith, Barbara Symie

    For the 8--10% of Americans (20--25 million people) that have implanted biomedical devices, biomaterial failure and the need for revision surgery are critical concerns. The major causes for failure in implantable biomedical devices promoting a need for re-implantation and revision surgery include thrombosis, post-operative infection, immune driven fibrosis and biomechanical failure. The successful integration of long-term implantable devices is highly dependent on the early events of tissue/biomaterial interaction, promoting either implant rejection or a wound healing response (extracellular matrix production and vasculature). Favorable interactions between the implant surface and the respective tissue are critical for the long-term success of any implantable device. Recent studies have shown that material surfaces which mimic the natural physiological hierarchy of in vivo tissue may provide a possible solution for enhancing biomaterial integration, thus preventing infection and biomaterial rejection. Titania nanotube arrays, fabricated using a simple anodization technique, provide a template capable of promoting altered cellular functionality at a hierarchy similar to that of natural tissue. This work focuses on the fabrication of immobilized, vertically oriented and highly uniform titania nanotube arrays to determine how this specific nano-architecture affects skin cell functionality, hemocompatibility, thrombogenicity and the immune response. The results in this work identify enhanced dermal matrix production, altered hemocompatibility, reduced thrombogenicity and a deterred immune response on titania nanotube arrays. This evidences promising implications with respect to the use of titania nanotube arrays as beneficial interfaces for the successful implantation of biomedical devices.

  17. Titania Photocatalysis beyond Recombination: A Critical Review

    Directory of Open Access Journals (Sweden)

    Bunsho Ohtani

    2013-11-01

    Full Text Available This short review paper shows the significance of recombination of a photoexcited electron and a hole in conduction and valence bands, respectively, of a titania photocatalyst, since recombination has not yet been fully understood and has not been evaluated adequately during the past several decades of research on heterogeneous photocatalysis.

  18. Effects of Yttrium and Iron co-doping on the high temperature thermoelectric properties of Ca{sub 3}Co{sub 4}O{sub 9+δ}

    Energy Technology Data Exchange (ETDEWEB)

    Wu, NingYu, E-mail: niwu@dtu.dk; Van Nong, Ngo; Pryds, Nini; Linderoth, Søren

    2015-07-25

    Highlights: • The Fe and Fe/Y doping at the Co- and Ca-sites of Ca{sub 3}Co{sub 4}O{sub 9+δ} were investigated. • The rising ρ by Y doping can be mitigated by the coupled Fe doping. • The increased Seebeck coefficient by Y doping can be maintained in co-doped system. • The co-doped system leads to an improvement of the thermoelectric performance. • The co-doped system may preserve the merits from each component doping. - Abstract: A series of Y and Fe co-doped Ca{sub 3−x}Y{sub x}Co{sub 4−y}Fe{sub y}O{sub 9+δ} (0 ⩽ x ⩽ 0.3, 0 ⩽ y ⩽ 0.1) samples synthesized by auto-combustion reaction and followed by a spark plasma sintering (SPS) processing with the effects of Fe and Y doping on the high temperature (RT to 800 °C) thermoelectric properties were systematically investigated. For the Fe-doped system (x = 0, y ⩽ 0.1), the electrical resistivity (ρ) decreased over the whole measured temperature range, while the Seebeck coefficient (S) remained almost the same. For the co-doped system, at any fixed Fe doping content, both ρ and S tended to increase with increasing Y dopants, however, the effect is more substantial on ρ than on S, particularly in the low temperature regime. In contrast to ρ and S, the in-plane thermal conductivity (κ) is only slightly influenced by Y and Fe substitutions. Among all the investigated samples, the co-doped sample with x = 0.1 and y = 0.03 showed a decrease of ρ, enhanced power factor over the measured temperature range, and improved ZT at 800 °C as compared to un-doped Ca{sub 3}Co{sub 4}O{sub 9+δ}.

  19. 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.

  20. Increased luminescence and improved decay kinetics in lithium and cerium co-doped yttrium aluminum garnet scintillators grown by the Czochralski method

    Science.gov (United States)

    Dickens, Peter T.; Haven, Drew T.; Friedrich, Stephan; Saleh, Muad; Lynn, Kelvin G.

    2017-03-01

    In this study, four yttrium aluminum garnet single crystals co-doped with cerium and lithium were produced by the Czochralski method and the scintillation and defect properties were investigated. Our results demonstrated an increase in luminescence with Li co-doping as well as elimination of longer decay times. Surprisingly, although Li is monovalent, no oxidation of cerium from Ce3+ to Ce4+ was found as would be expected to maintain charge neutrality. Additionally, thermoluminescence results indicated a reduction in the trapping of charge carriers by shallow and deep traps, and room temperature photoluminescence measurements showed an improvement in the Ce3+ 5d to 4f transition efficiency.

  1. Co-Doped Zn1-xCdxS nanocrystals from metal-organic framework precursors: porous microstructure and efficient photocatalytic hydrogen evolution.

    Science.gov (United States)

    Tang, Xiu; Zhao, Jia-Hui; Li, Yu-Han; Zhou, Zi-Ji; Li, Kui; Liu, Fu-Tian; Lan, Ya-Qian

    2017-08-15

    Nanoporous Co-doped Zn1-xCdxS were facilely fabricated via adopting ZIFs as templates, and Cd(NO3)2 and thiourea as precursors. The highly porous microstructure and uniform Co-doping of the photocatalyst afford a high H2-production rate (45.2 and 422.2 times larger than those of Zn0.5Cd0.5S and CdS), providing an effective way for the development of high performance nanoporous photocatalysts.

  2. Tuneable Giant Magnetocaloric Effect in (Mn,Fe)2(P,Si) Materials by Co-B and Ni-B Co-Doping

    OpenAIRE

    Nguyen Thang; Niels Harmen van Dijk; Ekkes Brück

    2016-01-01

    The influence of Co (Ni) and B co-doping on the structural, magnetic and magnetocaloric properties of (Mn,Fe) 2 (P,Si) compounds is investigated by X-ray diffraction (XRD), differential scanning calorimetry, magnetic and direct temperature change measurements. It is found that Co (Ni) and B co-doping is an effective approach to tune both the Curie temperature and the thermal hysteresis of (Mn,Fe) 2 (P,Si) materials without losing either the giant magnetocaloric effect or the pos...

  3. 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.

  4. Effect of thermal treatment on room-temperature ferromagnetism in Co-doped ZnO powders

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Xueyun [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Ge Shihui [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)], E-mail: zhxy06@lzu.cn; Yao Dongsheng; Zuo Yalu; Xiao Yuhua [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2008-09-01

    The Co-doped ZnO powders were synthesized by sol-gel method, and treated at different temperatures (673-873 K) in the presence or absence of NH{sub 3} atmosphere for 0.5 and 2 h, respectively. X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) show that better crystal structure can cause larger ferromagnetism and the second phase (Co{sub 3}O{sub 4}) is the reason for saturation magnetization decrease of the sample sintered at higher temperature in air. XPS and nuclear magnetic resonance (NMR) prove the existence of Co{sup 2+} ions in the Zn{sub 0.9}Co{sub 0.1}O and the absence of Co clusters, indicating intrinsic ferromagnetism of the samples treated in air. However, strong ferromagnetism of the samples annealed in NH{sub 3} is ascribed to cobalt nitride formed during annealing.

  5. Luminescence and cathodoluminescent properties of monoclinic Y2WO6 co-doped with Dy-Bi

    Science.gov (United States)

    Hu, Peiju; Zhang, Wei; Hu, Zhengfa; Feng, Zuyong; Ma, Lun; Zhang, Xiuping; Sheng, Xia; Luo, Li; Wang, Yinhai

    2017-08-01

    Dy-Bi co-doped yttrium tungstate crystal materials were synthesized by high temperature solid-state method. To reveal the photoluminescence features and properties of the samples, some measurements have been taken. It turned out that different Bi3+ concentrations play obvious influence in emission performance, and show visible light emission under ultraviolet light excitation. Besides, the effect of temperature on phase structure of samples has also been studied here. Superhigh X-ray luminescence of the phosphors exhibited the promising application in the field of high energy detection. The X-ray irradiation crystal resistance stability of the phosphors has also been investigated through the subsequent testing of XRD and spectra.

  6. Combinatorial approach to MgHf co-doped AlN thin films for Vibrational Energy Harvesters

    Science.gov (United States)

    Nguyen, H. H.; Oguchi, H.; Kuwano, H.

    2016-11-01

    In this report, we studied MgHf co-doped AlN ((Mg,Hf)xA11-xN) aiming for developing an AlN-based dielectric material with the large piezoelectric coefficient. To rapidly screen the wide range of composition, we applied combinatorial film growth approach. To get continuous composition gradient on a single substrate, films were deposited on Si (100) substrates by sputtering AlN and Mg-Hf targets simultaneously. Crystal structure was investigated by X-ray diffractometer equipped with a two-dimensional detector (2D-XRD). Composition was determined by Energy Dispersive Spectroscopy (EDS). These studies revealed that we successfully covered the widest ever composition range of 0 x x = 0.24, which will lead to the highest enhancement in the piezoelectric coefficient. The results of this study opened the way for high-throughput development of the dielectric materials.

  7. Optimized flat supercontinuum generation in high nonlinear fibers pumped by a nanosecond Er/Yb Co-doped fiber amplifier

    Science.gov (United States)

    Ouyang, D. Q.; Guo, C. Y.; Ruan, S. C.; Yan, P. G.; Wei, H. F.; Luo, J.

    2014-04-01

    Flat supercontinuum generation has been demonstrated in high nonlinear fibers with zero dispersion wavelengths at 1480 and 1500 nm, which were pumped by a MOPA structured Er/Yb co-doped fiber amplifier based on a modulated nanosecond seed laser with the wavelength of 1552 nm. The spectra and output powers affected by the zero dispersion wavelengths, fiber lengths and pump pulse widths were investigated experimentally. A flat spectrum with 5 dB bandwidth from 1220 nm to beyond 1700 nm (assuming the pump peak was filtered) in the optical spectrum analyzer detectable range was finally obtained by optimizing the fiber length and pump pulse width. The maximum output power was 1.02 W, including the peaks near 1550 nm.

  8. Twin grain boundary mediated ferromagnetic coupling in Co-doped ZnO: First-principles calculations

    Science.gov (United States)

    Wu, Jingjing; Tang, Xin; Pu, Chunying; Long, Fei; Tang, Biyu

    2017-01-01

    First principle calculation, based on density functional theory, is applied to study the electronic and magnetic properties of Co-doped ZnO ∑7 (12 3 ̅0) twin grain boundary. Co atoms substituting Zn at the threefold-coordination sites have the lowest formation energy, compared with other sites. More importantly, the configuration can result in the stable formation of ferromagnetic state (FM). Meanwhile, the strong Co-Co interaction is found to be responsible for the ferromagnetic state. Due to the structural character of the twin grain boundary, periodical defects can be offered, which favors the macroscopic FM ordering. The result also gives us a new thinking to understand the origin of FM in transition metal doped ZnO.

  9. Ion-exchanged Er3+/Yb3+ co-doped waveguide amplifiers longitudinally pumped by broad area lasers.

    Science.gov (United States)

    Donzella, V; Toccafondo, V; Faralli, S; Di Pasquale, F; Cassagnettes, C; Barbier, D; Figueroa, H Hernandez

    2010-06-07

    A multimode pumping scheme for Er(3+)/Yb(3+) co-doped waveguide amplifiers based on broad area lasers at around 980 nm is presented. The proposed amplifier is fabricated by ion-exchange (IE) technique on silicate and phosphate glasses. The highly efficient energy transfer from Yb(3+) to Er(3+) ions, combined with the use of low cost and high power broad area laser, allows the realization of high performance and cost-effective integrated amplifiers. The structure has been designed and numerically studied using a 3D finite element modelling tool, and over 3 dB/cm small signal gain has been predicted for an optimized amplifier. Preliminary characterization of an amplifier structure provides a first experimental evidence of the novel multimode longitudinal pumping.

  10. Phosphate modified N/Si co-doped rutile TiO2 nanorods for photoelectrochemical water oxidation

    Science.gov (United States)

    Zhang, Xiaofan; Zhang, Bingyan; Luo, Yanping; Lv, Xiaowei; Shen, Yan

    2017-01-01

    Surface modification of TiO2 film provides possibilities to improve photoelectrochemical (PEC) activity. In this study, we report on phosphate modified N/Si co-doped TiO2 nanorods films (Pi-N/Si-TiO2 NRs) for PEC water oxidation. Compared to the pristine TiO2 NRs, the Pi-N/Si-TiO2 NRs photoanode shows a 4.65-fold enhanced photocurrent density (1.44 mA cm-2) under light illumination. This significant improvement can be attributed to the synergistic effect of phosphate modification and the N and Si co-dopants. In addition to the improvement of ultraviolet and visible light response by N and Si co-dopants, phosphate modification is mainly responsible for charge transfer at the interface of the photoanode/electrolyte.

  11. Al and Fe co-doped transparent conducting ZnO thin film for mediator-less biosensing application

    Directory of Open Access Journals (Sweden)

    Shibu Saha

    2011-12-01

    Full Text Available Highly c-axis oriented Al and Fe co-doped ZnO (ZAF thin film is prepared by pulsed laser deposition. Fe introduces redox centre along with shallow donor level while Al doping enhances conductivity of ZnO, thus removing the requirement of both mediator and bottom conducting layer in bioelectrode. Model enzyme (glucose oxidase, was immobilized on surface of ZAF matrix. Cyclic voltammetry and photometric assay show that prepared bio-electrode is sensitive to glucose concentration with enhanced response of 0.18 μAmM-1cm-2 and low Km ∼ 2.01 mM. The results illustrate that ZAF is an attractive matrix for realization of miniaturized mediator-less solid state biosensor.

  12. Optical and Piezoelectric Study of KNN Solid Solutions Co-Doped with La-Mn and Eu-Fe

    Directory of Open Access Journals (Sweden)

    Jesús-Alejandro Peña-Jiménez

    2016-09-01

    Full Text Available The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN co-doped with the La3+–Mn4+ and Eu3+–Fe3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La3+–Mn4+ and Eu3+–Fe3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications.

  13. Yb3+ and Er3+ co-doped Y2Ce2O7 nanoparticles: synthesis and spectroscopic properties

    Indian Academy of Sciences (India)

    Honghui Jiang; Weixiong You; Xiaolin Liu; Jinsheng Liao; Ping Wang; Bin Yang

    2013-12-01

    Yb3+ and Er3+ co-doped Y2Ce2O7 nanoparticles sintered at different temperatures were prepared by homogeneous co-precipitation method. The products were characterized by X-ray powder diffraction (XRD), energy-dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The results indicated that the particle sizes and morphologies of the samples were heavily influenced by the sintering temperature. As temperature increased, the particle sizes became gradually larger and more agglomerate. The emissions including green and red upconversion emissions were investigated under 980 nm excitation. The emission intensities of the samples also depended on the sintering temperature. Two photon processes were mainly responsible for green and red upconversion emissions.

  14. Ferromagnetism in co-doped zno particles prepared by vaporization-condensation in a solar image furnace

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, B. [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus Universitari de Bellaterra, Bellaterra 08193 (Spain)]. E-mail: ben.martinez@icmab.es; Sandiumenge, F. [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus Universitari de Bellaterra, Bellaterra 08193 (Spain); Balcells, Ll. [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus Universitari de Bellaterra, Bellaterra 08193 (Spain); Fontcuberta, J. [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus Universitari de Bellaterra, Bellaterra 08193 (Spain); Sibieude, F. [CNRS/Institut de science et genie des Materiaux et Procedes, BP5 Odeillo, 66125-cedex Font Romeu (France); Monty, C. [CNRS/Institut de science et genie des Materiaux et Procedes, BP5 Odeillo, 66125-cedex Font Romeu (France)

    2005-04-15

    We report on the structural and magnetic properties of Co-doped ZnO particles prepared by vaporization-condensation in the solar furnace in Odeillo. X-ray diffraction data show no traces of Co segregation or any other phase different from ZnO. High-resolution electron microscopy (HREM) and transmision electron microscopy (TEM) techniques have also been used to characterize particles. Irrespective of their composition, the shape and size of the obtained particles, as well as their magnetic properties, clearly depend on the preparation conditions. The samples prepared in vacuum exhibit hysteretic behavior with low coercivity (about 100Oe) at T=5K and saturation magnetization well below that expecte for Co{sup 2+} in a tetrahedral crystal field. On the other hand, samples prepared at high pressure (70-100Torr inside the balloon) are paramagnetic.

  15. Strategy for the maximum extraction of information generated from combinatorial experimentation of Co-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Suh, C., E-mail: changwon.suh@nrel.gov [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO (United States); Gorrie, C.W. [Department of Materials Science and Engineering, University of Florida, Gainesville, FL (United States); Perkins, J.D.; Graf, P.A.; Jones, W.B. [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO (United States)

    2011-01-15

    By expanding our level of understanding of structure-processing-property relationships through a data-mining methodology, this study demonstrates how to remove obstructions in complex high-throughput (HT) data analyses for developing new transparent conducting oxides. The demonstration is performed with principal component analysis (PCA) as an exploratory data analysis tool in the context of Co-doped ZnO (Co:ZnO) thin films generated from combinatorial HT syntheses. With the use of minimal available information, X-ray diffraction (XRD) patterns and their corresponding processing conditions, PCA enabled effective detection of pervasive changes in intensity and peak shifts as a function of composition, processing or a combination of both. These identifications are nearly impossible to detect via normal data interpretation methods. It was also possible to identify abnormal XRD patterns, unusual composition arrays (i.e. libraries), key chemistries in compositional arrays and critical peak occurrences.

  16. Study of electro-caloric effect in Ca and Sn co-doped BaTiO3 ceramics

    Science.gov (United States)

    Upadhyay, Sanjay Kumar; Fatima, Iram; Raghavendra Reddy, V.

    2017-04-01

    The present work deals with the study of structural, ferroelectric, dielectric and electro-caloric effects in lead free ferroelectric polycrystalline Ba1-x Ca x Ti0.95Sn0.05O3 (x  =  2, 5 and 10%) i.e. Ca, Sn co-doped BaTiO3 (BTO). Phase purity of the samples is confirmed from x-ray data by using Rietveld refinement. 119Sn Mössbauer reveals homogenous phase as well as iso-valent substitution of Sn at Ti site. Enhancements in ferroelectric and dielectric properties have been observed. Indirect method which is based on Maxwell equation has been used to determine the electro-caloric (EC) effect in the studied ferroelectric ceramics and maximum EC coefficient is observed for Ba0.95Ca0.05Ti0.95Sn0.05O3.

  17. Color tuning of Eu-Tb co-doped borophosphate glasses for white light through valence state adjustment

    Institute of Scientific and Technical Information of China (English)

    XU Suo-cheng; ZHENG Xi; TIAN Hua; LV Tian-shuai; WANG Peng; WANG Da-jian

    2011-01-01

    The dependence of color points of white light on the composition of borophosphate glasses co-doped with europium (Eu) and terbium (Tb) has been investigated in terms of valence change of rare earth ions.Under ultraviolet (UV) excitation,the white light is observed to be from a combination of 4f65d → 4f7band transition emission at 425 nm for Eu2+,5D0 → 7FJ (J=-l,2) lineemissions at 593 nm and 611 nm for Eu3+,and 5D4 → 7F5 band transition emission at 545 nm for Tb3+.By varying the glass composition,the resultant emission color can be tuned efficiently.Eventually,the optimized white light with commission intemational de l'Eclairage (CIE) coordinate of (0.3382,0.2763) and the correlate color temperature (CCT) at 5010 K are achieved.

  18. Thermal barrier coating by electron beam-physical vapor deposition of zirconia co-doped with yttria and niobia

    Directory of Open Access Journals (Sweden)

    Daniel Soares de Almeida

    2010-08-01

    Full Text Available The most usual ceramic material for coating turbine blades is yttria doped zirconia. Addition of niobia, as a co-dopant in the Y2O3-ZrO2 system, can reduce the thermal conductivity and improve mechanical properties of the coating. The purpose of this work was to evaluate the influence of the addition of niobia on the microstructure and thermal properties of the ceramic coatings. SEM on coatings fractured cross-section shows a columnar structure and the results of XRD show only zirconia tetragonal phase in the ceramic coating for the chemical composition range studied. As the difference NbO2,5-YO1,5 mol percent increases, the tetragonality increases. A significant reduction of the thermal conductivity, measured by laser flash technique in the zirconia coating co-doped with yttria and niobia when compared with zirconia-yttria coating was observed.

  19. [Direct upconversion sensitization luminescence comparison of the ErYb co-doped oxyfluoride fluoride pentaphosphate glass].

    Science.gov (United States)

    Chen, Xiao-bo; Chen, Luan; Zhao, Chen-yi; Sawanobori, N; Ma, Hui; Song, Zeng-fu

    2003-02-01

    This paper investigates the direct upconversion sensitization luminescence of the ErYb co-doped oxyfluoride glass (ErYb: FOG), fluoride glass (ErYb: ZBLAN) and pentaphosphate noncrystalline (ErYb: PP) excited by a 966 nm diode laser. The splendid upconversion luminescence phenomenon is found. It is resulted from that the Yb3+ concentration in rather high, the energy transfer among Er(3+)-Yb3+ and Yb(3+)-Yb3+ ions is rather strong. An important fact is found that the direct upconversion sensitization luminescence of ErYb: FOG is about 100-100,000 times greater than that of ErYb: PP. And meanwhile it is interesting that the upconversion luminescence intensity of ErYb: FOG is near to that of ErYb: ZBLAN. It is significant to enhance the comprehensive level of up-conversion luminescence.

  20. Luminescent properties and quenching effects of Pr3+ co-doping in SiO2:Tb3+/Eu3+ nanophosphors

    CSIR Research Space (South Africa)

    Mhlongo, GH

    2014-02-01

    Full Text Available Luminescence properties of Pr(sup3+) single doped SiO2 and Pr(sup3+) co-doped SiO(sub2):Tb(sup3+)/Eu(sup3+) nanophosphors synthesized using sol–gel method were investigated. X-ray diffraction (XRD), and scanning electron microscope (SEM) were used...

  1. Nonlinear optical property and fluorescence quenching behavior of PVP capped ZnS nanoparticles co-doped with Mn{sup 2+} and Sm{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Prasanth, S.; Irshad, P.; Raj, D. Rithesh; Vineeshkumar, T.V. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686562 (India); Philip, Reji [Optics group, Raman Research Institute, C.V. Raman Avenue, Bangalore 560080 (India); Sudarsanakumar, C., E-mail: c.sudarsan.mgu@gmail.com [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686562 (India)

    2015-10-15

    ZnS nanoparticles co-doped with different percentages of Mn{sup 2+} and Sm{sup 3+} were synthesized by the chemical co-precipitation method using polyvinylpyrrolidone (PVP) as capping agent. Cubic zinc blende phase of the samples was confirmed from X-ray diffraction. The strong interaction between PVP and ZnS nanoparticles was studied from Fourier Transform Infrared (FTIR) spectrum. The band gap values of ZnS and co-doped ZnS nanoparticles were calculated from UV‐Visible spectra. The photoluminescence spectra of pure ZnS nanoparticles showed an emission at 436 nm and when doped with Mn{sup 2+} and Sm{sup 3+} an extra peak with high intensity was observed at 596 nm. On increasing the mole percentage of dopants the intensity of the extra peak showed an enhancement until a certain concentration and then a reduction with further increase in concentration. The binding parameters were determined by Stern‐Volmer relation. The nonlinear absorption coefficients of the doped and undoped samples were calculated using Z-scan technique. - Highlights: • PVP capped ZnS nanoparticles co-doped with Mn{sup 2+} and Sm{sup 3+} were synthesized. • The band gap of ZnS and co-doped ZnS nanoparticles were determined. • On increasing the percentage of dopants quenching of PL intensity was observed. • The nonlinear absorption coefficients of the samples were investigated.

  2. Increased fluorescence intensity in CaTiO3:Pr3+ phosphor due to NH3 treatment and Nb Co-doping

    Science.gov (United States)

    Holliday, K. S.; Kohlgruber, T. A.; Tran, I. C.; Åberg, D.; Seeley, Z. M.; Bagge-Hansen, M.; Srivastava, A. M.; Cherepy, N. J.; Payne, S. A.

    2016-10-01

    Development of next generation red phosphors for commercial lighting requires understanding of how increased luminescence is achieved by various treatment strategies. In this work, we compare co-doping with Nb to NH3 treatment of CaTiO3:Pr phosphors to reveal a general mechanism responsible for the increased luminescence. The phosphors were synthesized using standard solid-state synthesis techniques and the fluorescence was characterized for potential use in fluorescent lighting, with 254 nm excitation. The lifetime of the fluorescence was determined and used to identify a change in a trap state by the co-doping of Nb5+ in the phosphor. The oxidation state of the Pr was probed by NEXAFS and revealed that both Nb5+ co-doping and NH3 treatment reduced the number of non-fluorescing Pr4+ centers. Calculations were performed to determine the energetically favorable defects. Vacuum annealing was also used to further probe the nature of the trap state. It was determined that NH3 treatments reduce the number of Pr4+ non-fluorescing centers, while Nb5+ co-doping additionally reduces the number of excess oxygen trap states that quench the fluorescence.

  3. Co-doped LaLa1-xSrxTiO3-d : A Diluted Magnetic Oxide System with High Curie Temperature

    OpenAIRE

    2002-01-01

    Ferromagnetism is observed at and above room temperature in pulsed laser deposited epitaxial films of Co-doped Ti-based oxide perovskite (La1-xSrxTiO3-d). The system has the characteristics of an intrinsic diluted magnetic semiconductor (metal) at low concentrations (

  4. Large power factor and anomalous Hall effect and their correlation with observed linear magneto resistance in Co-doped Bi2Se3 3D topological insulator

    Science.gov (United States)

    Singh, Rahul; Shukla, K. K.; Kumar, A.; Okram, G. S.; Singh, D.; Ganeshan, V.; Lakhani, Archana; Ghosh, A. K.; Chatterjee, Sandip

    2016-09-01

    Magnetoresistance (MR), thermo power, magnetization and Hall effect measurements have been performed on Co-doped Bi2Se3 topological insulators. The undoped sample shows that the maximum MR as a destructive interference due to a π-Berry phase leads to a decrease of MR. As the Co is doped, the linearity in MR is increased. The observed MR of Bi2Se3 can be explained with the classical model. The low temperature MR behavior of Co doped samples cannot be explained with the same model, but can be explained with the quantum linear MR model. Magnetization behavior indicates the establishment of ferromagnetic ordering with Co doping. Hall effect data also supports the establishment of ferromagnetic ordering in Co-doped Bi2Se3 samples by showing the anomalous Hall effect. Furthermore, when spectral weight suppression is insignificant, Bi2Se3 behaves as a dilute magnetic semiconductor. Moreover, the maximum power factor is observed when time reversal symmetry (TRS) is maintained. As the TRS is broken the power factor value is decreased, which indicates that with the rise of Dirac cone above the Fermi level the anomalous Hall effect and linearity in MR increase and the power factor decreases.

  5. Photocatalytic hydrogen generation enhanced by band gap narrowing and improved charge carrier mobility in AgTaO3 by compensated co-doping.

    Science.gov (United States)

    Li, Min; Zhang, Junying; Dang, Wenqiang; Cushing, Scott K; Guo, Dong; Wu, Nianqiang; Yin, Penggang

    2013-10-14

    The correlation of the electronic band structure with the photocatalytic activity of AgTaO3 has been studied by simulation and experiments. Doping wide band gap oxide semiconductors usually introduces discrete mid-gap states, which extends the light absorption but has limited benefit for photocatalytic activity. Density functional theory (DFT) calculations show that compensated co-doping in AgTaO3 can overcome this problem by increasing the light absorption and simultaneously improving the charge carrier mobility. N/H and N/F co-doping can delocalize the discrete mid-gap states created by sole N doping in AgTaO3, which increases the band curvature and the electron-to-hole effective mass ratio. In particular, N/F co-doping creates a continuum of states that extend the valence band of AgTaO3. N/F co-doping thus improves the light absorption without creating the mid-gap states, maintaining the necessary redox potentials for water splitting and preventing from charge carrier trapping. The experimental results have confirmed that the N/F-codoped AgTaO3 exhibits a red-shift of the absorption edge in comparison with the undoped AgTaO3, leading to remarkable enhancement of photocatalytic activity toward hydrogen generation from water.

  6. Energy transfer based photoluminescence properties of co-doped (Er3+ + Pr3+): PEO + PVP blended polymer composites for photonic applications

    Science.gov (United States)

    Naveen Kumar, K.; Kang, Misook; Bhaskar Kumar, G.; Ratnakaram, Y. C.

    2016-04-01

    Er3+, Pr3+ singly doped and co-doped PEO + PVP polymer composites have been synthesized by conventional solution casting method. The structural analysis has been carried out for all these polymer composites from XRD analysis. Raman spectral studies confirm the ion-polymer interactions and polymer complex formation. Thermal properties of pure polymer film has also been clearly elucidated by TG/DTA profiles. Well defined optical absorption bands pertaining to Er3+ and Pr3+ are observed in the absorption spectral profile and these bands are assigned with corresponding electronic transitions. The polymer films containing singly doped Er3+ and Pr3+ ions have displayed green and red emissions at 510 nm (2H11/2 → 4I15/2) and 688 nm (3P0 → 3F3) respectively under UV excitation source. Comparing the emission spectra of singly Er3+ and co-doped Er3+ + Pr3+: PEO + PVP polymer films, a significant red emission pertaining to Pr3+ions is remarkably enhanced in co-doped polymer system. This could be ascribed to possible energy transfer from Er3+ to Pr3+ in co-doped polymer system. The energy transfer mechanism is clearly demonstrated using their emission performances, overlapped spectral profiles and also life time decay dynamics. Thus, it could be suggested that Er3+: PEO + PVP, Pr3+: PEO + PVP and (Er3+ + Pr3+): PEO + PVP blended polymer films are potential materials for several photonic applications.

  7. Hydrothermal fabrication of multi-functional Eu3+ and Tb3+ co-doped BiPO4: Photocatalytic activity and tunable luminescence properties

    Science.gov (United States)

    Wang, Yao; Huang, Hongwei; Quan, Chaoming; Tian, Na; Zhang, Yihe

    2016-01-01

    We demonstrated for first time the tunable photoluminescence (PL) properties and photocatalytic activity of the Tb3+ and Eu3+ co-doped BiPO4 assemblies. They are fabricated via a facile hydrothermal approach. Through co-doping of Eu3+ and Tb3+ ions and changing the doping ratio, the emission color of the co-doped BiPO4 phosphors can be tuned precisely from green to yellow and red. Meanwhile, a very efficient energy transfer from Tb3+ to Eu3+ can be observed. Fascinatingly, a warmwhite color has been realized in the co-doped sample by tuning the ratio of Tb3+/Eu3+ to a certain value as displayed in the CIE chromaticity diagram. The doped BiPO4 samples also exhibit significantly enhanced photocatalytic activity compared to the pristine BiPO4 pertaining to Rhodamine (RhB) degradation under UV light. This enhancement should be attributed to the trapping electron effect induced by ion doping that endows BiPO4 with high separation of photoinduced electron-hole pairs, thereby greatly promoting the photocatalytic reactivity. It was corroborated by the electrochemical impedance spectra (EIS). Moreover, the crystal structure, microstructure and optical properties of as-prepared samples were investigated in details.

  8. Defects induced in Yb3+/Ce3+ co-doped aluminosilicate fiber glass preforms under UV and γ-ray irradiation

    DEFF Research Database (Denmark)

    Chiesa, Mario; Mattsson, Kent Erik; Taccheo, Stefano;

    2014-01-01

    A set of Ce-/Yb-co-doped silica optical fiber preform cores, differing in terms of dopant concentrations are studied by Electron Paramagnetic Resonance (EPR) spectroscopy before and after irradiation of the samples with excimer UV laser light and γ-rays. Evidence of Yb3+ clustering in the case of...

  9. Lanthanum and boron co-doped BiVO4 with enhanced visible light photocatalytic activity for degradation of methyl orange

    Institute of Scientific and Technical Information of China (English)

    王敏; 车寅生; 牛超; 党明岩; 董多

    2013-01-01

    BiVO4 photocatalysts co-doped with La and B were prepared by sol-gel method using citric acid as chelate. The samples were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), Bru-mauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectra (DRS) and the photocatalytic activity was investigated by photo-catalytic degradation of methyl orange (MO). The results showed that boron and lanthanum ions incorporated into the lattice of BiVO4, and co-doping led to more surface oxygen vacancies, high specific surface areas, small crystallite size, narrow band gap and intense light absorbance in visible region. And the doped La(III) ions could help the separation of photogenerated electrons. Com-pared with BiVO4 and B-BiVO4, the photocatalytic activity of La-B co-doped BiVO4 was remarkably improved due to the synergistic effects of the co-doped ions. The degradation rate of MO in 60 min was 98.4%when La doping content was 0.05 mol.%, which was much higher than that of pure BiVO4(20%) and B-BiVO4(37%).

  10. Large power factor and anomalous Hall effect and their correlation with observed linear magneto resistance in Co-doped Bi2Se3 3D topological insulator.

    Science.gov (United States)

    Singh, Rahul; Shukla, K K; Kumar, A; Okram, G S; Singh, D; Ganeshan, V; Lakhani, Archana; Ghosh, A K; Chatterjee, Sandip

    2016-09-21

    Magnetoresistance (MR), thermo power, magnetization and Hall effect measurements have been performed on Co-doped Bi2Se3 topological insulators. The undoped sample shows that the maximum MR as a destructive interference due to a π-Berry phase leads to a decrease of MR. As the Co is doped, the linearity in MR is increased. The observed MR of Bi2Se3 can be explained with the classical model. The low temperature MR behavior of Co doped samples cannot be explained with the same model, but can be explained with the quantum linear MR model. Magnetization behavior indicates the establishment of ferromagnetic ordering with Co doping. Hall effect data also supports the establishment of ferromagnetic ordering in Co-doped Bi2Se3 samples by showing the anomalous Hall effect. Furthermore, when spectral weight suppression is insignificant, Bi2Se3 behaves as a dilute magnetic semiconductor. Moreover, the maximum power factor is observed when time reversal symmetry (TRS) is maintained. As the TRS is broken the power factor value is decreased, which indicates that with the rise of Dirac cone above the Fermi level the anomalous Hall effect and linearity in MR increase and the power factor decreases.

  11. Improved flux-pinning properties of REBa{sub 2}Cu{sub 3}O{sub 7-z} films by low-level Co doping

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wentao; Pu, Minghua; Wang, Weiwei; Lei, Ming [Key Laboratory of Magnetic Levitation and Maglev Trains, Ministry of Education of China, Superconductivity R and D Centre (SRDC), Southwest Jiaotong University, Erhuanlu Beiyiduan 111, 610031 Chengdu (China); Cheng, Cuihua [Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wales, 2052 NSW, Sydney (Australia); Zhao, Yong [Key Laboratory of Magnetic Levitation and Maglev Trains, Ministry of Education of China, Superconductivity R and D Centre (SRDC), Southwest Jiaotong University, Erhuanlu Beiyiduan 111, 610031 Chengdu (China); Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wales, 2052 NSW, Sydney (Australia)

    2011-09-15

    Biaxially textured REBa{sub 2}Cu{sub 3-x}Co{sub x}O{sub 7-z} (RE = Gd,Y) films were prepared on (00l) LaAlO{sub 3} substrate using self-developed fluorine-free chemical solution deposition (CSD) approach. The in-field J{sub c} values are significantly improved for REBa{sub 2}Cu{sub 3-x}Co{sub x}O{sub 7-z} films through low-level Co doping. Co-doped GdBa{sub 2}Cu{sub 3}O{sub 7-z} film shows the highest J{sub c} values at higher temperatures and fields, whereas the J{sub c} values of Co-doped YBa{sub 2}Cu{sub 3}O{sub 7-z} film surpass that of other films at lower temperatures and fields. In addition, the volume pinning force densities of films with Co doping have been distinctly enhanced in the applied fields, indicating improved flux-pinning properties. The possible reasons are discussed in detail. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Enhanced coercivity in Co-doped α-Fe2O3 cubic nanocrystal assemblies prepared via a magnetic field-assisted hydrothermal synthesis

    Directory of Open Access Journals (Sweden)

    Kinjal Gandha

    2017-05-01

    Full Text Available Ferromagnetic Co-doped α-Fe2O3 cubic shaped nanocrystal assemblies (NAs with a high coercivity of 5.5 kOe have been synthesized via a magnetic field (2 kOe assisted hydrothermal process. The X-ray diffraction pattern and Raman spectra of α-Fe2O3 and Co-doped α-Fe2O3 NAs confirms the formation of single-phase α-Fe2O3 with a rhombohedral crystal structure. Electron microscopy analysis depict that the Co-doped α-Fe2O3 NAs synthesized under the influence of the magnetic field are consist of aggregated nanocrystals (∼30 nm and of average assembly size 2 μm. In contrast to the NAs synthesized with no magnetic field, the average NAs size and coercivity of the Co-doped α-Fe2O3 NAs prepared with magnetic field is increased by 1 μm and 1.4 kOe, respectively. The enhanced coercivity could be related to the well-known spin–orbit coupling strength of Co2+ cations and the redistribution of the cations. The size increment indicates that the small ferromagnetic nanocrystals assemble into cubic NAs with increased size in the magnetic field that also lead to the enhanced coercivity.

  13. Electrodeposited Co-doped NiSe2 nanoparticles film: a good electrocatalyst for efficient water splitting

    Science.gov (United States)

    Liu, Tingting; Asiri, Abdullah M.; Sun, Xuping

    2016-02-01

    In this communication, we report that a Co-doped NiSe2 nanoparticles film electrodeposited on a conductive Ti plate (Co0.13Ni0.87Se2/Ti) behaves as a robust electrocatalyst for both HER and OER in strongly basic media, with good activity over a NiSe2/Ti counterpart. This Co0.13Ni0.87Se2/Ti catalytic electrode delivers 10 mA cm-2 at an overpotential of 64 mV for HER and 100 mA cm-2 at an overpotential of 320 mV for OER in 1.0 M KOH. A voltage of only 1.62 V is required to drive 10 mA cm-2 for the two-electrode alkaline water electrolyzer using Co0.13Ni0.87Se2/Ti as an anode and cathode.In this communication, we report that a Co-doped NiSe2 nanoparticles film electrodeposited on a conductive Ti plate (Co0.13Ni0.87Se2/Ti) behaves as a robust electrocatalyst for both HER and OER in strongly basic media, with good activity over a NiSe2/Ti counterpart. This Co0.13Ni0.87Se2/Ti catalytic electrode delivers 10 mA cm-2 at an overpotential of 64 mV for HER and 100 mA cm-2 at an overpotential of 320 mV for OER in 1.0 M KOH. A voltage of only 1.62 V is required to drive 10 mA cm-2 for the two-electrode alkaline water electrolyzer using Co0.13Ni0.87Se2/Ti as an anode and cathode. Electronic supplementary information (ESI) available: Experimental section and supplementary figures. See DOI: 10.1039/c5nr07170d

  14. The combined effect of alumina and silica co-doping on the ageing resistance of 3Y-TZP bioceramics.

    Science.gov (United States)

    Samodurova, Anastasia; Kocjan, Andraž; Swain, Michael V; Kosmač, Tomaž

    2015-01-01

    The combined effect of alumina and silica co-doping on the ageing resistance of 3Y-TZP bioceramics was investigated. In order to differentiate between the distinct contributions of two dopants to the overall resistance to low-temperature degradation (LTD), specimens were prepared by infiltration of silica sol into pre-sintered 3Y-TZP pellets, produced from commercially available powders, which were alumina-free or contained 0.05 and 0.25 wt.%. After sintering, specimens were exposed to accelerated ageing in distilled water at 134°C for 6-48 h. X-ray diffraction was applied to quantify the tetragonal-to-monoclinic (t-m) phase transformation associated with the LTD, while a focused ion beam-scanning electron microscopy technique was employed to study the microstructural features in the transformed layer. The results showed that the minor alumina and/or silica additions did not drastically change the densities, grain sizes or mechanical properties of 3Y-TZP, but they did significantly reduce LTD. The addition of either alumina or silica has the potential to influence both the nucleation and the propagation of moisture-induced transformation, but in different ways and to different extents. The co-doped ceramics exhibited predominantly transgranular fracture, reflecting strong grain boundaries (limiting microcracking of the transformed layer), for alumina doping, and rounded grains with a glassy phase at multiple grain junctions (reducing internal stresses) for silica-doped material. These two additives evidently have different dominant mechanisms associated with the deceleration of LTD of 3Y-TZP, but their combination increases resistance to ageing, importantly, without reducing the fracture toughness of this popular biomaterial.

  15. Structure and properties of Co-doped ZnO films prepared by thermal oxidization under a high magnetic field.

    Science.gov (United States)

    Li, Guojian; Wang, Huimin; Wang, Qiang; Zhao, Yue; Wang, Zhen; Du, Jiaojiao; Ma, Yonghui

    2015-01-01

    The effect of a high magnetic field applied during oxidation on the structure, optical transmittance, resistivity, and magnetism of cobalt (Co)-doped zinc oxide (ZnO) thin films prepared by oxidizing evaporated Zn/Co bilayer thin films in open air was studied. The relationship between the structure and properties of films oxidized with and without an applied magnetic field was analyzed. The results show that the high magnetic field obviously changed the structure and properties of the Co-doped ZnO films. The Lorentz force of the high magnetic field suppressed the oxidation growth on nanowhiskers. As a result, ZnO nanowires were formed without a magnetic field, whereas polyhedral particles formed under a 6 T magnetic field. This morphology variation from dendrite to polyhedron caused the transmittance below 1,200 nm of the film oxidized under a magnetic field of 6 T to be much lower than that of the film oxidized without a magnetic field. X-ray photoemission spectroscopy indicated that the high magnetic field suppressed Co substitution in the ZnO lattice, increased the concentration of oxygen vacancies, and changed the chemical state of Co. The increased concentration of oxygen vacancies affected the temperature dependence of the resistivity of the film oxidized under a magnetic field of 6 T compared with that of the film oxidized without a magnetic field. The changes of oxygen vacancy concentration and Co state caused by the application of the high magnetic field also increase the ferromagnetism of the film at room temperature. All of these results indicate that a high magnetic field is an effective tool to modify the structure and properties of ZnO thin films.

  16. Lanthanum and zirconium co-doped ZnO nanocomposites: synthesis, characterization and study of photocatalytic activity.

    Science.gov (United States)

    Moafi, Hadi Fallah; Zanjanchi, Mohammad Ali; Shojaie, Abdollah Fallah

    2014-09-01

    Nanocomposits of zinc oxide co-doped with lanthanum and zirconium were prepared using the modified sol-gel method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), and BET surface area measurement. For comparison, the La and Zr mono doped ZnO have also been prepared under the same conditions. The XRD results revealed that all the materials showed a hexagonal wurtzite crystal structure. It was found that the particle size of La-Zr-doped ZnO is much smaller as compared to that of pure ZnO. The effect of operational parameters such as, doping concentration, catalyst loading, pH and initial concentration of methylene blue on the extent of degradation was investigated. The photocatalytic activity of the undoped ZnO, mono-doped and La-Zr-ZnO photocatalysts was evaluated by the photocatalytic degradation of methylene blue in aqueous solution. The presence of lanthanium and/or zirconium causes a red shift in the absorption band of ZnO. The results show that the photocatalytic activity of the La-Zr-ZnO photocatalyst is much higher than that of undoped and mono-doped ZnO, resulting from the La and Zr synergistic effect. The co-operation of the lanthanum and zirconium ion leads to the narrowing of the band gap and greatly improves the photocatalytic activity. The photocatalyst co-doped with lanthanum and zirconium 4 mol% shows the best photoactivity and photodecomposition efficiencies were improved by 92% under UV-Vis irradiation at the end of 30 min, compared with the pure and mono doped samples.

  17. Downconversion in Pr{sup 3+}–Yb{sup 3+} co-doped ZBLA fluoride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Maalej, O. [Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, Université du Maine, Av. O. Messiaen, 72085 Le Mans cedex 09 (France); Laboratoire de Chimie Inorganique, Université de Sfax, Faculté des Sciences de Sfax, BP 1171, 3000 Sfax (Tunisia); Boulard, B., E-mail: brigitte.boulard@univ-lemans.fr [Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, Université du Maine, Av. O. Messiaen, 72085 Le Mans cedex 09 (France); Dieudonné, B. [Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, Université du Maine, Av. O. Messiaen, 72085 Le Mans cedex 09 (France); Ferrari, M. [Institute of Photonics and Nanotechnology (CNR), CSMFO Lab., Via alla Cascata 56/C Povo, 38123 Trento (Italy); Dammak, M. [Laboratoire de Physique Appliquée, Groupe des Matériaux Luminescents, Université de Sfax, Faculté des Sciences de Sfax, BP 1171, 3000 Sfax (Tunisia); Dammak, M. [Laboratoire de Chimie Inorganique, Université de Sfax, Faculté des Sciences de Sfax, BP 1171, 3000 Sfax (Tunisia)

    2015-05-15

    Fluorozirconate ZBLA glasses with molar composition 57ZrF{sub 4}–34BaF{sub 2}–5LaF{sub 3}–4AlF{sub 3}–0.5PrF{sub 3}–xYbF{sub 3} (from x=0 to 10) were synthesized to evaluate the rate of the conversion of visible photons into infrared photons. The emission spectra in the near infrared (NIR) at 950–1100 nm and the luminescence decays in the visible and NIR indicate an energy transfer from Pr{sup 3+} to Yb{sup 3+} upon blue excitation of Pr{sup 3+} at 440 nm. The energy transfer efficiency increases with Yb{sup 3+} concentration to reach 86% with 0.5Pr{sup 3+}–10Yb{sup 3+} co-doping (in mol%). However, the quenching of the Yb{sup 3+} emission strongly reduces the efficiency of the downconversion process: the decay time values decrease from 600 µs (x=0.5 mol%) to 85 µs (x=10 mol%). - Highlights: • We synthesized 0.5Pr{sup 3+}–xYb{sup 3+} co-doped ZBLA glasses (from x=0 to 10 mol %). • Photoluminescence of Yb{sup 3+} was observed at 980 nm under blue excitation. • Time resolved measurements have been performed in the visible and near infrared. • Energy transfer efficiency from Pr{sup 3+} to Yb{sup 3+} reaches 86% in 0.5 Pr{sup 3+}–10Yb{sup 3+} glass.

  18. First-principles study of p-type ZnO by S-Na co-doping

    Science.gov (United States)

    Tan, Xingyi; Li, Qiang; Zhu, Yongdan

    2017-08-01

    Using the first-principles method based on the density functional theory, the formation energy, electronic structures of S-Na co-doping in ZnO were calculated. The calculated results show that NaZn-SO have smaller formation energy than Nain-SO in energy ranges from -3.10 to 0 eV of {μ }{{O}}, indicating that it opens up a new opportunity for growth the p-type ZnO. The band structure shows that the NaZn system is a p-type direct-band-gap semiconductor material and the calculated band gap (0.84 eV) is larger than pure ZnO (0.74 eV). The NaZn-SO system is also a p-type semiconductor material with a direct band gap (0.80 eV). The influence of S-Na co-doping in ZnO on p-type conductivity is also discussed. The effective masses of NaZn-SO are larger than effective masses of NaZn and the NaZn-SO have more hole carriers than NaZn, meaning the hole in the NaZn-SO system may have a better carrier transfer character. So we inferred that NaZn-SO should be a candidate of p-type conduction. Project supported by the Natural Science Foundation of Hubei Province, China (Nos. 2014CFB342, 2014CFB619) and the Doctoral Foundation for Scientific Research of Hubei University for Nationalities (No. MY2013B020).

  19. Hydrogen sulfide conversion with nanophase titania

    Science.gov (United States)

    Beck, D.D.; Siegel, R.W.

    1996-08-20

    A process is described for disassociating H{sub 2}S in a gaseous feed using an improved catalytic material in which the feed is contacted at a temperature of at least about 275 C with a catalyst of rutile nanocrystalline titania having grain sizes in the range of from about 1 to about 100 nanometers. Other transition metal catalysts are disclosed, each of nanocrystalline material with grain sizes in the 1-100 nm range. 5 figs.

  20. Sustainable steric stabilization of colloidal titania nanoparticles

    Science.gov (United States)

    Elbasuney, Sherif

    2017-07-01

    A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180-240 °C to ensure DDSA ring opening and binding to titania nanoparticles. Organic-modified titania demonstrated complete change in surface properties from hydrophilic to hydrophobic and exhibited phase transfer from the aqueous phase to the organic phase. Exclusive surface modification in the reactor was found to be an effective approach; it demonstrated surfactant loading level 2.2 times that of post synthesis surface modification. Titania was also stabilized in aqueous media using poly acrylic acid (PAA) as polar polymeric dispersant. PAA-titania nanoparticles demonstrated a durable amorphous polymeric layer of 2 nm thickness. This

  1. Titania-Silica Materials for Enhanced Photocatalysis.

    Science.gov (United States)

    Rico-Santacruz, Marisa; Serrano, Elena; Marcì, Giuseppe; García-López, Elisa I; García-Martínez, Javier

    2015-12-01

    Mesoporous titania-organosilica nanoparticles comprised of anatase nanocrystals crosslinked with organosilica moieties have been prepared by direct co-condensation of a titania precursor, tetrabuthylortotitanate (TBOT), with two organosilica precursors, 1,4-bis(triethoxysilyl) benzene (BTEB) and 1,2-bis(triethoxysilyl) ethane (BTEE), in mild conditions and in the absence of surfactant. These hybrid materials show both high surface areas (200-360 m(2)  g(-1) ) and pore volumes (0.3 cm(3)  g(-1) ) even after calcination, and excellent photoactivity in the degradation of rhodamine 6G and in the partial oxidation of propene under UV irradiation, especially after the calcination of the samples. During calcination, there is a change in the Ti(IV) coordination and an increase in the content of SiOTi moieties in comparison with the uncalcined materials, which seems to be responsible for the enhanced photocatalytic activity of hybrid titania-silica materials as compared to both uncalcined samples and the control TiO2 .

  2. 掺氮TiO2-xNx薄膜托槽生物相容性的实验研究%Biocompatibility of MBT straight wire appliance with nitrogen-doped titania TiO2-xNx film

    Institute of Scientific and Technical Information of China (English)

    张颖杰; 曹宝成; 王育华; 王璞; 张旭; 李娜

    2012-01-01

    目的 制备掺氮TiO2-xNx薄膜托槽并评价薄膜托槽的生物相容性.方法 采用射频磁控溅射法在直丝弓金属托槽原材料试样表面制备锐钛矿相掺氮TiO2-xNx薄膜:①将薄膜材料(薄膜托槽组)和普通托槽材料(普通托槽组)分别缝合于大鼠颊黏膜2侧,2周后肉眼观察和组织学评价薄膜的口腔黏膜刺激性;②分别用薄膜材料(薄膜托槽组)、普通托槽材料(普通托槽组)浸提液和生理盐水(生理盐水组)给小鼠灌胃1周,观察小鼠的临床毒性体征、体质量增长率和重要脏器组织学变化以评价薄膜材料的短期全身毒性作用;③薄膜材料对兔血的溶血实验评价材料的溶血性;④分组同②,各组小鼠在24h内给予对应液灌胃2次,制备小鼠骨髓涂片评价薄膜材料可能的致畸致突变作用.结果 大鼠饮食、活动如常,薄膜托槽组的口腔黏膜与普通托槽组组织学表现一致,表明薄膜托槽无明显口腔黏膜刺激作用;短期全身毒性实验中,3组小鼠体质量增长率差异无统计学意义(P>0.05),所有动物未观察到明显的临床毒性体征,病理解剖也未观察到明显异常,表明薄膜托槽无明显短期全身毒性作用;溶血实验中,薄膜托槽组溶血率<5%,未发现红细胞破象,表明薄膜试样不引起急性溶血;微核实验中生理盐水组、薄膜托槽组和普通托槽组的微核率分别为1.48‰、2.08‰和2.16‰,均低于5‰,且两两之间差异无统计学意义(P>0.05).结论 掺氮TiO2-xNx薄膜托槽无口腔黏膜刺激性、无短期全身毒性、无溶血性以及无遗传毒性,具有良好的生物相容性.%Objective To produce nitrogen-doped titania (Ti02-xNx) film on MBT straight wire appliance and to evaluate its biocompatibility. Methods Radio-frequency magnetron sputtering was applied to produce TiO2-xNx film on the surface of raw material of MBT straight wire appliance. Biocompatibility was evaluated as

  3. Tuning the metal-insulator transition via epitaxial strain and Co doping in NdNiO3 thin films grown by polymer-assisted deposition

    Science.gov (United States)

    Yao, Dan; Shi, Lei; Zhou, Shiming; Liu, Haifeng; Zhao, Jiyin; Li, Yang; Wang, Yang

    2016-01-01

    The epitaxial NdNi1-xCoxO3 (0 ≤ x ≤ 0.10) thin films on (001) LaAlO3 and (001) SrTiO3 substrates were grown by a simple polymer-assisted deposition technique. The co-function of the epitaxial strain and Co doping on the metal-insulator transition in perovskite nickelate NdNiO3 thin films is investigated. X-ray diffraction and scanning electron microscopy reveal that the as-prepared thin films exhibit good crystallinity and heteroepitaxy. The temperature dependent resistivities of the thin films indicate that both the epitaxial strain and Co doping lower the metal-insulator (MI) transition temperature, which can be treated as a way to tune the MI transition. Furthermore, under the investigated Co-doping levels, the MI transition temperature (TMI) shifts to low temperatures with Co content increasing under both compressive and tensile strain, and the more distinction is in the former situation. When x is increased up to 0.10, the insulating phase is completely suppressed under the compressive strain. With the strain increases from compression to tension, the resistivities are enhanced both in the metal and insulating regions. However, the Co-doping effect on the resistivity shows a more complex situation. As Co content x increases from zero to 0.10, the resistivities are reduced both in the metal and insulating regions under the tensile strain, whereas they are enhanced in the high-temperature metal region under the compressive strain. Based on the temperature dependent resistivity in the metal regions, it is suggested that the electron-phonon coupling in the films becomes weaker with the increase of both the strain and Co-doping.

  4. Tuning the metal-insulator transition via epitaxial strain and Co doping in NdNiO{sub 3} thin films grown by polymer-assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Dan; Shi, Lei, E-mail: shil@ustc.edu.cn; Zhou, Shiming; Liu, Haifeng; Zhao, Jiyin; Li, Yang [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Yang [Instrumental Analysis Center, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2016-01-21

    The epitaxial NdNi{sub 1-x}Co{sub x}O{sub 3} (0 ≤ x ≤ 0.10) thin films on (001) LaAlO{sub 3} and (001) SrTiO{sub 3} substrates were grown by a simple polymer-assisted deposition technique. The co-function of the epitaxial strain and Co doping on the metal-insulator transition in perovskite nickelate NdNiO{sub 3} thin films is investigated. X-ray diffraction and scanning electron microscopy reveal that the as-prepared thin films exhibit good crystallinity and heteroepitaxy. The temperature dependent resistivities of the thin films indicate that both the epitaxial strain and Co doping lower the metal-insulator (MI) transition temperature, which can be treated as a way to tune the MI transition. Furthermore, under the investigated Co-doping levels, the MI transition temperature (T{sub MI}) shifts to low temperatures with Co content increasing under both compressive and tensile strain, and the more distinction is in the former situation. When x is increased up to 0.10, the insulating phase is completely suppressed under the compressive strain. With the strain increases from compression to tension, the resistivities are enhanced both in the metal and insulating regions. However, the Co-doping effect on the resistivity shows a more complex situation. As Co content x increases from zero to 0.10, the resistivities are reduced both in the metal and insulating regions under the tensile strain, whereas they are enhanced in the high-temperature metal region under the compressive strain. Based on the temperature dependent resistivity in the metal regions, it is suggested that the electron-phonon coupling in the films becomes weaker with the increase of both the strain and Co-doping.

  5. Cr3+ and Nb5+ co-doped Ti2Nb10O29 materials for high-performance lithium-ion storage

    Science.gov (United States)

    Yang, Chao; Yu, Shu; Ma, Yu; Lin, Chunfu; Xu, Zhihao; Zhao, Hua; Wu, Shunqing; Zheng, Peng; Zhu, Zi-Zhong; Li, Jianbao; Wang, Ning

    2017-08-01

    Ti2Nb10O29 is an advanced anode material for lithium-ion batteries due to its large specific capacity and high safety. However, its poor electronic/ionic conductivity significantly limits its rate capability. To tackle this issue, a Cr3+-Nb5+ co-doping is employed, and a series of CrxTi2-2xNb10+xO29 compounds are prepared. The co-doping does not change the Wadsley-Roth shear structure but increases the unit-cell volume and decreases the particle size. Due to the increased unit-cell volumes, the co-doped samples show increased Li+-ion diffusion coefficients. Experimental data and first-principle calculations reveal significantly increased electronic conductivities arising from the formation of impurity bands after the co-doping. The improvements of the electronic/ionic conductivities and the smaller particle sizes in the co-doped samples significantly contribute to improving their electrochemical properties. During the first cycle at 0.1 C, the optimized Cr0.6Ti0.8Nb10.6O29 sample delivers a large reversible capacity of 322 mAh g-1 with a large first-cycle Coulombic efficiency of 94.7%. At 10 C, it retains a large capacity of 206 mAh g-1, while that of Ti2Nb10O29 is only 80 mAh g-1. Furthermore, Cr0.6Ti0.8Nb10.6O29 shows high cyclic stability as demonstrated in over 500 cycles at 10 C with tiny capacity loss of only 0.01% per cycle.

  6. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid.

    Science.gov (United States)

    Xie, Yibing; Zhao, Ye

    2013-12-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. © 2013 Elsevier B.V. All rights reserved.

  7. Ultrahigh temperature-sensitive silicon MZI with titania cladding

    Directory of Open Access Journals (Sweden)

    Jong-Moo eLee

    2015-05-01

    Full Text Available We present a possibility of intensifying temperature sensitivity of a silicon Mach-Zehnder interferometer (MZI by using a highly negative thermo-optic property of titania (TiO2. Temperature sensitivity of an asymmetric silicon MZI with a titania cladding is experimentally measured from +18pm/C to -340 pm/C depending on design parameters of MZI.

  8. Nanostructured carbon-crystalline titania composites from microphase separation of poly(ethylene oxide-b-acrylonitrile) and titania sols.

    Science.gov (United States)

    Stefik, Morgan; Lee, Jinwoo; Wiesner, Ulrich

    2009-05-14

    A simple "one-pot" method utilizing a graphitic carbon source containing poly(ethylene oxide-b-acrylonitrile) diblock copolymer as a structure directing agent was used to synthesize carbon-crystalline titania composites as well as crystalline mesoporous titania materials after oxidative carbon removal.

  9. Highly efficient hydrophobic titania ceramic membranes for water desalination.

    Science.gov (United States)

    Kujawa, Joanna; Cerneaux, Sophie; Koter, Stanisław; Kujawski, Wojciech

    2014-08-27

    Hydrophobic titania ceramic membranes (300 kD) were prepared by grafting of C6F13C2H4Si(OC2H5)3 and C12F25C2H4Si(OC2H5)3 molecules and thus applied in membrane distillation (MD) process of NaCl solutions. Grafting efficiency and hydrophobicity were evaluated by contact angle measurement, atomic force microscopy, scanning electron microscopy, nitrogen adsorption/desorption, and liquid entry pressure measurement of water. Desalination of NaCl solutions was performed using the modified hydrophobic membranes in air gap MD (AGMD) and direct contact MD (DCMD) processes in various operating conditions. High values of NaCl retention coefficient (>99%) were reached. The permeate fluxes were in the range 231-3692 g·h(-1)·m(-2), depending on applied experimental conditions. AGMD mode appeared to be more efficient showing higher fluxes and selectivity in desalination. Overall mass transfer coefficients (K) for membranes tested in AGMD were constant over the investigated temperature range. However, K values in DCMD increased at elevated temperature. The hydrophobic layer was also stable after 4 years of exposure to open air.

  10. Hollow mesoporous titania microspheres: New technology and enhanced photocatalytic activity

    Science.gov (United States)

    Feng, Zhenliang; Wei, Wenrui; Wang, Litong; Hong, Ruoyu

    2015-12-01

    Hollow titania microspheres (HTS) were fabricated via a sol-gel process by coating the hydrolysis product of titanium tetrabutoxide (TBOT) onto the amino (-NH2) modified porous polystyrene cross-linked divinyl benzene (PS-DVB) microspheres under changing atmospheric pressure, followed by calcination in nitrogen and air atmosphere. Particularly, the atmospheric pressure was continuously and regularly changed during the formation process of PS-DVB@TiO2 microspheres. Then the TiO2 particles were absorbed into the pores and onto the surface of PS-DVB as well. The resultant HTS (around 2 μm in diameter) featured a high specific surface area (84.37 m2/g), anatase crystal and stable hollow microsphere structure, which led to high photocatalysis activity. The photocatalytic degradation of malachite green (MG) organic dye solution was conducted under ultraviolet (UV) light irradiation, which showed a high photocatalytic ability (81% of MG was degraded after UV irradiation for 88 min). Therefore, it could be potentially applied for the treatment of wastewater contaminated by organic pollutants.

  11. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    Science.gov (United States)

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  12. Systematic approach on the fabrication of Co doped ZnO semiconducting nanoparticles by mixture of fuel approach for Antibacterial applications

    Science.gov (United States)

    Rajendar, V.; Dayakar, T.; Shobhan, K.; Srikanth, I.; Venkateswara Rao, K.

    2014-11-01

    Zinc oxide (ZnO) is a wide band gap semiconductor (3.2 eV) with a high exciton binding energy (60 meV), where it has wide applications in advanced spintronic devices. The theoretical prediction of room temperature ferromagnetism and also antibacterial activity will be possible through the investigation of diluted magnetic semiconductors (DMS), such as transition metal doped ZnO, especially Cobalt doped ZnO. The aim of the work is the synthesis of Cobalt (Co) doped ZnO nanopowders were prepared Zn1-xCoxO (0 ⩽ x ⩾ 0.09) nanopowders from Sol-Gel auto combustion method have been synthesized with precursors such as Zinc and Cobalt nitrates with the assistance Ammonium acetate & Urea as fuel by increasing the cobalt concentration in zinc oxide and their structural, morphological, optical, Thermal, magnetic and antibacterial properties were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission Electron microscope (TEM), UV-visible spectroscopy, thermo gravimetric/differential thermal analysis (TG/DTA) and vibrating sample magneto meter (VSM). From the antibacterial studies, against gram positive Bacillus subtilis bacteria is most abundant bacteria in soil and indoor atmosphere, which affects the stored spintronic devices so that the devices should be made with antibacterial activity of DMS like Co doped ZnO. In this article is found that ZnO:Co nanopowders with higher Co doping level (0.07 and 0.09 wt%) exhibit good antibacterial efficiency. The magnetization curves obtained using vibrating sample magnetometer (VSM) show a sign of strong room temperature ferromagnetic behavior when the Co doping level is 0.05 wt% and a weak room temperature ferromagnetic behavior Co doping level is below 0.07 wt%, and also they found to exhibit antiferromagnetic and paramagnetic properties, when the Co doping levels are 0.07 and 0.09 wt%, respectively, to enhance and increase the special magnetic and antibacterial property for

  13. An insight into doping mechanism in Sn–F co-doped transparent conducting ZnO films by correlating structural, electrical and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Mallick, Arindam; Sarkar, Sanjit; Ghosh, Tushar; Basak, Durga, E-mail: sspdb@iacs.res.in

    2015-10-15

    On the face of massively growing market of transparent optoelectronics, developing ZnO-based transparent conductive thin films as a promising substitute for indium-free transparent electrode is extremely important. However, the detailed function of the dopants, especially co-dopants acting on the electrical and optical properties of ZnO-based transparent conductive thin films is not clear yet. We present a detailed comparative investigation on the structural, electrical and optical properties of pulsed laser deposited ZnO thin films co-doped with Sn and F for the first time. An unexpected expansion in the lattice structure has been observed when Zn{sup 2+} are replaced by Sn{sup 4+} having smaller ionic radius. Electrical measurements show that there is no anticipated change in the carrier concentration with the dopant concentration. A minimum resistivity of 2.56 × 10{sup −3} Ohm-cm with a carrier concentration of 4.41 × 10{sup 20} cm{sup −3} has been obtained for 1 at.% each Sn–F co-doped film. Most interestingly, a significant improvement in the ultraviolet (UV)/visible (VIS) photoluminescence peak intensity in Sn doped and Sn–F co-doped films in correlation with the structural and electrical properties allows us to propose that Sn doping into ZnO lattice causes a screening of the native Zn vacancy defects. While the presence of F co-dopant induces Sn{sup 2+} to occupy the lattice sites, as evidenced from the lattice expansion, an insignificant increase in the carrier concentration as well as enhanced UV emission of the co-doped films. The results obtained in this study shed light on the development of ZnO-based transparent electrodes. - Highlights: • A comparative investigation on electrical and optical properties of F, Sn and Sn–F co-doped ZnO films has been done. • There is no significant correlation between the carrier concentration and dopant content. • The UV/vis PL peak intensity of the films gets better in Sn doped and best in the Sn

  14. Enhancing the electrochemical kinetics of high voltage olivine LiMnPO4 by isovalent co-doping.

    Science.gov (United States)

    Ramar, Vishwanathan; Balaya, Palani

    2013-10-28

    We report here doping of Fe(2+) and/or Mg(2+) in LiMnPO4 cathode material to enhance its lithium storage performance and appraise the effect of doping. For this purpose, LiMn0.9Fe(0.1-x)MgxPO4/C (x = 0 and 0.05) and LiMn0.95Mg0.05PO4/C have been prepared by a ball mill assisted soft template method. These materials were prepared with similar morphology, particle size and carbon content. Amongst them, the isovalent co-doped LiMn0.9Fe0.05Mg0.05PO4/C sample shows better electrochemical performance compared to LiMn0.9Fe0.1PO4/C and LiMn0.95Mg0.05PO4/C samples. For instance, a lithium storage capacity of 159 mA h g(-1) is obtained at 0.1 C for LiMn0.9Fe0.05Mg0.05PO4/C material with a relatively low polarization of ~139 mV. This is in sharp contrast to LiMn0.9Fe0.1PO4/C and LiMn0.95Mg0.05PO4/C which show only 136.8 and 128.4 mA h g(-1) at 0.1 C with the polarization of ~222 and 334 mV respectively. Further, the LiMn0.9Fe0.05Mg0.05PO4/C electrode delivers discharge capacities of 155.8, 141.4, 118.8, 104.6, 81.4 and 51.8 mA h g(-1) at 0.2, 0.5, 1, 2, 5 and 10 C respectively. This electrode material also retains a capacity of 116 mA h g(-1) at 1 C after 200 cycles, which is 96% of its initial capacity. Such improved cycling stability of LiMn0.9Fe0.05Mg0.05PO4/C is attributed to the suppressed Mn dissolution in the electrolyte compared to the other samples. Further, during the Li extraction process, delithiated phases created from the Fe(2+)/Fe(3+) redox reaction (~3.45 V) favor enhanced electrochemical activity of the succeeding Mn(2+)/Mn(3+) redox couples. The fully charged state (4.6 V) contains a partially lithiated phase owing to the presence of electrochemically inactive Mg(2+). The presence of such lithiated phase provides a favourable environment for the subsequent lithium insertion process. We also observe improved electronic conductivity and Li-ion diffusion for the co-doped sample compared to LiMnPO4 doped with either Fe(2+) or Mg(2+) by impedance measurements

  15. Synthesis, characterization and tin/copper-nitrogen substitutional effect on photocatalytic activity of honeycomb ordered P2-Na2Ni2TeO6

    Science.gov (United States)

    Kadari, Ramaswamy; Velchuri, Radha; Sreenu, K.; Ravi, Gundeboina; Munirathnam, Nagegownivari R.; Vithal, Muga

    2016-11-01

    We have successfully prepared visible light active tin/copper-nitrogen co-doped honeycomb ordered P2-Na2Ni2TeO6 photocatalysts by solid state/ion exchange methods. Powder XRD, TG analysis, SEM, surface area, O-N-H analysis, ICP-OES, FT-IR and UV-DRS measurements are employed to characterize all the samples. All the doped compositions adopted hexagonal lattice with space group P63/mcm. The photocatalytic activity of all the samples was studied against the degradation of methyl violet (MV) and methylene blue (MB) under visible light irradiation. The variation of the photocatalytic activity due to the substitution of cation, anion and co-doping in Na2Ni2TeO6 is investigated. Co-doped samples have exhibited higher activity compared to rest of the materials. The role of reactive intermediate species in the photocatalytic degradation of dyes is also studied using appropriate scavengers.

  16. Enhanced superconductivity of SmFeAsO co-doped by Scandium and Fluorine to increase chemical inner pressure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Haijie; Zheng, Ming; Fang, Aihua; Yang, Jianhua [CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Huang, Fuqiang, E-mail: huangfq@mail.sic.ac.cn [CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Xie, Xiaoming; Jiang, Mianheng [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2012-10-15

    Sm{sub 1-x/3}Sc{sub x/3}FeAsO{sub 1-x}F{sub x} (x=0.09-0.27) were synthesized by the mechanical alloying and subsequent low temperature rapid sintering (2 h at 950 Degree-Sign C). The superconducting transition temperature (T{sub c}) increased with the doping level of x. The optimal doping achieved a T{sub c} up to 53.5 K in Sm{sub 0.93}Sc{sub 0.07}FeAsO{sub 0.79}F{sub 0.21}. The higher T{sub c} value was attributed to the increased chemical inner pressure from local lattice distortion induced by smaller-size dopants, which was further confirmed by Sm{sub 1-x}Sc{sub x}FeAsO{sub 0.88}F{sub 0.12} (x=0.04, 0.08, 0.12). Accordingly, larger lattice distortion can enhance the superconductivity below the doping limit. Similar phenomenon was also observed in the La{sub 1-x}Y{sub x}FeAsO{sub 0.8}F{sub 0.2} (x=0.4, 0.5, 0.6). - Graphical abstract: The introduction of Sc{sup 3+} and F{sup -} in SmFeAsO leads to higher chemical inner pressure generated by larger lattice distortion, which is the reason of the improved T{sub c}. Highlights: Black-Right-Pointing-Pointer The superconducting properties of Sm{sub 1-x/3}Sc{sub x/3}FeAsO{sub 1-x}F{sub x} are investigated. Black-Right-Pointing-Pointer The co-doping of Sc{sup 3+} and F{sup -} in SmFeAsO leads to higher chemical inner pressure. Black-Right-Pointing-Pointer Higher chemical inner pressure is beneficial to the superconductivity. Black-Right-Pointing-Pointer The co-doped samples of La{sub 1-x}Y{sub x}FeAsO{sub 0.8}F{sub 0.2} further demonstrate the assumption.

  17. Spectroscopic properties of tellurite glasses co-doped with Er{sup 3+} and Yb{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Leal, J.J. [Instituto Politécnico Nacional CICATA-Unidad Altamira, Tamaulipas 89600 (Mexico); Narro-García, R., E-mail: roberto.narro@gmail.com [Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, A.P. 1-1010, Querétaro 76000, Querétaro México (Mexico); Desirena, H. [Centro de Investigaciones en Óptica, A.P. 1-948, León, Gto. 37150 (Mexico); Marconi, J.D. [Universidade Federal do ABC, SP (Brazil); Rodríguez, E. [Instituto Politécnico Nacional CICATA-Unidad Altamira, Tamaulipas 89600 (Mexico); Linganna, K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); De la Rosa, E. [Centro de Investigaciones en Óptica, A.P. 1-948, León, Gto. 37150 (Mexico)

    2015-06-15

    Spectroscopic characterization of Er{sup 3+}/Yb{sup 3+} co-doped tellurite glasses 70.8TeO{sub 2}–5Al{sub 2}O{sub 3}–13K{sub 2}O–(11−x)–BaO–0.2Er{sub 2}O{sub 3}–xYb{sub 2}O{sub 3}, where x=0, 0.4, 0.8, 1.2 and 2 mol% has been carried out through X-ray diffraction, Raman, absorption and luminescence spectra. The Judd–Ofelt intensity parameters were calculated for 0.2 mol% Er{sup 3+}-doped glass and are used to evaluate radiative properties such as transition probabilities, branching ratios and radiative lifetime. The emission cross-section of the {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition has been calculated from the absorption data using McCumber's theory. The emission intensity of both, visible and infrared signals as a function of Yb{sub 2}O{sub 3}, have been studied under 980 nm and 375 nm laser excitation. The physical mechanisms responsible for both, visible and infrared signals in the tellurite samples have been explained in terms of the energy transfer and excited state absorption process. The FWHM of the {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition as a function of Yb{sub 2}O{sub 3} mol% and distance (δ) between the laser focusing point and the end-face of the glass has been reported. It was observed both, experimentally and numerically, a change in the FWHM with variations of δ less than 8 mm. The latter was attributed to the radiation trapping effect. - Highlights: • Er{sup 3+}/Yb{sup 3+} co-doped tellurite glasses were fabricated by the melt-quenching technique. • The structural, thermal and optical properties of the tellurite glasses were studied. • The radiation trapping effect has been observed in small tellurite glass samples. • Tellurite glasses could be a potential material for fiber fabrication.

  18. Luminescence of Eu{sup 3+}/Gd{sup 3+} co-doped silicate sol–gel powders

    Energy Technology Data Exchange (ETDEWEB)

    Szpikowska-Sroka, Barbara, E-mail: barbara.szpikowska-sroka@us.edu.pl [Institute of Chemistry, University of Silesia, Szkolna 9 Street, 40-007 Katowice (Poland); Pawlik, Natalia [Institute of Chemistry, University of Silesia, Szkolna 9 Street, 40-007 Katowice (Poland); Swinarew, Andrzej S. [Institute of Materials Science, University of Silesia, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Pisarski, Wojciech A. [Institute of Chemistry, University of Silesia, Szkolna 9 Street, 40-007 Katowice (Poland)

    2015-10-15

    Eu{sup 3+}/Gd{sup 3+} co-doped silicate sol–gel powders have been successfully obtained. The effect of high concentration of gadolinium ions on visible emission of europium ions in prepared materials has been studied under different excitation wavelengths. Spectroscopic properties of Eu{sup 3+} and Gd{sup 3+} ions in prepared powders were determined based on excitation and emission measurements as well as luminescence decay analysis. In the visible spectral range the observed emission bands correspond to transitions of trivalent Eu{sup 3+} and Gd{sup 3+} ions. The changes of excitation mechanism of optically active dopants significantly affect the increase of luminescence intensities. The luminescence lifetime for the {sup 5}D{sub 0} level of Eu{sup 3+} ions in examined samples upon excitation at λ{sub exc}=273 nm ({sup 8}S{sub 7/2}→{sup 6}I{sub J} transition of Gd{sup 3+}) is about 12 times longer in comparison to excitation at λ{sub exc}=393 nm ({sup 7}F{sub 0}→{sup 5}L{sub 6} transition of Eu{sup 3+}). The luminescence intensity coefficient R (Eu{sup 3+}) was also calculated, and it was found that ratio of the intensity of red to orange emission depends on the excitation wavelength. Based on determined spectroscopic parameters the energy transfer process from Gd{sup 3+} to Eu{sup 3+} ions was confirmed. - Highlights: • Eu{sup 3+}/Gd{sup 3+} co-doped silicate powders have been fabricated. • The emission bands in the visible range correspond to transitions of Eu{sup 3+} and Gd{sup 3+}. • The lifetime for the {sup 5}D{sub 0} state of Eu{sup 3+} upon excitation at 273 nm is strongly prolonged. • Efficient energy transfer from Gd{sup 3+} to Eu{sup 3+} ions was confirmed.

  19. Thermoluminescence analysis of co-doped NaCl at low temperature irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Zaragoza, E., E-mail: ecruz@nucleares.unam.m [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F. (Mexico); Ortiz, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F. (Mexico); Unidad Profesional Interdisciplinaria de Ingenieria y Tecnologias Avanzadas, IPN, Av. Instituto Politecnico Nacional 2580, Col. La Laguna Ticoman, 07340 Mexico D.F. (Mexico); Furetta, C. [Touro University Rome, Circne Gianicolense 15-17, 00153 Rome (Italy); Flores J, C.; Hernandez A, J.; Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, 01000 Mexico D.F. (Mexico)

    2011-02-15

    The thermoluminescent response and kinetics parameters of NaCl, doubly activated by Ca-Mn and Cd-Mn ions, exposed to gamma radiation are analyzed. The doped NaCl samples were irradiated at relative low temperature, i.e. at the liquid nitrogen temperature (LNT) and at dry ice temperature (DIT), and the glow curves obtained after 2 Gy of gamma irradiation were analyzed using the computerized glow curve deconvolution (CGCD). An evident variation in the glow curve structure after LNT and DIT was observed. It seems that different kinds of trapping levels are activated at relative low temperature. The original two prominent peaks in compositions A (Ca,Mn) and B (Ca,Mn) have been changed in only one main peak with satellites in the low temperature side of the glow curves. In compositions C (Cd,Mn) and D (Cd,Mn), low temperature peaks become stronger and prominent than the high temperature peaks; this effect could be explained considering that the trapping probability for low temperature traps, the one very close to the conduction band, is enhanced by low temperatures during irradiation.

  20. The synthesis of Fe-N co-doping nano TiO2/SO42-%Fe-N共掺杂纳米TiO2/SO42-的合成

    Institute of Scientific and Technical Information of China (English)

    张忠坤; 郭国伟; 张昊; 王玉童; 韩丽; 王剑峰

    2015-01-01

    Fe-N co-doping nano-particles TiO2/SO42- is synthesized by sol-gel method using titanium tetraisopropoxide as the precursor, n-propanol as solvent, concentrated sulfuric acid as catalyst and inhibitor, acetylacetone as stabilizer, Fe2(SO4)3 as iron source and urea as nitrogen source. The prepared products are characterized by XRD, SEM, UV-vis, and BET surface area. The results indicated that the Fe-N co-doping TiO2/SO42- nano-particles have been synthesized as anatase. The absorption edge of the material showed red-shift gradually with doping weight of Fe-N increasing, in which the most appropriate weight of both of Fe and N is 3.0 wt%. The absorption edge of the material reaches 495 nm.The absorption intensity of the material in the visible region increases with the increase of doping concentration.%以工业级异丙醇钛为钛源,正丙醇为溶剂,浓硫酸为催化剂和抑制剂,乙酰丙酮为稳定剂,硫酸铁为铁源,尿素为氮源,采用溶胶-凝胶法制备了Fe-N共掺杂的纳米TiO2/SO42-。利用XRD、UV-vis、N2吸附脱附、SEM对所制备的材料进行了表征。结果表明:合成的Fe-N共掺杂的纳米TiO2/SO42-为锐钛矿型,随着掺杂量的增加,吸收边逐渐红移,在Fe和N掺杂量均为3.0 wt%时红移效果最佳,且吸收边红移至495 nm附近,在可见光区的吸收强度随着掺杂量的增加而增大。

  1. 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.

  2. Hydrogen peroxide route to Sn-doped titania photocatalysts

    Science.gov (United States)

    2012-01-01

    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. PMID:23035821

  3. The mechanism of action of titania catalysts in sulfur recovery

    Energy Technology Data Exchange (ETDEWEB)

    Clark, P.D.; Dowling, N.I.; Huang, M.

    2010-01-15

    The mechanism recovering sulfur from hydrocarbons using titania catalysts in a commercial titanium oxide (TiO{sub 2}) Claus process was investigated. Titania (Ti{sup 3+}) was obtained by hydrogen sulfide (H{sub 2}S) treatment at 320 degrees C for 1 hour. The presence of Ti{sup 3+} increases carbon disulphide (CS{sub 2}) hydrolysis as well as the CS{sub 2} conversion activities at the first converter condition. The catalytic behaviour of titania in the Claus process was described. The high CS{sub 2} activity of titania at first and second converted conditions was described along with its ability to promote conversion via either hydrolysis or reaction with sulphur dioxide (SO{sub 2}). The surface sulfate on titania is more active at first converter condition, but the slow turnover of sulfate back to thiosulfates at low temperature inhibits the Claus reaction and the carbon disulphide conversion at the third converter condition. Comparing alumina and titania for carbon disulphide conversion, titania gives a better conversion over time, although during the first 6 hours of the process alumina appears to provide the better conversion. 12 figs.

  4. Hydrogen peroxide route to Sn-doped titania photocatalysts.

    Science.gov (United States)

    Stengl, Václav; Grygar, Tomáš Matys; Henych, Jiří; Kormunda, Martin

    2012-10-05

    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 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 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.

  5. Mid-infrared photo-luminescence and energy transfer around 2.8 μm from Dy3+/Tm3+ co-doped tellurite glass

    Science.gov (United States)

    Wang, Caizhi; Tian, Ying; Li, Huanhuan; Liu, Qunhuo; Huang, Feifei; Li, Bingpeng; Zhang, Junjie; Xu, Shiqing

    2017-09-01

    Tellurite glasses co-doped with Dy3+ and Dy3+/Tm3+ have been synthesized. Emission around 2.8 μm is successfully obtained in present glass upon excitation of a conventional 808 nm laser diode. Judd-Ofelt intensity parameters and radiative properties of Dy3+ ions are calculated using the Judd-Ofelt theory. The luminescence characteristics and energy transfer mechanism are investigated and discussed. According to the absorption, fluorescence spectra and lifetime measurements, Tm3+ ions can effectively absorb excitation and transfer their energy to Dy3+ ions with high efficiency (up to 86.80%). Hence, the results demonstrate that Dy3+/Tm3+ co-doped tellurite glasses possessing excellent spectroscopic properties is a potential medium for mid-infrared laser.

  6. The effect of Bi{sup 3+} and Li{sup +} co-doping on the luminescence characteristics of Eu{sup 3+}-doped aluminum oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Padilla-Rosales, I., E-mail: ipadilla@cinvestav.mx [Centro de Investigación y de Estudios Avanzados del IPN, Nanociencias y Nanotecnología, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Martinez-Martinez, R. [Instituto de Física y Matemáticas, Universidad Tecnológica de la Mixteca, Carretera a Acatlima Km. 2.5, CP 69000 Huajuapan de León, Oax, México (Mexico); Cabañas, G. [Centro de Investigación y de Estudios Avanzados del IPN, Nanociencias y Nanotecnología, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Falcony, C. [Centro de Investigación y de Estudios Avanzados del IPN, Departamento de Física, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico)

    2015-09-15

    The incorporation of Bi{sup 3+} and Li{sup +} as co-dopants in Eu{sup 3+}-doped aluminum oxide films deposited by the ultrasonic spray pyrolysis technique and its effect on the luminescence characteristics of this material are described. Both Bi{sup 3+} and Li{sup +} do not introduce new luminescence features but affect the luminescence intensity of the Eu{sup 3+} related emission spectra as well as the excitation spectra. The introduction of Bi{sup 3+} generates localized states in the aluminum oxide host that result in a quenching of the luminescence intensity, while Li{sup +} and Bi{sup 3+} co-doping increase the luminescence intensity of these films. - Highlights: • Li and Bi co-doping increase the luminescence. • Bi creates localized states in the Al{sub 2}O{sub 3} host. • Li was incorporated as a co-activator.

  7. Flat supercontinuum generation covering C-band to U-band in two-stage Er/Yb co-doped double-clad fiber amplifier

    Science.gov (United States)

    Zhang, B.; Hou, J.; Liu, P. Z.; Jin, A. J.; Jiang, Z. F.

    2011-11-01

    Supercontinuum generation in the gain fiber in two-stage nanosecond pulse Er/Yb co-doped double-clad fiber amplifier had been demonstrated for the first time to our knowledge instead of the conventional method in which nonlinear fiber was pumped by lasers. The Er/Yb co-doped double-clad fiber acts as the gain media and nonlinear media. This route reduces the splice between fiber laser and nonlinear fiber. The supercontinuum was achieved with spectrum range from 1530 nm to beyond 1700 nm at 6 W output power covering the total C-band to U-band. From the analyzing of the spectra at different stages in the amplifiers, it can be found that it is the modulation instability in the anomalous dispersion regime that initiates the supercontinuum gereration.

  8. 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.

  9. Electroluminescence of zinc selenium (ZnSe) nanocrystals co-doped with poly[2-methoxy-5-(2'-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV).

    Science.gov (United States)

    Yin, Yuehong; Deng, Zhenbo; Lü, Zhaoyue; Zou, Ye; Chen, Zheng; Du, Hailiang; Wang, Yongsheng

    2011-11-01

    We have synthesized water soluble zinc selenium (ZnSe) nanocrystals by using mercaotoacetic acid (TGA) as the stabilizer. The synthesized ZnSe nanocrystals were co-doped with poly[2-methoxy-5-(2'-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) to fabricate an organic/ inorganic hybrid multilayer light-emitting device (LED). The structure of the device was indium-tin-oxide (ITO)/poly (ethylene-dioxythiophene):poly(styrenesul-fonate) (PEDOT:PSS)/MEH-PPV:ZnSe/bathocuproine (BCP)/tris-(8-hydroxylquinoline)-aluminum (Alq3)/Al. We demonstrate that the device has a lower driving voltage and increased current densities and power efficiencies owing to the co-doped ZnSe quantum dots. We obtained good efficiency of the devices when the quality ratio of MEH-PPV and ZnSe quantum dots was 1:1.

  10. Zirconium and silver co-doped TiO2 nanoparticles as visible light catalyst for reduction of 4-nitrophenol, degradation of methyl orange and methylene blue

    Science.gov (United States)

    Naraginti, Saraschandra; Stephen, Finian Bernard; Radhakrishnan, Adhithya; Sivakumar, A.

    2015-01-01

    Catalytic activity of Zr and Ag co-doped TiO2 nanoparticles on the reduction of 4-nitrophenol, degradation of methylene blue and methyl orange was studied using sodium borohydride as reducing agent. The nanoparticles were characterized using X-ray diffraction, energy dispersive X-ray, high resolution transmission electron microscopy, selected area electron diffraction and UV-Vis spectroscopy. The rate of the reduction/degradation was found to increase with increasing amount of the photocatalyst which could be attributed to higher dispersity and small size of the nanoparticles. The catalytic activity of Zr and Ag co-doped TiO2 nanoparticles showed no significant difference even after recycling the catalyst four times indicating a promising potential for industrial application of the prepared photocatalyst.

  11. Zirconium and silver co-doped TiO2 nanoparticles as visible light catalyst for reduction of 4-nitrophenol, degradation of methyl orange and methylene blue.

    Science.gov (United States)

    Naraginti, Saraschandra; Stephen, Finian Bernard; Radhakrishnan, Adhithya; Sivakumar, A

    2015-01-25

    Catalytic activity of Zr and Ag co-doped TiO2 nanoparticles on the reduction of 4-nitrophenol, degradation of methylene blue and methyl orange was studied using sodium borohydride as reducing agent. The nanoparticles were characterized using X-ray diffraction, energy dispersive X-ray, high resolution transmission electron microscopy, selected area electron diffraction and UV-Vis spectroscopy. The rate of the reduction/degradation was found to increase with increasing amount of the photocatalyst which could be attributed to higher dispersity and small size of the nanoparticles. The catalytic activity of Zr and Ag co-doped TiO2 nanoparticles showed no significant difference even after recycling the catalyst four times indicating a promising potential for industrial application of the prepared photocatalyst.

  12. Upconversion Luminescence Properties of Ho3+, Tm3+, Yb3+ Co-Doped Nanocrystal NaYF4 Synthesized by Hydrothermal Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nanocrystal of upconversion (UC) phosphor Ho3+, Tm3+, and Yb3+ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho3+ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The result shows that Ho3+, Tm3+, and Yb3+ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.

  13. Photonic, and photocatalytic behavior of TiO{sub 2} mediated by Fe, CO, Ni, N doping and co-doping

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jia [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan (China); Zhao, Y.F. [Institute of Coordination Bond Metrology and Engineering, School of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Wang, T., E-mail: twang@zju.edu.cn [College of Electrical Engineering, Zhejiang University (China); Li, H., E-mail: Lihui02@tyut.edu.cn [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan (China); Li, C., E-mail: canli1983@gmail.com [Institute of Coordination Bond Metrology and Engineering, School of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China)

    2015-12-01

    Fe, Co, Ni, or N addition could modulate the photonic and catalytic responses of TiO{sub 2} for photocatalysts applications. Their morphologies, structures, compositions and photocatalytic performance in the degradation of methylene blue were characterized by scanning electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, Raman spectra and X-ray photoelectron spectroscopy. The results showed that dopants affect the electronic transition energies by changing the optical band gap and the impurity absorption peaks of the specimens. Especially, co-doping enhances the visible-light photocatalytic activity of TiO{sub 2} by 4–10 times that of pure TiO{sub 2}, and the Co and N co-doping derives 10-fold photocatalytic activity.

  14. Visible up-conversion and near-infrared luminescence of Er3+/Yb3+ co-doped SbPO4-GeO2 glasses

    Science.gov (United States)

    Manzani, D.; Montesso, M.; Mathias, C. F.; Krishanaiah, K. Venkata; Ribeiro, S. J. L.; Nalin, M.

    2016-07-01

    Recent advances in glass chemistry have led to new multifunctional optical glasses of great technological importance. Glasses containing high amounts of antimony have been studied for use in nonlinear optics, near-infrared transmission, and as hosts for rare-earth ions in photonic devices. This work describes a luminescence study of Er3+ and Er3+/Yb3+ co-doping in a new SbPO4-GeO2 binary glass system. Near-infrared and visible up-conversion emissions were observed in the green and red regions, which are enhanced when the samples are co-doped with Yb3+. Near-infrared emissions have good quantum efficiency and full width half maximum of 61 nm. Visible up-conversion emissions are governed by two photons and described by excited state absorption, energy transfer and cross-relaxation processes.

  15. γ irradiation induced effects on bismuth active centres and related photoluminescence properties of Bi/Er co-doped optical fibres

    Science.gov (United States)

    Sporea, D.; Mihai, L.; Neguţ, D.; Luo, Yanhua; Yan, Binbin; Ding, Mingjie; Wei, Shuen; Peng, Gang-Ding

    2016-07-01

    We investigate the effects of γ irradiation on bismuth active centres (BACs) and related photoluminescence properties of bismuth/erbium co-doped silica fibre (BEDF), [Si] ~28, [Ge] ~1.60, [Al] ~0.10, [Er] ~ BACs and their photoluminescence performance, as important changes in absorption and emission properties associated with the 830 nm pump produces the direct evidence of γ irradiation effects on BAC-Si. We notice that the saturable to unsaturable absorption ratio at pump wavelength could be increased with high dose γ irradiation, indicating that emission and pump efficiency could be increased by γ irradiation. Our experimental results also reveal good radiation survivability of the BEDF under low and moderate γ irradiation. Our investigation suggests the existence of irradiation related processing available for tailoring the photoluminescence properties and performance of bismuth doped/co-doped fibres.

  16. Characterization, Degradation, and Reaction Pathways of Indoor Toluene over Visible-light-driven S, Zn Co-doped TiO2

    Science.gov (United States)

    Chu, H.; Lin, Y. H.; Lin, C. Y.

    2017-01-01

    Sulfur and Zinc co-doped TiO2 prepared by a sol-gel method to degrade toluene under a fluorescent lamp was investigated. The results indicate that S,Zn co-doped TiO2 photocatalysts are mainly nano-size with an anatase phase structure. The degradation reactions of toluene were performed under various operation conditions. The results show that the toluene conversion increases with increasing toluene concentration and decreasing relative humidity. Based on the results of activity test, S0.05Zn0.001/TiO2 was chosen for further studies. The main oxidation products of toluene photodegradation are CO2, H2O, benzyl alcohol, acetone, butadiene and acetic acid. Two possible mechanisms have been developed for photodegradation of toluene in a dry and a humid environment.

  17. Iron-boron pairing kinetics in illuminated p-type and in boron/phosphorus co-doped n-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Möller, Christian, E-mail: cmoeller@cismst.de [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany); TU Ilmenau, Institut für Physik, Weimarer Str. 32, 98693 Ilmenau (Germany); Bartel, Til; Gibaja, Fabien [Calisolar GmbH, Magnusstraße 11, 12489 Berlin (Germany); Lauer, Kevin [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany)

    2014-07-14

    Iron-boron (FeB) pairing is observed in the n-type region of a boron and phosphorus co-doped silicon sample which is unexpected from the FeB pair model of Kimerling and Benton. To explain the experimental data, the existing FeB pair model is extended by taking into account the electronic capture and emission rates at the interstitial iron (Fe{sub i}) trap level as a function of the charge carrier densities. According to this model, the charge state of the Fe{sub i} may be charged in n-type making FeB association possible. Further, FeB pair formation during illumination in p-type silicon is investigated. This permits the determination of the charge carrier density dependent FeB dissociation rate and in consequence allows to determine the acceptor concentration in the co-doped n-type silicon by lifetime measurement.

  18. Effect of Mg co-doping on cathodoluminescence properties of LuGAGG:Ce single crystalline garnet films

    Science.gov (United States)

    Schauer, P.; Lalinský, O.; Kučera, M.; Lučeničová, Z.; Hanuš, M.

    2017-10-01

    Mg2+ co-doped (LuGd)3(GaAl)5O12:Ce (LuGAGG:Ce,Mg) multicomponent single crystalline epitaxial garnet films were prepared and their cathodoluminescence (CL) and thermoluminescence (TSL) properties were studied in this paper. The films were prepared using the liquid phase epitaxy from lead-free BaO-B2O3-BaF2 flux and their scintillation properties were characterized using the 10 keV collimated e-beam. More specifically, temperature dependent CL intensity, CL emission spectra, CL decay characteristics as well as TSL emission characteristics of the mentioned films were measured. At the highest content of Mg (700 ppm), the CL decay time was as low as 28 ns and the CL afterglow was as low as 0.01% at 1 μs after the e-beam excitation cut-off, which are important parameters for electron detectors in e-beam devices. The CL temperature quenching of the studied films began above room temperature. An increase of Mg concentration to or above 280 ppm quenched the characteristic CL emission of LuGAGG:Ce,Mg. The TSL measurements show that the trap population in studied garnet samples is considerably suppressed. The LuGAGG:Ce,Mg multicomponent single crystalline epitaxial films were evaluated as the perspective fast scintillators for the electron detectors in the e-beam devices.

  19. Enhancement of magnetic and ferroelectric behaviour in (Ca, Co) co-doped HoMnO3 multiferroics

    Science.gov (United States)

    Rout, P. P.; Pradhan, S. K.; Das, S. K.; Samantaray, S.; Roul, B. K.

    2013-11-01

    The effect of sintering temperature on structural, electrical and magnetic behaviours of polycrystalline samples of Ho0.9Ca0.1Mn0.9Co0.1O3 prepared by the solid state reaction route sintered at three different temperature 1250 °C, 1350 °C, 1450 °C for 10 h are investigated. XRD, SEM, magnetization, dielectric and ferroelectric measurements were carried out. Experimental results showed the nucleation of orthorhombic phase as the sintering temperature increases from 1250 °C to 1450 °C. Ferroelectric (Tc) and antiferromagnetic transition temperature (TN) increases with increase in sintering temperature. Strong bifurcation of FC and ZFC curve in sample sintered at 1450 °C showed a clear onset of ferromagnetic state around 165 °K, which is confirmed from M to H graph at 165 °K. All the sample showed ferroelectric behaviour at room temperature which are leaky in nature. Sintering temperature along with Ca and Co doping in HoMnO3 ceramics plays an important role in phase transformation along with enhancement in multiferroic properties.

  20. Enhanced lithium ion storage in TiO2 nanoparticles, induced by sulphur and carbon co-doping

    Science.gov (United States)

    Ivanov, Svetlozar; Barylyak, Adriana; Besaha, Khrystyna; Dimitrova, Anna; Krischok, Stefan; Bund, Andreas; Bobitski, Jaroslav

    2016-09-01

    Sulphur and carbon codoped anatase nanoparticles are synthesized by one-step approach based on interaction between thiourea and metatitanic acid. Electron microscopy shows micrometer-sized randomly distributed crystal aggregates, consisting of many 25-40 nm TiO2 nanoparticles. The obtained phase composition and chemical states of the elements in the structure are analyzed by means of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD shows that after doping the tetragonal anatase structure is preserved. Further data assessment by Rietveld refinement allows detection of a slight increase of the c lattice parameter and volume related to incorporation of the doping elements. XPS confirms the coexistence of both elemental and oxide carbon forms, which are predominantly located on the TiO2 particle surface. According to XPS analysis sulphur occupies titanium sites and the element is present in S6+ sulfate environment. Analysis based on cyclic voltammetry and galvanostatic intermittent titration (GITT) suggests an accelerated Li+ transport in the doped TiO2 structure. The synthesized S and C co-doped anatase has an excellent electrochemical performance in terms of capacity and very fast lithiation kinetics, superior to the non-doped TiO2. The material displays 83% capacity retention for 500 galvanostatic cycles and nearly 100% current efficiency.

  1. Magnetic and magnetocaloric properties of Ba and Ti co-doped SrRuO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal; De, S. K., E-mail: msskd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2014-12-28

    Temperature evolution of magnetic properties in Ba and Ti doped SrRuO{sub 3} has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161 K to 149 K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak which shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d{sup 0} orbitals for Ru with more delocalized 4d{sup 4} orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160 K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO{sub 3} makes the system more interesting.

  2. The effect of Pr co-doping on the densification and electrical properties of Sr-LaAlO3

    Directory of Open Access Journals (Sweden)

    L. A. Villas-Boas

    2013-01-01

    Full Text Available Perovskite-type materials have been investigated extensively in the attempt to discover new electrolyte materials for solid oxide fuel cells (SOFC operating at low temperatures. These materials include LaAlO3-based perovskite, which, when adequately doped, presents high ionic conductivity. However, despite the high conductivity of doped LaAlO3, two characteristics limit its application as solid electrolyte: low sinterability and p-type electronic conductivity in oxidizing conditions. The purpose of this work was to investigate the effect of Pr co-doping on the densification and electrical conductivity of Sr-doped LaAlO3. The addition of Pr eliminated the deficiencies mentioned above. Pr in solid solution acts as a perfect sintering aid because promoted densification without forming secondary phase which should be detrimental for electrical conduction. The addition of Pr also increased the bulk electrical conductivity measured in air atmosphere but had no effect at low oxygen partial pressure. However, the addition of Pr had a strong effect on the grain boundary, improving the ionic grain boundary electrical conductivity at air atmosphere which was attributed to the Pr influence on the space charge layer.

  3. Photoluminescence study of Sm{sup 3+}–Yb{sup 3+}co-doped tellurite glass embedding silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Reza Dousti, M., E-mail: mrdousti@ifsc.usp.br [Laboratório de Espectroscopia de Materiais Funcionais (LEMAF), Instituto de Fisica de São Carlos, Universidade de São Paulo, Av. Trabalhador So-carlense 400, São Carlos, SP 13566-590 (Brazil); Department of Physics, Tehran-North Branch, Islamic Azad University Tehran (Iran, Islamic Republic of); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Amjad, R.J. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Hosseinian S, R.; Salehi, M.; Sahar, M.R. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia)

    2015-03-15

    We report on the upconversion emission of Sm{sup 3+} ions doped tellurite glass in the presence of Yb{sup 3+} ions and silver nanoparticles. The enhancement of infrared-to-visible upconversion emissions is achieved under 980 nm excitation wavelength and attributed to the high absorption cross section of Yb{sup 3+} ions and an efficient energy transfer to Sm{sup 3+} ions. Further enhancements are attributed to the plasmonic effect via metallic nanoparticles resulting in the large localized field around rare earth ions. However, under excitation at 406 nm, the addition of Yb{sup 3+} content and heat-treated silver nanoparticles quench the luminescence of Sm{sup 3+} ions likely due to quantum cutting and plasmonic diluent effects, respectively. - Highlights: • Sm{sup 3+} tellurite glasses co-doped with Yb{sup 3+} ions and tri-doped with Yb{sup 3+}:Ag NPs were prepared. • In first step, Yb{sup 3+} ions enhanced the upconversion emissions of Sm{sup 3+} doped samples. • In second step, Ag NPs further enhanced the upconversion emissions in tri-doped glasses. • Finally, the quench in luminescence under 406 nm excitation is observed and discussed.

  4. Study on Co-doped ZnO comparatively by first-principles calculations and relevant experiments

    Science.gov (United States)

    Su, Y. L.; Zhang, Q. Y.; Zhou, N.; Ma, C. Y.; Liu, X. Z.; Zhao, J. J.

    2017-01-01

    Co-doped ZnO was studied using first-principles methods with comparison to experimental results taken from epitaxial Zn1-xCoxO (x 0.05) films. Density of Co2+ ions was determined using absorption spectra for the first time, and then a definite correlation between metallic Co clusters and the magnetism of the ZnCoO films was proved and the average number of Co atoms in the metallic Co clusters was estimated to be less than 200 using a superparamagnetic model. First-principles calculations of ZnCoO alloys and the relevant problems were discussed by comparing the electronic structures with absorption spectra and the results calculated by Tanabe-Sugano theory. U correction was proved to be necessary for calculating the band-gap energy of ZnCoO alloys, but other optical properties related to Co2+ ions are incorrect and the conclusion for magnetic properties is ambiguous due to uncertainty of the calculated highly localized states, which are in pressing for solution in study of material properties relevant to electronic structure.

  5. Synthesis and characterization of ZrO2-CuO co-doped ceria nanoparticles via chemical precipitation method

    Science.gov (United States)

    Viruthagiri, G.; Gopinathan, E.; Shanmugam, N.; Gobi, R.

    2014-10-01

    In the present study, the fluorite cubic phase of bare and ZrO2-CuO co-doped ceria (CeO2) nanoparticles have been synthesized through a simple chemical precipitation method. X-ray diffraction results revealed that average grain sizes of the samples are within 5-6 nm range. The functional groups present in the samples were identified by Fourier Transform Infrared Spectroscopy (FTIR) study. Surface area measurement was carried out for the ceria nanoparticles to characterize the surface properties of the synthesized samples. The direct optical cutoff wavelength from DRS analysis was blue-shifted evidently with respect to the bulk material and indicated quantum-size confinement effect in the nanocrystallites. PL spectra revealed the strong and sharp UV emission at 401 nm. The surface morphology and the element constitution of the pure and doped nanoparticles were studied by scanning electron microscope fitted with energy dispersive X-ray spectrometer arrangement. The thermal decomposition course was followed using thermo gravimetric and differential thermal analyses (TG-DTA).

  6. Structural, optical and photovoltaic properties of co-doped CdTe QDs for quantum dots sensitized solar cells

    Science.gov (United States)

    Ayyaswamy, Arivarasan; Ganapathy, Sasikala; Alsalme, Ali; Alghamdi, Abdulaziz; Ramasamy, Jayavel

    2015-12-01

    Zinc and sulfur alloyed CdTe quantum dots (QDs) sensitized TiO2 photoelectrodes have been fabricated for quantum dots sensitized solar cells. Alloyed CdTe QDs were prepared in aqueous phase using mercaptosuccinic acid (MSA) as a capping agent. The influence of co-doping on the structural property of CdTe QDs was studied by XRD analysis. The enhanced optical absorption of alloyed CdTe QDs was studied using UV-vis absorption and fluorescence emission spectra. The capping of MSA molecules over CdTe QDs was confirmed by the FTIR and XPS analyses. Thermogravimetric analysis confirms that the prepared QDs were thermally stable up to 600 °C. The photovoltaic performance of alloyed CdTe QDs sensitized TiO2 photoelectrodes were studied using J-V characteristics under the illumination of light with 1 Sun intensity. These results show the highest photo conversion efficiency of η = 1.21%-5% Zn & S alloyed CdTe QDs.

  7. TiO2 nanopowder co-doped with iodine and boron to enhance visible-light photocatalytic activity.

    Science.gov (United States)

    Ding, Jianqiang; Yuan, Yali; Xu, Jinsheng; Deng, Jian; Guo, Jianbo

    2009-10-01

    An iodine and boron co-doped TiO2 photocatalyst was prepared by the hydrolyzation-precipitation method. X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS) were applied to characterize the crystalline structure, light absorbing ability, and the chemical state of iodine and boron in the photocatalysts. The results of photocatalytic degradation of methyl orange demonstrated that the I-B-TiO2 catalyst prepared at 400 degrees C for 3 h exhibited the highest photocatalytic activity with a methyl orange degradation ratio of 61% under visible-light (lambda > or = 420 nm) irradiation for 120 min. The characterization results revealed that I-B-TiO2 is in conformity with the anatase TiO2 and that the doping of iodine and boron ions could efficiently inhibit the grain growth. Doped iodine was present in the multivalent forms of 17+, I- and I5+. Doped boron was present as B3+ in an as-prepared sample, forming a possible chemical environment such as B-O-Ti. Overall, the doping of I and B enhanced the ability of TiO2 to absorb visible-light, and it was observed that the photocatalytic activity of I-B-TiO2 was enhanced by the synergistic effect of I and B.

  8. Hydrothermal Synthesis and Up-Conversion Luminescence of Yb3+/Ho3+ Co-doped Y6WO12 Nanocrystals

    Science.gov (United States)

    Rao, Weifeng; Zhu, Qiansheng; Ren, Qiang; Wu, Chenchen; Miao, Juhong

    2017-08-01

    Yb3+/Ho3+ co-doped Y6WO12 nanocrystals with different concentrations of Ho3+ ions have been synthesized through a facile hydrothermal method followed by a subsequent heat treatment. The nanostructures, morphologies, and up-conversion luminescent properties of the as-prepared Y6WO12:Yb3+/Ho3+ nanocrystals were investigated by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence spectra. XRD results indicate that all the diffraction peaks of the samples match well with the cubic phase of Y6WO12. SEM images demonstrate that the samples consist of spherical-like nanoparticles ranging in size from about 30 nm to 50 nm, which increases slightly with the increase of sintering temperature. Under the excitation of a 980 nm diode laser, the as-prepared nanocrystals show bight red and green luminescence, which is attributed to the transition of 5F5 → 5I8 and 5F4, 5S2 → 5I8 of Ho3+, respectively. With the elevation of the heat treatment temperature from 700°C to 900°C, the up-conversion emission intensity goes up significantly. Additionally, the decay lifetimes data follow a bi-exponential nature. Both the emission intensity (red and green) and their corresponding decay lifetimes increase with increasing Ho3+ concentration, maximizing at 1.0 mol.%, and then decrease, which is mainly attributed to the concentration quenching effect.

  9. Effects of (La, Sr) co-doping on electrical conduction and magnetic properties of BiFeO3 nanoparticles

    Science.gov (United States)

    Liu, Li; Wang, Shouyu; Yin, Zi; Liu, Weifang; Xu, Xunling; Zhang, Chuang; Li, Xiu; Yang, Jiabin

    2016-09-01

    Multiferroic material as a photovoltaic material has gained considerable attention in recent years. Nanoparticles (NPs) La0.1Bi0.9-xSrxFeOy (LBSF, x = 0, 0.2, 0.4) with dopant Sr2+ ions were synthesized by the sol-gel method. A systematic change in the crystal structure from rhombohedral to tetragonal upon increasing Sr doping was observed. There is an obvious change in the particle size from 180 nm to 50 nm with increasing Sr substitution into LBFO. It was found that Sr doping effectively narrows the band gap from ˜ 2.08 eV to ˜ 1.94 eV, while it leads to an apparent enhancement in the electrical conductivity of LBSF NPs, making a transition from insulator to semiconductor. This suggests an effective way to modulate the conductivity of BiFeO3-based multiferroic materials with pure phase by co-doping with La and Sr at the A sites of BiFeO3. Project supported by the National Natural Science Foundation of China (Grant Nos. 11104202 and 51572193).

  10. Morphological evolution and electronic alteration of ZnO nanomaterials induced by Ni/Fe co-doping.

    Science.gov (United States)

    Fletcher, Cameron; Jiang, Yijiao; Sun, Chenghua; Amal, Rose

    2014-07-07

    Zinc oxide (ZnO) nanocrystals mono- and co-doped with nickel/iron were prepared using a facile solvothermal procedure. A significant change in the surface morphology from nanorods to plate-like nanoparticles was observed with an increase in the dopant concentration. The variations of their optical and electronic properties induced by metal dopants were investigated using a combination of characterization techniques and ab initio calculations. It is found that both nickel and iron atoms have been successfully incorporated into the crystal lattice rather than forming a secondary phase, suggesting good dispersion of dopants within the ZnO matrix. Doping with iron has red-shifted the absorption edges of ZnO towards the visible portion resulting in lower band gap energies with increasing dopant concentration. Evidenced by Raman and EPR spectroscopy, the addition of iron has been shown to promote the formation of more oxygen vacancy and crystal defects within the host lattice as well as increasing the free-electron density of the nanomaterial. The DFT plus Hubbard model calculations confirm that low concentration Ni-doping does not induce band gap narrowing but results in localized states. The calculations show that Fe-doping has the potential to greatly improve the optical absorption characteristics and lead to structural deformation, corroborating the UV-Vis, Raman, and EPR spectra.

  11. Synthesis and characterization of nanocrystalline Gd and Tb co-doped ceria-based electrolyte materials for IT-SOFC.

    Science.gov (United States)

    Choi, J W; Saradha, T; Heo, M H; Park, K

    2010-05-01

    Gd and Tb co-doped Ce0.8Gd0.2-xTb(x)O2-delta (0 < or = x < or = 0.09) nanopowders were synthesized by the combustion method using aspartic acid as fuel. The calcined powders formed a ceria-based single phase with a cubic fluorite structure. In addition, the powders were pure, homogeneous, and nanocrystalline nature, i.e., 20.1-23.4 nm in the calculated crystallite size. The partial incorporation of Tb for Gd caused a decrease in the average grain size of the sintered bodies. The high-quality nanosized Ce0.8Gd0.17Tb0.03O2-delta powders provided a high density, ultra-fine grain size, and high electrical conductivity even at the low sintering temperature of 1300 degrees C. The grain size and density of the Ce0.8Gd0.17Tb0.03O2-delta were approximately 146 nm and approximately 99% of the theoretical density, respectively, allowing enhanced electrical conductivity (0.106 Scm(-1) at 800 degrees C).

  12. 3D flexible O/N Co-doped graphene foams for supercapacitor electrodes with high volumetric and areal capacitances

    Science.gov (United States)

    Qin, Tianfeng; Wan, Zunyuan; Wang, Zilei; Wen, Yuxiang; Liu, Mengting; Peng, Shanglong; He, Deyan; Hou, Juan; Huang, Fei; Cao, Guozhong

    2016-12-01

    3D flexible O/N co-doped graphene foams (GF) have been designed and fabricated successfully via combining the compression/hot curing strategy with chemical reduction and hydrothermal treatment, in which melamine foams were used not only as the source of N/O functional groups for the introduction of pseudocapacitance but also as the sacrificial template to inhibit the agglomeration of graphene. Also, the mechanism for method of the compressing/hot curing has been investigated systematically. And the resultant GF demonstrates excellent mechanical strength and flexibility. When the compacting GF is used as free-standing electrodes for supercapacitor, it exhibits more excellent ability of charge storage than that of pristine graphene foams. And 10 MPa-GF electrodes delivers high areal capacitance of 375 μF cm-2 at a current density of 1 A g-1, excellent rate capabilities and superior cycling stability of above 100%. According to the analysis of capacitance contribution for 10 MPa-GF electrode, the pseudocapacitance originated from N/O functional groups is up to ∼65% of the contribution of total capacitance. Moreover, the symmetric supercapacitor comprised of 10 MPa-GF electrodes presents a maximum energy density of 16 Wh kg-1 (8 Wh L-1) and a maximum power density of 17 kW kg-1 (8.6 kW L-1).

  13. MOF-derived Co-doped nickel selenide/C electrocatalysts supported on Ni foam for overall water splitting

    KAUST Repository

    Ming, Fangwang

    2016-09-01

    It is of prime importance to develop dual-functional electrocatalysts with good activity for overall water splitting, which remains a great challenge. Herein, we report the synthesis of a Co-doped nickel selenide (a mixture of NiSe and NiSe)/C hybrid nanostructure supported on Ni foam using a metal-organic framework as the precursor. The resulting catalyst exhibits excellent catalytic activity toward the oxygen evolution reaction (OER), which only requires an overpotential of 275 mV to drive a current density of 30 mA cm. This overpotential is much lower than those reported for precious metal free OER catalysts. The hybrid is also capable of catalyzing the hydrogen evolution reaction (HER) efficiently. A current density of -10 mA cm can be achieved at 90 mV. In addition, such a hybrid nanostructure can achieve 10 and 30 mA cm at potentials of 1.6 and 1.71 V, respectively, along with good durability when functioning as both the cathode and the anode for overall water splitting in basic media.

  14. Adjustable up-conversion luminescence color in rare earth co-doped transparent oxyfluoride nano-glass-ceramics.

    Science.gov (United States)

    Song, Zhiguo; Zhou, Dacheng; Qiu, Jianbei

    2010-03-01

    Transparent oxyfluoride nano-glass-ceramics with highly efficient up-conversion and adjustable color luminescence were developed in the 28SiO2 x 17Al2O3 28PbF2 x 22CdF2 x 0.1NdF3 x xYbF3 x yHoF3 zTmF3 x (4.9 - x - y - z)GdF3 composition, in mol%. X-ray diffraction and transmission electron microscopy measurements revealed that heat treatments of the oxyfluoride glasses cause the homogeneous precipitation of rare-earth ions co-doped fluorite-type Pb(x)Cd1-xF2 nanocrystals of about 10 nm in diameter in the glass matrix. Under single 808 nm laser excitation, intense red, green and blue up-conversion luminescences were simultaneously observed in these transparent nano-glass-ceramics owing to the successive energy transfer from Nd3+ ions to Ho3+ and Tm3+ via Yb3+ ions. Various colors of luminescence, including bright perfect white light, can be tuned by adjusting the concentrations of the Tm3+ ions in the material. A possible energy transfer process and up-conversion luminescence mechanism in the nano-glass-ceramics are proposed and discussed.

  15. THE BAND STRUCTURE AND WORK FUNCTION OF TRANSPARENT CONDUCTING ALUMINUM AND MANGANESE CO-DOPED ZINC OXIDE FILMS

    Institute of Scientific and Technical Information of China (English)

    H.T. Cao; Z.L. Pei; X.B. Zhang; J. Gong; C. Sun; L.S. Wen

    2005-01-01

    Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reactive magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films have been investigated using optical spectroscopy, band structure analyses and ultraviolet photoelectron spectroscopy (UPS). ZnO films have direct allowed transition band structure, which has been confirmed by the character of the optical absorption coefficient. The apparent band gap has been found directly proportional to N2/3, showing that the effect of Burstein-Moss shift on the band gap variations dominates over the many-body effect. With only standard cleaning protocols, the work function of ZnO: (Al, Mn) and ZnO: Al films have been measured to be 4.26 and 4.21eV, respectively. The incorporation of Mn element into the matrix of ZnO, as a relatively deep donor, can remove some electrons from the conduction band and deplete the density of occupied states at the Fermi energy, which causes a loss in measured photoemission intensity and an increase in the surface work function. Based on the band gap and work function results, the energy band diagram of the ZnO: (Al, Mn)film near its surface is also given.

  16. Spectral downshifting from blue to near infer red region in Ce3+-Nd3+ co-doped YAG phosphor

    Science.gov (United States)

    Sawala, N. S.; Omanwar, S. K.

    2016-07-01

    The YAG phosphors co-doped with Ce3+-Nd3+ ions by varying concentration of Nd3+ ion from 1 mol% to 15 mol% were successfully synthesized by conventional solid state reaction method. The phosphors were characterized by powder X-ray powder diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied in near infra red (NIR) and ultra violet visible (UV-VIS) region. The synthesized phosphors can convert a blue region photon (453 nm) into photons of NIR region (1063 nm). The energy transfer (ET) process was studied by time decay curve and PL spectra. The theoretical value of energy transfer efficiency (ETE) was calculated from time decay luminescence measurement and the maximum efficiency approached up to 82.23%. Hence this phosphor could be prime candidate as a downshifting (DS) luminescent convertor (phosphor) in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss in the solar cells.

  17. Crystal structure, electrical conductivity and thermal expansion of Ni and Nb co-doped LaCoO3.

    Science.gov (United States)

    Øygarden, Vegar; Grande, Tor

    2013-02-28

    The effect of co-doping LaCoO(3) with Ni and Nb has been investigated in the two solid solution series (1 - x)LaCoO(3)-xLaNi(2/3)Nb(1/3)O(3) and (1 - y)LaCo(2/3)Ni(1/3)O(3)-yLaNi(2/3)Nb(1/3)O(3). The materials were shown to be stoichiometric with respect to oxygen. The compositional effect on the evolution of the crystal structure, thermal expansion and electrical conductivity is reported. The chemical stability of LaCoO(3) in a reducing atmosphere was improved and the thermal expansion was suppressed at higher levels of Nb-substitution. The materials with mixed oxidation states on the B-site possessed superior electrical transport properties compared to solid solutions with cations in mainly isovalent oxidation states. The evolution of the electronic conductivity, thermal expansion and crystal structural is discussed with emphasis on the oxidation states of Ni and Co, and the spin transitions of Co.

  18. Variable range hopping conduction and microstructure properties of semiconducting Co-doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Okutan, Mustafa [Department of Physics, Gebze Institute of Technology, 41400 Gebze (Turkey)]. E-mail: mokutan@gyte.edu.tr; Bakan, Halil I. [TUBITAK-MAM, Materials and Chemical Research Institute, 41470 Gebze (Turkey); Korkmaz, Kemal [Department of Material Science and Engineering, Gebze Institute of Technology, 41400 Gebze (Turkey); Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Arts and Science, Firat University, 23169 Elazig (Turkey)

    2005-01-31

    The surface morphology, phases existing in the microstructure and conductivity behavior of Co-doped TiO2 have been investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), electrical conductivity measurements and X-ray diffraction technique. The semiconducting phase is found to obey Mott's variable range hopping mechanism of the conduction. The conduction mechanism of the ceramic shows a crossover from the, exp[-(T0/T)1/4] law to a simply activated law, exp(-{delta}E/kT). This behavior is attributed to temperature-induced transition from 3D to thermally activated behavior. The hopping conduction parameters such as the characteristic temperature (T0), localization length ({alpha}), hopping distance (R), activation energy ({delta}E) and density of states at Fermi level (N(EF) have been calculated. Surface morphology shows that the ceramic has a regular surface. The SEM study indicates that there are grains which have a certain type in the microstructure. Rutile phases with different plane in microstructure were found.

  19. Thermal analysis and temperature dependent dielectric responses of Co doped anatase TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alamgir [Department of Physics, Aligarh Muslim University, Aligarh-202002 (India); Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202002 (India); Khan, Wasi; Ahammed, Nashiruddin; Naqvi, A. 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); Ahmad, Shabbir [Department of Physics, Aligarh Muslim University, Aligarh-202002 (India)

    2015-05-15

    Nanoparticles (NPs) of pure and 5 mol % cobalt doped TiO{sub 2} synthesized through acid modified sol-gel method were characterized to understand their thermal, structural, morphological, and temperature dependent dielectric properties. Thermogravimetric analysis (TGA) has been used for thermal studies and indicates the weight loss in two steps due to the removal of residual organics. X-ray diffraction study was employed to confirm the formation of single anatase phase with tetragonal symmetry for both pure and 5 mol % Co doped TiO{sub 2} NPs. The average crystallite size of both samples was calculated from the Scherrer’s formula and was found in the range from 9-11 nm. TEM micrographs of these NPs reflect their shape and distribution. The dielectric constant (ε′), dielectric loss (tanδ) and ac conductivity (σ{sub ac}) were also studied as a function of temperature at different frequencies. Electrical responses of the synthesized NPs have been analyzed carefully in the framework of relevant models. It is also noticed that the dielectric constant (ε′) of the samples found to decrease with increasing frequency but increases with increasing temperature up to a particular value and then sharply decreases. Temperature variation of dielectric constant exhibits step like escalation and shows relaxation behavior. Study of dielectric properties shows dominant dependence on the grain size as well as Co ion incorporation in TiO{sub 2}.

  20. Effect of W co-doping on the optical, magnetic and electrical properties of Fe-doped BaSnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Balamurugan, K., E-mail: balagan@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036 (India); Harish Kumar, N. [Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036 (India); Arout Chelvane, J. [Advanced Magnetics Group, Defence Metallurgical Research Laboratory, Hyderabad, Andhra Pradesh 500058 (India); Santhosh, P.N., E-mail: santhosh@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036 (India)

    2012-07-01

    The effect of W co-doping on the optical, magnetic and electrical properties of Fe-doped BaSnO{sub 3} has been studied. Polycrystalline BaSnO{sub 3}, BaSn{sub 0.96}Fe{sub 0.04}O{sub 3} and BaSn{sub 0.95}Fe{sub 0.04}W{sub 0.01}O{sub 3} samples were prepared using solid state reaction. In the analysis of powder X-ray diffraction patterns, the samples were found to be free of secondary phases. Diffuse reflectance spectra evidenced the substitution of Fe and W for Sn in the host BaSnO{sub 3}. Micro-Raman spectra confirmed the existence of oxygen vacancies in the samples. Upon W-1% co-doping, the ferromagnetic character of Fe-4% doped BaSnO{sub 3} is suppressed drastically and its Curie temperature is reduced to 310 K from 462 K. The existence of F-centers and ferromagnetic interactions at room temperature is evidenced by the electron paramagnetic resonance and ferromagnetic resonance signals observed in the electron spin resonance spectra of the undoped and Fe-4% doped, (Fe-4% and W-1%) co-doped BaSnO{sub 3} samples respectively. Suppression of ferromagnetism upon W co-doping is due to the fact that each W{sup 6+} ion donates two electrons to the host lattice and it reduces the number of oxygen vacancies that are essential for ferromagnetism to exist in the Fe-doped BaSnO{sub 3} samples.

  1. Effect of Al3+ co-doping on the dopant local structure, optical properties, and exciton dynamics in Cu+-doped ZnSe nanocrystals.

    Science.gov (United States)

    Gul, Sheraz; Cooper, Jason Kyle; Glans, Per-Anders; Guo, Jinghua; Yachandra, Vittal K; Yano, Junko; Zhang, Jin Zhong

    2013-10-22

    The dopant local structure and optical properties of Cu-doped ZnSe (ZnSe:Cu) and Cu and Al co-doped ZnSe (ZnSe:Cu,Al) nanocrystals (NCs) were studied with an emphasis on understanding the impact of introducing Al as a co-dopant. Quantum-confined NCs with zinc blende crystal structure and particle size of 6 ± 0.6 Å were synthesized using a wet chemical route. The local structure of the Cu dopant, studied by extended X-ray absorption fine structure, indicated that Cu in ZnSe:Cu NCs occupies a site that is neither substitutional nor interstitial and is adjacent to a Se vacancy. Additionally, we estimated that approximately 25 ± 8% of Cu was located on the surface of the NC. Al(3+) co-doping aids in Cu doping by accounting for the charge imbalance originated by Cu(+) doping and consequently reduces surface Cu doping. The Cu ions remain distorted from the center of the tetrahedron to one of the triangular faces. The lifetime of the dopant-related photoluminescence was found to increase from 550 ± 60 to 700 ± 60 ns after Al co-doping. DFT calculations were used to obtain the density of states of a model system to help explain the optical properties and dynamics processes observed. This study demonstrates that co-doping using different cations with complementary oxidation states is an effective method to enhance optical properties of doped semiconductor NCs of interest for various photonics applications.

  2. Effect of synergy on the visible light activity of B, N and Fe co-doped TiO2 for the degradation of MO.

    Science.gov (United States)

    Xing, Mingyang; Wu, Yongmei; Zhang, Jinlong; Chen, Feng

    2010-07-01

    Single doped, co-doped and tri-doped TiO(2) with B, N and Fe are successfully synthesized by using the hydrothermal method. The samples are characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples are evaluated for degradation of methyl-orange (MO, 20 mg L(-1)) in aqueous solutions under visible light (lambda > 420 nm). The results of XRD suggest that all the catalysts present anatase crystal. All the doping catalysts show higher photoactivities than pure TiO(2) under visible light irradiation. In the single nonmetal doped TiO(2), the localized dopant levels near the valence band (VB) are responsible for the enhancement of photoactivies. Fe(3+) impurity level formed under the conduction band (CB) induces the high photocatalytic activities of iron doped TiO(2). In the co-doped and tri-doped catalysts, the B 2p and N 2p acceptor states contribute to the band gap narrowing by mixing with O 2p states combined with the overlapping of the conduction band by the iron "d" orbital, resulting in improvement of the photo-performance under visible light irradiation. Iron co-doped with boron catalyst shows low photoactivity under visible light due to the absence of Fe(3+) impurity levels at the bottom of the conduction band. In addition, the XPS results indicate the presence of synergistic effects in co-doped and tri-doped catalysts, which contribute to the enhancement of photocatalytic activities.

  3. Titania coated hollow glass microspheres for environmental applications

    Science.gov (United States)

    Koopman, Mark C.

    The potential applicability of titania coated hollow glass microspheres (HGMs) to the photocatalytic degradation of microbiological and organic chemical water pollutants could have dramatic positive effects on improving the quality of industrial wastewaters that empty into rivers and streams, as well as potential use in economically improving the quality of drinking water. Heterogeneous photocatalysis using titania has been extensively studied since the 1990's because of its non-toxic nature, its high quantum yield of electrons and photo-holes, and its ability to use ambient solar radiation as a power source. Although titania embodies extraordinarily attractive properties for a range of environmental applications, a viable substrate or method of using the material effectively has not been recognized. HGMs are particularly attractive as a support for titania because of their low density and high surface area to volume ratio, but details of how they react to imposed loading, wear, and impact have not been addressed, nor have materials engineering analyses that could maximize their utility been made. In this study we have examined the microstructure, morphology and micro-compression properties of two types of titania coated hollow microspheres, a commercially produced HGM and cenospheres, a derivative of fly ash. Comparisons of uncoated and titania coated hollow microspheres showed improved failure loads and facture energies for the titania coated materials over the uncoated hollow microspheres. Also, the relationship between failure load and hollow microsphere diameter was characterized and the function employed to explain part of the gain in average failure load for the HGMs. Microscopic examination of titania coated HGMs that were subjected to various turbulent conditions, as well as intentional fracture, indicated good interfacial integrity, which supports the viability of both types of HGMs for potential applications. The photocatalytic reactivity of the titania

  4. Hydrogenations without Hydrogen: Titania Photocatalyzed Reductions of Maleimides and Aldehydes

    Directory of Open Access Journals (Sweden)

    David W. Manley

    2014-09-01

    Full Text Available A mild procedure for the reduction of electron-deficient alkenes and carbonyl compounds is described. UVA irradiations of substituted maleimides with dispersions of titania (Aeroxide P25 in methanol/acetonitrile (1:9 solvent under dry anoxic conditions led to hydrogenation and production of the corresponding succinimides. Aromatic and heteroaromatic aldehydes were reduced to primary alcohols in similar titania photocatalyzed reactions. A mechanism is proposed which involves two proton-coupled electron transfers to the substrates at the titania surface.

  5. Synergistic effect of Indium and Gallium co-doping on growth behavior and physical properties of hydrothermally grown ZnO nanorods

    Science.gov (United States)

    Lim, Jun Hyung; Lee, Seung Muk; Kim, Hyun-Suk; Kim, Hyun You; Park, Jozeph; Jung, Seung-Boo; Park, Geun Chul; Kim, Jungho; Joo, Jinho

    2017-01-01

    We synthesized ZnO nanorods (NRs) using simple hydrothermal method, with the simultaneous incorporation of gallium (Ga) and indium (In), in addition, investigated the co-doping effect on the morphology, microstructure, electronic structure, and electrical/optical properties. The growth behavior of the doped NRs was affected by the nuclei density and polarity of the (001) plane. The c-axis parameter of the co-doped NRs was similar to that of undoped NRs due to the compensated lattice distortion caused by the presence of dopants that are both larger (In3+) and smaller (Ga3+) than the host Zn2+ cations. Red shifts in the ultraviolet emission peaks were observed in all doped NRs, owing to the combined effects of NR size, band gap renormalization, and the presence of stacking faults created by the dopant-induced lattice distortions. In addition, the NR/p-GaN diodes using co-doped NRs exhibited superior electrical conductivity compared to the other specimens due to the increase in the charge carrier density of NRs and the relatively large effective contact area of (001) planes. The simultaneous doping of In and Ga is therefore anticipated to provide a broader range of optical, physical, and electrical properties of ZnO NRs for a variety of opto-electronic applications. PMID:28155879

  6. Low-temperature CO oxidation over Cu/Pt co-doped ZrO2 nanoparticles synthesized by solution combustion.

    Science.gov (United States)

    Singhania, Amit; Gupta, Shipra Mital

    2017-01-01

    Zirconia (ZrO2) nanoparticles co-doped with Cu and Pt were applied as catalysts for carbon monoxide (CO) oxidation. These materials were prepared through solution combustion in order to obtain highly active and stable catalytic nanomaterials. This method allows Pt(2+) and Cu(2+) ions to dissolve into the ZrO2 lattice and thus creates oxygen vacancies due to lattice distortion and charge imbalance. High-resolution transmission electron microscopy (HRTEM) results showed Cu/Pt co-doped ZrO2 nanoparticles with a size of ca. 10 nm. X-ray diffraction (XRD) and Raman spectra confirmed cubic structure and larger oxygen vacancies. The nanoparticles showed excellent activity for CO oxidation. The temperature T50 (the temperature at which 50% of CO are converted) was lowered by 175 °C in comparison to bare ZrO2. Further, they exhibited very high stability for CO reaction (time-on-stream ≈ 70 h). This is due to combined effect of smaller particle size, large oxygen vacancies, high specific surface area and better thermal stability of the Cu/Pt co-doped ZrO2 nanoparticles. The apparent activation energy for CO oxidation is found to be 45.6 kJ·mol(-1). The CO conversion decreases with increase in gas hourly space velocity (GHSV) and initial CO concentration.

  7. Li{sup +} co-doping effect on the photoluminescence time decay behavior of Y{sub 2}O{sub 3}:Er{sup 3+} films

    Energy Technology Data Exchange (ETDEWEB)

    Meza-Rocha, A.N., E-mail: ameza@fis.cinvestav.mx [Centro de Investigación y de Estudios Avanzados del IPN. Departamento de Física, Av. IPN 2508 Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Huerta, E.F.; Caldiño, U. [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, CP 09340 México D.F. (Mexico); Zaleta-Alejandre, E. [Centro de Investigación y de Estudios Avanzados del IPN. Departamento de Física, Av. IPN 2508 Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Murrieta S, H.; Hernández A, J.M.; Camarillo, E. [Instituto de Física UNAM, A.P. 20-364 Del. A. Obregón 01000 México D.F. (Mexico); Rivera-Álvarez, Z. [Centro de Investigación y de Estudios Avanzados del IPN. Departamento de Física, Av. IPN 2508 Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Righini, G.C. [Instituto di Fisica Applicata Nello Carrara, C.N.R., Via Madonna del Piano 10, Sesto Fiorentino, 50019 Florence (Italy); Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Piazza del Viminale 2, 00184 Rome (Italy); Falcony, C. [Centro de Investigación y de Estudios Avanzados del IPN. Departamento de Física, Av. IPN 2508 Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico)

    2014-10-15

    The effect of Li{sup +} co-doping on photoluminescence time decay characteristics of Y{sub 2}O{sub 3}:Er{sup 3+} is reported for films deposited by ultrasonic spray pyrolysis at 500 °C. The Er{sup 3+} content was fixed at 1.5 at% while the Li{sup +} content in the spraying solution was varied from 1 to 4 at% in relation to Y{sup 3+}. It is observed that the addition of Li{sup +} content up to 2 at%, besides resulting in an increase of the luminescence emission intensity, modifies the luminescence time decay behavior as well. A simple model in which charge transfer from localized centers to the Er{sup 3+} ions is used to describe the evolution with time of the luminescence emission. The introduction of Li{sup +} ions in Y{sub 2}O{sub 3}:Er{sup 3+} seems to have an impact on the charge transfer process and on the total number of Er{sup 3+} ions contributing to the luminescence emission. - Highlights: • Luminescence time decay characteristics of Y{sub 2}O{sub 3}:Er{sup 3+} films were measured as a function of the Li{sup +} co-doping. • The time decay behaviors were analyzed by a simple charge transfer model. • The Li{sup +} co-doping creates localized states which have an impact on the Er{sup 3+} emission.

  8. Synergistic Effects of Sm and C Co-Doped Mixed Phase Crystalline TiO2 for Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Fuchang Peng

    2017-02-01

    Full Text Available Mixed phase TiO2 nanoparticles with element doping by Sm and C were prepared via a facile sol-gel procedure. The UV-Vis light-diffuse reflectance spectroscopy analysis showed that the absorption region of co-doped TiO2 was shifted to the visible-light region, which was attributed to incorporation of samarium and carbon into the TiO2 lattice during high-temperature reaction. Samarium effectively decreased the anatase-rutile phase transformation. The grain size can be controlled by Sm doping to achieve a large specific surface area useful for the enhancement of photocatalytic activity. The photocatalytic activities under visible light irradiation were evaluated by photocatalytic degradation of methylene blue (MB. The degradation rate of MB over the Sm-C co-doped TiO2 sample was the best. Additionally, first-order apparent rate constants increased by about 4.3 times compared to that of commercial Degusssa P25 under the same experimental conditions. Using different types of scavengers, the results indicated that the electrons, holes, and •OH radicals are the main active species for the MB degradation. The high visible-light photocatalytic activity was attributed to low recombination of the photo-generated electrons and holes which originated from the synergistic effect of the co-doped ions and the heterostructure.

  9. The Gadolinium (Gd3+) and Tin (Sn4+) Co-doped BiFeO3 Nanoparticles as New Solar Light Active Photocatalyst

    Science.gov (United States)

    Irfan, Syed; Rizwan, Syed; Shen, Yang; Li, Liangliang; Asfandiyar; Butt, Sajid; Nan, Ce-Wen

    2017-02-01

    The process of photocatalysis is appealing to huge interest motivated by the great promise of addressing current energy and environmental issues through converting solar light directly into chemical energy. However, an efficient solar energy harvesting for photocatalysis remains a critical challenge. Here, we reported a new full solar spectrum driven photocatalyst by co-doping of Gd3+ and Sn4+ into A and B-sites of BiFeO3 simultaneously. The co-doping of Gd3+ and Sn4+ played a key role in hampering the recombination of electron-hole pairs and shifted the band-gap of BiFeO3 from 2.10 eV to 2.03 eV. The Brunauer-Emmett-Teller (BET) measurement confirmed that the co-doping of Gd3+ and Sn4+ into BiFeO3 increased the surface area and porosity, and thus the photocatalytic activity of the Bi0.90Gd0.10Fe0.95Sn0.05O3 system was significantly improved. Our work proposed a new photocatalyst that could degrade various organic dyes like Congo red, Methylene blue, and Methyl violet under irradiation with different light wavelengths and gave guidance for designing more efficient photocatalysts.

  10. Effect of concentration quenching on the spectroscopic properties of Er3+/Yb3+ co-doped AlF3-based glasses

    Institute of Scientific and Technical Information of China (English)

    Junjie Zhang(张军杰); Shixun Dai(戴世勋); Shiqing Xu(徐时清); Guonian Wang(汪国年); Liyan Zhang(张丽艳); Lili Hu(胡丽丽)

    2004-01-01

    A series of highly Er3+/Yb3+ co-doped fluoroaluminate glasses have been investigated in order to develop a microchip laser at 1.54 μm under 980 nm excitation. Measurements of absorption, emission and upconversion spectra have been performed to examine the effect of Er3+/Yb3+ concentration quenching on spectroscopic properties. In the glasses with Er3+ concentrations below 10 mol%, concentration quenching is very low and the Er3+/Yb3+ co-doped fluoroaluminate glasses have stronger fluorescence of 1.54 μm due to the 4I13/2 → 4I15/2 transition than that of Er3+ singly-doped glasses. As Er3+ concentrations above 10 mol% in the Er3+/Yb3+ co-doped samples, concentration quenching of 1.54 μm does obviously occur as a result of the back energy transfer from Er3+ to Yb3+. To obtain the highest emission efficiency at 1.54 μm, the optimum doping-concentration ratio of Er3+/Yb3+ was found to be approximately 1:1 in mol fraction when the Er3+ concentration is less than 10 mol%.

  11. Sr and Mn co-doped sol-gel derived BiFeO3 ceramics with enhanced magnetism and reduced leakage current

    Science.gov (United States)

    Sharma, Nandni; Kumar, Sanjeev; Mall, Ashish Kumar; Gupta, Rajeev; Garg, Ashish

    2017-01-01

    In this manuscript, we report the effect of Sr and Mn doping on the electrical and magnetic characteristics of BiFeO3 nanoparticles, synthesized by sol-gel technique. While powder diffraction analysis of the samples suggested absence of any structural distortion in both Sr-doped and Sr and Mn co-doped BiFeO3 nanoparticles, Rietveld refinement of the data suggested that the unit cell volume decreases with doping. Room temperature Raman studies of the samples confirmed the incorporation of Sr and Mn in BiFeO3. It was seen that Sr doping of BiFeO3 showed substantial reduction in the leakage current whilst co-doping with Sr and Mn led to lower reduction in the leakage current through offering better performance over undoped BiFeO3, due to changes brought in the defect chemistry upon doping. Additionally, Sr and Mn co-doped BiFeO3 samples exhibit enhanced magnetization in comparison to undoped and Sr doped BiFeO3, possibly due to interruptions in the spin cycloid of BiFeO3.

  12. Microstructure and mechanical properties of Ti/Al co-doped DLC films: Dependence on sputtering current, source gas, and substrate bias

    Science.gov (United States)

    Guo, Ting; Kong, Cuicui; Li, Xiaowei; Guo, Peng; Wang, Zhenyu; Wang, Aiying

    2017-07-01

    Co-doping two metal elements into diamond-like carbon (DLC) films can reach the desirable combined properties, but the preparation and commercialized application of metal co-doped DLC films with well-defined structural properties are currently hindered by the non-comprehensive understanding of structural evolutions under different process parameters. Here, we fabricated the Ti/Al-DLC films using a unique hybrid ion beam system which enabled the independent control of metal content and carbon structure. The evolutions of microstructure, residual compressive stress and mechanical properties induced by the different process parameters including sputtering currents, C2H2 or CH4 source gases and bias voltages were investigated systematically in order to perform in-depth analysis on the relation between the structure and properties in Ti/Al-DLC films. Results revealed that the variations of process parameters seriously affected the concentration and chemical bond state of co-doped Ti/Al atoms in amorphous carbon matrix or incident energies of C ions, which brought the complicated effect on amorphous carbon structures, accounting for the change of residual compressive stress, hardness and toughness. The present results provide the guidance for suitable, effective parameters selection to tailor the Ti/Al-DLC films with high performance for further applications.

  13. Synthesis and Characterization of La, Sc, Yb and Nd co-doped Gadolinium doped Cerium (GDC) Composite Electrolyte for IT-SOFC

    Science.gov (United States)

    Damisih; Raharjo, Jarot; Masmui; Setya Aninda, Raffty; Ami Lestari, Novita

    2017-07-01

    Composite based on gadolinium doped cerium (GDC) co-doped Lanthanum (La), Scandium (Sc), Ytterbium (Yb) were investigated as electrolyte for solid oxide fuel cell (SOFC), namely GDC-La, GDC-Sc, GDC-Yb and GDC-Nd, respectively. The second co-doped La, Sc, Yb and Nd ensured the stability and high ionic conductivity of the GDC ceria-based electrolyte materials for SOFC. The GDC powder was synthesized via sol-gel technique. Then the La-GDC, Sc-GDC, Yb-GDC and GDC-Nd were subsequently prepared by mixing the GDC with La, Sc, Yb, and Nd respectively, through solid-state reaction in ballmill at 200rpm alumina balls. The composite electrolytes were then characterized in terms of its morphology, phase and thermal properties of the powders. Among the composite electrolytes investigated, GDC-Yb powder show higher purity and better dispersion than the others co-doped GDC. TGA analysis present that the addition of co-dopant led to improve thermal resistance and stability of solid electrolyte powders. The results confirm that GDC with co-dopant is promising alternative electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFC).

  14. The Gadolinium (Gd3+) and Tin (Sn4+) Co-doped BiFeO3 Nanoparticles as New Solar Light Active Photocatalyst

    Science.gov (United States)

    Irfan, Syed; Rizwan, Syed; Shen, Yang; Li, Liangliang; Asfandiyar, A; Butt, Sajid; Nan, Ce-Wen

    2017-01-01

    The process of photocatalysis is appealing to huge interest motivated by the great promise of addressing current energy and environmental issues through converting solar light directly into chemical energy. However, an efficient solar energy harvesting for photocatalysis remains a critical challenge. Here, we reported a new full solar spectrum driven photocatalyst by co-doping of Gd3+ and Sn4+ into A and B-sites of BiFeO3 simultaneously. The co-doping of Gd3+ and Sn4+ played a key role in hampering the recombination of electron-hole pairs and shifted the band-gap of BiFeO3 from 2.10 eV to 2.03 eV. The Brunauer-Emmett-Teller (BET) measurement confirmed that the co-doping of Gd3+ and Sn4+ into BiFeO3 increased the surface area and porosity, and thus the photocatalytic activity of the Bi0.90Gd0.10Fe0.95Sn0.05O3 system was significantly improved. Our work proposed a new photocatalyst that could degrade various organic dyes like Congo red, Methylene blue, and Methyl violet under irradiation with different light wavelengths and gave guidance for designing more efficient photocatalysts. PMID:28195198

  15. Up-conversion of Er3+/Yb3+co-doped transparent glass-ceramics containing Ba2LaF7 nanocrystals

    Institute of Scientific and Technical Information of China (English)

    胡金民; 周大成; 王荣飞; 陈明厚; 焦清; 余雪; 邱建备

    2013-01-01

    The up-conversion of Er3+/Yb3+co-doped transparent glass-ceramics 50SiO2-10AlF3-5TiO2-30BaF2-4LaF3-0.5ErF3-0.5YbF3 containing Ba2LaF7 nanocrystals under the changing of heat treatment temperature and time were investigated. The Ba2LaF7 nanocrystals precipitated from the glass matrix was confirmed by X-ray diffraction (XRD). The structural investigation carried out by XRD and trans-mission electron microscopy (TEM) evidenced the formation of cubic Ba2LaF7 nanocrystals with crystal size of about 14 nm. Comparing with the samples before heat treatment, the high efficiency up-conversion emission of Er3+/Yb3+co-doped samples was observed in the glass-ceramics under 980 nm laser diode excitation. The increase in red emission intensity bands was stronger than the green bands when the crystal size increased. The mechanism for the up-conversion process in the glass-ceramics and the reasons for the increase of Er3+/Yb3+co-doped up-conversion intensity after heat treatment were discussed.

  16. Enhanced 1.8 μm emission in Er3+/Tm3+co-doped lead silicate glasses under different excitations for near infrared laser

    Institute of Scientific and Technical Information of China (English)

    朱婷婷; 唐国武; 陈晓东; 孙敏; 钱奇; 杨中民

    2016-01-01

    A detailed study of the fluorescence emission properties and energy transfer mechanism in Er3+/Tm3+co-doped lead sili-cate glasseswas reported. Enhanced nearinfrared 1.8 μm and visible up-conversion emissions were investigated under 808 and 980 nm excitations, respectively. The energy transfer mechanism between Er3+and Tm3+was analyzed according to the absorption spectra, the emission spectra and the level structures of Er3+and Tm3+. The energy transfer efficiency between Er3+and Tm3+reached 68.1% in the Er3+/Tm3+co-doped lead silicate glasses when pumped by 808 nm laser diode. Based on the absorption spectra, the Judd-Ofelt parameters, spontaneous emission probability, absorption and emission cross sections, gain coefficients were calculated and analyzed. Itwas found that the calculated emission cross section and the maximum gain coefficient around 1.8 μmwere 4.9×10–21cm2and 1.12cm–1, respectively. These results indicatedthat the Er3+/Tm3+co-doped lead-silicate glasses hadpotential application in near infrared lasers.

  17. Effect of Mg$^{2+}$ ions co-doping on timing performance and radiation tolerance of Cerium doped Gd$_{3}$Al$_{2}$Ga$_{3}$O$_{12}$ crystals

    CERN Document Server

    Lucchini, M.T.; Bohacek, P.; Gundacker, S.; Kamada, K.; Nikl, M.; Petrosyan, A.; Yoshikawa, A.; Auffray, E.

    2016-01-01

    Inorganic scintillators with high density and high light yield are of major interest for applications in medical imaging and high energy physics detectors. In this work, the optical and scintillation properties of Mg co-doped Ce:Gd3Al2Ga3O12 crystals, grown using Czochralski technique, have been investigated and compared with Ce:Gd3Al2Ga3O12 ones prepared with identical technology. Improvements in the timing performance of the Mg co-doped samples with respect to Ce:Gd3Al2Ga3O12 ones have been measured, namely a substantial shortening of the rise time and scintillation decay components and lower afterglow were achieved. In particular, a significantly better coincidence time resolution of 233 ps FWHM, being a fundamental parameter for TOF-PET devices, has been observed in Mg co-doped crystals. The samples have also shown a good radiation tolerance under high doses of γ-rays, making them suitable candidates for applications in harsh radiation environments, such as detectors at future collider experiments.

  18. Evidences of grain boundary capacitance effect on the colossal dielectric permittivity in (Nb + In) co-doped TiO2 ceramics.

    Science.gov (United States)

    Li, Jinglei; Li, Fei; Li, Chao; Yang, Guang; Xu, Zhuo; Zhang, Shujun

    2015-02-06

    The (Nb + In) co-doped TiO2 ceramics were synthesized by conventional solid-state sintering (CSSS) and spark plasma sintering (SPS) methods. The phases and microstructures were studied by X-ray diffraction, Raman spectra, field-emission scanning electron microscopy and transmission electron microscopy, indicating that both samples were in pure rutile phase while showing significant difference in grain size. The dielectric and I-V behaviors of SPS and CSSS samples were investigated. Though both possess colossal permittivity (CP), the SPS samples exhibited much higher dielectric permittivity/loss factor and lower breakdown electric field when compared to their CSSS counterparts. To further explore the origin of CP in co-doped TiO2 ceramics, the I-V behavior was studied on single grain and grain boundary in CSSS sample. The nearly ohmic I-V behavior was observed in single grain, while GBs showed nonlinear behavior and much higher resistance. The higher dielectric permittivity and lower breakdown electric field in SPS samples, thus, were thought to be associated with the feature of SPS, by which reduced space charges and/or impurity segregation can be achieved at grain boundaries. The present results support that the grain boundary capacitance effect plays an important role in the CP and nonlinear I-V behavior of (Nb + In) co-doped TiO2 ceramics.

  19. Ultrasonic-assisted sol-gel synthesis of samarium, cerium co-doped TiO2 nanoparticles with enhanced sonocatalytic efficiency.

    Science.gov (United States)

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Ziarani, Ghodsi Mohammadi

    2015-09-01

    In this work, pure TiO2 and samarium, cerium mono-doped and co-doped TiO2 catalysts were synthesized by an ultrasonic-assisted sol-gel method and their sonocatalytic efficiency studied toward removal of Methyl Orange as a model organic pollutant from the textile industry. The relationship of structure and sonocatalytic performance of catalysts was established by using various techniques, such as XRD, TEM, SEM, EDX, DRS, and PL. A comparison on the removal efficiency of sonolysis alone and sonocatalytic processes was performed. The results showed that the samarium, cerium co-doped TiO2 catalyst with narrower band gap energy and smaller particle size leads to a rapid removal of pollutant. It was believed that Sm(3+) and Ce(4+) ions can serve as superficial trapping for electrons at conduction band of TiO2 and prolonged the lifetime of electron-hole pairs. Finally, the effect of synthesis and operational variables on the sonocatalytic activity of co-doped TiO2 catalyst was studied and optimized using response surface methodology as a statistical technique. The results showed that the maximum removal efficiency (96.33%) was achieved at the optimum conditions: samarium content of 0.6 wt%, cerium content of 0.82 wt%, initial pollutant concentration of 4.31 mg L(-1), catalyst dosage of 0.84 mg L(-1), ultrasonic irradiation power of 700 W, and irradiation time of 50 min.

  20. Photocatalytic activity of titania coatings synthesised by a combined laser/sol–gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Adraider, Y. [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Pang, Y.X., E-mail: F6098038@tees.ac.uk [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Nabhani, F.; Hodgson, S.N. [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Sharp, M.C.; Al-Waidh, A. [General Engineering Research Institute, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)

    2014-06-01

    Highlights: • Sol–gel method was used to prepare titania coatings. • Titania thin films were coated on substrate surface by dip coating. • Fibre laser was employed to irradiate the titania coated surfaces. • Photocatalytic efficiency of titania coatings was significantly improved after laser processing. - Abstract: Titania coatings were prepared using sol–gel method and then applied on the substrate surface by dip coating. Fibre laser (λ = 1064 nm) in continuous wave mode was used to irradiate the titania coated surfaces at different specific energies. The ATR-FTIR, XRD, SEM, EDS and contact angle measurement were employed to analyse surface morphology, phase composition and crystalline structure of laser-irradiated titania coatings, whilst the photocatalytic activity was evaluated by measuring the decomposition of methylene blue (MB) after exposure to the visible light for various illumination times. Results showed that the laser-irradiated titania coatings demonstrate significant different composition and microstructure in comparison with the as-coated from the same sol–gel titania. Photocatalytic efficiency of titania coatings was significantly improved after laser processing. The photocatalytic activity of laser-irradiated titania coatings was higher than that of the as-coated titania. The titania coating processed at laser specific energy of 6.5 J/mm{sup 2} exhibited the highest photocatalytic activity among all titania samples.