Layered SmBaCuCoO5+δ and SmBaCuFeO5+δ perovskite oxides as cathode materials for proton-conducting SOFCs

International Nuclear Information System (INIS)

Nian Qiong; Zhao Ling; He Beibei; Lin Bin; Peng Ranran; Meng Guangyao; Liu Xingqin

2010-01-01

A dense BaCe 0.8 Sm 0.2 O 5+δ (BCS) electrolyte was fabricated on a porous anode by in situ drop-coating to develop a simple and cost-effective route to fabricate proton-conducting solid oxide fuel cells (SOFCs). Layered perovskite-structure oxides SmBaCuCoO 5+δ (SBCC) and SmBaCuFeO 5+δ (SBCF) were prepared and the electrical conductivity, the thermal expansion coefficient and electrochemical performance were investigated as potential cathode materials for proton-conducting SOFCs. Thermal expansion coefficients of SBCC and SBCF were suitable for BCS electrolyte and the electrical conductivity of the SBCC is higher than that of the SBCF. The maximum power density of 449 mW cm 2 and 333 mW cm 2 at 700 o C were obtained for the SBCC/BCS/NiO-BCS and SBCF/BCS/NiO-BCS cells, respectively. The interfacial polarization resistances for SBCC and SBCF cathode are as low as 0.137 Ω cm -2 and 0.196 Ω cm -2 at 700 o C, respectively. The results indicate that the SBCC and SBCF are promising cathode materials for proton-conducting SOFCs.

Thermochemical studies on complex of [Sm(o-NBA)_3phen]_2

Institute of Scientific and Technical Information of China (English)

肖圣雄; 张建军; 李旭; 李强国; 任宁; 李环

2010-01-01

A ternary complex [Sm(o-NBA)3phen]2 (o-NBA: o-Nitrobenzoate; phen: 1,10-phenanthroline) was synthesized and characterized by elemental analysis, IR, molar conductance, and thermogravimetric analysis. The dissolution enthalpies of SmCl3·6H2O(s), o-HNBA(s) and phen·H2O(s) in mixed solvent (VHCl :VDMF :VDMSO=2:2:1) were determined by calorimetry at 298.15 K. The enthalpy change of the reaction was determined to be rHmΔθ=252.49±1.60 kJ/mol. Using the relevant data in the literature and a thermochemical recycle ...

Complexes of o-Vanillin oxime with La(III), Ce(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III), Ho(III) and Yb(III)

International Nuclear Information System (INIS)

Dhar, M.L.; Gupta, V.K.; Singh, Onkar

1988-01-01

Ten complexes of lanthanides with o-vanillin oxime have been swynthesised and characterised. The composition of the complexes as determined by elemental and thermal analyses, infrared electronic spectral and magnetic moment studies is [Ln(C 8 H 8 NO 3 ) 3 .XH 2 O], where X=2 when Ln=La, Ce, Pr, Nd, Sm and X=3 when Ln=Gd, Dy, Tb, Ho, Yb; C 8 H 8 NO 3 - represents the anion of the ligand. (author). 16 refs., 2 figs., 2 tables

Isolated centres versus defect associates in Sm3+-doped CeO2: a spectroscopic investigation

International Nuclear Information System (INIS)

Tiseanu, Carmen; Avram, Daniel; Cojocaru, Bogdan; Parvulescu, Vasile I; Vela-Gonzalez, Andrea V; Sanchez-Dominguez, Margarita

2013-01-01

The interactions between Sm 3+ and oxygen vacancies in CeO 2 are probed by the use of tuneable laser excited time-resolved photoluminescence and Raman spectroscopies. It is found that Sm 3+ (with doping concentrations of 0.1, 0.3, 1 and 5 wt%) substitutes largely for Ce 4+ in sites with cubic symmetry and the corresponding emission is sensitized via the Ce 4+ –O 2− charge-transfer band of CeO 2 . It is established from the photoluminescence spectra measured at long delay after the laser pulse that the local environment around cubic Sm 3+ centres is not changed with concentration and ceria size. In addition to cubic symmetry Sm 3+ centres, low-symmetry Sm 3+ centres tentatively assigned to the Sm 3+ –oxygen vacancy associates of nearest-neighbour type are also observed. Their emission is preferentially excited via the weak f–f absorption transitions of Sm 3+ . A relatively strong concentration-induced quenching of Sm 3+ emission was inferred from the decrease in the average emission lifetimes from 2.1 ms (0.1 wt%) to 0.87 ms (5 wt%). The local environments of Sm 3+ and Eu 3+ in CeO 2 are also compared on the basis of their emission spectra and decays. (paper)

InAs quantum dots as charge storing elements for applications in flash memory devices

Energy Technology Data Exchange (ETDEWEB)

Islam, Sk Masiul; Biswas, Pranab [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Banerji, P., E-mail: pallab@matsc.iitkgp.ernet.in [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India)

2015-08-15

Graphical abstract: - Highlights: • Catalyst-free growth of InAs quantum dots was carried out on high-k ZrO{sub 2}. • Memory device with InAs quantum dots as charge storage nodes are fabricated. • Superior memory window, low leakage and reasonably good retention were observed. • Carrier transport phenomena are explained in both program and erase operations. - Abstract: InAs quantum dots (QDs) were grown by metal organic chemical vapor deposition technique to use them as charge storage nodes. Uniform QDs were formed with average diameter 5 nm and height 5–10 nm with a density of 2 × 10{sup 11} cm{sup −2}. The QDs were grown on high-k dielectric layer (ZrO{sub 2}), which was deposited onto ultra-thin GaP passivated p-GaAs (1 0 0) substrate. A charge storage device with the structure Metal/ZrO{sub 2}/InAs QDs/ZrO{sub 2}/(GaP)GaAs/Metal was fabricated. The devices containing InAs QDs exhibit superior memory window, low leakage current density along with reasonably good charge retention. A suitable electronic band diagram corresponding to programming and erasing operations was proposed to explain the operation.

Magneto-optical imaging of iron-oxypnictide SmFeAsO1-xFx and SmFeAsO1-y

International Nuclear Information System (INIS)

Tamegai, T.; Nakajima, Y.; Tsuchiya, Y.; Iyo, A.; Miyazawa, K.; Shirage, P.M.; Kito, H.; Eisaki, H.

2009-01-01

We have prepared iron-oxypnictide SmFeAsO 1-x F x by ambient-pressure technique and SmFeAsO 1-y by high-pressure technique, and characterized their bulk and local magnetic properties by using SQUID magnetometer and magneto-optical imaging. While the high-pressure samples have densities close to the theoretical value, the ambient-pressure samples have several small voids. Despite these structural differences between the two kinds of samples, they both have superconducting transition temperature above 50 K. In addition, magneto-optical images for both samples show similar kinds of inhomogeneities with large current concentrated in several grains and with small intergranular current. The estimated intragranular currents for both samples are over 10 5 A/cm 2 at low temperatures and low fields.

Optical spectroscopy of Sm(3+) doped Na2O-ZnO-La2O3-TeO2 glasses.

Science.gov (United States)

Sobczyk, Marcin

2015-10-05

Telluride glasses with the composition xSm2O3-(7-x)La2O3-3Na2O-25ZnO-65TeO2 (where x=0.1, 1, 2, 5 and 7 mol%) were obtained by the melt quenching technique. Electronic absorption and fluorescence spectra as well as fluorescence dynamics of the Sm(3+)-doped title glasses are presented and analysed in detail. A Judd-Ofelt intensity analysis of the absorption spectrum at 300 K has been applied for determination of Ωλ parameters (Ω2=3.10, Ω4=3.80, Ω6=1.61×10(-20) cm(2)) which in turn have been used for calculations of the radiative transition probabilities (AT), the natural (radiative) lifetimes (τR) of the (4)G5/2 level of Sm(3+), the fluorescence branching ratios (β) and the emission cross-sections (σem). The τR value of the (4)G5/2 level amount to 1546 μs and is slightly higher than the measured decay time of 1306 μs. With the increasing of Sm2O3 concentration from 0.1 to 7.0 mol% the experimental lifetime of the fluorescent level decreases from 1306 to 41 μs. An analysis of the non-radiative decay was based on the cross-relaxation mechanisms. The optical achieved results indicate that the investigated glasses are potentially applicable as an orange and/or red laser host. Copyright © 2015 Elsevier B.V. All rights reserved.

Crystal structure of Sm(NO3)3x6H2O

International Nuclear Information System (INIS)

Espenbetov, A.A.; Gerr, R.G.; Struchkov, Yu.T.; Sal'nikova, N.A.; Akimov, V.M.; Odinets, Z.K.

1985-01-01

X-ray diffraction study of a salt, prepared when mixing concentrated nitric acid solutions of NaNO 3 and Sm(NO 3 ) 3 , has been carried out. It is established, that the salt is a concretion of two crystals: NaNO 3 and Sm(NO 3 ) 3 x6H 2 O (1). X-ray diffraction study of 1 is carried out (lambda Mo, diffractometer, 1511 reflections, the method of heavy atom, the least square method in anisotropic approximation up to R=0.0348). The crystals of 1 are triclinic: a=6.755, b=9.168, c=11.684 A, α=69.93, β=88.86, γ=69.28, Z=2, Fedorov group P anti 1. Symmetery of 10-vertex coordination polyhedron (CP) of Sm atom is close to Csub(s). Sm atom coordination can be described as 4;5:1. Four H 2 O molecules are included into CP, at the expense of two remaining H 2 O molecules CP are bound with each other

The comparative study on microstructure and properties of nano-CeO 2 and Sm 2O 3 particulate reinforced nickel-based composites by laser deposition

Science.gov (United States)

Zhang, Shihong; Li, Mingxi; Yoon, Jae Hong; Cho, Tong Yul; Lee, Chan Gyu; He, Yizhu

2008-09-01

Micron size Ni-based alloy (NBA) powders are mixed with both 1.5 wt% nano-CeO 2 (n-CeO 2) and nano-Sm 2O 3 (n-Sm 2O 3) powders. These mixtures are coated on low carbon steel by laser deposition. Based on the thermodynamic characteristic of rare earth oxides, evolution of microstructure and variety of phase and properties of the coatings by the addition of n-CeO 2 and Sm 2O 3 powders to NBA have been investigated comparatively. The morphology of dendrite is transformed from bulky without n-CeO 2 and Sm 2O 3 into fine and compact with the addition of 1.5% n-CeO 2 and Sm 2O 3. And lamellar spacing of the eutectic of n-CeO 2/NBA is smaller than that of n-Sm 2O 3/NBA. The microhardness, wear resistance and corrosion resistance of the coatings are greatly improved by n-CeO 2 and Sm 2O 3 powder addition.

The comparative study on microstructure and properties of nano-CeO2 and Sm2O3 particulate reinforced nickel-based composites by laser deposition

International Nuclear Information System (INIS)

Zhang Shihong; Li Mingxi; Yoon, Jae Hong; Cho, Tong Yul; Lee, Chan Gyu; He Yizhu

2008-01-01

Micron size Ni-based alloy (NBA) powders are mixed with both 1.5 wt% nano-CeO 2 (n-CeO 2 ) and nano-Sm 2 O 3 (n-Sm 2 O 3 ) powders. These mixtures are coated on low carbon steel by laser deposition. Based on the thermodynamic characteristic of rare earth oxides, evolution of microstructure and variety of phase and properties of the coatings by the addition of n-CeO 2 and Sm 2 O 3 powders to NBA have been investigated comparatively. The morphology of dendrite is transformed from bulky without n-CeO 2 and Sm 2 O 3 into fine and compact with the addition of 1.5% n-CeO 2 and Sm 2 O 3 . And lamellar spacing of the eutectic of n-CeO 2 /NBA is smaller than that of n-Sm 2 O 3 /NBA. The microhardness, wear resistance and corrosion resistance of the coatings are greatly improved by n-CeO 2 and Sm 2 O 3 powder addition

Enhanced Photoluminescence of Sm3+/Bi3+ Co-Doped La2O3 Nanophosphors by Combustion Synthesis

Science.gov (United States)

Zhang, Ying; Wu, Muying; Zhang, W. F.

Nanosized La2O3:Sm3+ and La2O3:Sm3+, Bi3+ phosphor powders were prepared via combustion synthesis. The structures and morphology were examined using powder X-ray diffraction and transmission electron microscope, respectively. The photoluminescence spectra were investigated at different doping concentrations of Sm3+ and Bi3+ ions. The results indicate that La2O3:Sm3+ (Bi3+) exhibited good crystallinity and spherical-like particles. All phosphors give emission bands centered at 564, 608 and 650 nm corresponding to 4G5/2→6HJ (J=5/2, 7/2 and 9/2) transitions of Sm3+ ions, respectively. Interestingly, the emission intensity of Sm3+ ions is significantly enhanced with the addition of Bi3+ ions to La2O3:Sm3+ and the maximum occurs at a Bi3+ concentration of 0.8 mol%. The La2O3:Sm3+, Bi3+ phosphor with highly enhanced luminescence is very encouraging for applications in display and tunable solid lasers.

Effect of the addition of Sm2O3 on the microstructure of laser cladding alloy coating layers

Science.gov (United States)

Zhang, Shi Hong; Li, Ming Xi; Cho, Tong Yul; Yoon, Jae Hong; Fang, Wei; Joo, Yun Kon; Kang, Jin Ho; Lee, Chan Gyu

2008-06-01

The effects on the microstructures and phases of coating layers by the addition of micron-sized (m) and nano-sized (n) (m&n) Sm2O3 powders were investigated. The coating materials, which were prepared by means of 2.0 kW CO2 laser cladding, consist of a powder mixture of m Ni-based alloy (NBA) powders comprising 1.5 wt.% m Sm2O3 and 3.0% n Sm2O3 powders. The results indicate that γ-Ni, Cr23C6 and Ni3B are the primary phases of the NBA coatings. The Fe7Sm and Ni3Si phases are highlighted by the addition of m&n Sm2O3 powders. From the substrate, planar crystal layers are first grown in all NBA and m&n Sm2O3/NBA coatings. The dendrite growth then occurs as a result of the addition of the m Sm2O3 powder, and the equiaxed dendrite growth occurs as a result of the addition of the n Sm2O3. With the addition of a rare earth oxide such as Sm2O3 powder, the width of the planar crystal becomes smaller than that of the NBA coating.

Physicochemical investigation of Bi2MoO6 solid-phase interaction with Sm2MoO6

International Nuclear Information System (INIS)

Khajkina, E.G.; Kovba, L.M.; Bazarova, Zh.G.; Khal'baeva, K.M.; Khakhinov, V.V.; Mokhosoev, M.V.

1986-01-01

Bi 2 MoO 6 -Sm 2 MoO 6 interaction in the temperature range of 700-1000 deg C is studied using X-ray phase analysis and vibrational spectroscopy. Formation of monoclinic solid solutions based on γ'-Bi 2 MoO 6 and B 2-x Sm x MoO 6 varied composition phase with α-Ln 2 MoO 6 structure which homogeneity region extent at 1000 deg C constitutes ∼ 50 mol % (0.7≤x≤1.7) is stated. Crystallographic characteristics of the synthesized phases are determined

Photoluminescence properties of a new orange-red-emitting Sm(3+)-La3SbO7 phosphor.

Science.gov (United States)

Li, Zeng-Mei; Deng, Li-Gang; Zhao, Shan-Cang; Zhang, Shu-Qiu; Guo, Chang-Ying; Liang, Jing-Yun; Yue, Hui; Wan, Chun-Yan

2016-03-01

The antimonate compound La3SbO7 has high chemical stability, lattice stiffness and thermal stability. Orange-red-emitting antimonate-based phosphors La3SbO7:xSm(3+) (x = 0.02, 0.05, 0.08, 0.10, 0.15, 0.20 and 0.25) were synthesized. The phase structure and photoluminescence properties of these phosphors were investigated. The emission spectrum obtained on excitation at 407 nm contained exclusively the characteristic emissions of Sm(3+) at 568, 608, 654 and 716 nm, which correspond to the transitions from (4)G5/2 to (6)H5/2, (6)H7/2, (6)H9/2 and (6)H11/2 of Sm(3+), respectively. The strongest emission was located at 608 nm due to the (4)G5/2→(6)H7/2 transition of Sm(3+), generating bright orange-red light. The critical quenching concentration of Sm(3+) in La3SbO7:Sm(3+) phosphor was determined as 10% and the energy transfer between Sm(3+) was found to be through an exchange interaction. The International Commission on Illumination chromaticity coordinates of the La3SbO7:0.10Sm(3+) phosphors are located in the orange-red region. The La3SbO7:Sm(3+) phosphors may be potentially used as red phosphors for white light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.

Growth and electrical characterization of Zn-doped InAs and InAs1-xSbx

International Nuclear Information System (INIS)

Venter, A.; Shamba, P.; Botha, L.; Botha, J.R.

2009-01-01

The electrical properties of Zn doped InAs and InAsSb layers grown on semi-insulating GaAs by metal organic vapour phase epitaxy, using dimethyl zinc as the p-type dopant source, have been studied. The influence of dopant flow rate, V/III ratio and substrate orientation on the electrical properties of these InAs and InAs 1-x Sb x layers have been studied at a few appropriate growth temperatures. A promising group V source, tertiary butyl arsenic was used as an alternative to arsenic hydride in the case of InAs growth. The electrical properties of the InAs and InAs 1-x Sb x epitaxial layers were mainly studied by the Hall effect. However, surface accumulation in these materials results in deceptive Hall results being extracted. A two layer model (assuming the layer to consist of two parallel conducting paths viz. surface and bulk) has therefore been used to extract sensible transport properties. In addition, conventional Hall measurements ignores the high electron to hole mobility ratio in InAs and InAsSb leading to erroneous transport properties.

Blue-green and red photoluminescence in CaTiO3:Sm

International Nuclear Information System (INIS)

Figueiredo, Alberthmeiry T. de; Longo, Valeria M.; Lazaro, Sergio de; Mastelaro, Valmor R.; De Vicente, Fabio S.; Hernandes, Antonio C.; Siu Li, Maximo; Varela, Jose A.; Longo, Elson

2007-01-01

Blue-green and red photoluminescence (PL) emission in structurally disordered CaTiO 3 :Sm (CT:Sm) powders was observed at room temperature with laser excitation at 350.7 nm. The perovskite-like titanate CT:Sm powders prepared by a soft chemical processing at different temperatures of annealing were structurally characterized by X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES). The results indicate that the generation of the broad PL band is related to order-disorder degree in the perovskite-like structure

Subcoulomb fusion of 16O in odd Sm isotopes

International Nuclear Information System (INIS)

Pacheco, A.J.

1989-01-01

Cross sections for the formation of evaporation residues were measured for the reaction of 16 O with the odd 147 Sm and 149 Sm nuclei at near barrier energies. The results are well described by statistical model calculations. Fusion cross sections as a function of energy do not show any unusual behaviour that could be attributed to the presence of unpaired nucleons. An analysis based on a one-dimensional penetration model that includes the effect of permanent quadrupolar deformations shows that the extracted values of the parameter β 2 follow the systematics established by the rest of the even samarium isotopes. The dependence of β 2 on the mass of the target nucleus indicates that the influence exerted by collective aspects upon the subbarrier fusion process increases rapidly as a function of the number of neutrons added to the spherical semimagic 144 Sm nucleus. (Author) [es

An alternative gas sensor material: Synthesis and electrical characterization of SmCoO3

International Nuclear Information System (INIS)

Michel, Carlos Rafael; Delgado, Emilio; Santillan, Gloria; Martinez, Alma H.; Chavez-Chavez, Arturo

2007-01-01

Single-phase perovskite SmCoO 3 was prepared by a wet-chemical synthesis technique using metal-nitrates and citric acid; after its characterization by thermal analyses and X-ray diffraction, sintering at 900 deg. C in air, gave single phase and well crystallized powders. The powders were mixed with an organic solvent to prepare a slurry, which was deposited on alumina substrates as thick films, using the screen-printing technique. Electrical and gas sensing properties of sintered SmCoO 3 films were investigated in air, O 2 and CO 2 , the results show that sensitivity reached a maximum value at 420 deg. C, for both gases. Dynamic tests revealed a better behavior of SmCoO 3 in CO 2 than O 2 , due to a fast response and a larger electrical resistance change to this gas. X-ray diffraction made on powders after electrical characterization in gases, showed that perovskite-type structure was preserved

Crystal growth and optical properties of Sm:CaNb2O6 single crystal

International Nuclear Information System (INIS)

Di Juqing; Xu Xiaodong; Xia Changtai; Zeng Huidan; Cheng Yan; Li Dongzhen; Zhou Dahua; Wu Feng; Cheng Jimeng; Xu Jun

2012-01-01

Highlights: ► Sm:CaNb 2 O 6 single crystal was grown by the Czochralski method. ► Thermal expansion coefficients and J–O parameters were calculated. ► We found that this crystal had high quantum efficiency of 97%. - Abstract: Sm:CaNb 2 O 6 single crystal has been grown by the Czochralski method. Its high-temperature X-ray powder diffraction, optical absorption, emission spectroscopic as well as lifetime have been studied. Thermal expansion coefficients (α), J–O parameters (Ω i ), radiative lifetime (τ rad ), branching ratios (β) and stimulated emission cross-sections (σ e ) were calculated. The quantum efficiency (η) was calculated to be 97%. The intense peak emission cross section at 610, 658 nm were calculated to be 2.40 × 10 −21 , 2.42 × 10 −21 cm 2 . These results indicate that Sm:CaNb 2 O 6 crystal has potential use in visible laser and photonic devices area.

Enhancing Sm{sup 3+} red emission via energy transfer from Bi{sup 3+}→Sm{sup 3+} based on terbium bridge mechanism in Ca{sub 2}Al{sub 2}SiO{sub 7} phosphors

Energy Technology Data Exchange (ETDEWEB)

Li, Minhong; Wang, LiLi; Ran, Weiguang; Ren, Chunyan; Song, Zeling; Shi, Jinsheng, E-mail: jsshiqn@aliyun.com

2017-04-15

Currently, the key change for white-LED is to improve the luminescence efficiency of red phosphor. Sm{sup 3+} activated phosphor was considered due to suitable emission position of red light. However, the luminescence intensity in the red region is weak. For enhancing red-emitting of Sm{sup 3+}, Bi{sup 3+} and Tb{sup 3+} ions were introduced into Ca{sub 2}Al{sub 2}SiO{sub 7}:Sm{sup 3+} phosphors based on the concept of energy transfer. For Ca{sub 2}Al{sub 2}SiO{sub 7}:Bi{sup 3+}, Sm{sup 3+} samples, it can be observed that the energy transfer process was blocked. Hence, Tb{sup 3+} was introduced into Ca{sub 2}Al{sub 2}SiO{sub 7}:Bi{sup 3+}, Sm{sup 3+} samples to increase Sm{sup 3+} luminescence intensity based on Bi{sup 3+}→Tb{sup 3+}→Sm{sup 3+} energy transfer process. Compared with Sm{sup 3+} single-doped Ca{sub 2}Al{sub 2}SiO{sub 7} phosphor, the luminescence intensity of Sm{sup 3+} was enhanced by 2.6 times. It can be found that Tb{sup 3+} ions play a role of storing the energy or transfer bridge from Bi{sup 3+}→ Sm{sup 3+} by investigating the Ca{sub 2}Al{sub 2}SiO{sub 7}:Bi{sup 3+}, Tb{sup 3+} and Ca{sub 2}Al{sub 2}SiO{sub 7}:Tb{sup 3+}, Sm{sup 3+} energy transfer mechanism. All these results suggest that terbium branch mechanism plays an important role on enhancing activators luminescence intensity.

Hierarchical structured Sm2O3 modified CuO nanoflowers as electrode materials for high performance supercapacitors

Science.gov (United States)

Zhang, Xiaojuan; He, Mingqian; He, Ping; Liu, Hongtao; Bai, Hongmei; Chen, Jingchao; He, Shaoying; Zhang, Xingquan; Dong, Faqing; Chen, Yang

2017-12-01

By a simple and cost effective chemical precipitation-hydrothermal method, novel hierarchical structured Sm2O3 modified CuO nanoflowers are prepared and investigated as electrode materials for supercapacitors. The physical properties of prepared materials are characterized by XRD, FE-SEM, EDX and FTIR techniques. Furthermore, electrochemical performances of prepared materials are investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum in 1.0 M KOH electrolyte. The resulting Sm2O3 modified CuO based electrodes exhibit obviously enhanced capacitive properties owing to the unique nanostructures and strong synergistic effects. It is worth noting that the optimized SC-3 based electrode exhibits the best electrochemical performances in all prepared electrodes, including higher specific capacitance (383.4 F g-1 at 0.5 A g-1) and good rate capability (393.2 F g-1 and 246.3 F g-1 at 0.3 A g-1 and 3.0 A g-1, respectively), as well as excellent cycling stability (84.6% capacitance retention after 2000 cycles at 1.0 A g-1). The present results show that Sm2O3 is used as a promising modifier to change the morphology and improve electrochemical performances of CuO materials.

Equilibrium studies on mixed ligand complexes of some tripositive rare earth ions

International Nuclear Information System (INIS)

Vimal, Rashmi; Singh, Mamta; Ram Nayan

1996-01-01

Interaction of the rare earth ions, La 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ and Eu 3+ with the pair of ligands 1-amino-2-naphthol-4-sulphonic acid (an, H 2 A) and o-aminophenol (ap, HB) have been studied in aqueous solution at 25 degC (μ=0.1 M KNO 3 /NaCl). Equilibrium constants of the reactions involving the formations of the mixed ligand species MAB, MA 2 B 2- , MB 2 A - (M = metal ion) and the binary complexes containing up to three ligand molecules have been evaluated from the pH-metric data, and coordinating behaviour of the ligands in the formation of the mixed ligand complexes has been discussed. (author). 10 refs., 1 tab., 1 fig

Characterization on the coatings of Ni-base alloy with nano- and micron-size Sm2O3 addition prepared by laser deposition

International Nuclear Information System (INIS)

Zhang Shihong; Li Mingxi; Yoon, Jae Hong; Cho, Tong Yul

2008-01-01

The coating materials are the powder mixture of micron-size Ni-base alloy powders with both 1.5 wt.% micron-size and nano-size Sm 2 O 3 powders, which are prepared on Q235 steel plate by 2.0 kW CO 2 laser deposition. The results indicate that with rare earth oxide Sm 2 O 3 addition, the width of planar crystallization is smaller than that of the Ni-base alloy coatings. Micron- and nano-Sm 2 O 3 /Ni-base alloy coatings have similar microstructure showing the primary phase of γ-Ni dendrite and eutectic containing γ-Ni and Cr 23 C 6 phases. However, compared to micron-Sm 2 O 3 /Ni-base alloy, preferred orientation of γ-Ni dendrite of nano-Sm 2 O 3 /Ni-base alloy is weakened. Planar crystal of several-μm thickness is first grown and then dendrite growth is observed at 1.5% micron-Sm 2 O 3 /Ni-base alloy coating whereas equiaxed dendrite is grown at 1.5% nano-Sm 2 O 3 /Ni-base alloy coating. Hardness and wear resistance of the coating improves with decreasing Sm 2 O 3 size from micron to nano. The improvement on tribological property of nano-Sm 2 O 3 /Ni-base alloy over micron-Sm 2 O 3 /Ni-base alloy coatings can be attributed to the better resistance of equiaxed dendrite to adhesion interactions during the wear process. In 6 M HNO 3 solution, the corrosion resistance is greatly improved with nano-Sm 2 O 3 addition since the decrease of corrosion ratio along grain-boundary in nano-Sm 2 O 3 /Ni-base alloy coating contributes to harmonization of corrosion potential

InaSAFE applications in disaster preparedness

Science.gov (United States)

Pranantyo, Ignatius Ryan; Fadmastuti, Mahardika; Chandra, Fredy

2015-04-01

Disaster preparedness activities aim to reduce the impact of disasters by being better prepared to respond when a disaster occurs. In order to better anticipate requirements during a disaster, contingency planning activities can be undertaken prior to a disaster based on a realistic disaster scenario. InaSAFE is a tool that can inform this process. InaSAFE is a free and open source software that estimates the impact to people and infrastructure from potential hazard scenarios. By using InaSAFE, disaster managers can develop scenarios of disaster impacts (people and infrastructures affected) to inform their contingency plan and emergency response operation plan. While InaSAFE provides the software framework exposure data and hazard data are needed as inputs to run this software. Then InaSAFE can be used to forecast the impact of the hazard scenario to the exposure data. InaSAFE outputs include estimates of the number of people, buildings and roads are affected, list of minimum needs (rice and clean water), and response checklist. InaSAFE is developed by Indonesia's National Disaster Management Agency (BNPB) and the Australian Government, through the Australia-Indonesia Facility for Disaster Reduction (AIFDR), in partnership with the World Bank - Global Facility for Disaster Reduction and Recovery (GFDRR). This software has been used in many parts of Indonesia, including Padang, Maumere, Jakarta, and Slamet Mountain for emergency response and contingency planning.

Structural and magnetic properties of Fe{sub 2-x}CoSm{sub x}O{sub 4}-nanoparticles and Fe{sub 2-x}CoSm{sub x}O{sub 4}-PDMS magnetoelastomers as a function of Sm content

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Mariano M.; Mietta, Jose L.; Soledad Antonel, P. [Instituto de Quimica Fisica de Materiales, Ambiente y Energia (INQUIMAE), Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Cantilo s/n (1428), Buenos Aires (Argentina); Perez, Oscar E. [Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Cantilo s/n (1428), Buenos Aires (Argentina); Martin Negri, R. [Instituto de Quimica Fisica de Materiales, Ambiente y Energia (INQUIMAE), Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Cantilo s/n (1428), Buenos Aires (Argentina); Jorge, Guillermo, E-mail: gjorge@df.uba.ar [Instituto de Fisica de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Cantilo s/n (1428), Buenos Aires (Argentina); Instituto de Ciencias, Universidad Nacional de General Sarmiento, J.M. Gutierrez 1150 (1613), Los Polvorines, Buenos Aires (Argentina)

2013-02-15

We have synthesized magnetic Fe{sub 2-x}CoSm{sub x}O{sub 4} nanoparticles (NPs) by means of the coprecipitation method, varying Sm content from x=0 to x=0.5. Energy-dispersive X-ray spectroscopy showed agreement between the metal proportion of the obtained nanoparticles and the stoichiometric mixture of cations used for the synthesis. Part of the particles were heated at 800 Degree-Sign C, and both were characterized by X-ray diffraction, scanning electron microscope imaging and magnetization measurements. Physical and magnetic properties were analyzed as a function of Sm content, before and after the heating treatment. A phase segregation is found for the calcined nanoparticles with large Sm content. The magnetic remanence, saturation and coercive field were investigated as a function of Sm content for both heated and unheated (as-prepared) particles. Polydimethylsiloxane-NPs magnetoelastomers were prepared and cured under an external uniform magnetic field, obtaining structured anisotropic composites, in which inorganic needles (columnar micrometric structures) oriented in the direction of the magnetic field are formed. Young modulus and remanent magnetic moment were measured and magnetization time relaxation experiments were performed in the directions parallel and perpendicular to the needles in order to determine the magnetic and elastic anisotropy of the composites. The elastic modulus measured parallel to the needles resulted almost twice in magnitude with respect to the perpendicular modulus. The measured magnetic anisotropy of the composites is probably due to the enhanced interparticle interaction within a needle and the freezing of an preferred easy axis distribution among the particles at the curing process. - Highlights: Black-Right-Pointing-Pointer We study magnetic and physical properties of Sm-substituted Fe{sub 2}CoO{sub 4} nanoparticles. Black-Right-Pointing-Pointer Magnetic nanoparticles were synthesized by the coprecipitation method. Black

Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3}+Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} composite cathode for cermet supported thin Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} electrolyte SOFC operating below 600{sup o}C

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xinge; Robertson, Mark; Yick, Sing; Deces-Petit, Cyrille; Styles, Edward; Qu, Wei; Xie, Yongsong; Hui, Rob; Roller, Justin; Kesler, Olivera; Maric, Radenka; Ghosh, Dave [Institute for Fuel Cell Innovation, National Research Council Canada, 3250 East Mall, Vancouver, BC (Canada V6T 1W5)

2006-10-06

The cathode is a key component in low temperature solid oxide fuel cells. In this study, composite cathode, 75wt.% Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3} (SSC)+25wt.% Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} (SDC), was applied on the cermet supported thin SDC electrolyte cell which was fabricated by tape casting, screen-printing, and co-firing. Single cells with the composite cathodes sintered at different temperatures were tested from 400 to 650{sup o}C. The best cell performance, 0.75Wcm{sup -2} peak power operating at 600{sup o}C, was obtained from the 1050{sup o}C sintered cathode. The measured thin SDC electrolyte resistance R{sub s} was 0.128{omega}cm{sup 2} and total electrode polarization R{sub p}(a+c) was only 0.102{omega}cm{sup 2} at 600{sup o}C. (author)

Preparation and characterization of SiO2:Sm3+ nanotube arrays with 1.06 μm laser antireflective property

International Nuclear Information System (INIS)

Tan, Wei-min; Huang, Ning; Wang, Li-jun; Song, Tian-shun; Lu, Chun-hua; Wang, Liu-fang; Zhang, Jun-zhi

2013-01-01

SiO 2 : Sm 3+ nanotube arrays with excellent antireflective property at 1.06 μm were synthesized by a template-assisted sol–gel process. The molecular structure, morphology and optical properties of the fabricated SiO 2 :Sm 3+ nanotube arrays were investigated by a Fourier transform infrared spectroscope (FTIR), a Scanning electron microscope (SEM), and a spectro-fluorometer, respectively. The experimental results demonstrate that the SiO 2 :Sm 3+ nanotube arrays were formed via the AAO membrane during the sol–gel process. The remarkable antireflective characteristic of about 0.166% at 1.06 μm was attributed to the drastic decrease of effective refraction index which enhances the matching effect between air and substrate. As well as the absorption performance of Sm3+ at 1.06 μm which consumes the energies of incident light. - Graphical abstract: Directional aligned SiO 2 :Sm 3+ nanotube arrays were synthesized in AAO template by sol–gel process, and the antiflective performance of arrays is prominent comparing to the blank AAO template. Highlights: ► SiO 2 :Sm 3+ nanotube arrays are synthesized by a template-assisted sol–gel process. ► SiO 2 :Sm 3+ nanotube arrays have remarkable antireflective properties at 1.06 μm. ► The subwavelength structure results in a decrease of effective refraction index. ► The absorption performance of Sm 3+ at 1.06 μm consume the energies of incident light

Effect of Zr addition on structure and electrical properties of SmFeO3 prepared by solid state reaction method

Directory of Open Access Journals (Sweden)

Abdalla M. Abdalla

2017-12-01

Full Text Available Series of Sm1-xFe1-3xZr3xO3 (SFZO, where x = 0.0, 0.01, 0.02, 0.033, 0.05, 0.1 and 0.15, was synthesised by the solid state reaction method and sintered at 1500 °C in air. X-ray diffraction (XRD and scanning electron microscopy (SEM were used to investigate the structure of the materials. The XRD results indicated that the pure SmFeO3 and Sm0.99Fe0.97Zr0.03O3 samples are single phase materials with an orthorhombic symmetry and Pbnm space group. The increase of Zr content (x ≥ 0.02 causes a phase change from single to two-phase system with orthorhombic (Pbnm and fluorite symmetry (Fm3m. The microstructural analyses showed that the Zr4+ doping resulted in an increase of porosity in the sintered SFZO compared to SmFeO3 sample. The direct current (DC electrical conductivity at 850 °C in air was found to be 0.045 S/cm and 0.007 S/cm for Sm0.99Fe0.97Zr0.03O3 and SmFeO3, respectively, showing a significant enhancement compared to the pure SmFeO3.

Avaliação de solução concentrada de albumina eqüina na fluidoterapia em eqüinos com desidratação leve a moderada

OpenAIRE

Carla Bargi Belli

2005-01-01

A utilização de colóides é indicada em várias situações, mas nem sempre aplicável na clínica de eqüinos. O objetivo desse trabalho foi avaliar o uso de solução concentrada de albumina eqüina (diluída a 5%) durante fluidoterapia em eqüinos com desidratação leve a moderada, comparando-a com fluidoterapia apenas com solução fisiológica. Foram utilizados dois grupos de cinco eqüinos adultos, sem alterações clínicas. Cada animal passou pelo protocolo dos dois grupos experimentais (fluidoterapia ap...

Temperature induced Spin Switching in SmFeO3 Single Crystal

Science.gov (United States)

Cao, Shixun; Zhao, Huazhi; Kang, Baojuan; Zhang, Jincang; Ren, Wei

2014-08-01

The prospect of controlling the magnetization (M) of a material is of great importance from the viewpoints of fundamental physics and future applications of emerging spintronics. A class of rare-earth orthoferrites RFeO3 (R is rare-earth element) materials exhibit striking physical properties of spin switching and magnetization reversal induced by temperature and/or applied magnetic field. Furthermore, due to the novel magnetic, magneto-optic and multiferroic properties etc., RFeO3 materials are attracting more and more interests in recent years. We have prepared and investigated a prototype of RFeO3 materials, namely SmFeO3 single-crystal. And we report magnetic measurements upon both field cooling (FC) and zero-field cooling (ZFC) of the sample, as a function of temperature and applied magnetic field. The central findings of this study include that the magnetization of single-crystal SmFeO3 can be switched by temperature, and tuning the magnitude of applied magnetic field allows us to realize such spin switching even at room temperature.

Electrical and magnetic properties of spherical SmFeO{sub 3} synthesized by aspartic acid assisted combustion method

Energy Technology Data Exchange (ETDEWEB)

Yuvaraj, Subramanian [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Layek, Samar [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Vidyavathy, S. Manisha [Department of Ceramic Technology, Anna University, Chennai 600 025 (India); Yuvaraj, Selvaraj [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Meyrick, Danielle [School of Engineering and Information Technology, Murdoch University, South St. Murdoch, WA 6150 (Australia); Selvan, R. Kalai, E-mail: selvankram@buc.edu.in [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India)

2015-12-15

Highlights: • SmFeO{sub 3} is synthesized by simple combustion method using aspartic acid as the fuel. • The particles are spherical in shape with the size ranges between 150 and 300 nm. • Cole–Cole plot infers the bulk conduction mechanism. • Room temperature VSM analysis reveal the weak ferromagnetic behaviour of SmFeO{sub 3}. • Mössbauer analysis elucidates the +3 oxidation state of Fe atoms. - Abstract: Samarium orthoferrite (SmFeO{sub 3}) is synthesized by a simple combustion method using aspartic acid as fuel. Phase purity and functional groups are analyzed via X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) analysis, which confirms the single phase formation of orthorhombic SmFeO{sub 3}. Approximately spherical particles with size range 150–300 nm is revealed by scanning electron microscope (SEM). The conductivity of the material is identified by the single semicircle obtained in the solid state impedance spectra at elevated temperatures. The calculated electrical conductivity increases with increasing temperature, inferring the semiconducting nature of SmFeO{sub 3}. A magnetic study at room temperature revealed weak ferromagnetic behaviour in SmFeO{sub 3} due to Dzyaloshinsky–Moriya antisymmetric exchange interaction mechanism. Mössbauer analysis confirmed the +3 oxidation state of iron and magnetic ordering of the sample at room temperature.

Luminescence properties of the Sm-doped borate glasses

International Nuclear Information System (INIS)

Kindrat, I.I.; Padlyak, B.V.; Drzewiecki, A.

2015-01-01

The optical absorption and photoluminescence (emission and excitation) spectra as well as decay kinetics of a series of the Sm-doped glasses with Li 2 B 4 O 7 , LiKB 4 O 7 , CaB 4 O 7 , and LiCaBO 3 compositions were investigated and analysed. The Li 2 B 4 O 7 :Sm, LiKB 4 O 7 :Sm, CaB 4 O 7 :Sm, and LiCaBO 3 :Sm glasses of high optical quality have been obtained from the corresponding polycrystalline compounds in the air atmosphere, using a standard glass technology. On the basis of electron paramagnetic resonance (EPR) and optical spectra analysis it was shown that the samarium impurity is incorporated into the glass network as Sm 3+ (4f 5 , 6 H 5/2 ) ions, exclusively. All observed 4f – 4f transitions of the Sm 3+ centres in the optical absorption and luminescence spectra of the investigated glasses are identified. Most intense emission band of the Sm 3+ ions peaked about 598 nm ( 4 G 5/2 → 6 H 7/2 transition) is characterised by a single exponential decay with typical lifetime values, which depend on the basic glass composition as well as concentration and local structure of the Sm 3+ luminescence centres. The quantum efficiency has been evaluated for observed transitions of the Sm 3+ centres using obtained experimental lifetimes and radiative lifetimes calculated by Judd–Ofelt theory. The calculated high quantum efficiencies and measured quantum yields of luminescence show that the investigated borate glasses are perspective luminescence materials. Energy transfer from the Ce 3+ non-controlled impurity and intrinsic luminescence centres to the Sm 3+ centres has been observed. Peculiarities of the Sm 3+ local structure in the network of investigated glasses have been discussed based on the obtained spectroscopic results and structural data. - Highlights: • The Sm-doped Li 2 B 4 O 7 , LiKB 4 O 7 , CaB 4 O 7 , and LiCaBO 3 glasses of high quality were obtained. • EPR, optical absorption and luminescence spectra of Sm 3+ ions in obtained glasses were

Sm2FeTaO7 Photocatalyst for Degradation of Indigo Carmine Dye under Solar Light Irradiation

Directory of Open Access Journals (Sweden)

Leticia M. Torres-Martínez

2012-01-01

Full Text Available This paper is focused to study Sm2FeTaO7 pyrochlore-type compound as solar photocatalyst for the degradation of indigo carmine dye in aqueous solution. Sm2FeTaO7 was synthesized by using conventional solid state reaction and sol-gel method. X-ray diffraction results indicated that Sm2FeTaO7 exhibit a monoclinic crystal structure. By scanning electron microscopy analysis, it was observed that sol-gel material presents particle size of around 150 nm. The specific surface area and energy bandgap values were 12 m2 g−1 and 2.0 eV, respectively. The photocatalytic results showed that indigo carmine molecule can be degraded under solar light irradiation using the synthesized materials, sol-gel photocatalyst was 8 times more active than solid state. On the other hand, when Sm2FeTaO7 was impregnated with CuO as cocatalyst the photocatalytic activity was increased because CuO acts as electron trap decreasing electron-hole pair recombination rates.

SmBa2NbO6 Nanopowders, an Effective Percolation Network Medium for YBCO Superconductors

Directory of Open Access Journals (Sweden)

S. Vidya

2013-01-01

Full Text Available The percolation behavior of superconductor-insulator composite, YBa2Cu3O7–δ, and nano SmBa2NbO2 synthesized by modified combustion technique was studied. Particle size of nano SmBa2NBO6 was determined using transmission electron microscopy. The chemical nonreactivity of nano SmBa2NbO6 with YBCO is evident from the X-Ray diffraction study which makes it a suitable nanoceramic substrate material for high temperature superconducting films. A systematic increase in the sintered density, approaching the optimum value of the insulating nanophase is clearly observed, as the vol.% of YBCO in the composite decreases. SEM micrograph showed uniform distribution of nanopowder among the large clusters of YBCO. The obtained percolation threshold is ~26 vol% of YBCO in the composite. All the composites below the threshold value showed TC(0~92 K even though the room resistivity increases with increase in vol.% of nano SmBa2NbO6. The values of critical exponents obtained matches well with the theoretically expected ones for an ideal superconductor-insulator system.

Syntheses, crystal structures and spectroscopic properties of copper(II)-tetracyanometallate(II) complexes with nicotinamide and isonicotinamide ligands

Science.gov (United States)

Sayın, Elvan; Kürkçüoğlu, Güneş Süheyla; Yeşilel, Okan Zafer; Hökelek, Tuncer

2015-09-01

Four new one dimensional (1D) cyanide complexes, namely {[Cu(NH3)4(μ-na)][M‧(CN)4]}n and {[Cu(NH3)2(ina)2M‧(μ-CN)2(CN)2]}n (M‧(II) = Pd (1 and 3) or Pt (2 and 4), na:nicotinamide and ina:isonicotinamide) have been synthesized and characterized by elemental, spectral (FT-IR and Raman), and thermal (TG, DTG and DTA) analyses. The crystal structures of complexes 1-3 have been determined by single crystal X-ray diffraction technique. In complexes 1 and 2, na ligand is coordinated to the adjacent Cu(II) ions as a bridging ligand, giving rise to 1D linear cationic chain and the [M‧(CN)4]2- anionic complex acts as a counter ion. Complexes 3 and 4 are also 1D linear chain in which two cyanide ligands bridged neighboring M‧(II) and Cu(II) ions, while ina ligand is coordinated Cu(II) ion through nitrogen atom of pyridine ring. In the complexes, the Cu(II) ions adopt distorted octahedral geometries, while M‧(II) ions are four coordinated with four carbon atoms from cyanide ligands in square-planar geometries. The adjacent chains are further stacked through intermolecular hydrogen bond, Nsbnd Hṡṡṡπ, Csbnd H⋯M‧ and M‧⋯π interactions to form 3D supramolecular networks. Vibration assignments are given for all the observed bands. In addition, thermal stabilities of the compounds are also discussed.

Raman spectrum, quantum mechanical calculations and vibrational assignments of (95% alpha-TeO2/5% Sm2O3) glass.

Science.gov (United States)

Shaltout, I; Mohamed, Tarek A

2007-06-01

Chozen system of tellurite glasses doped with rare earth oxides (95% alpha-TeO(2)+5% Sm2O3) was prepared by melt quenching. Consequently, the Raman spectrum (150-1250 cm(-1)) of the modified tellurite have been recorded. As a continuation to our normal coordinate analysis, force constants and quantum mechanical (QM) calculations for tbp TeO4(4-) (triagonal bipyramid, C(2v)) and TeO(3+1); Te2O7(6-) (bridged tetrahedral), we have carried out ab initio frequency calculations for tpy TeO3(2-) (triagonal pyramidal, C(3v) and C(s)) and tp TeO3(2-) (triagonal planar, D(3h)) ions. The quantum mechanical calculations at the levels of RHF, B3LYP and MP2 allow confident vibrational assignments and structural identification in the binary oxide glass (95% alpha-TeO2 +5% Sm2O3). The dominant three-dimensional network structures in the modified glass are triagonal pyramidal TeO3 with minor features of short range distorted tbp TeO4 and bridged tetrahedral unit of TeO(3+1), leading to a structure of infinite chain. Therefore, alpha-TeO2/Sm2O3 (95/5%) glass experience structural changes from TeO4 (tbp); Te2O7 (TeO(3+1))-->TeO3 (tpy).

Crystal structure of a mixed-ligand terbium(III coordination polymer containing oxalate and formate ligands, having a three-dimensional fcu topology

Directory of Open Access Journals (Sweden)

Chainok Kittipong

2016-01-01

Full Text Available The title compound, poly[(μ3-formato(μ4-oxalatoterbium(III], [Tb(CHO2(C2O4]n, is a three-dimensional coordination polymer, and is isotypic with the LaIII, CeIII and SmIII analogues. The asymmetric unit contains one TbIII ion, one formate anion (CHO2− and half of an oxalate anion (C2O42−, the latter being completed by application of inversion symmetry. The TbIII ion is nine-coordinated in a distorted tricapped trigonal–prismatic manner by two chelating carboxylate groups from two C2O42− ligands, two carboxylate oxygen atoms from another two C2O42− ligands and three oxygen atoms from three CHO2− ligands, with the Tb—O bond lengths and the O—Tb—O bond angles ranging from 2.4165 (19 to 2.478 (3 Å and 64.53 (6 to 144.49 (4°, respectively. The CHO2− and C2O42− anions adopt μ3-bridging and μ4-chelating-bridging coordination modes, respectively, linking adjacent TbIII ions into a three-dimensional 12-connected fcu topology with point symbol (324.436.56. The title compound exhibits thermal stability up to 623 K, and also displays strong green photoluminescence in the solid state at room temperature.

Enhanced photoluminescence of Sm{sup 3+}/Bi{sup 3+} co-doped Gd{sub 2}O{sub 3} phosphors by combustion synthesis

Energy Technology Data Exchange (ETDEWEB)

Liu Guangsheng; Zhang Ying [Institute of Micro-system Physics, School of Physics and Electronics, Henan University, Kaifeng 475001 (China); Yin Jiang [Department of Physics, Nanjing University, Nanjing 210093 (China); Zhang, W.F. [Institute of Micro-system Physics, School of Physics and Electronics, Henan University, Kaifeng 475001 (China)], E-mail: wfzhang@henu.edu.cn

2008-12-15

Gd{sub 2}O{sub 3}:Sm{sup 3+} and Gd{sub 2}O{sub 3}:Sm{sup 3+},Bi{sup 3+} powders were prepared by a combustion method. Their structures were determined using X-ray diffraction. UV-visible absorption and photoluminescence spectra were investigated for Gd{sub 2}O{sub 3}:Sm{sup 3+} and Gd{sub 2}O{sub 3}:Sm{sup 3+},Bi{sup 3+} at different annealing temperatures and different doping concentrations. The emission spectra of all samples presented the characteristic emission narrow lines arising from the {sup 4}G{sub 5/2}{yields}{sup 6}H{sub J} transitions (J=5/2, 7/2, and 9/2) of Sm{sup 3+} ions upon excitation with UV irradiation. The emission intensity of Sm{sup 3+} ions was largely enhanced with introducing Bi{sup 3+} ions into Gd{sub 2}O{sub 3}:Sm{sup 3+} and the maximum occurred at a Bi{sup 3+} concentration of 0.5 mol%. The relevant mechanisms were discussed with the sensitization theory by Dexter and the aggregation behavior of Bi{sup 3+} ions.

Emission analysis of RE3+ (RE = Sm, Dy):B2O3-TeO2-Li2O-AlF3 glasses.

Science.gov (United States)

Raju, C Nageswara; Sailaja, S; Kumari, S Pavan; Dhoble, S J; Kumar, V Ramesh; Ramanaiah, M V; Reddy, B Sudhakar

2013-01-01

This article reports on the optical properties of 0.5% mol of Sm(3+), Dy(3+) ion-doped B2O3-TeO2-Li2O-AlF3 (LiAlFBT) glasses. The glass samples were characterized by optical absorption and emission spectra. Judd-Ofelt theory was applied to analyze the optical absorption spectra and calculate the intensity parameters and radiative properties of the emission transitions. The emission spectra of Sm(3+) and Dy(3+):LiAlFBT glasses showed a bright reddish-orange emission at 598 nm ((4)G5/2 → (6)H7/2) and an intense yellow emission at 574 nm ((4)F9/2 → (6)H13/2), respectively. Full width at half maximum (FWHM), stimulated emission cross section, gain bandwidth and optical gain values were also calculated to extend the applications of the Sm(3+) and Dy(3+):LiAlFBT glasses. Copyright © 2012 John Wiley & Sons, Ltd.

Thermal Behaviour of Sm0.5 R 0.5FeO3 (R = Pr, Nd) Probed by High-Resolution X-ray Synchrotron Powder Diffraction.

Science.gov (United States)

Pavlovska, Olena; Vasylechko, Leonid; Buryy, Oleh

2016-12-01

Mixed ferrites Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 with orthorhombic perovskite structure isotypic with GdFeO3 were synthesized by solid-state reaction technique in air at 1473 K. Structural parameters obtained at room temperature prove a formation of continuous solid solutions in the SmFeO3-PrFeO3 and SmFeO3-NdFeO3 pseudo-binary systems. Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 show strongly anisotropic nonlinear thermal expansion: thermal expansion in the b direction is twice lower than in the a and c directions. The average linear thermal expansion coefficients of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 in the temperature range of 298-1173 K are in the limits of (9.0-11.1) × 10(-6) K(-1), which is close to the values reported for the parent RFeO3 compounds. Subtle anomalies in the lattice expansion of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 detected at 650-750 K reflect magnetoelastic coupling at the magnetic ordering temperature T N.

Luminescence properties of the Sm-doped borate glasses

Energy Technology Data Exchange (ETDEWEB)

Kindrat, I.I. [University of Zielona Góra, Institute of Physics, Division of Spectroscopy of Functional Materials, 4a Szafrana Street, 65-516 Zielona Góra (Poland); Padlyak, B.V., E-mail: B.Padlyak@if.uz.zgora.pl [University of Zielona Góra, Institute of Physics, Division of Spectroscopy of Functional Materials, 4a Szafrana Street, 65-516 Zielona Góra (Poland); Vlokh Institute of Physical Optics, 23 Dragomanov Street, 79-005 Lviv (Ukraine); Drzewiecki, A. [University of Zielona Góra, Institute of Physics, Division of Spectroscopy of Functional Materials, 4a Szafrana Street, 65-516 Zielona Góra (Poland)

2015-10-15

The optical absorption and photoluminescence (emission and excitation) spectra as well as decay kinetics of a series of the Sm-doped glasses with Li{sub 2}B{sub 4}O{sub 7}, LiKB{sub 4}O{sub 7}, CaB{sub 4}O{sub 7}, and LiCaBO{sub 3} compositions were investigated and analysed. The Li{sub 2}B{sub 4}O{sub 7}:Sm, LiKB{sub 4}O{sub 7}:Sm, CaB{sub 4}O{sub 7}:Sm, and LiCaBO{sub 3}:Sm glasses of high optical quality have been obtained from the corresponding polycrystalline compounds in the air atmosphere, using a standard glass technology. On the basis of electron paramagnetic resonance (EPR) and optical spectra analysis it was shown that the samarium impurity is incorporated into the glass network as Sm{sup 3+} (4f{sup 5}, {sup 6}H{sub 5/2}) ions, exclusively. All observed 4f – 4f transitions of the Sm{sup 3+} centres in the optical absorption and luminescence spectra of the investigated glasses are identified. Most intense emission band of the Sm{sup 3+} ions peaked about 598 nm ({sup 4}G{sub 5/2} → {sup 6}H{sub 7/2} transition) is characterised by a single exponential decay with typical lifetime values, which depend on the basic glass composition as well as concentration and local structure of the Sm{sup 3+} luminescence centres. The quantum efficiency has been evaluated for observed transitions of the Sm{sup 3+} centres using obtained experimental lifetimes and radiative lifetimes calculated by Judd–Ofelt theory. The calculated high quantum efficiencies and measured quantum yields of luminescence show that the investigated borate glasses are perspective luminescence materials. Energy transfer from the Ce{sup 3+} non-controlled impurity and intrinsic luminescence centres to the Sm{sup 3+} centres has been observed. Peculiarities of the Sm{sup 3+} local structure in the network of investigated glasses have been discussed based on the obtained spectroscopic results and structural data. - Highlights: • The Sm-doped Li{sub 2}B{sub 4}O{sub 7}, LiKB{sub 4}O{sub 7}, Ca

Pulsed laser deposition of SmFeAsO1-δ on MgO(100) substrates

Science.gov (United States)

Haindl, Silvia; Kinjo, Hiroyuki; Hanzawa, Kota; Hiramatsu, Hidenori; Hosono, Hideo

2018-04-01

Layered iron oxyarsenides are novel interesting semimetallic compounds that are itinerant antiferromagnets in their ground state with a transition to high-temperature superconductivity upon charge carrier doping. The rare earth containing mother compounds offer rich physics due to different antiferromagnetic orderings: the alignment of Fe magnetic moments within the FeAs sublattice, which is believed to play a role for the superconducting pairing mechanism, and the ordering of the rare-earth magnetic moments at low temperatures. Here, we present thin film preparation and a film growth study of SmFeAsO on MgO(100) substrates using pulsed laser deposition (PLD). In general, the PLD method is capable to produce iron oxyarsenide thin films, however, competition with impurity phase formation narrows the parameter window. We assume that the film growth in an ultra-high vacuum (UHV) environment results in an oxygen-deficient phase, SmFeAsO1-δ. Despite the large lattice misfit, we find epitaxial oxyarsenide thin film growth on MgO(100) with evolving film thickness. Bragg reflections are absent in very thin films although they locally show indications for pseudomorphic growth of the first unit cells. We propose the possibility for a Stranski-Krastanov growth mode as a result of the large in-plane lattice misfit between the iron oxypnictide and the MgO unit cells. A columnar 3-dimensional film growth mode dominates and the surface roughness is determined by growth mounds, a non-negligible parameter for device fabrication as well as in the application of surface sensitive probes. Furthermore, we found evidence for a stratified growth in steps of half a unit cell, i.e. alternating growth of (FeAs)- and (SmO1-δ)+ layers, the basic structural components of the unit cell. We propose a simple model for the growth kinetics of this compound.

Investigations on the determination of traces of some rare earths (Eu, Sm, Gd, Y) in oxides of rare earths (Y2O3, Sm2O3, Gd2O3) by emission spectrography in d.c. arc

International Nuclear Information System (INIS)

Dittrich, K.; Gajek, M.; Luan, P.

1978-01-01

The evaporation of traces and matrices of rare earth elements was investigated in different atmospheres. It was found, that low-boiling rare earths elements, because of their extended formation of carbides evaporate more slowly than high-boiling rare earths elements. The evaporation of the traces depends on the matrices. 3 cases for the determination of traces of rare earths elements in oxides of other rare earths elements are derived from the results of the evaporation: Low- to high-boiling traces of rare earths elements in low-boiling matrices of rare earths elements, low-boiling traces in medium- to high-boiling matrices, and medium- to high-boiling traces in medium- to high-boiling matrices. The results of the determination are: in Y 2 O 3 : 14 ppm Sm, 2 ppm Eu; in Gd 2 O 3 : 18 ppm Y, 3 ppm Sm, 2 ppm Eu; in Sm 2 O 3 : 70 ppm Y, 370 ppm Gd, 16 ppm Eu. (author)

Electrical characterization of InAs thin films

Energy Technology Data Exchange (ETDEWEB)

Botha, L.; Shamba, P.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

2008-07-01

It is known that parallel conduction as a result of surface and /or interface charge accumulation significantly shields the bulk electrical properties of InAs thin films when characterized using Hall measurements. This parallel conduction in InAs can be modeled by using the two-layer model of Nedoluha and Koch [Zeitschrift fuer Physik 132, 608 (1952)]; where an InAs epilayer is treated as consisting of two conductors connected in parallel viz. a bulk and a surface layer. Here, this two-layer model is used to simulate Hall coefficient and conductivity data of InAs thin films ranging from strongly n-doped (n=10{sup 18} cm{sup -3}) to strongly p-doped (p{proportional_to}10{sup 19} cm{sup -3}) material. Conventional Hall approximations, i.e. those that assume uniform conduction from a single band, are then used to predict the apparent carrier concentration and mobility that will be determined from conventional Hall measurements, with the aim of illustrating the error of such a simplified analysis of InAs Hall data. Results show that, in addition to ignoring parallel conduction, the approximations of conventional Hall data analysis have a further inadequacy for p-type InAs, in that the high electron to hole mobility ratio in InAs is not taken into account. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Electrical characterization of InAs thin films

International Nuclear Information System (INIS)

Botha, L.; Shamba, P.; Botha, J.R.

2008-01-01

It is known that parallel conduction as a result of surface and /or interface charge accumulation significantly shields the bulk electrical properties of InAs thin films when characterized using Hall measurements. This parallel conduction in InAs can be modeled by using the two-layer model of Nedoluha and Koch [Zeitschrift fuer Physik 132, 608 (1952)]; where an InAs epilayer is treated as consisting of two conductors connected in parallel viz. a bulk and a surface layer. Here, this two-layer model is used to simulate Hall coefficient and conductivity data of InAs thin films ranging from strongly n-doped (n=10 18 cm -3 ) to strongly p-doped (p∝10 19 cm -3 ) material. Conventional Hall approximations, i.e. those that assume uniform conduction from a single band, are then used to predict the apparent carrier concentration and mobility that will be determined from conventional Hall measurements, with the aim of illustrating the error of such a simplified analysis of InAs Hall data. Results show that, in addition to ignoring parallel conduction, the approximations of conventional Hall data analysis have a further inadequacy for p-type InAs, in that the high electron to hole mobility ratio in InAs is not taken into account. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Room temperature exchange bias in SmFeO_3 single crystal

International Nuclear Information System (INIS)

Wang, Xiaoxiong; Cheng, Xiangyi; Gao, Shang; Song, Junda; Ruan, Keqing; Li, Xiaoguang

2016-01-01

Exchange bias phenomenon is generally ascribed to the unidirectional magnetic shift along the field axes at interface of two magnetic materials. Room temperature exchange bias is found in SmFeO_3 single crystal. The behavior after different cooling procedure is regular, and the training behavior is attributed to the athermal training and its pinning origin is attributed to the antiferromagnetic clusters. Its being single phase and occurring at room temperature make it an appropriate candidate for application. - Graphical abstract: Room temperature exchange bias was found in oxide single crystal. Highlights: • Room temperature exchange bias has been discovered in single-crystalline SmFeO_3. • Its pinning origin is attributed to the antiferromagnetic clusters. • Its being single phase and occurring at room temperature make it an appropriate candidate for application.

Real-time observation of growth and orientation of Sm-Ba-Cu-O phases on a Sm-211 whisker substrate by high-temperature optical microscopy

Czech Academy of Sciences Publication Activity Database

Sun, J.L.; Huang, Y.B.; Cheng, L.; Yao, X.; Lai, Y.J.; Jirsa, Miloš

2009-01-01

Roč. 9, č. 2 (2009), 898-902 ISSN 1528-7483 R&D Projects: GA ČR GA202/08/0722 Institutional research plan: CEZ:AV0Z10100520 Keywords : high-temperature optical microscopy * growth and orientation of Sm-Ba-Cu-O phases * Sm-211 whisker substrate Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.162, year: 2009

Voltage color tunable OLED with (Sm,Eu)-β-diketonate complex blend

Science.gov (United States)

Reyes, R.; Cremona, M.; Teotonio, E. E. S.; Brito, H. F.; Malta, O. L.

2004-09-01

Light emission from organic electroluminescent diodes (OLEDs) in which mixed samarium and europium β-diketonate complexes, [Sm 0.7Eu 0.3(TTA) 3(TPPO) 2], was used as the emitting layer is described. The electroluminescence spectra exhibit narrow peaks arising from 4f-intraconfigurational transitions of the Sm 3+ and Eu 3+ ions and a broad emission band attributed to the electrophosphorescence of the TTA ligand. The intensity ratio of the peaks determined by the bias voltage applied to the OLED, together with the ligand electrophosphorescence, allows to obtain a voltage-tunable color light source.

Bulk magnetic characterization of RCaCrO4 (Rrl02=Y, Pr, Sm ) oxides

International Nuclear Information System (INIS)

Martinez, J.L.; Fernandez-Diaz, M.T.; Chen, Q.; Prieto, C.; Andres, A. de; Saez-Puche, R.; Romero, J.

1995-01-01

The system RCaCrO 4 (R=Y, Sm, Pr) presents an orthorhombic structure (space group Bmab) at room temperature (RT), similar to that observed in La 2 MO 4 (M=Cu, Ni, Co). The magnetic susceptibility for RCaCrO 4 shows a weak temperature dependence down to 250 K, probably due to the antiferromagnetic ordering of the Cr sublattice above RT. Below RT there is a strong upturn anomaly at 210, 190 and 130 K for Pr, Sm and Y, respectively. This anomaly is associated with the appearance of a weak ferromagnetic component, and could be related to a low temperature structural phase transition, similar to that observed in the related compounds R 2 NiO 4 or La 1.88 Ba 0.12 CuO 4 . In the case of YCaCrO 4 this ferromagnetic component produces a hysteresis curve at 4.5 K with a coercive field of 0.7 T. For PrCaCrO 4 the coercive field is very small ( 4 shows a more complicated behavior with a low temperature magnetic transition (T N2 ∼40 K), which could be associated with either the antiferromagnetic ordering of the Sm sublattice or a spin reorientation in the Cr sublattice. ((orig.))

The Effect of INA [(R)-1-O-(1-Pyrenylmethyl)Glycerol] Insertions on the Structure and Biological Activity of a G-Quadruplex from a Critical Kras G-Rich Sequence

DEFF Research Database (Denmark)

Cogoi, Susanna; Paramasivan, Manikandan; Xodo, Luigi E.

2007-01-01

Quadruplex-forming oligonucleotides containing INA [(R)-1-O-(1-pyrenylmethyl)glycerol] insertions have been designed and studied for their capacity to inhibit the expression of the KRAS oncogene in pancreatic adenocarcinoma cells. It is found that INA can influence the folding topology of the G-q...

Crystallographic and magnetic properties of nanocrystalline perovskite structure SmFeO3 orthoferrite

Science.gov (United States)

Kumar, Ashwini; Shen, Jingdong; Zhao, Huihui; Zhengjian, Qi; Li, Qi

2018-05-01

In this article, we present the structural and magnetic studies of pristine SmFeO3 nanocrystalline ceramic samples as sintered at temperature 850 °C and 1000 °C. X-ray powder diffraction data confirm the existence of single-phase nature with orthorhombic (Pbnm) structure of the samples. The SEM image reveals spherical particles with a size range of 60-130 nm for SFO-850 and SFO-1000 samples. X-ray absorption spectroscopy studies on Fe L3,2 and O K-edges of SmFeO3 sample revealed the homo-valence state of Fe in these materials. From magnetization studies it has been observed the materials exhibit ferromagnetic and antiferromagnetic (canted spin structure) sub-lattices, which results strong magnetic anisotropy in the system.

Synthesis by two methods and crystal structure determination of a new pyrochlore-related compound Sm{sub 2}FeTaO{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Torres-Martinez, Leticia M., E-mail: lettorresg@yahoo.com [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Ruiz-Gomez, Miguel A. [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P. 78290 (Mexico); Figueroa-Torres, M.Z.; Juarez-Ramirez, Isaias [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Moctezuma, Edgar [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P. 78290 (Mexico); and others

2012-04-16

Graphical abstract: The monoclinic (space group C2/c) structure of a new compound, Sm{sub 2}FeTaO{sub 7} shows an alternating Sm-O and Fe/Ta-O layers. In the Fe/Ta-O layer, Fe/Ta1 and Fe/Ta3 cations are coordinated by six oxygen atoms, forming irregular octahedral interconnected into a hexagonal tungsten bronze (HTB) type network. The HTB layer is a fundamental framework in the pyrohlore-related structure. Highlights: Black-Right-Pointing-Pointer Pyrochlore-related compound Sm{sub 2}FeTaO{sub 7} prepared by solid state reaction and sol-gel. Black-Right-Pointing-Pointer Sm{sub 2}FeTaO{sub 7} crystallizes with a monoclinic crystal structure and space group C2/c. Black-Right-Pointing-Pointer The compound is synthesized by sol-gel at lower temperature and time than solid state. Black-Right-Pointing-Pointer Surface area of sol-gel Sm{sub 2}FeTaO{sub 7} is 10 times higher than that prepared by solid state. - Abstract: This paper reports on the synthesis of a new pyrochlore-related compound Sm{sub 2}FeTaO{sub 7} by both solid state reaction and sol-gel synthesis routes. Structural features were determined by X-ray powder diffraction and Rietveld refinement and were corroborated using Transmission Electron Microscopy (TEM). The results revealed that Sm{sub 2}FeTaO{sub 7} crystallized in the monoclinic system with space group C2/c and the following cell parameters: a = 13.1307(5) Angstrom-Sign , b = 7.5854(3) Angstrom-Sign , c = 11.6425(4) Angstrom-Sign and {beta} = 100.971(2) Degree-Sign . The monoclinic structure of Sm{sub 2}FeTaO{sub 7} showed an arrangement of alternating Sm-O and Fe/Ta-O layers and two types of irregular octahedra of Fe/Ta-O, which are interconnected into a hexagonal tungsten bronze (HTB)-type network. On the other hand, Sm{sub 2}FeTaO{sub 7} prepared by sol-gel was obtained with lower particle sizes than the solid state produced compound. The difference in particle size causes a difference of one order of magnitude in the specific surface area. In

Spectroscopic studies of some lanthanide(III nitrate complexes synthesized from a new ligand 2,6-bis-(salicylaldehyde hydrazone-4-chlorophenol

Directory of Open Access Journals (Sweden)

A.S. Sall

2003-06-01

Full Text Available The ligand 2,6-bis-(salicylaldehydehydrazone-4-chlorophenol (H5L and its binuclear lanthanide(III nitrate complexes {[Ln2(H4L3(NO3](NO32.mH2O} where Ln = La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb and Y, have been synthesized. The complexes were characterized by chemical analysis, conductance, magnetic moment measurements and infrared spectra. Infrared study indicates that the ligand behaves both as neutral and ionic O donors and as neutral N donors.

Characterization on the coatings of Ni-base alloy with nano- and micron-size Sm{sub 2}O{sub 3} addition prepared by laser deposition

Energy Technology Data Exchange (ETDEWEB)

Zhang Shihong [School of Materials Science and Engineering, Anhui University of Technology, Maanshan City, Anhui Province 243002 (China); School of Nano and Advanced Materials Engineering, Changwon National University, 9, Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of)], E-mail: zsh10110903@hotmail.com; Li Mingxi [School of Materials Science and Engineering, Anhui University of Technology, Maanshan City, Anhui Province 243002 (China); Yoon, Jae Hong; Cho, Tong Yul [School of Nano and Advanced Materials Engineering, Changwon National University, 9, Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of)

2008-12-01

The coating materials are the powder mixture of micron-size Ni-base alloy powders with both 1.5 wt.% micron-size and nano-size Sm{sub 2}O{sub 3} powders, which are prepared on Q235 steel plate by 2.0 kW CO{sub 2} laser deposition. The results indicate that with rare earth oxide Sm{sub 2}O{sub 3} addition, the width of planar crystallization is smaller than that of the Ni-base alloy coatings. Micron- and nano-Sm{sub 2}O{sub 3}/Ni-base alloy coatings have similar microstructure showing the primary phase of {gamma}-Ni dendrite and eutectic containing {gamma}-Ni and Cr{sub 23}C{sub 6} phases. However, compared to micron-Sm{sub 2}O{sub 3}/Ni-base alloy, preferred orientation of {gamma}-Ni dendrite of nano-Sm{sub 2}O{sub 3}/Ni-base alloy is weakened. Planar crystal of several-{mu}m thickness is first grown and then dendrite growth is observed at 1.5% micron-Sm{sub 2}O{sub 3}/Ni-base alloy coating whereas equiaxed dendrite is grown at 1.5% nano-Sm{sub 2}O{sub 3}/Ni-base alloy coating. Hardness and wear resistance of the coating improves with decreasing Sm{sub 2}O{sub 3} size from micron to nano. The improvement on tribological property of nano-Sm{sub 2}O{sub 3}/Ni-base alloy over micron-Sm{sub 2}O{sub 3}/Ni-base alloy coatings can be attributed to the better resistance of equiaxed dendrite to adhesion interactions during the wear process. In 6 M HNO{sub 3} solution, the corrosion resistance is greatly improved with nano-Sm{sub 2}O{sub 3} addition since the decrease of corrosion ratio along grain-boundary in nano-Sm{sub 2}O{sub 3}/Ni-base alloy coating contributes to harmonization of corrosion potential.

Luminescent properties of Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}AlO{sub 4}F oxyfluorides

Energy Technology Data Exchange (ETDEWEB)

Park, Sangmoon, E-mail: spark@silla.ac.kr [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of)

2012-04-15

Effective orange Sm{sup 3+}-doped Sr{sub 2.5}Ba{sub 0.5}AlO{sub 4}F phosphors excited at 254 and 408 nm excitation were prepared by the solid-state method. The excitation and emission spectra of Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}AlO{sub 4}F and Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}AlO{sub 4-{alpha}}F{sub 1-{delta}} (x=0.001{approx}0.1) based on photoluminescence spectroscopy are investigated. The defects in anion-deficient Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}AlO{sub 4-{alpha}}F{sub 1-{delta}} (x=0.001, 0.01) are monitored by broad-band photoluminescence emission centered near 480 nm along with the orange emission transitions of Sm{sup 3+}. CIE values and relative luminescent intensities of Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}AlO{sub 4}F and Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}AlO{sub 4-{alpha}}F{sub 1-{delta}} by changing the Sm{sup 3+} content (x=0.001{approx}0.1) are discussed. - Highlights: Black-Right-Pointing-Pointer Under the excitation of 408 nm competent orange emitting Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}AlO{sub 4}F phosphor is initiated. Black-Right-Pointing-Pointer Sm{sup 3+}-activated oxyfluoride phosphor is quite effective to prepare white-emitting light for near-UV LED applications. Black-Right-Pointing-Pointer Defects could be visibly created in the Sr{sub 2.5-3x/2}Ba{sub 0.5}Sm{sub x}Al O{sub 4}F host lattices when Sm{sup 3+} ions are doped less than 5 mol %. Black-Right-Pointing-Pointer The gradual substitution of Sm{sup 3+} contents in oxyfluoride hosts is amenable to change CIE values and desired emitting intensity.

Emission analysis of Tb3+ -and Sm3+ -ion-doped (Li2 O/Na2 O/K2 O) and (Li2 O + Na2 O/Li2 O + K2 O/K2 O + Na2 O)-modified borosilicate glasses.

Science.gov (United States)

Naveen Kumar Reddy, B; Sailaja, S; Thyagarajan, K; Jho, Young Dahl; Sudhakar Reddy, B

2018-05-01

Four series of borosilicate glasses modified by alkali oxides and doped with Tb 3+ and Sm 3+ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B 2 O 3 + 10SiO 2 + 5MgO + R + 0.5(Tb 2 O 3 /Sm 2 O 3 ) [where R = 10(Li 2 O /Na 2 O/K 2 O) for series A and C, and R = 5(Li 2 O + Na 2 O/Li 2 O + K 2 O/K 2 O + Na 2 O) for series B and D]. The X-ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the 5 D 4 → 7 F 5 (543 nm) transition of the Tb 3+ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm 3+ ions with the series C and D glasses showed strong reddish-orange emission at 600 nm ( 4 G 5/2 → 6 H 7/2 ) with an excitation wavelength λ exci = 404 nm ( 6 H 5/2 → 4 F 7/2 ). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb 3+ and Sm 3+ ions was studied to optimize the potential alkali-oxide-modified borosilicate glass. Copyright © 2017 John Wiley & Sons, Ltd.

Influence of Sm{sup 3+} substitution on the mutiferroic effect in NdCrTiO{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Qian, X.L., E-mail: xiaolongqian@shu.edu.cn [Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Department of Physics, Shanghai University, Shanghai 200444 (China); Fang, Y.F.; Kang, J.; Cao, S.X. [Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Department of Physics, Shanghai University, Shanghai 200444 (China); Zhang, J.C., E-mail: jczhang@shu.edu.cn [Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Department of Physics, Shanghai University, Shanghai 200444 (China)

2016-08-15

The effects of Sm{sup 3+} substitution on the magnetic and electric properties of NdCrTiO{sub 5} are investigated by magnetization and polarization measurements. X-ray diffraction patterns confirm that our samples are single phase with an orthorhombic crystal structure in the space group of Pbam. The DC magnetization study at an external field of 0.1 T reveals the variation of the anti-ferromagnetic transition temperature. The disappearance of the ferroelectricity–paraelectricity phase transition in Nd{sub 0.5}Sm{sub 0.5}CrTiO{sub 5} indicates the suppression on the linear magnetoelectric coupling by Sm{sup 3+}. The disparate 3d−4f interactions between Sm and Cr potentially affect the mutiferroic effect in this system.

Structural and spectral properties of MgZnO2:Sm3+ phosphor

Science.gov (United States)

Rajput, Preasha; Sharma, Pallavi; Biswas, Pankaj; Kamni

2018-05-01

The samarium doped MgZnO2 phosphor was synthesized by the low-cost combustion method. The powder X-ray diffraction (XRD) analysis confirmed the crystallinity and phase purity of the phosphor. The lattice parameters were determined by indexing the diffraction peaks. The photoluminescence (PL) study revealed that the phosphor exhibited a broad excitation band in the UV region ranging between 200 to 350 nm. The 601 nm emission was ascribed to 4G5/2 to 6H7/2 transitions of the Sm3+ ion. The optical bandgap of MgZnO2:Sm3+ was obtained to be 3.56 eV. The phosphor can be projected as a useful material in X- and gamma-ray scintillators.

Selective area growth of InAs nanowires from SiO2/Si(1 1 1) templates direct-written by focused helium ion beam technology

Science.gov (United States)

Yang, Che-Wei; Chen, Wei-Chieh; Chou, Chieh; Lin, Hao-Hsiung

2018-02-01

We report on the selective area growth of InAs nanowires on patterned SiO2/Si (1 1 1) nano-holes, prepared by focused helium ion beam technology. We used a single spot mode, in which the focused helium ion beam was fixed on a single point with a He+-ion dosage, ranging from 1.5 pC to 8 pC, to drill the nano-holes. The smallest hole diameter achieved is ∼8 nm. We found that low He+-ion dosage is able to facilitate the nucleation of (1 1 1)B InAs on the highly mismatched Si, leading to the vertical growth of InAs nanowires (NWs). High He-ion dosage, on the contrary, severely damaged Si surface, resulting in tilted and stripe-like NWs. In addition to titled NW grown from (1 1 1)A InAs domain, a new titled growth direction due to defect induced twinning was observed. Cross-sectional TEM images of vertical NWs show mixed wurtizite (WZ) and zincblende (ZB) phases, while WZ phase dominants. The stacking faults resulting from the phase change is proportional to NW diameter, suggesting that the critical diameter of phase turning is larger than 110 nm, the maximum diameter of our NWs. Period of misfit dislocation at the InAs/Si interface of vertical NW is also found larger than the theoretical value when the diameter of heterointerface is smaller than 50 nm, indicating that the small contact area is able to accommodate the large lattice and thermal mismatch between InAs and Si.

Shape tunable synthesis of Eu- and Sm-doped ZnO microstructures ...

Indian Academy of Sciences (India)

Shape tunable synthesis of Eu- and Sm-doped ZnO microstructures: a morphological ... different microstructures material at relatively low temper- ..... Chem. C 114. 2776. 5. Gao P X and Wang Z L 2003 J. Am. Chem. Soc. 125 11299. 6.

Formation constants of Sm(III), Dy(III), Gd(III), Pr(III) and Nd(III) complexes of tridentate schiff base, 2-[(1H-benzimidazol-2-yl-methylene) amino] phenol

International Nuclear Information System (INIS)

Omprakash, K.L.; Chandra Pal, A.V.; Reddy, M.L.N.

1982-01-01

A new tridentate schiff base, 2- (1H-benzimidazol-2-yl-methylene)amino phenol derived from benzimididazole-2-carbo-xaldehyde and 2-aminophenol has been synthesised and characterised by spectral and analytical data. Proton-ligand formation constants of the schiff base and metal-ligand formation constants of its complexes with Sm(III), Dy(III), Gd(III), Nd(III) and Pr(III) have been determined potentiometrically in 50% (v/v) aqueous dioxane at an ionic strength of 0.1M (NaClO 4 ) and at 25deg C using the Irving-Rossotti titration technique. The order of stability constants (logβ 2 ) is found to be Sm(III)>Dy(III)>Gd(III)>Pr(III)>Nd(III). (author)

Formation constants of Sm(III), Dy(III), Gd(III), Pr(III) and Nd(III) complexes of tridentate schiff base, 2-((1H-benzimidazol-2-yl-methylene) amino) phenol

Energy Technology Data Exchange (ETDEWEB)

Omprakash, K L; Chandra Pal, A V; Reddy, M L.N. [Osmania Univ., Hyderabad (India). Dept. of Chemistry

1982-03-01

A new tridentate schiff base, 2- (1H-benzimidazol-2-yl-methylene)amino phenol derived from benzimididazole-2-carbo-xaldehyde and 2-aminophenol has been synthesised and characterised by spectral and analytical data. Proton-ligand formation constants of the schiff base and metal-ligand formation constants of its complexes with Sm(III), Dy(III), Gd(III), Nd(III) and Pr(III) have been determined potentiometrically in 50% (v/v) aqueous dioxane at an ionic strength of 0.1M (NaClO/sub 4/) and at 25deg C using the Irving-Rossotti titration technique. The order of stability constants (log..beta../sub 2/) is found to be Sm(III)>Dy(III)>Gd(III)>Pr(III)>Nd(III).

Effect of Sr doping on structural and magnetic behavior of SmBa1-xSrxCo2O5+δ (x = 0 and 1)

Science.gov (United States)

Kumari, Archana; Dhanasekhar, C.; Das, A. K.

2018-05-01

Layered double perovskite, SmBa1-xSrxCo2O5+δ (x = 0, δ = 0.5 and x = 1, δ = 1) samples were prepared by solid state reaction method. X-ray diffraction studies show that the SmBaCo2O5.5 sample crystallizes in the orthorhombic crystal structure with Pmmm space group, whereas SmSrCo2O6 sample crystallizes in the orthorhombic crystal structure with Pnma space group. The temperature dependent magnetization of the SmBaCo2O5.5 sample shows a paramagnetic (PM)-ferromagnetic (FM) and a FM-antiferromagnetic (AFM) transitions at TC = 267 K and TN = 221 K, respectively. In contrast, the SmSrCo2O6 sample shows a PM-FM transition at TC = 175 K. According to Goodenough-Kanamori-Anderson rules, the ferromagnetic behavior in SmSrCo2O6 can be understood from the super exchange interaction between the intermediate spin Co3+ and low spin Co4+ via O2- (IS Co3+ -O2- - LS Co4+). The change in magnetic entropy (ΔSMmax) is found to be maximum for the SmSrCo2O6 sample.

Charge pumping in InAs nanowires by surface acoustic waves

NARCIS (Netherlands)

Roddaro, Stefano; Strambini, Elia; Romeo, Lorenzo; Piazza, Vincenzo; Nilsson, Kristian; Samuelson, Lars; Beltram, Fabio

2010-01-01

We investigate the interaction between surface acoustic waves on a piezoelectric LiNbO3 substrate and charge carriers in InAs nanowire transistors. Interdigital transducers are used to excite electromechanical waves on the chip surface and their influence on the transport in the nanowire devices is

Orbital ordering in {sup 154}SmNiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Medarde, M.; Rosenkranz, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Rodrigeuez-Carvajal, J. [Laboratoire Leon Brillouin (LLB) - Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Lacorre, P. [Lab. Fluorures, LeMans (France); Trounov, V. [PNPI, Gatchina (Russian Federation); Fernandez-Diaz, M.T. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)

1997-09-01

We have investigated the existence of a structural distortion associated to the k = (1/2 0 1/2) orbital ordering recently proposed to explain the magnetic structure of RNiO{sub 3} perovskites (R = rare earth). Our results on a {sup 154}SmNiO{sub 3} powder sample indicate that, if existing, the associated superstructure reflections are as a maximum 10{sup 4} times smaller than the largest nuclear reflection. (author) 2 figs., 3 refs.

Characterization of Nd{sub 2}AlO{sub 3}N and Sm{sub 2}AlO{sub 3}N oxynitrides synthesized by carbothermal reduction and nitridation

Energy Technology Data Exchange (ETDEWEB)

Chevire, Francois, E-mail: francois.chevire@univ-rennes1.fr [UMR CNRS 6226 ' Sciences Chimiques de Rennes' , Equipe Verres et Ceramiques, Groupe Materiaux Azotes et Ceramiques, Universite de Rennes 1, 35042 Rennes Cedex (France); Pallu, Arthur; Ray, Erwan; Tessier, Franck [UMR CNRS 6226 ' Sciences Chimiques de Rennes' , Equipe Verres et Ceramiques, Groupe Materiaux Azotes et Ceramiques, Universite de Rennes 1, 35042 Rennes Cedex (France)

2011-05-12

Research highlights: > Carbothermal reduction and nitridation leads to rare earth aluminum oxynitride starting from oxide mixture. > Absorption shifts towards visible in Nd{sub 2}AlO{sub 3}N (orange) and Sm{sub 2}AlO{sub 3}N (yellow). > Oxynitrides are stable up to 600 deg. C in air. > The so-called 'intermediate phase' phenomenon is evidenced in Sm{sub 2}AlO{sub 3}N. - Abstract: The Nd{sub 2}AlO{sub 3}N and Sm{sub 2}AlO{sub 3}N oxynitrides with the K{sub 2}NiF{sub 4}-type structure have been prepared from oxide mixture at 1250 deg. C using the carbothermal reduction and nitridation route (CRN). Optimization of the process is discussed to prevent surface oxidation of the oxynitrides during the synthesis. The absorption of Nd{sub 2}AlO{sub 3}N and Sm{sub 2}AlO{sub 3}N, orange and yellow respectively, has been characterized by diffuse reflectance as well as their thermal stability versus oxidation by thermogravimetric analyses.

Enhanced solar light photodegradation of brilliant black bis-azo dye in aqueous solution by F, Sm3+ codoped TiO2

Science.gov (United States)

Mukonza, Sabastian S.; Nxumalo, Edward N.; Mamba, Bhekie B.; Mishra, Ajay K.

2017-05-01

This research focuses on improving the photocatalytic efficiency of TiO2 during the photo-mineralisation of brilliant black (BN) bis-azo dye pollutant in aqueous solution. This was achieved by improving the visible light activity of TiO2 photocatalyst semiconductor through co-doping of fluorine (F) and trivalent samarium ions (Sm3+) into a TiO2 matrix using a modified sol-gel synthesis method. Structural, morphological, and textural properties were evaluated using ultra-violet /visible spectroscopy (UV-visible), Raman spectroscopy, scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction spectroscopy (XRD). Photocatalytic and degradation efficiencies were assessed by decolourisation of BN dye in aqueous solution. Complete degradation of BN was attained after an irradiation time of 3 h using F, Sm3+-TiO2 (0.6% Sm3+) compared to 73.4% achieved using pristine TiO2. Pseudo first order kinetics rate constants (Ka) were 2.73×10-2 and 6.6×10-3 min-1 for Sm3+-TiO2 (0.6%Sm3+) and pristine TiO2, respectively, which translates to a remarkably high enhancement factor of 4. The results obtained established that doping of TiO2 by F and Sm3+ enhances the photocatalytic performance of TiO2 during solar light radiation which enables the utilisation of freely available and clean solar energy.

Evaluation of Radioisotope Production Process of 153Sm and 153Sm-EDTMP Radiopharmaceuticals

International Nuclear Information System (INIS)

Kadarisman; Sri Hastini; Yayan Tahyan; Abidin; Dadang Hafid; Enny Lestari

2007-01-01

Experiments on the process of 153 Sm radioisotope and labeling of 153 Sm-EDTMP radiopharmaceuticals were carried out. This experiments included preparation of Sm 2 O 3 target, dissolution of post irradiation, determination of radioactivity concentration of 153 Sm radioisotope, radionuclide purity, EDTMP labeling, determination of radiochemical purity and pH. In these experiments the total radioactivity 153 Sm product is round about 2845.83 mCi to 36963.31 mCi, or with the radioactivity concentration between 474 mCi/ml to 6160.55 mCi/ml in the SmCl 3 solution form, each its volume is 6.0 ml, and the samarium content is 5.76 mg/ml, and the radionuclide purity of 153 Sm is 100 %. All of the 153 Sm- EDTMP radiopharmaceuticals product are fulfilled requirements the radioactivity concentration, Sm content, radiochemical purity and pH. The radioactivity concentration of 153 Sm-EDTMP radiopharmaceuticals is 37.50 mCi/ml (minimum) to 283.50 mCi/ml (highest). The pH 7.5 were 8 products, and the rest are pH 8.5. Radiochemical purity of 153 Sm-EDTMP are round about 90.00 % to 99.44 %. (author)

Solid solutions in the system Nd2(SeO4)3 - Sm2(SeO4)3 - H2O

International Nuclear Information System (INIS)

Serebrennikov, V.V.; Tsybukova, T.N.; Velikov, A.A.

1984-01-01

Using the method of isothermal solubility at 25 deg C the system Nd 2 (SeO 4 ) 3 -Sm 2 (SeO 4 ) 3 -H 2 O has been studied. Roentgenographic recording of solid ''residues'' is realized. For solid solutions energies of interchange and formation heats are calculated. Formation heats of solid solutions on the basis of samarium selenates are also found experimentally

Hydrothermal synthesis, structure, heterogeneous catalytic activity and photoluminescent properties of a novel homoleptic Sm(III)-organic framework

Energy Technology Data Exchange (ETDEWEB)

Ay, Burak [Department of Chemistry, Arts and Science Faculty,Çukurova University, 01330 Adana (Turkey); Yildiz, Emel, E-mail: eeyildiz@cu.edu.tr [Department of Chemistry, Arts and Science Faculty,Çukurova University, 01330 Adana (Turkey); Felts, Ashley C.; Abboud, Khalil A. [Department of Chemistry, University of Florida, Gainesville, FL 32611 (United States)

2016-12-15

A novel metal-organic framework, (H{sub 2}pip){sub n}[Sm{sub 2}(pydc){sub 4}(H{sub 2}O){sub 2}]{sub n} (1) (H{sub 2}pydc=2,6-pyridinedicarboxylic acid, H{sub 2}pip=piperazine) has been synthesized under hydrothermal conditions and characterized by the elemental analysis, inductively coupled plasma (ICP) spectrometer, fourier transform infrared (FT-IR) spectra, thermogravimetric analysis (TGA), single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). The structure of 1 was determined to be three-dimensional, linked along Sm-O-Sm chains. The asymmetric unit consisted of one singly anionic fragment consisting of Sm(III) coordinated to two H{sub 2}pydc ligands and one water, and one half of a protonated H{sub 2}pip, which sits on an inversion center. 1 exhibited luminescence emission bands at 534 nm at room temperature when excited at 440 nm. Its thermal behavior and catalytic performance were investigated and the selectivity was measured as 100% for the oxidation of thymol to thymoquinone. - Graphical abstract: A novel 3D lanthanide-organic framework has been synthesized under hydrothermal conditions. The thermal behavior and catalytic performance of 1 were investigated and its selectivity was measured as 100% for the oxidation of thymol to thymoquinone.

Sr_2SmNbO_6 perovskite: Synthesis, characterization and density functional theory calculations

International Nuclear Information System (INIS)

Dutta, Alo; Mukhopadhyay, P.K.; Sinha, T.P.; Shannigrahi, Santiranjan; Himanshu, A.K.; Sen, Pintu; Bandyopadhyay, S.K.

2016-01-01

The density functional theory (DFT) under the generalized gradient approximation (GGA) has been used to investigate the electronic structure of double perovskite oxide Sr_2SmNbO_6 synthesized by the solid-state reaction technique. The Rietveld refinement of the X-ray diffraction pattern of the sample shows the monoclinic P2_1/n phase at room temperature. The X-ray photoemission spectrum (XPS) of the material is collected in the energy window of 0–1200 eV. The chemical shift of the constituent elements calculated from the core level XPS spectra is used to analyze the covalency between the O anion and Sm/Nb cations. The valence band (VB) XPS spectrum is compared with the calculated VB spectrum using partial density of states in a standard way. The Raman spectrum is employed to investigate the phonon modes of the material in the monoclinic phase. Lorentzian lines are used to fit the experimental Raman spectrum, which present 24 phonon modes corresponding to the stretching and banding of NbO_6/SmO_6 octahedra and translational motion of Sr along the Sr−O bond. The discrepancy between the measured and calculated band gap values has been removed by applying modified Becke-Johnson (mBJ) potential in the DFT calculations. The experimental optical band gap obtained from the UV–visible reflectance spectrum is found to be 3.42 eV, which is well matched with the DFT calculated value of 3.2 eV, and suggests the semiconducting nature of the material. The real (ε′) and imaginary (ε″) parts of the optical dielectric constant as a function of energy along the x-, y- and z-polarization directions using mBJ potential are calculated. The collective vibrational modes of the atoms, the Born effective charge of the ions and their effect on the static dielectric constant of the material are studied using DFT. The calculated value of static dielectric constant for SSN is found to be 41.3. - Highlights: • Electronic structure and dynamical properties of Sr_2SmNbO_6 (SSN

Investigation of BaMoO4-Ln2(MoO4)3 systems (Ln = Nd, Sm, Yb)

International Nuclear Information System (INIS)

Vakulyuk, V.V.; Evdokimov, A.A.; Khomchenko, G.P.

1982-01-01

Using the methods of X-ray phase and differential-thermal analyses phase ratios in the systems BaMoO 4 -Ln 2 (MoO 4 ) 3 (Ln=Nd, Sm, Yb); BaNd 2 (MoO 4 ) 4 -MaGd 2 (MoO 4 ) are studied. Unit cell parameters and the character of melting of the compounds BaLn 2 (MoO 4 ) 4 are specified. Effect of growth conditions on laminated nature of BaGd 2 (MoO 4 ) 4 monocrystals is studied

A 3d-4f complex constructed by the assembly of a cationic template, [Cu(en){sub 2}]{sup 2+}, and a 3D anionic coordination polymer, [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}(C{sub 5}O{sub 5})(H{sub 2}O){sub 2}]{sup 2-}

Energy Technology Data Exchange (ETDEWEB)

Ke, Szu-Yu; Yeh, Chang-Tsung; Wang, Chih-Chieh [Department of Chemistry, Soochow University, Taipei, Taiwan (China); Lee, Gene-Hsiang [Instrumentation Center, National Taiwan University, Taipei, Taiwan (China); Sheu, Hwo-Shuenn [National Synchrotron Radiation Research Center, Hsinchu, Taiwan (China)

2017-05-18

A three-dimensional (3D) 3d-4f complex, [Cu(en){sub 2}][Sm{sub 2}(C{sub 5}O{sub 5})(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 2}].8H{sub 2}O (1) (en = ethylenediamine, C{sub 5}O{sub 5}{sup 2-} = dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione), were prepared via the in-situ ring-opening oxidation reaction of croconate in the presence of the template-directed complex, [Cu(en){sub 2}]{sup 2+} cation. The structural characterization determined by X-ray diffraction determination reveals that the 3D anionic coordination polymer of [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}(C{sub 5}O{sub 5})(H{sub 2}O){sub 2}]{sup 2-} in 1 can be describe in terms of in-plane 2D honeycomb-like [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}] layered frameworks bridged by oxalate with bis-chelating mode, being mutually interlinked via the bridge of μ{sub 1,2,3,4}-croconate ligands with bis-chelating coordination mode to complete the 3D open framework, which gives rise to 1D channels with pore size of 14.023 x 11.893 Aa (longest atom-atom contact distances) along the b axis. The structure-directing complex, [Cu(en){sub 2}]{sup 2+}, and solvated water molecules are resided into these honeycomb-type hexagonal channels. The thermal stability of 1 was further studied by TGA and in-situ powder X-ray diffraction measurement. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Weak ferromagnetism in Re0.67Ca0.33FeO3 (Re=La, Sm, Gd) nanoparticles

International Nuclear Information System (INIS)

Li Jiangong; Kou Xinli; Qin Yong; He Haiying

2003-01-01

Perovskite-type complex ferrite Re 0.67 Ca 0.33 FeO 3 (Re=La, Sm, Gd) nanoparticles of nearly the same particle size were prepared using sol-gel method. The influence of rare-earth ions on weak ferromagnetism in the Re 0.67 Ca 0.33 FeO 3 nanoparticles has been studied. The spontaneous magnetization M s of the Sm 0.67 Ca 0.33 FeO 3 nanoparticles is greater than that of Gd 0.67 Ca 0.33 FeO 3 nanoparticles; and M s of Gd 0.67 Ca 0.33 FeO 3 nanoparticles is greater than that of La 0.67 Ca 0.33 FeO 3 nanoparticles. The ferromagnetic component arising from the Fe sublattice increases with the decreasing rare-earth ionic radii. The magnetization of the rare-earth ions in the Sm 0.67 Ca 0.33 FeO 3 nanoparticles is smaller than that in the Gd 0.67 Ca 0.33 FeO 3 nanoparticles. The influences of the geometric and intrinsic magnetic characters of rare-earth ions as well as the particle size of the nanoparticles on weak ferromagnetism are discussed

Methylene blue degradation by NaTaO3 sol-gel doped with Sm and La

International Nuclear Information System (INIS)

Torres-Martinez, Leticia M.; Cruz-Lopez, Arquimedes; Juarez-Ramirez, Isaias; Meza-de la Rosa, Ma. Elena

2009-01-01

In this work, NaTaO 3 compounds doped with 1 M% of La and Sm, were prepared by the sol-gel (SG) method and solid state (SS) reaction; and tested as photocatalysts on the degradation of methylene blue (MB) under UV light. The structural characterization by X-ray powder diffraction revealed that the crystallization of the NaTaO 3 phase prepared by the sol-gel method started at 600 deg. C, reaching maximum crystallization at 800 deg. C. It was determined that the presence of Sm and La retard the crystallization of the NaTaO 3 phase. On the other hand, the compounds synthesized in this work showed particle sizes in the nanometric scale, as it was observed by scanning electron microscopy (SEM). The specific surface area of the compounds synthesized by the sol-gel method, showed values 4 times higher than those obtained by the solid state reaction, favoring their functional and photocatalytic performance in the methylene blue degradation. In addition, the best photocatalytic performance was shown by the NaTaO 3 doped with Sm and heated at 600 deg. C, having a half-life time of 65 min.

Mass of the 158Sm

International Nuclear Information System (INIS)

Zhao Kui; Guo Jiyu; Lu Xiuqin; Cheng Yehao; Huang Xiaolin; Ma Yong; Li Shuyuan; Ruan Ming; Li Zhichang; Jiang Chenglie

1997-01-01

A preliminary result was reported for the experiment to determine the mass of the heavier neutron-rich nucleus 158 Sm using the 160 Gd( 18 O, 20 Ne) two proton transfer reaction in last progress report. The average Q-value of (4.046 +- 0.102) MeV for the 160 Gd( 18 O, 20 Ne) 158 Sm reaction is given. A mass excess for 158 Sm of (-65.738 +- 0.102) MeV was derived. This is the first experimentally measured value of the mass of 158 Sm which is about 450 keV higher than the evaluation value from systematic trends listed in the 1993 atomic mass table. The new prediction shows better agreement with the measured values and a significant improvement over the earlier FRDM (finite-range droplet model) value

New family of lanthanide-based inorganic-organic hybrid frameworks: Ln2(OH)4[O3S(CH2)nSO3]·2H2O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4) and their derivatives.

Science.gov (United States)

Liang, Jianbo; Ma, Renzhi; Ebina, Yasuo; Geng, Fengxia; Sasaki, Takayoshi

2013-02-18

We report the synthesis and structure characterization of a new family of lanthanide-based inorganic-organic hybrid frameworks, Ln(2)(OH)(4)[O(3)S(CH(2))(n)SO(3)]·2H(2)O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4), and their oxide derivatives. Highly crystallized samples were synthesized by homogeneous precipitation of Ln(3+) ions from a solution containing α,ω-organodisulfonate salts promoted by slow hydrolysis of hexamethylenetetramine. The crystal structure solved from powder X-ray diffraction data revealed that this material comprises two-dimensional cationic lanthanide hydroxide {[Ln(OH)(2)(H(2)O)](+)}(∞) layers, which are cross-linked by α,ω-organodisulfonate ligands into a three-dimensional pillared framework. This hybrid framework can be regarded as a derivative of UCl(3)-type Ln(OH)(3) involving penetration of organic chains into two {LnO(9)} polyhedra. Substitutional modification of the lanthanide coordination promotes a 2D arrangement of the {LnO(9)} polyhedra. A new hybrid oxide, Ln(2)O(2)[O(3)S(CH(2))(n)SO(3)], which is supposed to consist of alternating {[Ln(2)O(2)](2+)}(∞) layers and α,ω-organodisulfonate ligands, can be derived from the hydroxide form upon dehydration/dehydroxylation. These hybrid frameworks provide new opportunities to engineer the interlayer chemistry of layered structures and achieve advanced functionalities coupled with the advantages of lanthanide elements.

High power density cell using nanostructured Sr-doped SmCoO3 and Sm-doped CeO2 composite powder synthesized by spray pyrolysis

Science.gov (United States)

Shimada, Hiroyuki; Yamaguchi, Toshiaki; Suzuki, Toshio; Sumi, Hirofumi; Hamamoto, Koichi; Fujishiro, Yoshinobu

2016-01-01

High power density solid oxide electrochemical cells were developed using nanostructure-controlled composite powder consisting of Sr-doped SmCoO3 (SSC) and Sm-doped CeO2 (SDC) for electrode material. The SSC-SDC nano-composite powder, which was synthesized by spray pyrolysis, had a narrow particle size distribution (D10, D50, and D90 of 0.59, 0.71, and 0.94 μm, respectively), and individual particles were spherical, composing of nano-size SSC and SDC fragments (approximately 10-15 nm). The application of the powder to a cathode for an anode-supported solid oxide fuel cell (SOFC) realized extremely fine cathode microstructure and excellent cell performance. The anode-supported SOFC with the SSC-SDC cathode achieved maximum power density of 3.65, 2.44, 1.43, and 0.76 W cm-2 at 800, 750, 700, and 650 °C, respectively, using humidified H2 as fuel and air as oxidant. This result could be explained by the extended electrochemically active region in the cathode induced by controlling the structure of the starting powder at the nano-order level.

Ab initio study of vacancy formation in cubic LaMnO{sub 3} and SmCoO{sub 3} as cathode materials in solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Olsson, Emilia; Aparicio-Anglès, Xavier [Department of Chemistry, University College London, London WC1H 0AJ (United Kingdom); Leeuw, Nora H. de, E-mail: deleeuwn@cardiff.ac.uk [Department of Chemistry, University College London, London WC1H 0AJ (United Kingdom); School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom)

2016-07-07

Doped LaMnO{sub 3} and SmCoO{sub 3} are important solid oxide fuel cell cathode materials. The main difference between these two perovskites is that SmCoO{sub 3} has proven to be a more efficient cathode material than LaMnO{sub 3} at lower temperatures. In order to explain the difference in efficiency, we need to gain insight into the materials’ properties at the atomic level. However, while LaMnO{sub 3} has been widely studied, ab initio studies on SmCoO{sub 3} are rare. Hence, in this paper, we perform a comparative DFT + U study of the structural, electronic, and magnetic properties of these two perovskites. To that end, we first determined a suitable Hubbard parameter for the Co d–electrons to obtain a proper description of SmCoO{sub 3} that fully agrees with the available experimental data. We next evaluated the impact of oxygen and cation vacancies on the geometry, electronic, and magnetic properties. Oxygen vacancies strongly alter the electronic and magnetic structures of SmCoO{sub 3}, but barely affect LaMnO{sub 3}. However, due to their high formation energy, their concentrations in the material are very low and need to be induced by doping. Studying the cation vacancy concentration showed that the formation of cation vacancies is less energetically favorable than oxygen vacancies and would thus not markedly influence the performance of the cathode.

Fabrication of High-Quality SmBa2Cu3O7-δ Thin Films by a Modified TFA-MOD Process

International Nuclear Information System (INIS)

Kim, Duck Jin; Moon, Seung Hyun; Park, Chan; Yoo, Sang Im; Song, Kyu Jeong

2005-01-01

We report a successful fabrication of high-quality SmBa 2 Cu 3 O 7-δ (SmBCO) thin films on LaAlO 3 (LAO)(100) single crystalline substrates by a modified TFA-MOD method. After the pyrolysis heat treatment of spin-coated films up to 400 degree C, SmBCO films were fired at various temperatures ranging from 810 to 850 degree C in a reduced oxygen atmosphere (10 ppm O 2 in Ar). Optimally processed SmBCO films exhibited the zero-resistance temperature (T c ,zero) of 90.2 K and the critical current density (J c ) of 0.8 MA/cm 2 at 77K in self-field. Compared with the J c values (normally, > 2 MA/cm 2 at 77 K) of MOD-TFA processed YBCO films, rather depressed J c values in SmBCO films are most probably attributed to the existence of alpha-axis oriented grains.

Reddish orange long afterglow phosphor Ca2SnO4:Sm3+prepared by sol-gel method

International Nuclear Information System (INIS)

Ju Zhenghua; Zhang Shuihe; Gao Xiuping; Tang Xiaoliang; Liu Weisheng

2011-01-01

Highlights: → A promising reddish orange emissive long afterglow phosphor Ca 2 SnO 4 :Sm 3+ prepared by sol-gel method was firstly reported. → The optics properties of Ca 2 SnO 4 :Sm 3+ were discussed. → Very useful tool, thermoluminscent technique was chosen to investigate the traps in the material. The results of thermoluminscent spectra indicating that the depth and number of traps are critical factors in determining their performance. → Furthermore, the phosphorescence mechanism was discussed successfully. → This work provides a potential approach to develop reddish orange light emitting long afterglow phosphor. - Abstract: A reddish orange light emissive long afterglow phosphor, Ca 2 SnO 4 :Sm 3+ was prepared by sol-gel method at lower temperature. The synthesized phosphors were characterized by X-ray diffraction, scanning electron micrograph images, photoluminescence spectra, afterglow decay curves and thermoluminescence spectra. Three emission peaks locate at 565 nm, 609 nm and 655 nm corresponding to CIE chromaticity coordinates of x = 0.53 and y = 0.47, which indicates the reddish orange light emitting. The fluorescent intensity and the afterglow characteristic depends on the concentration of Sm 3+ and the optimized concentration is 1.5 mol%. The afterglow decay curves are well fitted with triple-exponential decay models. The thermoluminescence glow curves show that the Sm 3+ induces suitable trap depth and result in the long afterglow phenomenon, and the corresponding increase or decrease in afterglow is associated with trap concentration, nearly no change in trap depth. The 1.5 mol% Sm 3+ -doped Ca 2 SnO 4 sample has the biggest trap concentration and exhibit the best afterglow characteristic, its' afterglow time is about 1 h. The phosphorescence mechanism of this long afterglow phosphor was discussed.

Photoluminescence in Sm3+ doped Ba2P2O7 phosphor prepared by solution combustion method

Science.gov (United States)

Ghawade, Sonal P.; Deshmukh, Kavita A.; Dhoble, S. J.; Deshmukh, Abhay D.

2018-05-01

In this paper, Sm3+ doped Ba2P2O7 phosphors were synthesized via a Solution combustion method. The crystal structure of the phosphor was characterized by XRD. Orange-red emission was observed from these phosphors under near-ultraviolet (UV) excitation at 404 nm. The luminescence properties of the obtained phosphors were characterized by different techniques. The Ba2P2O7:Sm3+ phosphor can be efficiently excited by near-UV and blue light, and their emission spectrum consists of three emission peaks, at 564, 602, and 646 nm, respectively. Based on the results, the as prepared Ba2P2O7:Sm3+ phosphors are promising orange-red-emitting phosphors exhibit great potential may be applicable as a spectral convertor in c-Si solar cell to enhance the efficiency of solar cell in future.

Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

Science.gov (United States)

Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

2018-05-01

Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

Quenched-disorder-induced magnetization jumps in (Sm,Sr)MnO3

NARCIS (Netherlands)

Fisher, LM; Kalinov, AV; Voloshin, IF; Babushkina, NA; Khomskii, DI; Zhang, Y; Palstra, TTM

2004-01-01

Magnetic field induced steplike changes in magnetization and resistivity of Sm1-xSrxMnO3 manganites were studied. A strong dependence of these features on the cooling rate was observed. Magnetostriction, however, does not show the presence of large strain in our samples. From all these features we

checkCIF/PLATON report Datablock: Sm

Indian Academy of Sciences (India)

Moiety formula C59 H45 N2 O6 Sm. Sm (C14 H12 N2) ... 4.0 Ratio. PLAT234_ALERT_4_C Large Hirshfeld Difference O4 -- C24 .. 0.16 Ang. ... outliers and unusual parameters, but every test has its limitations and alerts that are not important.

Crossrelaxations and non-radiative energy transfer from (4G5/2) Sm3+ → (5D0) Eu3+: B2O3–ZnO glasses

International Nuclear Information System (INIS)

Naresh, V.; Rudramadevi, B.H.; Buddhudu, S.

2015-01-01

Graphical abstract: The energy transfer process occurring from Sm 3+ to Eu 3+ in B 2 O 3 –ZnO (BZn) glasses is analyzed. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm 3+ and Eu 3+ has been demonstrated from the spectral overlap of Eu 3+ absorption and Sm 3+ emission, photoluminescence spectra, energy level diagram and lifetime measurements. The energy transfer mechanism in (Sm 3+ + Eu 3+ ) co-doped glass is governed by dipole–dipole interaction. - Highlights: • Spectroscopic properties of individually doped Sm 3+ , Eu 3+ & co-doped (Sm 3+ + Eu 3+ ) in BZn glasses were studied separately. • The effect of Eu 3+ concentration on luminescence properties is explained from cross-relaxations. • Energy transfer from Sm 3+ ( 4 G 5/2 ) to Eu 3+ ( 5 D 0 ) has been explained from Foster–Dexter theory. • Dipole–dipole mechanism governs the energy transfer from Sm 3+ to Eu 3+ . - Abstract: The present paper reports on the results concerning to photoluminescence features of Eu 3+ , Sm 3+ ions and energy transfer process occurring from Sm 3+ to Eu 3+ doped in 45 B 2 O 3 –55 ZnO (BZn) glasses prepared by melt quenching technique. Luminescence quenching as a function of Eu 3+ concentration in BZn glasses has been discussed. Among the studied concentrations, 0.5 mol% of Eu 3+ is optimized because it has exhibited red emission transition 5 D 0 → 7 F 2 . With regard to Sm 3+ glasses, orange emission at 602 nm ( 4 G 5/2 → 6 H 7/2 ) has been noticed on exciting with λ exci = 403 nm. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm 3+ and Eu 3+ has been explained from the spectral overlap of Eu 3+ absorption and Sm 3+ emission. The optimized concentration 0.5 mol% of Eu 3+ is co-doped with Sm 3+ in various concentrations ranging from 0.1 to 1.5 mol% inorder to study the sensitization effect of Sm 3+ on Eu 3+ luminescence. The results have revealed that with the addition of Sm 3+ to Eu 3+ : BZn

High-pressure effect in spectroscopic and structural properties of Sm{sup 3+} doped GeO{sub 2}-PbO glass

Energy Technology Data Exchange (ETDEWEB)

Rovani, Pablo Roberto; Herrera, Alvaro; Azevedo, Gustavo de Medeiros; Balzaretti, Naira Maria, E-mail: rovani.pr@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre (Brazil)

2016-07-01

Full text: The effect of densification under high pressure (7.7 GPa) on spectroscopic and structural properties of Ge{sub 2}O-PbO glass doped with Sm{sup 3+} ion were investigated. Raman spectroscopy and Extended X-ray Absorption Fine Structure (EXAFS) were used to investigate the effect of high pressure on the structural properties. The spectroscopic properties were investigated through the absorption and luminescence spectra recorded at room temperature The splitting in the VIS-NIR fluorescence bands increased after densification. Judd-Ofelt (J-O) theory was applied to evaluate phenomenological JO intensity parameters Ω (λ = 2, 4 and 6). The effect of high pressure on the transition probabilities (A{sub R}), radiative lifetimes (t{sub R}), branching ratio (b{sub R}) and stimulated emission cross-section s(l{sub p}) was also investigated. The results obtained from EXAFS indicated changes around the vicinity of Sm{sup 3+} ion which would explain the quenching in emission intensities in the visible range. A novel band related to the transition {sup 4}G{sub 5/2} to {sup 6}F{sub 11/2} was observed in the Sm{sup 3+} doped GeO{sub 2}-PbO. The obtained results may be useful for compact light sources, optical devices in the visible region and optoelectronic devices. (author)

Luminescence properties of Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor

Energy Technology Data Exchange (ETDEWEB)

Lei Bingfu, E-mail: tleibf@jnu.edu.cn [Department of Physics, Jinan University, Guangzhou 510632 (China); Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Man Shiqing [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Department of Electronic Engineering, Jinan University, Guangzhou 510632 (China); Liu Yingliang [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Yue Song [Department of Physics, Jinan University, Guangzhou 510632 (China)

2010-12-01

We report on a luminescent phenomenon in Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} afterglow phosphor. XRD, photoluminescence, afterglow emission spectra and long-lasting phosphorescence decay curve are used to characterize this phosphor. After irradiation by a 267-nm UV light for 5 min, the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor emits intense reddish-orange emitting afterglow from the {sup 4}G{sub 5/2} to {sup 6}H{sub J} (J = 5/2, 7/2, 9/2) transitions, and its afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source. Photoluminescence spectra reveal that the reddish-orange light-emitting long-lasting phosphorescence originate from the mixture of Sm{sup 3+} characteristic transitions. The afterglow decay curve of the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor contains a fast decay component and another slow decay one. The possible mechanism of this reddish-orange light-emitting LLP phosphor is also discussed based on the experiment results.

Comparison of the reactivity of alkyl and alkyl amine precursors with native oxide GaAs(100) and InAs(100) surfaces

Energy Technology Data Exchange (ETDEWEB)

Henegar, A.J., E-mail: henegar1@umbc.edu; Gougousi, T., E-mail: gougousi@umbc.edu

2016-12-30

Graphical abstract: The interaction of the native oxides of GaAs(100) and InAs(100) with alkyl (trimethyl aluminum) and alkyl amine (tetrakis dimethylamino titanium) precursors during thermal atomic layer deposition (ALD) of Al{sub 2}O{sub 3} and TiO{sub 2} is compared. Al{sub 2}O{sub 3} if found to be a significantly better barrier against the transport of the surface native oxide during the film deposition as well as after post-deposition heat treatment. This superior blocking ability also limits the removal of the native oxides during the Al{sub 2}O{sub 3} ALD process. - Highlights: • Native oxide diffusion is required for continuous native oxide removal. • The diffusion barrier capabilities of Al{sub 2}O{sub 3} limits native oxide removal during ALD. • Arsenic oxide exhibits higher mobility from InAs compared to GaAs substrates. • Oxygen scavenging from the surface by trimethyl aluminum is confirmed. - Abstract: In this manuscript we compare the interaction of alkyl (trimethyl aluminum) and alkyl amine (tetrakis dimethylamino titanium) precursors during thermal atomic layer deposition with III-V native oxides. For that purpose we deposit Al{sub 2}O{sub 3} and TiO{sub 2}, using H{sub 2}O as the oxidizer, on GaAs(100) and InAs(100) native oxide surfaces. We find that there are distinct differences in the behavior of the two films. For the Al{sub 2}O{sub 3} ALD very little native oxide removal happens after the first few ALD cycles while the interaction of the alkyl amine precursor for TiO{sub 2} and the native oxides continues well after the surface has been covered with 2 nm of TiO{sub 2}. This difference is traced to the superior properties of Al{sub 2}O{sub 3} as a diffusion barrier. Differences are also found in the behavior of the arsenic oxides of the InAs and GaAs substrates. The arsenic oxides from the InAs surface are found to mix more efficiently in the growing dielectric film than those from the GaAs surface. This difference is attributed to

Comparison of the reactivity of alkyl and alkyl amine precursors with native oxide GaAs(100) and InAs(100) surfaces

International Nuclear Information System (INIS)

Henegar, A.J.; Gougousi, T.

2016-01-01

Graphical abstract: The interaction of the native oxides of GaAs(100) and InAs(100) with alkyl (trimethyl aluminum) and alkyl amine (tetrakis dimethylamino titanium) precursors during thermal atomic layer deposition (ALD) of Al_2O_3 and TiO_2 is compared. Al_2O_3 if found to be a significantly better barrier against the transport of the surface native oxide during the film deposition as well as after post-deposition heat treatment. This superior blocking ability also limits the removal of the native oxides during the Al_2O_3 ALD process. - Highlights: • Native oxide diffusion is required for continuous native oxide removal. • The diffusion barrier capabilities of Al_2O_3 limits native oxide removal during ALD. • Arsenic oxide exhibits higher mobility from InAs compared to GaAs substrates. • Oxygen scavenging from the surface by trimethyl aluminum is confirmed. - Abstract: In this manuscript we compare the interaction of alkyl (trimethyl aluminum) and alkyl amine (tetrakis dimethylamino titanium) precursors during thermal atomic layer deposition with III-V native oxides. For that purpose we deposit Al_2O_3 and TiO_2, using H_2O as the oxidizer, on GaAs(100) and InAs(100) native oxide surfaces. We find that there are distinct differences in the behavior of the two films. For the Al_2O_3 ALD very little native oxide removal happens after the first few ALD cycles while the interaction of the alkyl amine precursor for TiO_2 and the native oxides continues well after the surface has been covered with 2 nm of TiO_2. This difference is traced to the superior properties of Al_2O_3 as a diffusion barrier. Differences are also found in the behavior of the arsenic oxides of the InAs and GaAs substrates. The arsenic oxides from the InAs surface are found to mix more efficiently in the growing dielectric film than those from the GaAs surface. This difference is attributed to lower native oxide stability as well as an initial diffusion path formation by the indium oxides.

Physical and electrical properties of thermal oxidized Sm{sub 2}O{sub 3} gate oxide thin film on Si substrate: Influence of oxidation durations

Energy Technology Data Exchange (ETDEWEB)

Goh, Kian Heng; Haseeb, A.S.M.A.; Wong, Yew Hoong, E-mail: yhwong@um.edu.my

2016-05-01

Growth of 150 nm Sm{sub 2}O{sub 3} films by sputtered pure samarium metal film on silicon substrates and followed by thermal oxidation process in oxygen ambient at 700 °C through various oxidation durations (5 min, 10 min, 15 min and 20 min) has been carried out. The crystallinity of Sm{sub 2}O{sub 3} film and existence of interfacial layer have been evaluated by X-ray diffraction, Fourier transform infrared and Raman analysis. Crystallite size and microstrain of Sm{sub 2}O{sub 3} were estimated by Williamson–Hall plot analysis. Calculated crystallite size of Sm{sub 2}O{sub 3} from Scherrer equation has similar trend with the value from Williamson–Hall plot. The presence of interfacial layer is supported by composition line scan by energy dispersive X-ray spectroscopy analysis. The surface roughness and surface topography of Sm{sub 2}O{sub 3} film were examined by atomic force microscopy analysis. The electrical characterization revealed that 15 min of oxidation durations with smoothest surface has highest breakdown voltage, lowest leakage current density and highest barrier height value. - Highlights: • Thermal oxidation of sputtered pure metallic Sm in oxygen ambient • Formation of polycrystalline Sm{sub 2}O{sub 3} and semi-polycrystalline interfacial layers • Optimization of oxidation duration of pure metallic Sm in oxygen ambient • Enhanced electrical performance with smooth surface and increased barrier height.

Effects of synthesis conditions on structure and surface properties of SmMn{sub 2}O{sub 5} mullite-type oxide

Energy Technology Data Exchange (ETDEWEB)

Thampy, Sampreetha; Ibarra, Venessa; Lee, Yun-Ju [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); McCool, Geoffrey [Nanostellar Inc., 3696 Haven Avenue, Redwood City, CA 94063 (United States); Cho, Kyeongjae [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Hsu, Julia W.P., E-mail: jwhsu@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States)

2016-11-01

Highlights: • Investigate the effects of calcination temperature and precipitation pH on crystallinity, phase purity, particle size, surface composition, and NO adsorption capacity of SmMn{sub 2}O{sub 5}. • High calcination temperature increases mullite phase purity but decreases specific surface area (SSA). • Mullite phase purity is independent of pH while SSA monotonically increases. • SSA and surface Mn/Sm ratio determine NO uptake. - Abstract: A mixed-phase compound that contains SmMn{sub 2}O{sub 5} mullite-type oxides has been reported to display excellent catalytic activity for nitric oxide (NO) oxidation. Here we investigate the effects of calcination temperature and precipitation pH on structural, physical, chemical, and surface properties of SmMn{sub 2}O{sub 5}. As the calcination temperature increases from 750 °C to 1000 °C, mullite phase purity increases from 74% to 100%, while specific surface area (SSA) decreases from 23.6 m{sup 2}/g to 5.1 m{sup 2}/g with particle size increases correspondingly. Mullite phase purity (87%) is independent of pH between 8.5–10.4, whereas SSA monotonically increases from 12.5 m{sup 2}/g at pH 8.1 to 27.4 m{sup 2}/g at pH 13. X-ray photoelectron spectroscopy (XPS) studies reveal that the surface Mn/Sm ratio is similar to the bulk value and is unaffected by calcination temperature and pH values up to 10.4, whereas sample precipitated at pH 13 is surface-rich in Sm. NO chemisorption studies show that the SSA and surface Mn/Sm ratio determine NO uptake by SmMn{sub 2}O{sub 5} mullite oxides.

Quasistatic antiferromagnetism in the quantum wells of SmTiO3/SrTiO3 heterostructures

Science.gov (United States)

Need, Ryan F.; Marshall, Patrick B.; Kenney, Eric; Suter, Andreas; Prokscha, Thomas; Salman, Zaher; Kirby, Brian J.; Stemmer, Susanne; Graf, Michael J.; Wilson, Stephen D.

2018-03-01

High carrier density quantum wells embedded within a Mott insulating matrix present a rich arena for exploring unconventional electronic phase behavior ranging from non-Fermi-liquid transport and signatures of quantum criticality to pseudogap formation. Probing the proposed connection between unconventional magnetotransport and incipient electronic order within these quantum wells has however remained an enduring challenge due to the ultra-thin layer thicknesses required. Here we address this challenge by exploring the magnetic properties of high-density SrTiO3 quantum wells embedded within the antiferromagnetic Mott insulator SmTiO3 via muon spin relaxation and polarized neutron reflectometry measurements. The one electron per planar unit cell acquired by the nominal d0 band insulator SrTiO3 when embedded within a d1 Mott SmTiO3 matrix exhibits slow magnetic fluctuations that begin to freeze into a quasistatic spin state below a critical temperature T*. The appearance of this quasistatic well magnetism coincides with the previously reported opening of a pseudogap in the tunneling spectra of high carrier density wells inside this film architecture. Our data suggest a common origin of the pseudogap phase behavior in this quantum critical oxide heterostructure with those observed in bulk Mott materials close to an antiferromagnetic instability.

Surface morphology and in-plane-epitaxy of SmBa2Cu3O7-δ films on SrTiO3 (001) substrates studied by STM and grazing incidence x-ray diffraction

DEFF Research Database (Denmark)

Jiang, Q.D.; Smilgies, D.M.; Feidenhans'l, R.

1996-01-01

The surface morphology and in-plane epitaxy of thin films of SmBa(2)Cu3O(7-delta) (Sm-BCO) grown on SrTiO3 (001) substrates with various thicknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD, SmBCO films as ...... films above h(c2), introduction of screw dislocations leads to spiral growth.......The surface morphology and in-plane epitaxy of thin films of SmBa(2)Cu3O(7-delta) (Sm-BCO) grown on SrTiO3 (001) substrates with various thicknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD, SmBCO films...... substrate. Three different types of surface morphology were observed by STM with increasing film thickness h: a) 2D growth for hh(c2). With GIXRD, a density modulation is observed in the films with a thickness below h(c2). For thicker...

Synthesis RMn{sub 2}O{sub 5} (R = Gd and Sm) nano- and microstructures by a simple hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Zhu Gangqiang, E-mail: zgq2006@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062 (China); Liu Peng [School of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062 (China); Hojamberdiev, Mirabbos [Shaanxi Key Laboratory of Nano-materials and Technology, Xi' an University of Architecture and Technology, Xi' an 710055 (China); Ge Bao [School of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062 (China); Liu Yun; Miao Hongyan; Tan Guoqiang [College of Materials Science and Engineering, Shaanxi University of Science and Technology, Xi' an 710021 (China)

2009-12-15

Single-phase RMn{sub 2}O{sub 5} (R = Gd and Sm) nano- and microstructures have been successfully synthesized via a simple hydrothermal process at 250 deg. C for 24 h using NaOH as mineralizer. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selective area electron diffraction patterns (SAED) were used to characterize the as-synthesized GdMn{sub 2}O{sub 5} and SmMn{sub 2}O{sub 5} samples. The effect of NaOH concentration and the molar ratio of Mn{sup 2+}/Mn{sup 7+} on the morphology and size of the final products was studied, and a possible formation mechanism of RMn{sub 2}O{sub 5} (R = Gd and Sm) nanoplates and nanorods under hydrothermal conditions was proposed.

Complexes of Sm(III) and Dy(III) with piperazines

Energy Technology Data Exchange (ETDEWEB)

Manhas, B S; Trikha, A K [Punjabi Univ., Patiala (India). Dept. of Chemistry; Singh, M [Guru Nanak Dev Univ., Amritsar (India). Dept. of Chemistry

1981-09-01

Complexes of SmCl/sub 3/, DyCl/sub 3/, Sm(NO/sub 3/)/sub 3/ and Dy(NO/sub 3/) with piperazine, N-methylpiperazine, 2-methylpiperazine, N-phenyl-piperazine and N, N'-dimethyl-piperazine have been prepared and characterized on the basis of elemental analyses, IR and electronic reflectance spectra and magnetic susceptibility measurements. IR data indicate that the ligands are coordinated in the chair conformation giving polymeric bridged complexes and that the nitrate group is bidentate. Coordination numbers from 6 to 12 are proposed for the lanthanide ions.

The Preparation and Optical Properties of Novel LiLa(MoO42:Sm3+,Eu3+ Red Phosphor

Directory of Open Access Journals (Sweden)

Jiaxi Wang

2018-02-01

Full Text Available Novel LiLa1−x−y(MoO42:xSm3+,yEu3+ (in short: LL1−x−yM:xSm3+,yEu3+ double molybdate red phosphors were synthesized by a solid-state reaction at as low temperature as 610 °C. The optimal doping concentration of Sm3+ in LiLa1−x(MoO42:xSm3+ (LL1−xM:xSm3+ phosphor is x = 0.05 and higher concentrations lead to emission quenching by the electric dipole—electric dipole mechanism. In the samples co-doped with Eu3+ ions, the absorption spectrum in the near ultraviolet and blue regions became broader and stronger than these of the Sm3+ single-doped samples. The efficient energy transfer from Sm3+ to Eu3+ was found and the energy transfer efficiency was calculated. Under the excitation at 403 nm, the chromaticity coordinates of LL0.95−yM:0.05Sm3+,yEu3+ approach to the NTSC standard values (0.670, 0.330 continuously with increasing Eu3+ doping concentration. The phosphor exhibits high luminous efficiency under near UV or blue light excitation and remarkable thermal stability. At 150 °C, the integrated emission intensity of the Eu3+ remained 85% of the initial intensity at room temperature and the activation energy is calculated to be 0.254 eV. The addition of the LL0.83M:0.05Sm3+,0.12Eu3+ red phosphors can improve the color purity and reduce the correlated color temperature of WLED lamps. Hence, LL1−x−yM:xSm3+,yEu3+ is a promising WLED red phosphor.

Lanthanide(III) complexes with tridentate Schiff base ligand ...

African Journals Online (AJOL)

The X-ray study reveals isotopic Nd/Sm binuclear structures were each metal ion is nine-coordinated in the same fashion. Both metal centers have distorted tricapped trigonal prism geometry, with the Schiff base acting as tridentate ligand. The DPPH· radical scavenging effects of the Schiff base ligand and its Ln(III) ...

Synthesis, crystal structure and thermal decomposition mechanism of the complex [Sm(p-BrBA)3bipy.H2O]2.H2O

International Nuclear Information System (INIS)

Zhang Haiyan; Zhang Jianjun; Ren Ning; Xu Suling; Tian Liang; Bai Jihai

2008-01-01

A new binuclear samarium (III) complex [Sm(p-BrBA) 3 bipy.H 2 O] 2 .H 2 O (p-BrBA = p-bromobenzoic acid; bipy = 2,2'-bipyridine) has been synthesized and characterized by elemental analysis, UV, IR, molar conductance and TG-DTG techniques. The structure of the complex was established by single crystal X-ray diffraction. It crystallizes in triclinic, space group P1-bar with a = 8.2476(7) A, b = 13.3483(10) A, c = 15.9035(13) A, α 73.9160(10) o , β = 78.9630(10) o , γ = 74.4770(10) o , Z = 1, D c 1.947 g cm -3 , F(000) = 910. The carboxylic groups are bonded to the samarium ion in two modes: bidentate bridging, monodentate. Each center Sm 3+ ion is eight-coordinated by one 2,2'-bipyridine molecular, four bidentate bridging and a monodentate carboxylic group, as well as one water molecular. The coordination polyhedron around each Sm 3+ ion can be described as bi-capped triangular prism geometry. The thermal decomposition behavior of the title complex in a static air atmosphere was investigated by TG-DTG and IR techniques

Local symmetry breaking and spin–phonon coupling in SmCrO3 orthochromite

International Nuclear Information System (INIS)

El Amrani, M.; Zaghrioui, M.; Ta Phuoc, V.; Gervais, F.; Massa, Néstor E.

2014-01-01

Raman scattering and infrared reflectivity performed on polycrystalline SmCrO 3 support strong influence of the antiferromagnetic order on phonon modes. Both measurements show softening of some modes below T N . Such a behavior is explained by spin–phonon coupling in this compound. Furthermore, temperature dependence of the infrared spectra has demonstrated important changes compared to the Raman spectra, suggesting strong structural modifications due to the cation displacements rather to those of the oxygen ions. Our results reveal that polar distortions originating in local symmetry breaking, i.e. local non-centrosymmetry, resulting in Cr off-centring. - Highlights: • We investigated Raman and infrared phonon modes of SmCrO 3 versus temperature. • Results reveal strong influence of the antiferromagnetic order on phonon modes. • Temperature dependence of the infrared spectra shows strong structural modifications suggesting local symmetry breaking

Femtosecond upconverted photocurrent spectroscopy of InAs quantum nanostructures

Energy Technology Data Exchange (ETDEWEB)

Yamada, Yasuhiro [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Tex, David M.; Kanemitsu, Yoshihiko, E-mail: kanemitu@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Japan Science and Technology Agency, CREST, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kamiya, Itaru [Toyota Technological Institute, Nagoya, Aichi 468-8511 (Japan)

2015-07-06

The carrier upconversion dynamics in InAs quantum nanostructures are studied for intermediate-band solar-cell applications via ultrafast photoluminescence and photocurrent (PC) spectroscopy based on femtosecond excitation correlation (FEC) techniques. Strong upconverted PC-FEC signals are observed under resonant excitation of quantum well islands (QWIs), which are a few monolayer-thick InAs quantum nanostructures. The PC-FEC signal typically decays within a few hundred picoseconds at room temperature, which corresponds to the carrier lifetime in QWIs. The photoexcited electron and hole lifetimes in InAs QWIs are evaluated as functions of temperature and laser fluence. Our results provide solid evidence for electron–hole–hole Auger process, dominating the carrier upconversion in InAs QWIs at room temperature.

Absorption Spectra of BaF2 Sm2O3, Sm, Gd, and Ho Plasmas

Science.gov (United States)

Martin, Michael; Bastiani-Ceccotti, Serena

2009-11-01

Knowledge of the opacities of high Z element plasmas is important in indirect drive ICF and the study of stellar evolution. There are few experimental measurements of this quantity, and its theoretical determination is difficult due to the number of possible bound electron configurations. This study aims to better the theoretical understanding of this parameter by looking at the 3d-4f transitions of BaF2, Sm2O3, Sm, Gd, and Ho plasmas at the LULI2000 facility. The plasmas are produced by radiative heating and are cold, 15 -- 40 eV, and relatively dense, ˜ .01gm/cm^3 A plasma is produced by a .5 ns laser pulse irradiating a gold hohlraum and then probed by an x-ray source created by a gold foil irradiated by a 10 ps laser pulse. The transmission is found with simultaneous source and absorption measurements by an x-ray spectrometer in the 8 - 20 å range We will compare the results with statistical atomic structure codes. From this experiment we will gain further insight into the spectral broadening of neighboring Z elements due to changing plasma temperature and into mixture thermodynamics. This is a first step towards an experimental study of astrophysical domains.

Polarized and resonant Raman spectroscopy on single InAs nanowires

Science.gov (United States)

Möller, M.; de Lima, M. M., Jr.; Cantarero, A.; Dacal, L. C. O.; Madureira, J. R.; Iikawa, F.; Chiaramonte, T.; Cotta, M. A.

2011-08-01

We report polarized Raman scattering and resonant Raman scattering studies on single InAs nanowires. Polarized Raman experiments show that the highest scattering intensity is obtained when both the incident and analyzed light polarizations are perpendicular to the nanowire axis. InAs wurtzite optical modes are observed. The obtained wurtzite modes are consistent with the selection rules and also with the results of calculations using an extended rigid-ion model. Additional resonant Raman scattering experiments reveal a redshifted E1 transition for InAs nanowires compared to the bulk zinc-blende InAs transition due to the dominance of the wurtzite phase in the nanowires. Ab initio calculations of the electronic band structure for wurtzite and zinc-blende InAs phases corroborate the observed values for the E1 transitions.

O-fucosylation of the notch ligand mDLL1 by POFUT1 is dispensable for ligand function.

Directory of Open Access Journals (Sweden)

Julia Müller

Full Text Available Fucosylation of Epidermal Growth Factor-like (EGF repeats by protein O-fucosyltransferase 1 (POFUT1 in vertebrates, OFUT1 in Drosophila is pivotal for NOTCH function. In Drosophila OFUT1 also acts as chaperone for Notch independent from its enzymatic activity. NOTCH ligands are also substrates for POFUT1, but in Drosophila OFUT1 is not essential for ligand function. In vertebrates the significance of POFUT1 for ligand function and subcellular localization is unclear. Here, we analyze the importance of O-fucosylation and POFUT1 for the mouse NOTCH ligand Delta-like 1 (DLL1. We show by mass spectral glycoproteomic analyses that DLL1 is O-fucosylated at the consensus motif C²XXXX(S/TC³ (where C² and C³ are the second and third conserved cysteines within the EGF repeats found in EGF repeats 3, 4, 7 and 8. A putative site with only three amino acids between the second cysteine and the hydroxy amino acid within EGF repeat 2 is not modified. DLL1 proteins with mutated O-fucosylation sites reach the cell surface and accumulate intracellularly. Likewise, in presomitic mesoderm cells of POFUT1 deficient embryos DLL1 is present on the cell surface, and in mouse embryonic fibroblasts lacking POFUT1 the same relative amount of overexpressed wild type DLL1 reaches the cell surface as in wild type embryonic fibroblasts. DLL1 expressed in POFUT1 mutant cells can activate NOTCH, indicating that POFUT1 is not required for DLL1 function as a Notch ligand.

Sr{sub 2}SmNbO{sub 6} perovskite: Synthesis, characterization and density functional theory calculations

Energy Technology Data Exchange (ETDEWEB)

Dutta, Alo, E-mail: alo_dutta@yahoo.com [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector III, Salt Lake, Kolkata, 700106 (India); Mukhopadhyay, P.K. [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector III, Salt Lake, Kolkata, 700106 (India); Sinha, T.P. [Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata, 700 009 (India); Shannigrahi, Santiranjan [Institute of Materials Research and Engineering, Agency for Science Technology and Research, 3 Research Link, Singapore, 117602 (Singapore); Himanshu, A.K.; Sen, Pintu; Bandyopadhyay, S.K. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata, 700064 (India)

2016-08-15

The density functional theory (DFT) under the generalized gradient approximation (GGA) has been used to investigate the electronic structure of double perovskite oxide Sr{sub 2}SmNbO{sub 6} synthesized by the solid-state reaction technique. The Rietveld refinement of the X-ray diffraction pattern of the sample shows the monoclinic P2{sub 1}/n phase at room temperature. The X-ray photoemission spectrum (XPS) of the material is collected in the energy window of 0–1200 eV. The chemical shift of the constituent elements calculated from the core level XPS spectra is used to analyze the covalency between the O anion and Sm/Nb cations. The valence band (VB) XPS spectrum is compared with the calculated VB spectrum using partial density of states in a standard way. The Raman spectrum is employed to investigate the phonon modes of the material in the monoclinic phase. Lorentzian lines are used to fit the experimental Raman spectrum, which present 24 phonon modes corresponding to the stretching and banding of NbO{sub 6}/SmO{sub 6} octahedra and translational motion of Sr along the Sr−O bond. The discrepancy between the measured and calculated band gap values has been removed by applying modified Becke-Johnson (mBJ) potential in the DFT calculations. The experimental optical band gap obtained from the UV–visible reflectance spectrum is found to be 3.42 eV, which is well matched with the DFT calculated value of 3.2 eV, and suggests the semiconducting nature of the material. The real (ε′) and imaginary (ε″) parts of the optical dielectric constant as a function of energy along the x-, y- and z-polarization directions using mBJ potential are calculated. The collective vibrational modes of the atoms, the Born effective charge of the ions and their effect on the static dielectric constant of the material are studied using DFT. The calculated value of static dielectric constant for SSN is found to be 41.3. - Highlights: • Electronic structure and dynamical

Guided ion beam and theoretical studies of the bond energy of SmS+

Science.gov (United States)

Armentrout, P. B.; Demireva, Maria; Peterson, Kirk A.

2017-12-01

Previous work has shown that atomic samarium cations react with carbonyl sulfide to form SmS+ + CO in an exothermic and barrierless process. To characterize this reaction further, the bond energy of SmS+ is determined in the present study using guided ion beam tandem mass spectrometry. Reactions of SmS+ with Xe, CO, and O2 are examined. Results for collision-induced dissociation processes with all three molecules along with the endothermicity of the SmS+ + CO → Sm+ + COS exchange reaction are combined to yield D0(Sm+-S) = 3.37 ± 0.20 eV. The CO and O2 reactions also yield a SmSO+ product, with measured endothermicities that indicate D0(SSm+-O) = 3.73 ± 0.16 eV and D0(OSm+-S) = 1.38 ± 0.27 eV. The SmS+ bond energy is compared with theoretical values characterized at several levels of theory, including CCSD(T) complete basis set extrapolations using all-electron basis sets. Multireference configuration interaction calculations with explicit spin-orbit calculations along with composite thermochemistry using the Feller-Peterson-Dixon method and all-electron basis sets were also explored for SmS+, and for comparison, SmO, SmO+, and EuO.

INA-Rxiv: The Missing Puzzle in Indonesia’s Scientific Publishing Workflow

Science.gov (United States)

Rahim, R.; Irawan, D. E.; Zulfikar, A.; Hardi, R.; Arliman S, L.; Gultom, E. R.; Ginting, G.; Wahyuni, S. S.; Mesran, M.; Mahjudin, M.; Saputra, I.; Waruwu, F. T.; Suginam, S.; Buulolo, E.; Abraham, J.

2018-04-01

INA-Rxiv is the first Indonesia preprint server marking the new development initiated by the open science community. This study aimed at describing the development of INA-Rxiv and its conversations. It usedanalyzer of Inarxiv.id, WhatsApp Group Analyzer, and Twitter Analytics as the tools for data analysis complemented with observation.The results showed that INA-Rxiv users are growing because of the numerous discussions in social media, e.g.WhatsApp,as well as some other positive response of writers who have been using INA- Rxiv. The perspective of growth mindset and the implication of INA-Rxiv movement for filling up the gap in accelerating scientific dissemination process are presented at the end of this article.

Spectroscopic attributes of Sm3+ doped magnesium zinc sulfophosphate glass: Effects of silver nanoparticles inclusion

Science.gov (United States)

Ahmadi, F.; Hussin, R.; Ghoshal, S. K.

2017-11-01

We report the modified optical properties of Sm3+ doped magnesium zinc sulfophosphate glass system with silver nanoparticles (Ag NPs) inclusion. Three glass samples were prepared using melt quenching method and characterized. TEM images revealed the nucleation of Ag NPs with average diameter ≈12.50 nm. The UV-Vis-NIR spectra showed thirteen absorption bands. The surface plasmon resonance (SPR) band of Ag NPs was manifested at 446 nm. FTIR spectra disclosed the bonding vibrations for P-O bonds, P-O-P linkages, and PO2 units. Ag NPs concentration dependent bonding parameters and Judd-Ofelt (JO) intensity parameters were calculated. The JO parameter Ω2 was reduced with the increase of Ag NPs contents, indicating the ionicity and symmetry enhancement between Sm3+ ions with their surrounding ligands. The emission spectra of all samples under the excitation wavelength of 402 nm exhibited four significant peaks centered at 562, 599, 644 and 702 nm which are allocated to 4G5/2 →6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions, respectively. Inclusion of Ag NPs was discerned to augment the luminescence intensity by a factor of two, which was majorly ascribed to the local field effect of Ag NPs and subsequent energy transfer from the NPs to Sm3+ ions.

22 CFR 40.68 - Aliens subject to INA 222(g).

Science.gov (United States)

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Aliens subject to INA 222(g). 40.68 Section 40... § 40.68 Aliens subject to INA 222(g). An alien who, under the provisions of INA 222(g), has voided a... new nonimmigrant visa unless the alien complies with the requirements in 22 CFR 41.101 (b) or (c...

The Preparation and Optical Properties of Novel LiLa(MoO4)2:Sm3+,Eu3+ Red Phosphor

Science.gov (United States)

Luo, Li; Huang, Baoyu; He, Jingqi; Zhang, Wei; Zhao, Weiren; Wang, Jianqing

2018-01-01

Novel LiLa1−x−y(MoO4)2:xSm3+,yEu3+ (in short: LL1−x−yM:xSm3+,yEu3+) double molybdate red phosphors were synthesized by a solid-state reaction at as low temperature as 610 °C. The optimal doping concentration of Sm3+ in LiLa1−x(MoO4)2:xSm3+ (LL1−xM:xSm3+) phosphor is x = 0.05 and higher concentrations lead to emission quenching by the electric dipole—electric dipole mechanism. In the samples co-doped with Eu3+ ions, the absorption spectrum in the near ultraviolet and blue regions became broader and stronger than these of the Sm3+ single-doped samples. The efficient energy transfer from Sm3+ to Eu3+ was found and the energy transfer efficiency was calculated. Under the excitation at 403 nm, the chromaticity coordinates of LL0.95−yM:0.05Sm3+,yEu3+ approach to the NTSC standard values (0.670, 0.330) continuously with increasing Eu3+ doping concentration. The phosphor exhibits high luminous efficiency under near UV or blue light excitation and remarkable thermal stability. At 150 °C, the integrated emission intensity of the Eu3+ remained 85% of the initial intensity at room temperature and the activation energy is calculated to be 0.254 eV. The addition of the LL0.83M:0.05Sm3+,0.12Eu3+ red phosphors can improve the color purity and reduce the correlated color temperature of WLED lamps. Hence, LL1−x−yM:xSm3+,yEu3+ is a promising WLED red phosphor. PMID:29443910

Preparation, structural characterization, and enhanced electrical conductivity of pyrochlore-type (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics

Energy Technology Data Exchange (ETDEWEB)

Xia, X.L. [Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin (China); Institute of Oceanography Instruments, Shandong Academy of Science, Chinese National Engineering Research Center for Marine Monitoring Equipment, Qingdao (China); Liu, Z.G.; Ouyang, J.H. [Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin (China); Zheng, Y. [Institute of Oceanography Instruments, Shandong Academy of Science, Chinese National Engineering Research Center for Marine Monitoring Equipment, Qingdao (China)

2012-08-15

(Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} (0 {<=} x {<=} 1.0) samples are prepared by solid state reaction method using Sm{sub 2}O{sub 3}, Eu{sub 2}O{sub 3}, and ZrO{sub 2} as starting materials. The phase composition and microstructure of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics are investigated by X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM) coupled with selected area electron diffraction and Raman spectroscopy. XRD and TEM show that all the samples exhibit a single pyrochlore-type structure. HRTEM observation indicates that the whole grain interior of Sm{sub 2}Zr{sub 2}O{sub 7} ceramic is a perfect crystal free of any dislocation. Raman spectroscopy reveals that the degree of structural disorder of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics increases gradually with increasing Eu content. The electrical conductivity of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics is investigated by impedance spectroscopy in the air and hydrogen atmospheres, respectively. The electrical conductivity of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics increases with increasing Eu content at identical temperature levels. Both the activation energy E{sub g} and the pre-exponential factor {sigma}{sub 0g} for the grain conductivity gradually increase with increasing Eu content. As the ionic conductivity shows no obvious change in both air and hydrogen atmospheres, the conduction of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} is purely ionic with negligible electronic conduction. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Interaction of La3+, Ce3+, Pr3+ and Sm3+ with DL-aspartic acid in dimethyl sulphoxide

International Nuclear Information System (INIS)

Saxena, M.C.; Saxena, R.S.

1980-01-01

La(III), Ce(III), Pr(III) and Sm(III) form 1:1 and 1:2 complexes with DL-aspartic acid in 20% aq. dimethyl sulphoxide at μ = 0.1M (NaClO 4 ) as revealed by pH-metric and conductometric titrations. Stabilities of the complexes follow the order: La 3+ 3+ 3+ 3+ . The overall changes in ΔG, ΔH and ΔS for the metal-ligand interaction have also been reported at 30deg C. (auth.)

Observation of magnetization reversal behavior in Sm0.9Gd0.1Cr0.85Mn0.15O3 orthochromites

Science.gov (United States)

Panwar, Neeraj; Joby, Jostin P.; Kumar, Surendra; Coondoo, Indrani; Vasundhara, M.; Kumar, Nitu; Palai, Ratnakar; Singhal, Rahul; Katiyar, Ram S.

2018-05-01

Impact of co-doping (Gd and Mn) on the magnetic properties has been systematically investigated in SmCrO3 compound. For the synthesized compound Sm0.9Gd0.1Cr0.85Mn0.15O3 (SGCMO), below the Neel transition temperature and under low applied magnetic field, temperature induced magnetization reversal at 105 K (crossover temperature) was noticed in the field cooled magnetization curve. Magnetization reversal attained maximum value of -1.03 emu/g at 17 K where spin reorientation occurred. The magnetization reversal disappeared under higher applied field. From the M-H plots an enhancement in the magnetization was observed due to Gd doping. Magnetocaloric effect at low temperatures measured through the magnetic entropy change was found sixteen times higher for this compound as compared to pristine SmCrO3 and twice to that of SmCr0.85Mn0.15O3 compound. The study reveals the importance of co-doping in tailoring the magnetic properties of rare-earth chromites.

Spin Injection, Manipulation, and Detection, in InAs Nanodevices

Science.gov (United States)

Jones, G. M.; Jonker, B. T.; Bennett, B. R.; Meyer, J. R.; Twigg, M. E.; Reinecke, T. L.; Park, D.; Pereverzev, S. V.; Badescu, C. S.; Li, C. H.; Hanbicki, A. T.; van'terve, O.; Vurgaftman, I.

2008-03-01

In this talk the authors will discuss their progress using InAs heterostructures to produce spin-polarized injection and detection, as well as manipulation of coherent spin-polarized electrons for a spin-based FET (SpinFET). High-quality n-type InAs heterostructures demonstrate many favorable characteristics necessary to the study of spin dynamics, including 2DEG's with small effective mass (m* = 0.023) and large g-factor (g = -15). Previously, high-mobility InAs heterostructures have been demonstrated in which electrons pass ballistically over hundreds of nanometers up to room temperature. Our devices seek to exploit the strong Spin-Orbit effect present in InAs to manipulate coherent spin-polarized electrons during transport, by producing perpendicular electric field using isolated top-gates fabricated over the electron transport region.

Potential Fluctuations at Low Temperatures in Mesoscopic-Scale SmTiO3/SrTiO3/SmTiO3 Quantum Well Structures.

Science.gov (United States)

Hardy, Will J; Isaac, Brandon; Marshall, Patrick; Mikheev, Evgeny; Zhou, Panpan; Stemmer, Susanne; Natelson, Douglas

2017-04-25

Heterointerfaces of SrTiO 3 with other transition metal oxides make up an intriguing family of systems with a bounty of coexisting and competing physical orders. Some examples, such as LaAlO 3 /SrTiO 3 , support a high carrier density electron gas at the interface whose electronic properties are determined by a combination of lattice distortions, spin-orbit coupling, defects, and various regimes of magnetic and charge ordering. Here, we study electronic transport in mesoscale devices made with heterostructures of SrTiO 3 sandwiched between layers of SmTiO 3 , in which the transport properties can be tuned from a regime of Fermi-liquid like resistivity (ρ ∝ T 2 ) to a non-Fermi liquid (ρ ∝ T 5/3 ) by controlling the SrTiO 3 thickness. In mesoscale devices at low temperatures, we find unexpected voltage fluctuations that grow in magnitude as T is decreased below 20 K, are suppressed with increasing contact electrode size, and are independent of the drive current and contact spacing distance. Magnetoresistance fluctuations are also observed, which are reminiscent of universal conductance fluctuations but not entirely consistent with their conventional properties. Candidate explanations are considered, and a mechanism is suggested based on mesoscopic temporal fluctuations of the Seebeck coefficient. An improved understanding of charge transport in these model systems, especially their quantum coherent properties, may lead to insights into the nature of transport in strongly correlated materials that deviate from Fermi liquid theory.

High coercivity Sm-Co thin films from elemental Sm/Co multilayer deposition and their microstructural aspects

Energy Technology Data Exchange (ETDEWEB)

Krishnan, M. [Surface Engineering Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India); Department of Physics, National Institute of Technology Calicut, Calicut 673601 (India); Predeep, P. [Department of Physics, National Institute of Technology Calicut, Calicut 673601 (India); Sridhara Rao, D.V. [Defence Metallurgical Research Laboratories, Hyderabad 500058 (India); Prajapat, C.L.; Singh, M.R. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Barshilia, Harish C. [Surface Engineering Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India); Chowdhury, P., E-mail: pchowdhury@nal.res.in [Surface Engineering Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India)

2017-05-15

Hard magnetic thin films with high coercivity were fabricated by magnetron sputtering on MgO(100) and quartz substrates. The films were grown by depositing sequentially Sm and Co layers at an elevated substrate temperature of 500 °C. Subsequent post-annealing was carried out at various temperatures in range of 500–700 °C to form Sm-Co hard magnetic thin films. X-ray diffraction studies revealed the formation of randomly oriented SmCo{sub 5} crystallites on quartz substrate, whereas, a textured growth of Sm{sub 2}Co{sub 7} with strong (110) crystalline phases was observed on MgO substrate. Microstructural analyses were carried out using Transmission Electron Microscopy (TEM) for samples grown on MgO substrate at 650 °C and inferred the presence of high density planar defects along with large grain boundaries. Further microdiffraction studies confirmed the presence of SmCo{sub 3} as an impurity phase in the films. Magnetic hysteresis measurements indicate the square hysteresis behaviors with high coercivity value of 3.1 T and 2.7 T for 650 °C annealed samples on both MgO and quartz substrates, respectively. The origin of such high coercivity value was then correlated with pinning type of spin reversal mechanism as confirmed through the analyses of demagnetization curves. The magnetic force microscopy images for films on MgO substrate, annealed at 650 °C, revealed the presence of magnetic domains with size higher than 1 µm. The formed magnetic domains lacked well defined boundaries indicating an enhanced exchange coupling between the grain clusters. - Highlights: • Ewald technique in micromagnetic simulations with periodic boundary conditions. • Effect of micromagnetic parameters on hysteresis in exchange spring magnets. • Importance of the interface exchange coupling for hard-soft nanocomposites. • Geometry dependence of the optimal soft phase size in exchange spring magnets.

Superconductivity at 43K in SmFeAsO1-xFx

Science.gov (United States)

Chen, X. H.; Wu, T.; Wu, G.; Liu, R. H.; Chen, H.; Fang, D. F.

2008-06-01

Since the discovery of high-transition-temperature (high-Tc) superconductivity in layered copper oxides, extensive effort has been devoted to exploring the origins of this phenomenon. A Tc higher than 40K (about the theoretical maximum predicted from Bardeen-Cooper-Schrieffer theory), however, has been obtained only in the copper oxide superconductors. The highest reported value for non-copper-oxide bulk superconductivity is Tc = 39K in MgB2 (ref. 2). The layered rare-earth metal oxypnictides LnOFeAs (where Ln is La-Nd, Sm and Gd) are now attracting attention following the discovery of superconductivity at 26K in the iron-based LaO1-xFxFeAs (ref. 3). Here we report the discovery of bulk superconductivity in the related compound SmFeAsO1-xFx, which has a ZrCuSiAs-type structure. Resistivity and magnetization measurements reveal a transition temperature as high as 43K. This provides a new material base for studying the origin of high-temperature superconductivity.

Nonlinear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) phosphate glasses

International Nuclear Information System (INIS)

Senin, H.B.; Sidek, H.A.A.; Saunders, G.A.

1994-01-01

From measurements of changes in transit time of 10 MHz of ultrasonic wave as a function of temperature and hydrostatic pressure, the linear and non-linear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses with compositions near to that corresponding to the metaphosphate have been determined. For each glass the second order elastic stiffness tensor components C sub ijs (SOEC) continue to increase down to 10K in a manner consistent with phonons interactions with two level systems. Measurements of the effects of hydrostatic pressure on the ultrasonic wave velocities have been used to determine the hydrostatic pressure derivatives (dC sub ij/dP) sub T,P=0 of the SOEC and (dB0 sup s)/dP) sub T,P=0 of the bulk modulus B0 sup s at room temperature (293K). For the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses, (dC sub 11/dP), (dC sub 44/dP), and (dBo/dP), are small but positives; these glasses stiffen under pressure. The elastic behaviour of these ternary glasses lies intermediate between those of (Sm sub 2 O sub 3)(P sub 2 O sub 5) sub (1-x) and (La sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses. Replacement of the Sm sup 3+ by La sup 3+ in the ternary phosphate glasses negates the acoustic mode softening. Possible sources of the different effects of La sub 3+ and Sm sub 3+ modifiers on the nonlinear acoustic properties of metaphosphate glasses are discussed

Local symmetry breaking and spin–phonon coupling in SmCrO{sub 3} orthochromite

Energy Technology Data Exchange (ETDEWEB)

El Amrani, M. [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Zaghrioui, M., E-mail: zaghrioui@univ-tours.fr [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Ta Phuoc, V.; Gervais, F. [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Massa, Néstor E. [Laboratorio Nacional de Investigacion y Servicios en Espectroscopia Optica-Centro CEQUINOR, Universidad Nacional de La Plata, C. C. 962, 1900 La Plata (Argentina)

2014-06-01

Raman scattering and infrared reflectivity performed on polycrystalline SmCrO{sub 3} support strong influence of the antiferromagnetic order on phonon modes. Both measurements show softening of some modes below T{sub N}. Such a behavior is explained by spin–phonon coupling in this compound. Furthermore, temperature dependence of the infrared spectra has demonstrated important changes compared to the Raman spectra, suggesting strong structural modifications due to the cation displacements rather to those of the oxygen ions. Our results reveal that polar distortions originating in local symmetry breaking, i.e. local non-centrosymmetry, resulting in Cr off-centring. - Highlights: • We investigated Raman and infrared phonon modes of SmCrO{sub 3} versus temperature. • Results reveal strong influence of the antiferromagnetic order on phonon modes. • Temperature dependence of the infrared spectra shows strong structural modifications suggesting local symmetry breaking.

Women Fellows of INAE | Women in Science | Initiatives | Indian ...

Indian Academy of Sciences (India)

Women Fellows of INAE. INAE - Indian National Academy of Engineering. Ms. Alpa Sheth Civil Engineering. Prof. Bharathi Bhat Electronics & Communication Engineering. Prof. Dipanwita Roy Chowdhury Computer Engineering and Information Technology. Prof. Kamala Krithivasan Computer Engineering and Information ...

Multifunctional Sm2-xDyxZr2O7 pyrochlore system: potential ionic conductors and photocatalysts

International Nuclear Information System (INIS)

Grover, V.; Sayed, Farheen N.; Bhattacharyya, K.; Jain, D.; Pillai, C.G.S.; Tyagi, A.K.; Arya, A.

2010-01-01

Full text: Pyrochlores have garnered considerable interest over the years because of a range of potentially useful properties such as fast-ion (mainly anion) conductivity, electrical conductivity, catalysis, luminescence etc. In present work a series of Sm 2-x Dy x Zr 2 O 7 compounds (0.0 ≤ x ≤ 2.0) were synthesized by gel combustion and characterized by Powder XRD and Raman spectroscopic studies. XRD studies revealed the system to be single-phasic throughout with the retention of pyrochlore phase till 40 mol% of Dy 3+ beyond which, an order-disorder phase transition occurred resulting in a defect fluorite structure. Surprisingly, Raman studies showed the retention of pyrochlore type ordering till the other end member, i.e. Dy 2 Zr 2 O 7 . This is the first study, which reports the retention of a weak pyrochlore type superstructure in Dy 2 Zr 2 O 7 system. Ionic conductivity measurements were performed on these samples, which showed that the activation Energy (E a ) increases with increase in Dy 3+ mol% owing to the decreased mobility with increasing degree of disorder. The representative nquist Plots are given for Sm 2 Zr 2 O 7 . These materials have a definite band gap absorbing mainly in the UV region which makes them good candidates for photocatalysed dye degradation studies. Potential of some of these compositions as photocatalysts was also explored and they were found to efficiently catalyse the degradation of Xylenol Orange with t 1/2 decreasing from pure Sm 2 Zr 2 O 7 to pure Dy 2 Zr 2 O 7

Electronic structure of GaAs with InAs (001) monolayer

International Nuclear Information System (INIS)

Tit, N.; Peressi, M.

1995-04-01

The effect on the electronic structure of an InAs monomolecular plane inserted in bulk GaAs is investigated theoretically. The (InAs) 1 (GaAs) n (001) strained superlattice is studied via ab-initio self-consistent pseudopotential calculations. Both electrons and holes are localized nearby the inserted InAs monolayer, which therefore acts as a quantum well for all the charge carriers. The small thickness of the inserted InAs slab is responsible of high confinement energies for the charge carriers, and therefore the interband electron-heavy-hole transition energy is close to the energy gap of the bulk GaAs, in agreement with recent experimental data. (author). 18 refs, 4 figs

A study of the Fe-based superconductor SmFeAsO{sub 1-x}F{sub x} by x-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zhang, Y; Chen, Y L; Cui, Y J; Cheng, C H; Zhao, Y [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhang, H [Department of Physics, Peking University, Beijing 100871 (China)], E-mail: yzhao@swjtu.edu.cn

2009-01-15

The electronic structure of the Fe-based superconductor SmFeAsO{sub 1-x}F{sub x} (x = 0 and 0.2) is studied with x-ray photoemission spectroscopy (XPS) through comparing the band structures of the nonsuperconducting parent material SmFeAsO and the superconducting SmFeAsO{sub 0.8}F{sub 0.2} (T{sub c} = 52.5 K). A small peak centered at 0.2 eV below the Fermi level, E{sub F}, in the valence band is observed in the parent material SmFeAsO, which is due to the low-spin state of the Fe 3d electrons. With fluorine doping, the peak at 0.2 eV disappears and a broad plateau forms near the Fermi level; in the meantime, the density of states at E{sub F} is slightly suppressed. The O 1s and Sm 3d core levels shift towards high energy by {approx}0.55 eV with fluorine doping, but in a sharp comparison, the Fe 2p and As 3d core levels do not shift significantly (the binding energy shift is less than 0.01 eV). It is deduced from the core-level shifts that the Fermi level of the system moves up by 0.55 eV by fluorine doping.

Growth and characterization of InAs quantum dots on silicon

Energy Technology Data Exchange (ETDEWEB)

Hansen, L.; Ankudinov, A.; Bensing, F.; Wagner, J.; Wagner, V.; Geurts, J. [Wuerzburg Univ. (Germany). Lehrstuhl fuer Experimentelle Physik 3; Ade, G.; Hinze, P. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Waag, A. [Ulm Univ. (Germany). Abt. Halbleiterphysik

2001-03-08

We present a comprehensive investigation of molecular beam epitaxial (MBE) grown InAs quantum dots (QD) on silicon (001) and (111) by reflection high energy electron diffraction (RHEED) and Raman spectroscopy in UHV environment and ex-situ by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Two different ways were developed to prepare up to 10{sup 11} cm{sup -2} InAs QDs on Si(001). One is the conventional mode by exceeding a critical thickness of deposition at which 2D growth changes towards a 3D growth mode. A second way is a dewetting transition, induced by cooling an approximately 1 ML thin 2D InAs layer from growth temperature below a critical temperature at which RHEED indicates the formation of nanoislands. Samples grown in both manners show significant differences in morphology and shape though RHEED, TEM and Raman studies correspondingly indicate strain relaxation. On Si(111) InAs grows in the common temperature range for InAs growth ({proportional_to}400 C) in flat clusters separated by deep trenches. A previous passivation of the Si(111) surface with arsenic at {proportional_to}700 C on the other hand leads to the formation of large InAs nanocrystals. (orig.)

Komunikační mix Svatebního salonu INA

OpenAIRE

Rybníčková, Michala

2015-01-01

Rybníčková, M. Marketing mix for Wedding Boutique INA. Bachelor thesis, Brno: Mendel university in Brno, 2015 This Bechelor thesis focuses on the marketing mix for the company Wedding Boutique INA. Survey results are used to evaluate the effectiveness of marketing tools currently used by INA. Furthermore, the results are used to recommend improvements to the marketing mix. Thesis also includes calculation of costs and scheduling for the year 2015.

Investigations of surface related electronic properties in SmB6 and LaAlO3/SrTiO3 heterostructures

Science.gov (United States)

Adhikari, Sanjay

This dissertation reports research performed on two types of two-dimensional. systems: SmB6 and LaAlO3/SrTiO3 (LAO/STO). SmB6 has been proposed to be. a topological Kondo insulator at low temperature. In order to understand carriers/. lattice dynamics and their interactions, femtosecond pump-probe spectroscopy. is performed in SmB6 single crystals and thin lms at variable temperatures. The. collective oscillation modes in GHz - THz and the change of carrier relaxations is. observed as a function of temperature. From the temperature dependent results. f 􀀀?d hybridization, opening of the hybridization gap, phonon bottleneck", and th. possible topological surface state formation is revealed. The topological surface state. should support helical Dirac dispersion with momentum-spin lockage. This dissertation. reports on current injection in SmB6 thin lm with circularly polarized light. at oblique incidence. This spin polarized photocurrent is concluded to be a direct. result of spin momentum lockage in SmB6. LAO/STO interface shows 2-dimensional electron gas (2DEG) at the interface. when the thickness of LAO is more than 3 unit cell. Carrier properties at the. LAO/STO interfaces are highly sensitive to the top surface termination of LAO. The spontaneous dissociation of water on LAO surface is systematically studied by. density functional theory and experimental surface characterizations. Extrinsic effects. from surface adsorbates were often ignored in the previous studies of the 2DEG. From the experiments, it is found that the dissociated water molecules, especially the. surface protons, strongly aect the interface density of states, electron distributions. and lattice distortions. The investigations also reveal the importance of additional. molecular water layers. These additional water layers, through hydrogen bonds, provide. an energetically feasible pathway for manipulating the surface-bonded protons. and thus, the interface electrical characteristics.

Syntheses and evaluation of 68 Ga- and 153 Sm-labeled DOTA-conjugated bisphosphonate ligand for potential use in detection of skeletal metastases and management of pain arising from skeletal metastases.

Science.gov (United States)

Chakraborty, Sudipta; Goswami, Dibakar; Chakravarty, Rubel; Mohammed, Sahiralam Khan; Sarma, Haladhar Deb; Dash, Ashutosh

2018-05-05

This article reports the syntheses and evaluation of 68 Ga- and 153 Sm-complexes of a new DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)-conjugated geminal bisphosphonate, DOTA-Bn-SCN-BP, for their potential uses in the early detection of skeletal metastases by imaging and palliation of pain arising from skeletal metastases, respectively. The conjugate was synthesized in high purity following an easily adaptable three-step reaction scheme. Gallium-68- and 153 Sm-complexes were prepared in high yield (>98%) and showed excellent in vitro stability in phosphate-buffered saline (PBS) and human serum. Both the complexes showed high affinity for hydroxyapatite particles in in vitro binding study. In biodistribution studies carried out in normal Wistar rats, both the complexes exhibited rapid skeletal accumulation with almost no retention in any other major organ. The newly synthesized molecule DOTA-Bn-SCN-BP would therefore be a promising targeting ligand for the development of radiopharmaceuticals for both imaging skeletal metastases and palliation of pain arising out of it in patients with cancer when radiolabeled with 68 Ga and 153 Sm, respectively. A systematic comparative evaluation, however, showed that there was no significant improvement of skeletal accumulation of the 153 Sm-DOTA-Bn-SCN-BP complex over 153 Sm-DOTMP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephosphonic acid) as the later itself demonstrated optimal properties required for an agent for bone pain palliation. © 2018 John Wiley & Sons A/S.

Spin-reorientation magnetic transitions in Mn-doped SmFeO3

Directory of Open Access Journals (Sweden)

Jian Kang

2017-09-01

Full Text Available Spin reorientation is a magnetic phase transition in which rotation of the magnetization vector with respect to the crystallographic axes occurs upon a change in the temperature or magnetic field. For example, SmFeO3 shows a magnetization rotation from the c axis above 480 K to the a axis below 450 K, known as the Γ4 → Γ2 transition. This work reports the successful synthesis of the new single-crystal perovskite SmFe0.75Mn0.25O3 and finds interesting spin reorientations above and below room temperature. In addition to the spin reorientation of the Γ4 → Γ2 magnetic phase transition observed at around TSR2 = 382 K, a new spin reorientation, Γ2 → Γ1, was seen at around TSR1 = 212 K due to Mn doping, which could not be observed in the parent rare earth perovskite compound. This unexpected spin configuration has complete antiferromagnetic order without any canting-induced weak ferromagnetic moment, resulting in zero magnetization in the low-temperature regime. M–T and M–H measurements have been made to study the temperature and magnetic-field dependence of the observed spin reorientation transitions.

Growth, and magnetic study of Sm0.4Er0.6FeO3 single crystal grown by optical floating zone technique

Science.gov (United States)

Wu, Anhua; Zhao, Xiangyang; Man, Peiwen; Su, Liangbi; Kalashnikova, A. M.; Pisarev, R. V.

2018-03-01

Sm0.4Er0.6FeO3 single crystals were successfully grown by optical floating zone method; high quality samples with various orientations were manufactured. Based on these samples, Magnetic property of Sm0.4Er0.6FeO3 single crystals were investigated systemically by means of the temperature dependence of magnetization. It indicated that compositional variations not only alter the spin reorientation temperature, but also the compensation temperature of the orthoferrites. Unlike single rare earth orthoferrites, the reversal transition temperature point of Sm0.4Er0.6FeO3 increases as magnetic field increases, which is positive for designing novel spin switching or magnetic sensor device.

Structural and luminescence behavior of Sm{sup 3+} ions doped lead boro-telluro-phosphate glasses

Energy Technology Data Exchange (ETDEWEB)

Selvi, S.; Marimuthu, K.; Muralidharan, G., E-mail: muraligru@gmail.com

2015-03-15

The Sm{sup 3+} ions doped lead boro-telluro-phosphate glasses with the chemical composition 30H{sub 3}O{sub 3}+(20–x)PbO+15TeO{sub 2}+10P{sub 2}O{sub 5}+10ZnO+15BaCO{sub 3}+xSm{sub 2}O{sub 3} (x=0.05, 0.1, 0.25, 0.5, 1.0 and 2.0 in wt%) have been prepared by a melt quenching technique and their structural and optical behavior were studied and reported. The physical properties like, refractive index, density and dielectric constant etc., have been estimated. FTIR and Raman spectral studies have been made to explore the presence of functional groups and various structural units in the prepared glasses. The formation of bridging and non-bridging oxygens of BO{sub 4}, BO{sub 3}, TeO{sub 3}, TeO{sub 6} and PbO{sub 4} structural units have been investigated. From the absorption spectra, the direct (n=1/2), indirect (n=2) band gap, band tailing parameter (B) and Urbach energy (ΔE) values were estimated. The ionic nature of the metal–ligand bond in the title glasses has been discussed. The Judd–Ofelt intensity parameters (Ω{sub λ,}λ=2, 4, and 6), oscillator strength of ƒ−ƒ electric dipole transitions and transition probability (A) have been evaluated. The predicted radiative lifetime (τ{sub rad}) and branching ratio (β{sub R}) values of the {sup 4}G{sub 5/2} excited level of the Sm{sup 3+} ions to the lower energy levels were determined and compared with the experimentally measured values. From the recorded fluorescence spectra, the strong transitions of Sm{sup 3+} ions {sup 4}G{sub 5/2}→{sup 6}H{sub 5/2} (565 nm), {sup 4}G{sub 5/2}→{sup 6}H{sub 7/2} (602 nm), {sup 4}G{sub 5/2}→{sup 6}H{sub 9/2} (648 nm) and a weak transition, {sup 4}G{sub 5/2}→{sup 6}H{sub 11/2} (709 nm) have been observed. The significant laser parameters like, gain bandwidth (σ{sub p}{sup E}×λ{sub eff}), optical gain (σ{sub p}{sup E}×τ{sub rad}) and stimulated emission cross-section (σ{sub p}{sup E}) values were estimated for the {sup 4}G{sub 5/2}→{sup 6}H{sub J} (J=5

Progress in low light-level InAs detectors- towards Geiger-mode detection

Science.gov (United States)

Tan, Chee Hing; Ng, Jo Shien; Zhou, Xinxin; David, John; Zhang, Shiyong; Krysa, Andrey

2017-05-01

InAs avalanche photodiodes (APDs) can be designed such that only electrons are allowed to initiate impact ionization, leading to the lowest possible excess noise factor. Optimization of wet chemical etching and surface passivation produced mesa APDs with bulk dominated dark current and responsivity that are comparable and higher, respectively, than a commercial InAs detector. Our InAs electron-APDs also show high stability with fluctuation of 0.1% when operated at a gain of 11.2 over 60 s. These InAs APDs can detect very weak signal down to 35 photons per pulse. Fabrication of planar InAs by Be implantation produced planar APDs with bulk dominated dark current. Annealing at 550 °C was necessary to remove implantation damage and to activate Be dopants. Due to minimal diffusion of Be, thick depletion of 8 μm was achieved. Since the avalanche gain increases exponentially with the thickness of avalanche region, our planar APD achieved high gain > 300 at 200 K. Our work suggest that both mesa and planar InAs APDs can exhibit high gain. When combined with a suitable preamplifier, single photon detection using InAs electron-APDs could be achieved.

Combustion synthesis of micron-sized Sm2Co17 particles via mechanochemical processing

International Nuclear Information System (INIS)

Liu, W.; McCormick, P.G.

1998-01-01

Full text: The spontaneous formation of Sm 2 Co 17 micron-sized particles via a mechanically induced combustion reaction has been investigated. Sm 2 Co 17 alloy particles of 0.1--2 μm in size embedded in a CaO matrix formed directly via a combustion reaction induced by milling the powder mixture of Sm 2 O 3 , CoO, CaO and Ca over a critical time. The micron-sized Sm 2 Co 17 particles were found to have the TbCu 7 -type structure and characterized by a coercivity value of 7.8 kOe while embedded in the CaO matrix. The effect of subsequent heat treatment on the structure and magnetic properties of as-milled samples was also investigated. Removal of the CaO by a carefully controlled washing process yielded micron-sized Sm 2 Co 17 particles without significant oxidation of the particles. These fine Sm 2 Co 17 particles can be used to produce anisotropic bulk or bonded magnets

Antimony substitution in SmFeAsO

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Daniel; Braun, Hans F. [Universitaet Bayreuth (Germany)

2015-07-01

In the iron based compounds structural and magnetic phase transitions can be suppressed by applying external hydrostatic pressure and superconductivity emerges. Beside hydrostatic pressure, it is possible to apply chemical pressure by the substitution of atoms in the compounds with smaller ones. Such a substitution was successful for example in LaFeAs{sub 1-x}P{sub x}O, where the parent compound shows a structural and a spin-density-wave transition and the P doped samples become superconducting. We are interested in the opposite way and substitute the As by the bigger Sb. In literature, the substitution in the La-1111 compounds was possible up to a substitution level of 40 %. With Sm, instead of La, we used a smaller rare-earth metal. We present the results obtained on polycrystalline samples characterized by Xray powder diffraction and resistivity measurements.

Homo- and heteroepitaxial growth behavior of upright InAs nanowires on InAs and GaAs substrates

Energy Technology Data Exchange (ETDEWEB)

Bauer, Jens; Gottschalch, Volker; Paetzelt, Hendrik [Institut fuer Anorganische Chemie, Universitaet Leipzig, Johannesallee 29, D-04103 Leipzig (Germany); Wagner, Gerald [Institut fuer Kristallographie und Mineralogie, Universitaet Leipzig, Linnestr. 5, D-04103 Leipzig (Germany); Pietsch, Ulrich [Festkoerperphysik, Universitaet Siegen, D-57068 Siegen (Germany)

2008-07-01

Semiconductor nanowires (NW) acquire recently attraction because of promising new application fields in electronics and optoelectronic. We applied the vapor-liquid-solid mechanism with gold seeds in combination with low-pressure metal-organic vapor phase epitaxy (LP-MOVPE) to achieve replicable InAs NW growth with high growth rates. Since the initial alloying of the gold seeds with the substrate material plays a deciding role for the inceptive NW growth, InAs free standing nanowires were grown on GaAs(111)B substrate as well as on InAs/GaAs(111)B quasi-substrate. The influence of the MOVPE parameters will be discussed with respect to NW morphology and real-structure. A special focus will be set on the heteroepitaxial InAs NW growth on GaAs substrates. Gracing-incidence X-ray studies and transmission electron microscopy investigations revealed the existence of a thin Ga{sub x}In{sub 1-x}As graduated alloy layer with embedded crystalline gold alloy particles at the NW substrate interface. The effect of droplet composition on the VLS growth will be presented in a thermodynamic model.

Identification of Ina proteins from Fusarium acuminatum

Science.gov (United States)

Scheel, Jan Frederik; Kunert, Anna Theresa; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

2015-04-01

Freezing of water above -36° C is based on ice nucleation activity (INA) mediated by ice nucleators (IN) which can be of various origins. Beside mineral IN, biological particles are a potentially important source of atmospheric IN. The best-known biological IN are common plant-associated bacteria. The IN activity of these bacteria is induced by a surface protein on the outer cell membrane, which is fully characterized. In contrast, much less is known about the nature of fungal IN. The fungal genus Fusarium is widely spread throughout the earth. It belongs to the Ascomycota and is one of the most severe fungal pathogens. It can affect a variety of organisms from plants to animals including humans. INA of Fusarium was already described about 30 years ago and INA of Fusarium as well as other fungal genera is assumed to be mediated by proteins or at least to contain a proteinaceous compound. Although many efforts were made the precise INA machinery of Fusarium and other fungal species including the proteins and their corresponding genes remain unidentified. In this study preparations from living fungal samples of F. acuminatum were fractionated by liquid chromatography and IN active fractions were identified by freezing assays. SDS-page and de novo sequencing by mass spectrometry were used to identify the primary structure of the protein. Preliminary results show that the INA protein of F. acuminatum is contained in the early size exclusion chromatography fractions indicating a high molecular size. Moreover we could identify a single protein band from IN active fractions at 130-145 kDa corresponding to sizes of IN proteins from bacterial species. To our knowledge this is for the first time an isolation of a single protein from in vivo samples, which can be assigned as IN active from Fusarium.

Structure–function analysis and genetic interactions of the SmG, SmE, and SmF subunits of the yeast Sm protein ring

Science.gov (United States)

Schwer, Beate; Kruchten, Joshua; Shuman, Stewart

2016-01-01

A seven-subunit Sm protein ring forms a core scaffold of the U1, U2, U4, and U5 snRNPs that direct pre-mRNA splicing. Using human snRNP structures to guide mutagenesis in Saccharomyces cerevisiae, we gained new insights into structure–function relationships of the SmG, SmE, and SmF subunits. An alanine scan of 19 conserved amino acids of these three proteins, comprising the Sm RNA binding sites or inter-subunit interfaces, revealed that, with the exception of Arg74 in SmF, none are essential for yeast growth. Yet, for SmG, SmE, and SmF, as for many components of the yeast spliceosome, the effects of perturbing protein–RNA and protein–protein interactions are masked by built-in functional redundancies of the splicing machine. For example, tests for genetic interactions with non-Sm splicing factors showed that many benign mutations of SmG, SmE, and SmF (and of SmB and SmD3) were synthetically lethal with null alleles of U2 snRNP subunits Lea1 and Msl1. Tests of pairwise combinations of SmG, SmE, SmF, SmB, and SmD3 alleles highlighted the inherent redundancies within the Sm ring, whereby simultaneous mutations of the RNA binding sites of any two of the Sm subunits are lethal. Our results suggest that six intact RNA binding sites in the Sm ring suffice for function but five sites may not. PMID:27417296

Structural and photoluminescence investigations of Sm{sup 3+} doped BaY{sub 2}ZnO{sub 5} nanophosphors

Energy Technology Data Exchange (ETDEWEB)

Chahar, Sangeeta; Taxak, V.B.; Dalal, Mandeep; Singh, Sonika; Khatkar, S.P., E-mail: s_khatkar@rediffmail.com

2016-05-15

Highlights: • BaY{sub 2(1−x)}Sm{sub 2x}ZnO{sub 5} nanophosphors have been synthesized via solution combustion. • The nanophosphors have been characterized by XRD, TEM and PL spectroscopy. • The crystal structure reveals influence of doping on lattice parameters. • This nanophosphor executes orange–red emission under near UV excitation. - Abstract: BaY{sub 2}ZnO{sub 5}:Sm{sup 3+} nanophosphor was successfully synthesized using solution combustion process. XRD and photoluminescence (PL) techniques were used to analyze the structural and photoluminescence properties. Morphological study of the thermally stable powder was carried out using transmission electron microscope (TEM). Rietveld refinement technique has been used to analyze the samples qualitatively as well as quantitatively. X-Ray diffraction analysis confirms that the highly crystalline single phased Sm{sup 3+} doped BaY{sub 2}ZnO{sub 5} nanophosphor crystallizes in orthorhombic lattice with Pbnm space group. The average particle size lies in the range 80–90 nm with spherical morphology. The photoluminescence excitation at 411 nm yields an intense orange–red emission centered at 610 nm due to {sup 4}G{sub 5/2}–{sup 6}H{sub 7/2} transition. The concentration dependent luminescent behavior of BaY{sub 2(1−x)}Sm{sub 2x}ZnO{sub 5} nanophosphor shows that the optimum concentration for best luminescence is 3 mol%. These results indicate that these nanophosphors find potential applications in the field of phosphor-converted white LED systems.

Two novel mixed-ligand complexes containing organosulfonate ligands.

Science.gov (United States)

Li, Mingtian; Huang, Jun; Zhou, Xuan; Fang, Hua; Ding, Liyun

2008-07-01

The structures reported herein, viz. bis(4-aminonaphthalene-1-sulfonato-kappaO)bis(4,5-diazafluoren-9-one-kappa(2)N,N')copper(II), [Cu(C(10)H(8)NO(3)S)(2)(C(11)H(6)N(2)O)(2)], (I), and poly[[[diaquacadmium(II)]-bis(mu-4-aminonaphthalene-1-sulfonato)-kappa(2)O:N;kappa(2)N:O] dihydrate], {[Cd(C(10)H(8)NO(3)S)(2)(H(2)O)(2)].2H(2)O}(n), (II), are rare examples of sulfonate-containing complexes where the anion does not fulfill a passive charge-balancing role, but takes an active part in coordination as a monodentate and/or bridging ligand. Monomeric complex (I) possesses a crystallographic inversion center at the Cu(II) atom, and the asymmetric unit contains one-half of a Cu atom, one complete 4-aminonaphthalene-1-sulfonate (ans) ligand and one 4,5-diazafluoren-9-one (DAFO) ligand. The Cu(II) atom has an elongated distorted octahedral coordination geometry formed by two O atoms from two monodentate ans ligands and by four N atoms from two DAFO molecules. Complex (II) is polymeric and its crystal structure is built up by one-dimensional chains and solvent water molecules. Here also the cation (a Cd(II) atom) lies on a crystallographic inversion center and adopts a slightly distorted octahedral geometry. Each ans anion serves as a bridging ligand linking two Cd(II) atoms into one-dimensional infinite chains along the [010] direction, with each Cd(II) center coordinated by four ans ligands via O and N atoms and by two aqua ligands. In both structures, there are significant pi-pi stacking interactions between adjacent ligands and hydrogen bonds contribute to the formation of two- and three-dimensional networks.

Structure-function analysis and genetic interactions of the SmG, SmE, and SmF subunits of the yeast Sm protein ring.

Science.gov (United States)

Schwer, Beate; Kruchten, Joshua; Shuman, Stewart

2016-09-01

A seven-subunit Sm protein ring forms a core scaffold of the U1, U2, U4, and U5 snRNPs that direct pre-mRNA splicing. Using human snRNP structures to guide mutagenesis in Saccharomyces cerevisiae, we gained new insights into structure-function relationships of the SmG, SmE, and SmF subunits. An alanine scan of 19 conserved amino acids of these three proteins, comprising the Sm RNA binding sites or inter-subunit interfaces, revealed that, with the exception of Arg74 in SmF, none are essential for yeast growth. Yet, for SmG, SmE, and SmF, as for many components of the yeast spliceosome, the effects of perturbing protein-RNA and protein-protein interactions are masked by built-in functional redundancies of the splicing machine. For example, tests for genetic interactions with non-Sm splicing factors showed that many benign mutations of SmG, SmE, and SmF (and of SmB and SmD3) were synthetically lethal with null alleles of U2 snRNP subunits Lea1 and Msl1. Tests of pairwise combinations of SmG, SmE, SmF, SmB, and SmD3 alleles highlighted the inherent redundancies within the Sm ring, whereby simultaneous mutations of the RNA binding sites of any two of the Sm subunits are lethal. Our results suggest that six intact RNA binding sites in the Sm ring suffice for function but five sites may not. © 2016 Schwer et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

The lanthanoid(III) chloride oxoselenates(IV) MCl[SeO3] (M = Sm - Lu) with HoCl[TeO3]- or B-type structure

International Nuclear Information System (INIS)

Lipp, C.; Schleid, T.

2008-01-01

The B-type lanthanoid(III) chloride oxoselenates(IV) MCl[SeO 3 ] (M = Sm - Lu) crystallize in the orthorhombic space group Pnma (no. 62) with Z = 4 in the structure type of HoCl[TeO 3 ]. Their lattice constants are decreasing following the lanthanoid contraction from a = 730.01(7), b = 707.90(7), c 895.64(9) pm for SmCl[SeO 3 ] to a = 714.63(7), b = 681.76(7), c = 864.05(9) pm for LuCl[SeO 3 ]. In contrast to NdCl[SeO 3 ], the only representative of the A-type structure, where the coordination numbers of the Nd 3+ cations are 7+2 and 8, the B-type structure is dominated by pentagonal bipyramids [MO 5 Cl 2 ] 9- (CN(M 3+ ) = 7), which are connected via trans-oriented O..O edges to ∞ 1 {[MO 4/2 e O 1/1 t Cl 2/1 t ] 5- } chains (e = edge-sharing, t = terminal) running parallel to the [010] direction. Their inclination relative to each other allows for an alternating interconnection of these chains via Cl - and ψ 1 -tetrahedral [SeO 3 ] 2- anions to form a three-dimensional structure. The distances within the [SeO 3 ] 2- groups are in the normal range (d(Se-O) = 165 - 172 pm), while those of the O 2- and Cl - anions to the central M 3+ cation diminish in dependence of the increasing atomic number (d(M-O) = 226 - 244 pm / 216 - 232 pm, d(M-Cl) 277 - 278 pm / 266 - 270 pm, M = Sm / Lu). For the synthesis of the chloride oxoselenates(IV) MCl[SeO 3 ] the respective lanthanoid sesquioxide (M 2 O 3 ) and selenium dioxide (SeO 2 ) were reacted with either an eutectic mixture of RbCl and LiCl or with the corresponding lanthanoid trichloride (MCl 3 ) in evacuated silica ampoules for either five weeks at 500 C or one week at 850 C. (orig.)

Design, fabrication, and properties of a continuous carbon-fiber reinforced Sm_2O_3/polyimide gamma ray/neutron shielding material

International Nuclear Information System (INIS)

Wang, Peng; Tang, Xiaobin; Chai, Hao; Chen, Da; Qiu, Yunlong

2015-01-01

Highlights: • Sm_2O_3 is used for neutron absorber instead of B_4C, and Sm_2O_3 has a good photon-shielding effect. • Carbon-fiber cloth and polyimide were used to enhance shielding materials’ mechanical behavior and thermal behavior. • Both Monte Carlo method and shielding test were used to evaluate shielding performance of the novel shielding material. - Abstract: The design and fabrication of shielding materials with good heat-resistance and mechanical properties is a major problem in the radiation shielding field. In this paper, based on gamma ray and neutron shielding theory, a continuous carbon-fiber reinforced Sm_2O_3/polyimide gamma ray/neutron shielding material was fabricated by hot-pressing method. The material's application behavior was subsequently evaluated using neutron shielding, photon shielding, mechanical tensile, and thermogravimetric analysis–differential scanning calorimetry tests. The results show that the tensile strength of the novel shielding material exceeds 200 MPa, which makes it of similar strength to aluminum alloy. The material does not undergo crosslinking and decomposition reactions at 300 °C and it can be used in such environments for long periods of time. The continuous carbon-fiber reinforced Sm_2O_3/polyimide material has a good shielding performance with respect to gamma rays and neutrons. The material thus has good prospects for use in fusion reactor system and nuclear waste disposal applications.

Mapping the Conformational Dynamics of E-selectin upon Interaction with its Ligands

KAUST Repository

Aleisa, Fajr A

2013-05-15

Selectins are key adhesion molecules responsible for initiating a multistep process that leads a cell out of the blood circulation and into a tissue or organ. The adhesion of cells (expressing ligands) to the endothelium (expressing the selectin i.e.,E-selectin) occurs through spatio-temporally regulated interactions that are mediated by multiple intra- and inter-cellular components. The mechanism of cell adhesion is investigated primarily using ensemble-based experiments, which provides indirect information about how individual molecules work in such a complex system. Recent developments in single-molecule (SM) fluorescence detection allow for the visualization of individual molecules with a good spatio-temporal resolution nanometer spatial resolution and millisecond time resolution). Furthermore, advanced SM fluorescence techniques such as Förster Resonance Energy Transfer (FRET) and super-resolution microscopy provide unique opportunities to obtain information about nanometer-scale conformational dynamics of proteins as well as nano-scale architectures of biological samples. Therefore, the state-of-the-art SM techniques are powerful tools for investigating complex biological system such as the mechanism of cell adhesion. In this project, several constructs of fluorescently labeled E-selectin will be used to study the conformational dynamics of E-selectin binding to its ligand(s) using SM-FRET and combination of SM-FRET and force microscopy. These studies will be beneficial to fully understand the mechanistic details of cell adhesion and migration of cells using the established model system of hematopoietic stem cells (HSCs) adhesion to the selectin expressing endothelial cells (such as the E-selectin expressing endothelial cells in the bone marrow).

Electrical characterisation of Sn doped InAs grown by MOVPE

International Nuclear Information System (INIS)

Shamba, P.; Botha, L.; Krug, T.; Venter, A.; Botha, J.R.

2008-01-01

The feasibility of tetraethyl tin (TESn) as an n-type dopant for InAs is investigated. The electrical properties of Sn doped InAs films grown on semi-insulating GaAs substrates by MOVPE are extensively studied as a function of substrate temperature, V/III ratio, substrate orientation and TESn flow rate. Results from this study show that Sn concentrations can be controlled over 2 orders of magnitude. The Sn doped InAs layers exhibit carrier concentrations between 2.7 x 10 17 and 4.7 x 10 19 cm -3 with 77 K mobilities ranging from 12 000 to 1300 cm 2 /Vs. Furthermore, the influence of the variation of these parameters on the structural properties of InAs are also reported. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Mieloencefalite protozoária eqüina (Relato de caso.

Directory of Open Access Journals (Sweden)

R. C. Gonçalves

2005-03-01

Full Text Available RESUMO :O objetivo deste trabalho foi relatar um caso de mieloencefalite protozoária eqüina no Estado de São Paulo, Brasil. O diagnóstico se baseou nos sinais clínicos, no resultado positivo para anticorpos contra Sarcocystis neurona no soro e no líquor pela técnica de Western blot. Palavras chave: Mieloencefalite, Sarcocystis neurona, eqüinos. SUMMARY: The purpose of this work was to present a case of equine protozoal myeloencephalitis (EPM in the State of São Paulo, Brazil. The diagnosis was based on the clinical sings, the positive results of the serum and cerebrospinal fluid analysis (Western blot for antibodies against Sarcocystis neurona. Keywords: Myeloencephalitis, Sarcocystis neurona,

Role of improving the physical properties of Sm-123 phase by adding nano-magnetic MnFe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Abdeen, W. [Superconductivity and Metallic Glass Lab, Physics Department, Faculty of Science, Alexandria University, Alexandria (Egypt); Physics Department, Physics Department – University College at Al-Gamom, Umm Al-Qura University (Saudi Arabia); El-Tahan, A. [Physics Department, Faculty of Science, Tanta University, Tanta (Egypt); Roumié, M. [Accelerator Laboratory, Lebanese Atomic Energy Commission, CNRS, Beirut (Lebanon); Awad, R. [Physics Department, Faculty of Science, Beirut Arab University (BAU), Beirut (Lebanon); Aly, A.I. Abou [Superconductivity and Metallic Glass Lab, Physics Department, Faculty of Science, Alexandria University, Alexandria (Egypt); El-Maghraby, E.M.; Khalaf, A. [Physics Department, Faculty of Science, Damanhur University, Damanhur (Egypt)

2016-12-01

Superconducting samples of SmBa{sub 2}Cu{sub 3}O{sub 7−δ} (Sm-123) added with various amounts of nanosized MnFe{sub 2}O{sub 4} addition (0.0−0.20 wt%) were investigated. The investigated samples prepared by the solid-state reaction method. The phase formation and microstructure of these samples were examined using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), proton induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS). XRD data indicate that the volume fraction of Sm-123 increases as nanosized MnFe{sub 2}O{sub 4} increases up to 0.02 wt%. The elemental distribution and oxygen content were deduced from PIXE and RBS. The oxygen content slightly decreases as MnFe{sub 2}O{sub 4} wt% increases. The superconducting transition temperature (T{sub c}) and critical current density (J{sub c}) of the prepared samples were estimated from electrical resistivity and transport critical current density measurements. It was found that T{sub c} decreases as nanosized MnFe{sub 2}O{sub 4} addition increases, while J{sub c} enhances up to 0.02 wt%. Moreover, the temperature dependence of normal state electrical resistivity was studied in view of the pseudogap opening in order to determine the pseudogap temperature T* as a function of nanosized MnFe{sub 2}O{sub 4} addition. T* increases as nanosized MnFe{sub 2}O{sub 4} increased, indicating the enhancement of the pseudogap formation in HTSCs by adding magnetic impurities. The crossover to fluctuation conductivity near the T{sub c} is discussed. - Highlights: • Nanosized MnFe{sub 2}O{sub 4} most likely does not enter the Sm-123 crystal structure. • Samples present a metallic-like behavior in the normal state at high temperature. • Nanosized MnFe{sub 2}O{sub 4} lead to enhancement the formation of pseudogap in cuprates HTSCs. • The increase in T{sub LD} crossover temperature up to x=0.02 wt% has been observed. • Nanosized MnFe{sub 2}O{sub 4} can

Effect of annealing on luminescence of Eu{sup 3+}- and Sm{sup 3+}-doped Mg{sub 2}TiO{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Medić, Mina; Antić, Željka; Đorđević, Vesna [University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Ahrenkiel, Phillip S. [South Dakota School of Mines & Technology, Rapid City, SD (United States); Marinović-Cincović, Milena [University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Dramićanin, Miroslav D., E-mail: dramican@vinca.rs [University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia)

2016-02-15

This work explores the influence of annealing temperature on the structure and luminescence of 2 at% Eu{sup 3+} and 1 at% Sm{sup 3+}-doped Mg{sub 2}TiO{sub 4} nanopowders produced via Pechini-type polymerized complex route. Mg{sub 2}TiO{sub 4} samples were annealed at 7 different temperatures (400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C and 700 °C) to determine the temperature range in which cubic inverse spinel structure is stable and to follow the changes of material luminescence properties. X-ray diffraction revealed that crystallization of both Eu{sup 3+} and Sm{sup 3+}-doped Mg{sub 2}TiO{sub 4} nanopowders starts at 400 °C, and that Sm{sup 3+} doped Mg{sub 2}TiO{sub 4} starts to decompose at 650 °C, while Eu{sup 3+} doped Mg{sub 2}TiO{sub 4} starts to decompose at 700 °C. Samples annealed at higher temperatures show higher crystallinity and larger crystallite size. Mg{sub 2}TiO{sub 4} powder annealed at 600 °C is composed of ~5 nm size nanoparticles agglomerated in micron-size and dense chunks. The emission spectra of nanoparticles are composed of emissions from defects in Mg{sub 2}TiO{sub 4} host and characteristic emissions of Eu{sup 3+} ({sup 5}D{sub 0}→{sup 7}F{sub J}) and Sm{sup 3+} ({sup 4}G{sub 5/2}→{sup 6}H{sub J}) ions. The stronger emission and longer emission decays are observed with samples annealed at high temperatures. In the case of the Eu{sup 3+} ions emission intensity increased one order of magnitude between samples annealed at 400 °C and 650 °C. - Highlights: • Mg{sub 2}TiO{sub 4} nanoparticles of 5–10 nm in size are prepared by polymerized complex route. • Emission spectra and decays of Eu{sup 3+} and Sm{sup 3+} doped Mg{sub 2}TiO{sub 4} nanoparticles are shown. • Eu{sup 3+}(Sm{sup 3+}) doped Mg{sub 2}TiO{sub 4} can be annealed at temperatures <700 °C (650 °C). • Emission intensity of nanoparticles increases with increase of annealing temperature.

Site-selective laser spectroscopy of Sm{sup 3+} ions in Y{sub 4}Al{sub 2}O{sub 9}

Energy Technology Data Exchange (ETDEWEB)

Kaczkan, M., E-mail: m.kaczkan@elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics, Koszykowa 75, Warsaw 00-662 (Poland); Boruc, Z. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, Warsaw 00-662 (Poland); Turczyński, S.; Pawlak, D. [Institute of Electronic Materials Technology, Wolczynska 133, Warsaw 01-919 (Poland); Malinowski, M. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, Warsaw 00-662 (Poland)

2016-02-15

Sm{sup 3+} doped Y{sub 4}Al{sub 2}O{sub 9} (YAM) crystals were prepared by the micro-pulling down method. Optical-absorption and laser-selective-excitation techniques along with luminescence decays have been used to reveal that Sm{sup 3+} ions in YAM normally occupy four sites, which were characterized and discussed. The comprehensive sets of Stark energy levels of the four Sm{sup 3+} centers in YAM were established. The intensity ratio of forced electric dipole ({sup 4}G{sub 5/2} → {sup 6}H{sub 9/2}) and magnetic dipole ({sup 4}G{sub 5/2} → {sup 6}H{sub 5/2}) transitions has been used to estimate the degree of asymmetry of Sm{sup 3+} sites. The lifetime of Sm{sup 3+} ions and the cross-relaxation rates were experimentally determined as a function of concentration for two distinct crystallographic Sm{sup 3+} centers. The dependencies of the nearest surroundings on the relaxation of the {sup 4}G{sub 5/2} excited state was discussed.

Enhanced visible light-responsive photocatalytic activity of LnFeO3 (Ln = La, Sm) nanoparticles by synergistic catalysis

International Nuclear Information System (INIS)

Li, Li; Wang, Xiong; Zhang, Yange

2014-01-01

Highlights: • LnFeO 3 (Ln = La, Sm) nanoparticles were prepared by a facile sol–gel method. • The samples exhibit superior visible-light-responsive photocatalytic activity. • Synergistic effect will enhance the photodegradation of RhB under visible light. - Abstract: LnFeO 3 (Ln = La, Sm) nanoparticles were prepared by a facile sol–gel method with assistance of glycol at different calcination temperatures. The as-synthesized LnFeO 3 was characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimeter and thermogravimetric analysis, and UV–vis absorption spectroscopy. The photocatalytic behaviors of LnFeO 3 nanoparticles were evaluated by photodegradation of rhodamine B under visible light irradiation. The results indicate that the visible light-responsive photocatalytic activity of LnFeO 3 nanoparticles was enhanced remarkably by the synergistic effect between the semiconductor photocatalysis and Fenton-like reaction. And a possible catalytic mechanism was also proposed based on the experimental results

The microwave magnetic performance of Sm3+ doped BaCo2Fe16O27

International Nuclear Information System (INIS)

Wang Lixi; Song Jie; Zhang Qitu; Huang Xiaogu; Xu Naicen

2009-01-01

W-type barium hexaferrites doped with Sm 3+ , Ba 1-x Sm x Co 2 Fe 16 O 27 (x = 0.0, 0.05, 0.1, 0.15, 0.2) were prepared by the conventional solid-state reaction. The structure and electromagnetic properties of the calcined samples were studied using powder X-ray diffraction (XRD) and network analyzer (Agilent 8722ET). All the XRD patterns showed the single phase of the magnetoplumbite barium ferrite without other intermediate phase when x ≤ 0.15. The microwave electromagnetic properties of the samples have been studied at the frequency range from 2 GHz to 18 GHz. It was shown that ε' and ε'' increased slightly, and the maximum of ε'' shifted to low frequency position with Sm 3+ ions doping. The μ'' and μ' values were improved significantly when x = 0.15, and the peak value of μ'' was about 1.6 at 7 GHz and 1.75 at 18 GHz position, respectively, exhibiting excellent microwave magnetic performance. Furthermore, the reasons have also been discussed using electromagnetic theory. Ba 0.85 Sm 0.15 Co 2 Fe 16 O 27 powders (85% by weight) were mixed with epoxy resin to form compound coating materials with different thicknesses, the reflection loss values of which were also measured. It is shown that the reflection loss value increases with the increase of the coating thickness under our experimental range. The maximum of reflection loss reached about -23 dB and it was below -10 dB at the frequency range from 8 GHz to 18 GHz, when the thickness was 1.8 mm.

Chemical and biological evaluation of 153Sm and 46/47Sc complexes of indazolebisphosphonates for targeted radiotherapy

International Nuclear Information System (INIS)

Neves, Maria; Teixeira, Fatima C.; Antunes, Ines; Majkowska, Agnieszka; Gano, Lurdes; Santos, Ana Cristina

2011-01-01

Introduction: Novel 1-hydroxy-1,1-bisphosphonates derived from indazole and substituted at the C-3 position were labeled with the radionuclides 46 Sc and 153 Sm. Several parameters such as molar ligand concentration, pH, reaction time and temperature were studied. The radiolabelling yield, reaction kinetics and stability were assessed and radiocomplexes were evaluated by in vitro and in vivo experiments. Methods: The radionuclides 46 Sc and 153 Sm were obtained by neutron irradiation of natural Sc 2 O 3 and enriched 152 Sm 2 O 3 (98.4%) targets at the neutron flux of 3x10 14 n cm -2 s -1 . The radiolabelling yield, reaction kinetics and stability were accomplished by ascending instant thin layer chromatography. The radiocomplexes were submitted to in vitro experiments (hydroxyapatite binding and lipophilicity) and biodistribution studies in animal models. Results: The radionuclides 46 Sc and 153 Sm were produced with specific activities of 100 and 430 MBq mg -1 , respectively. High radiochemical yields were achieved and the hydrophilic radiocomplexes have shown high degree of binding to hydroxyapatite. Biodistribution studies at 1, 3 and 24 h of the 4 radiocomplexes under study, have showed a similar biodistribution profile with a relatively high bone uptake, slow clearance from blood and a very slow rate of total radioactivity excretion from the whole animal body. Conclusion: We have developed a new class of indazolebisphosphonates complexes with radioisotopes of samarium and scandium. All complexes have shown high degree of binding to hydroxyapatite, which could be attributed to the ionized phosphonate groups. The bone uptake and the bone-to-muscle ratios were relatively low.

Synthesis and characterization of multiferroic Sm-doped BiFeO{sub 3} nanopowders and their bulk dielectric properties

Energy Technology Data Exchange (ETDEWEB)

Yotburut, Benjaporn [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Thongbai, Prasit [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Yamwong, Teerapon [National Metals and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani 12120 (Thailand); Maensiri, Santi, E-mail: santimaensiri@g.sut.ac.th [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); SUT Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand)

2017-09-01

Highlights: • Bi{sub 1−x}Sm{sub x}FeO{sub 3} nanopowders were prepared by a simple co-precipitation method. • The prepared samples were well characterized by XRD, TEM, SEM, and XAS. • The XANES spectra identified the valence state of Fe ion in all nanopowders as 3+. • Increasing in applied dc bias voltage from 0 to 20 V causes a decrease in the dielectric constant. • The relaxation activation energy of a LFR is larger than that of a HFR. - Abstract: Multiferroic Bi{sub 1−x}Sm{sub x}FeO{sub 3} (x = 0, 0.05, 0.1, 0.2, and 0.3) nanopowders with particle sizes of 69–22.6 nm were prepared by a simple co-precipitation method. The structure and morphology of the samples were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns confirmed the phase transition from rhombohedral to orthorhombic phases. The results of X-ray absorption spectroscopy (XAS) data indicate that the oxidation state of Fe in the sample was Fe{sup 3+}. The results of magnetic properties revealed the enhancement of weak ferromagnetic property with increasing Sm doping in BFO nanopowders. SEM images revealed that the average grain size decreased with an increase in Sm concentration. Undoped BFO ceramics exhibited a high dielectric constant ε′ ∼1.1 × 10{sup 4} and a low loss tangent of tan δ ∼0.5 at room temperature for 1 kHz. The room temperature dielectric constant decreased with increasing concentration of Sm doping and the dielectric relaxation peaks were observed at x ≤ 0.1. The dielectric relaxation peaks which were observed at all frequency ranges were x ≤ 0.1 samples which were attributed to Maxwell-Wagner relaxation. As the temperature increased, great increases in dielectric permittivity were observed in all the Bi{sub 1−x}Sm{sub x}FeO{sub 3} samples. The effects of grain boundaries on the dielectric properties of Sm-doped BFO ceramics were investigated by measuring the dielectric responds in the frequencies of 100 Hz–1

Potentiometric studies on some ternary complexes of Nd(III), Sm(III), Gd(III) and Ho(III) with cyclohexanediaminetetraacetic acid as primary ligand

International Nuclear Information System (INIS)

Marathe, D.G.; Munshi, K.N.

1983-01-01

The formation constants of the ternary complexes of neodymium(III), samarium(III), gadlonium(III) and holmium(III) with cyclohexanediaminetetraacetic acid (CyDTA) as primary ligand and dihydroxynaphthalene (DHN), dihydroxynaphthalene-6-sulphonic acid (DHNSA) and cateechol-3,5-disulphonic acid (CDSA) as secondary ligands have been investigated by potentiometric titration technique. The secondary ligands have been investigated by potentiometric titration technique. The values of formation constants of 1:1:1 ternary chelates are reported at three different temperatures, and at a fixed ionic strength, μ = 0.1 M (NaClO 4 ). (author)

SmBaCoCuO5+x as cathode material based on GDC electrolyte for intermediate-temperature solid oxide fuel cells

International Nuclear Information System (INIS)

Lue Shiquan; Long, Guohui; Ji Yuan; Meng Xiangwei; Zhao Hongyuan; Sun Cuicui

2011-01-01

Research highlights: → We synthesize a new kind of layered perovskite SmBaCoCuO 5+x (SBCCO) as a cathode material of a solid oxide fuel cell. → There are some reports on the performance of cathodes in proton-conducting SOFCs based on BaCe 0.8 Sm 0.2 O 3-δ electrolyte. → However, to the best of our knowledge, the performance of SBCCO cathodes in oxygen-ion conducting SOFCs has not been reported to date. → In this work, the ceramic powder SBCCO is examined as a cathode for IT-SOFCs based on Ce 0.9 Gd 0.1 O 1.95 (GDC) electrolyte. - Abstract: The performance of SmBaCoCuO 5+x (SBCCO) cathode has been investigated for their potential utilization in intermediate-temperature solid oxide fuel cells (IT-SOFCs). The powder X-ray diffraction (XRD), thermal expansion and electrochemical performance on Ce 0.9 Gd 0.1 O 1.95 (GDC) electrolyte are evaluated. XRD results show that there is no chemical reaction between SBCCO cathode and GDC electrolyte when the temperature is below 950 o C. The thermal expansion coefficient (TEC) value of SBCCO is 15.53 x 10 -6 K -1 , which is ∼23% lower than the TEC of the SmBaCo 2 O 5+x (SBCO) sample. The electrochemical impedance spectra reveals that SBCCO symmetrical half-cells by sintering at 950 deg. C has the best electrochemical performance and the area specific resistance (ASR) of SBCCO cathode is as low as 0.086 Ω cm 2 at 800 o C. An electrolyte-supported fuel cell generates good performance with the maximum power density of 517 mW cm -2 at 800 deg. C in H 2 . Preliminary results indicate that SBCCO is promising as a cathode for IT-SOFCs.

Ag-catalyzed InAs nanowires grown on transferable graphite flakes

DEFF Research Database (Denmark)

Meyer-Holdt, Jakob; Kanne, Thomas; Sestoft, Joachim E.

2016-01-01

on exfoliated graphite flakes by molecular beam epitaxy. Ag catalyzes the InAs nanowire growth selectively on the graphite flakes and not on the underlying InAs substrates. This allows for easy transfer of the flexible graphite flakes with as-grown nanowire ensembles to arbitrary substrates by a micro...

20 CFR 668.860 - What cash management procedures apply to INA grant funds?

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false What cash management procedures apply to INA... Administrative Requirements § 668.860 What cash management procedures apply to INA grant funds? INA grantees must... implement the Cash Management Improvement Act, found at 31 CFR part 205, apply by law to most recipients of...

Growth, mechanical, and magnetic study of SmFeO{sub 3} single crystal grown by optical floating zone technique

Energy Technology Data Exchange (ETDEWEB)

Babu, P. Ramesh [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhaumik, Indranil [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India); Ganesamoorthy, S. [Material Science Group, IGCAR, Kalpakkam, Tamil Nadu (India); Kalainathan, S., E-mail: kalainathan@yahoo.com [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhatt, R.; Karnal, A.K.; Gupta, P.K. [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India)

2016-08-15

Single crystals of Samarium orthoferrite (SmFeO{sub 3}) have been grown by the optical floating zone technique. The growth parameters to yield good quality crystals are 5 mm/h for pulling and 30–40 rpm for rotation. The mechanical behavior of the grown crystal has been investigated. Rosette pattern has been observed around the indentation and the microhardness has been found to decreases non-linearly with the applied load. For load higher than 1.96 N there is a transition from palmqvist to median crack due to plastic deformation of the crystal. The hardness parameters like fracture toughness, brittleness index, and yield strength have also been calculated for palmqvist and median cracks occurring on the crystal surface. The magnetic investigations revealed that a magnetic transition in the range of 300–180 K. Above 180 K, the magnetization decreases as Sm and Fe sublattices have opposite spins. At high temperature, two anomalies are observed, one due to near spin reorientation (T{sub SR} = 480 K) and the other is AFM to paramagnetic transitions (T{sub N} = 670 K). The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state of the SmFeO{sub 3} crystals. Bloch parameter (3.28 × 10{sup −5} K{sup −3/2}) has also been evaluated. - Highlights: • SmFeO{sub 3} single crystals have been grown by OFZ technique in air. • The microhardness has been found to decreases non-linearly with the applied load. • At 472 K, spin reorientation occurs in Fe sublattice. • The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state. • Bloch 3/2-law holds good for SmFeO{sub 3} (B-parameter as 3.28 × 10{sup −5} K{sup −3/2}).

SmShb, the SH2-Containing Adaptor Protein B of Schistosoma mansoni Regulates Venus Kinase Receptor Signaling Pathways.

Directory of Open Access Journals (Sweden)

Marion Morel

Full Text Available Venus kinase receptors (VKRs are invertebrate receptor tyrosine kinases (RTKs formed by an extracellular Venus Fly Trap (VFT ligand binding domain associated via a transmembrane domain with an intracellular tyrosine kinase (TK domain. Schistosoma mansoni VKRs, SmVKR1 and SmVKR2, are both implicated in reproductive activities of the parasite. In this work, we show that the SH2 domain-containing protein SmShb is a partner of the phosphorylated form of SmVKR1. Expression of these proteins in Xenopus oocytes allowed us to demonstrate that the SH2 domain of SmShb interacts with the phosphotyrosine residue (pY979 located in the juxtamembrane region of SmVKR1. This interaction leads to phosphorylation of SmShb on tyrosines and promotes SmVKR1 signaling towards the JNK pathway. SmShb transcripts are expressed in all parasite stages and they were found in ovary and testes of adult worms, suggesting a possible colocalization of SmShb and SmVKR1 proteins. Silencing of SmShb in adult S. mansoni resulted in an accumulation of mature sperm in testes, indicating a possible role of SmShb in gametogenesis.

SmShb, the SH2-Containing Adaptor Protein B of Schistosoma mansoni Regulates Venus Kinase Receptor Signaling Pathways.

Science.gov (United States)

Morel, Marion; Vanderstraete, Mathieu; Cailliau, Katia; Hahnel, Steffen; Grevelding, Christoph G; Dissous, Colette

2016-01-01

Venus kinase receptors (VKRs) are invertebrate receptor tyrosine kinases (RTKs) formed by an extracellular Venus Fly Trap (VFT) ligand binding domain associated via a transmembrane domain with an intracellular tyrosine kinase (TK) domain. Schistosoma mansoni VKRs, SmVKR1 and SmVKR2, are both implicated in reproductive activities of the parasite. In this work, we show that the SH2 domain-containing protein SmShb is a partner of the phosphorylated form of SmVKR1. Expression of these proteins in Xenopus oocytes allowed us to demonstrate that the SH2 domain of SmShb interacts with the phosphotyrosine residue (pY979) located in the juxtamembrane region of SmVKR1. This interaction leads to phosphorylation of SmShb on tyrosines and promotes SmVKR1 signaling towards the JNK pathway. SmShb transcripts are expressed in all parasite stages and they were found in ovary and testes of adult worms, suggesting a possible colocalization of SmShb and SmVKR1 proteins. Silencing of SmShb in adult S. mansoni resulted in an accumulation of mature sperm in testes, indicating a possible role of SmShb in gametogenesis.

La costituzione dell’INA e il monopolio statale delle assicurazioni (1912-1922 = The constitution of INA and the state monopoly of insurance (1912-1922

Directory of Open Access Journals (Sweden)

Serena Potito

2012-07-01

Full Text Available Il saggio –basato principalmente su documenti attualmente conservati presso l’Archivio Storico dell’INA, a Roma– esamina le vicende legate alla nascita dell’Istituto, costituito in un regime transitorio di monopolio relativo nel settore delle assicurazioni sulla vita.A causa del suo significato economico e politico, questa speciale forma di monopolio statale diede luogo a molte reazioni nell’ambito finanziario e politico nazionale, pertanto l’INA iniziò i primi anni di attività in una situazione conflittuale ed incerta.Il saggio inoltre approfondisce le ripercussioni sul mercato assicurativo internazionale in seguito alla nascita dell’INA.Durante il decennio di monopolio parziale dell’Istituto nel settore delle assicurazioni sulla vita (1912-1922, le compagnie di assicurazione straniere ritennero compromessi i loro interessi finanziari nel mercato italiano, e lo osteggiarono fino al 1923, quando una nuova legge riformò il mercato assicurativo sulla vita, abolendo il regime di monopolio.The essay –mainly based on documents actually preserved in the Historical Archives of INA, in Rome– examines the events connected with the foundation of the Institute, established in a transient condition of partial monopoly system in life insurance sector. Because of its economic and political meaning, this special form of state monopoly gave rise to many reactions in the financial and political national context, and so INA started its first years of activity in a troubled and unstable situation. The essay also discusses about the repercussions on international insurance market in consequence of the foundation of INA.During the ten-year perior of partial monopoly of the Institute in life insurance sector (1912-1922, foreign insurance companies deemed their financial interest in Italian market jeopardized, and contrasted with it until 1923, when a new act reformed life insurance market, abrogating monopoly system. 

Crystal structures of orthorhombic, hexagonal, and cubic compounds of the Sm(x)Yb(2−x)TiO5 series

International Nuclear Information System (INIS)

Aughterson, Robert D.; Lumpkin, Gregory R.; Reyes, Massey de los; Sharma, Neeraj; Ling, Christopher D.; Gault, Baptiste; Smith, Katherine L.; Avdeev, Maxim; Cairney, Julie M.

2014-01-01

A series of single phase compounds with nominal stoichiometry Sm (x) Yb (2−x) TiO 5 (x=2, 1.4, 1, 0.6, and 0) have been successfully fabricated to generate a range of crystal structures covering the most common polymorphs previously discovered in the Ln 2 TiO 5 series (Ln=lanthanides and yttrium). Four of the five samples have not been previously fabricated in bulk, single phase form so their crystal structures are refined and detailed using powder synchrotron and single crystal x-ray diffraction, neutron diffraction and transmission electron microscopy. Based on the phase information from diffraction data, there are four crystal structure types in this series; orthorhombic Pnma, hexagonal P6 3 /mmc, cubic (pyrochlore-like) Fd-3m and cubic (fluorite-like) Fm-3m. The cubic materials show modulated structures with variation between long and short range ordering and the variety of diffraction techniques were used to describe these complex crystal structure types. - Graphical abstract: A high resolution image of the compound Sm 0.6 Yb 1.4 TiO 5 showing contrast from lattice fringes and the corresponding fast Fourier transform (FFT) of the HREM image with pyrochlore related diffraction spots marked “P” and fluorite marked “F”. The crystal is oriented down the [1 1 0] zone axis based on the Fd-3m structure. The ideal crystal structure (no vacancies) of the cubic, pyrochlore-like (Sm 0.6 Yb 1.4 TiO 5 ). - Highlights: • First fabrication of bulk single-phase material with stoichiometry Sm 2 TiO 5 . • Systematic study of crystal structure types within Ln 2 TiO 5 series (Ln=lanthanides). • A novel technique using IFFT of HREM images to study cubic structures

Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

Directory of Open Access Journals (Sweden)

Tyagi Renu

2009-01-01

Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

Tailoring the luminescence properties of Y_2O_3:Sm"3"+ nanophosphors by 6 MeV electron beam irradiation

International Nuclear Information System (INIS)

Sunitha, D.V.; Nagabhushana, H.; Hareesh, K.; Bhoraskar, V.N.; Dhole, S.D.

2017-01-01

Sm"3"+ (3 mol%) ions doped Y_2O_3 nanophosphors were synthesized by green synthesis route using Aloe Vera gel as fuel. The final product was irradiated by 6 MeV electron beam (E-beam) to different fluences in the range (2–10 × 10"1"3 e"− cm"−"2) and well characterized. Powder X-ray Diffractogram (PXRD) results revealed the loss of crystalline nature due to lattice disorder created during irradiation. Fourier Transform Infrared (FTIR) spectroscopic results showed absorption peaks around 688–843 cm"−"1 (Y-O bond), 1076 and 1398 cm"−"1 (C-O bond), 1505–1765 cm"−"1 and 3498 cm"−"1 (O-H bond). Scanning Electron Microscopic (SEM) images showed flake like morphological features. The Photoluminescence (PL) emission spectrum recorded at 407 nm excitation showed magnetic and electric dipole transitions at ∼569–575 ("4G_5_/_2 → "6H_5_/_2), ∼607–623 ("4G_5_/_2 → "6H_7_/_2) and ∼655–668 nm ("4G_5_/_2 → "6H_9_/_2) respectively. Thermoluminescence (TL) glow curve consists of three peaks in E-beam irradiated nanophosphors at 158, 243 and 352 °C due to creation of more number of trapping and luminescent centers. The E-beam irradiated Y_2O_3:Sm"3"+ nanophosphors showed strong PL emission with color co-ordinate values lying in the orange-red region. Therefore, this material can be potentially used as a red component in WLEDs (White LEDs). - Highlights: • Y_2O_3:Sm"3"+ nanophosphor was synthesized by solution combustion technique using Aloe Vera gel as a fuel. • Y_2O_3:Sm"3"+ nanophosphor was irradiated with 6 MeV E-beam in the fluence range 2–10 × 10"1"3e"− cm"−"2. • The size of the particle decreases and surface area increases with increase in E-beam fluence. • The E-beam irradiated Y_2O_3:Sm"3"+ nanophosphors PL intensity increases and CIE coordinate values moves towards red region indicating the potential usage of this phosphor for LED applications.

PANP is a novel O-glycosylated PILR{alpha} ligand expressed in neural tissues

Energy Technology Data Exchange (ETDEWEB)

Kogure, Amane [Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871 (Japan); Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Osaka 565-0871 (Japan); Shiratori, Ikuo [Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871 (Japan); Wang, Jing [Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871 (Japan); Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Osaka 565-0871 (Japan); Lanier, Lewis L. [Department of Microbiology and Immunology and the Cancer Research Institute, University of California San Francisco, San Francisco, CA 94143 (United States); Arase, Hisashi, E-mail: arase@biken.osaka-u.ac.jp [Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871 (Japan); Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Osaka 565-0871 (Japan); JST CREST, Saitama 332-0012 (Japan)

2011-02-18

Research highlights: {yields} A Novel molecule, PANP, was identified to be a PILR{alpha} ligand. {yields} Sialylated O-glycan structures on PANP were required for PILR{alpha} recognition. {yields} Transcription of PANP was mainly observed in neural tissues. {yields} PANP seems to be involved in immune regulation as a ligand for PILR{alpha}. -- Abstract: PILR{alpha} is an immune inhibitory receptor possessing an immunoreceptor tyrosine-based inhibitory motif (ITIM) in its cytoplasmic domain enabling it to deliver inhibitory signals. Binding of PILR{alpha} to its ligand CD99 is involved in immune regulation; however, whether there are other PILR{alpha} ligands in addition to CD99 is not known. Here, we report that a novel molecule, PILR-associating neural protein (PANP), acts as an additional ligand for PILR{alpha}. Transcription of PANP was mainly observed in neural tissues. PILR{alpha}-Ig fusion protein bound cells transfected with PANP and the transfectants stimulated PILR{alpha} reporter cells. Specific O-glycan structures on PANP were found to be required for PILR recognition of this ligand. These results suggest that PANP is involved in immune regulation as a ligand of the PILR{alpha}.

Combustion synthesis and characterization of MV0.5P0.5O4: Sm3+, Tm3+ (M = Gd, La, Y)

Science.gov (United States)

Motloung, Selepe J.; Lephoto, Mantwa A.; Tshabalala, Kamohelo G.; Ntwaeaborwa, Odireleng M.

2018-04-01

In this paper, GdV0.5P0.5O4: Sm3+, Tm3+, LaV0.5P0.5O4: Sm3+, Tm3+ and YV0.5P0.5O4: Sm3+, Tm3+ phosphor powders were prepared by solution combustion method using urea as a fuel. The phase purity, surface morphology, optical and photoluminescence properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence spectroscopy. The XRD results indicated that the prepared powders are of a single phase and crystallized in tetragonal structure for Gd and Y systems while monoclinic phase was observed for La system. SEM showed that the samples consisted of mixed structures. The estimated band gaps were 2.2, 2.4 and 2.3 eV for Y, Gd and La systems respectively. The photoluminescence results showed four emission peaks. One peak is assigned to 1G4 - 3H6 transition of Tm3+, and three other emission peaks are attributed to 6G5/2 - 6H5/2, 6G5/2 - 6H7/2 and 6G5/2 - 6H9/2 transitions of Sm3+. The photoluminescent intensity was the highest in the gadolinium system.

Preparation and Luminescent Properties of the antibacterial materials of the La3+ Doped Sm3+-Hydroxyapatite

Science.gov (United States)

Lv, Yuguang; Shi, Qi; Jin, Yuling; Ren, Hengxin; Qin, Yushan; Wang, Bo; Song, Shanshan

2018-03-01

In this paper, the La3+-doped Sm3+ hydroxyapatite (La/Sm/HAP) complexes were prepared by a precipitation method. The sample was defined by IR spectra, fluorescence spectra and X ray diffraction analysis et al. The structure of complexes were discussed. The emission wavelength of heat treatment of Sm3+ do not change, but will affect the intensity of the peak Sm3+ luminescence properties and the occupy hydroxyapatite in the lattice Ca( II )and Ca( I ) loci with Sm3+ doped concentration and the proportion of the sintering temperature change and change: The nano hydroxyapatite complex of the La3+ doped samarium obtain the good fluorescence intensity, by La3+ doping content of Sm3+ were hydroxyapatite 6% (La3+, Sm3+ mole ratio) device. The complex of La3+ doped samarium HAP have Stable chemical property, fluorescence property and excellent biological activity. The ligand HAP absorbs energy or captures an electron-hole pair and then transfers it to the lanthanide ions. The catalytic activity influence of the La3+-doped Sm3+hydroxyapatite was discussed, the La/Sm/HAP had excellent antibacterial property, which used as potential biological antibacterial material.

Application of multiple parallel perfused microbioreactors: Synthesis, characterization and cytotoxicity testing of the novel rare earth complexes with indole acid as a ligand.

Science.gov (United States)

Guan, Qing-Lin; Xing, Yong-Heng; Liu, Jing; Wei, Wen-Juan; Zhang, Rui; Wang, Xuan; Bai, Feng-Ying

2013-11-01

Three novel complexes, [La(phen)2(IAA)2]·NO3 (1), [Sm(phen)2(IAA)2]·NO3 (2) and [Sm(IBA)3(phen)]·phen·HNO3·H2O (3) (phen: 1,10-phenanthroline, IAA: indole-3-acetic acid, IBA: indole-3-butyric acid), were synthesized and characterized with spectroscopy (infrared and UV-visible), X-ray crystal diffraction and elemental analysis. Structural analysis revealed that each lanthanide atom in complexes 1-3 held a distorted tricapped trigonal prism geometry in a nine-coordinate mode. There were two types of coordination modes of the IAA ligand in complexes 1 and 2: a μ2-η(1):η(2) bridging mode linking two lanthanide atoms and a μ2-η(1):η(1) double monodentate bridging mode. There were three types of coordination modes of the IBA ligand: a μ2-η(1):η(1) double monodentate bridging mode, a μ1-η(2) bridging mode and a μ2-η(1):η(2) bridging mode linking two lanthanide atoms. Adjacent Sm atoms were linked via the μ2-bridging carboxylate groups of the IBA ligands to generate a binuclear building unit. The biological activity of the complexes was evaluated in human adipose tissue-derived stem cells (hADSCs) and Chang liver cells using a multiple parallel perfused microbioreactor. The results showed that cytotoxicity increased as the concentrations of complexes 1-3 increased. © 2013.

Wet-chemical passivation of InAs: toward surfaces with high stability and low toxicity.

Science.gov (United States)

Jewett, Scott A; Ivanisevic, Albena

2012-09-18

In a variety of applications where the electronic and optical characteristics of traditional, siliconbased materials are inadequate, recently researchers have employed semiconductors made from combinations of group III and V elements such as InAs. InAs has a narrow band gap and very high electron mobility in the near-surface region, which makes it an attractive material for high performance transistors, optical applications, and chemical sensing. However, silicon-based materials remain the top semiconductors of choice for biological applications, in part because of their relatively low toxicity. In contrast to silicon, InAs forms an unstable oxide layer under ambient conditions, which can corrode over time and leach toxic indium and arsenic components. To make InAs more attractive for biological applications, researchers have investigated passivation, chemical and electronic stabilization, of the surface by adlayer adsorption. Because of the simplicity, low cost, and flexibility in the type of passivating molecule used, many researchers are currently exploring wet-chemical methods of passivation. This Account summarizes much of the recent work on the chemical passivation of InAs with a particular focus on the chemical stability of the surface and prevention of oxide regrowth. We review the various methods of surface preparation and discuss how crystal orientation affects the chemical properties of the surface. The correct etching of InAs is critical as researchers prepare the surface for subsequent adlayer adsorption. HCl etchants combined with a postetch annealing step allow the tuning of the chemical properties in the near-surface region to either arsenic- or indium-rich environments. Bromine etchants create indium-rich surfaces and do not require annealing after etching; however, bromine etchants are harsh and potentially destructive to the surface. The simultaneous use of NH(4)OH etchants with passivating molecules prevents contact with ambient air that can

First-principles study of native defects in bulk Sm2CuO4 and its (001) surface structure

Science.gov (United States)

Zheng, Fubao; Zhang, Qinfang; Meng, Qiangqiang; Wang, Baolin; Song, Fengqi; Yunoki, Seiji; Wang, Guanghou

2018-04-01

Using the first-principles calculations based on the density functional theory, we have studied the bulk defect formation and surface structures of Sm2CuO4. To ensure the accuracy of calculations, the spin order of Cu atoms is rechecked and it is the well-known nearest-neighbor antiferromagnetic ground state, which can be attributed to the hole-mediated superexchange through the strong pdσ hybridization interaction between Cu dx2-y2 electron and the neighboring oxygen px (or py) electron. Under each present experimental condition, the Sm vacancy has a very high formation energy and is unlikely to be stable. The Cu vacancy is a shallow acceptor, which is preferred under O-rich conditions, whereas the O vacancy is a donor and energetically favorable under O-poor conditions. To construct its (001) surface structure, CuOO, CuO, and Cu terminated surfaces are found to be most favorable under different experimental conditions. The stable surface structures are always accompanied by significant surface atomic reconstructions and electron charge redistribution, which are intimately correlated to each other.

1,3-thiazole as suitable antenna ligand for lanthanide photoluminescence in [LnCl{sub 3}(thz){sub 4}].0.5thz, Ln = Sm, Eu, Gd, Tb, Dy

Energy Technology Data Exchange (ETDEWEB)

Dannenbauer, Nicole; Mueller-Buschbaum, Klaus [Wuerzburg Univ. (Germany). Inst. for Inorganic Chemistry; Kuzmanoski, Ana; Feldmann, Claus [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Inorganic Chemistry

2014-02-15

The series of luminescent monomeric lanthanide thiazole complexes [LnCl{sub 3}(thz){sub 4}].0.5thz (Ln = Sm, Eu, Gd, Tb, Dy; thz = 1,3-thiazole) has been synthesised and characterised by powder and single-crystal X-ray diffraction, IR and photoluminescence spectroscopy, DTA/TG as well as elemental analysis. The colourless compounds exhibit photoluminescence in the visible region with varying quantum efficiencies up to QY = 48 % for [LnCl{sub 3}(thz){sub 4}].0.5thz. Both, the lanthanide ions as well as the thiazole ligand contribute to the luminescence. Excitation can be achieved via intra-4f transitions and by exciting the ligand, emission is observed mainly from the lanthanide ions again by 4f transitions. Thiazole can transfer energy to the lanthanide ions, which further feeds the lanthanide emission by an efficient antenna effect even at room temperature. The lanthanide ions show pentagonal-bipyramidal coordination by three chloride anions and four N atoms of 1,3-thiazole, which leads to a strong {sup 5}D{sub 0} → {sup 7}F{sub 4} transition for europium. Significant differences arise as compared to thiophene complexes because no sulphur atom is involved in the metal coordination, as the thiazole ligand is solely coordinated via its nitrogen function. (orig.)

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.

Preparation of MAl O : Eu2+, Sm3+ (M = Ca, Sr, Ba) Phosphors by ...

African Journals Online (AJOL)

NJD

2007-10-15

Oct 15, 2007 ... clearly show that most peaks are assigned to those of the MAl2O4 structure. Moreover, their structures change with change of M. Samples A and B exhibit monoclinic crystal systems and sample. C a hexagonal structure. The doping Eu2+ and co-doping Sm3+ have very little influence on the structure of the ...

Preparation of MAl 2 O 4 : Eu 2+ , Sm 3+ (M = Ca, Sr, Ba) Phosphors ...

African Journals Online (AJOL)

A series of MAl2O4: Eu2+, Sm3+ (M = Ca, Sr, Ba) phosphors was prepared by the combustion method, and the influence of these alkaline earth metals on the structure and luminescent performances for these phosphors was investigated. A relationship was established between their composition, crystallization capacity and ...

Lanthanide-organic frameworks constructed from multi-functional ligands: Syntheses, structures, near-infrared and visible photoluminescence properties

International Nuclear Information System (INIS)

Li Xinfa; Xie Zailai; Lin Jingxiang; Cao Rong

2009-01-01

A series of multi-functional ligands supported lanthanide-organic frameworks, formulated as [Ln(HL 1 )(H 2 L 2 ) 0.5 (H 4 L 2 ) 0.5 (H 2 O)].(H 2 O) 1.5 .{Ln=La (1), Pr (2), Nd (3), Sm (4), Eu (5); H 3 L 1 =5-Sulfosaclicylic acid; H 4 L 2 =N,N'-piperazine (bis-methylene phosphonic acid)}, have been synthesized by hydrothermal reactions. Single crystal X-ray diffractions and powder XRD patterns confirm they are isostructural. They feature 3D framework structures based on extension of a 'zigzag' inorganic chain by organic linkers. Moreover, the photoluminescence properties of 5 and 3 have been investigated, and they show strong solid-state emissions in the visible and near-infrared (IR) regions at room temperature. - Graphical abstract: Five multi-functional ligands supported 3D lanthanide-organic frameworks have been synthesized and structurally characterized. Compounds 5 and 3 displayed strong solid-state emissions in the visible and near-infrared region at room temperature.

Phase relations in the pseudobinary systems RAO3-R2Ti2O7 (R: rare earth element and Y, A: Fe, Ga, Al, Cr and Mn) and syntheses of new compounds R(A1-xTix)O3+x/2 (2/3≤x≤3/4) at elevated temperatures in air

Science.gov (United States)

Brown, Francisco; Jacobo-Herrera, Ivan; Alvarez-Montaño, Victor; Kimizuka, Noboru; Kurashina, Keiji; Michiue, Yuichi; Matsuo, Yoji; Mori, Shigeo; Ikeda, Naoshi; Medrano, Felipe

2017-07-01

Phase relations in the pseudo-binary systems RFeO3-R2Ti2O7 (R: Lu, Ho and Dy), RGaO3-R2Ti2O7 (R: Lu and Er), LuAlO3-Lu2Ti2O7 and RAO3-R2Ti2O7 (R: Lu and Yb. A: Cr and Mn) at elevated temperatures in air were determined by means of a classic quenching method. There exist Lu(Fe1-xTix)O3+x/2, R(Ga1-xTix)O3+x/2 (R: Lu and Er) and Lu(Al1-xTix)O3+x/2 (2/3≤ x≤3/4) having the Yb(Fe1-xTix)O3+x/2-type of crystal structure (x=0.72, space group: R3m, a(Å)=17.9773 and c(Å)=16.978 as a hexagonal setting) in these pseudo binary systems. Eighteen compounds R(A1-xTix)O3+x/2 (R: Lu-Sm and Y, A: Fe, Ga and Al) were newly synthesized and their lattice constants as a hexagonal setting were measured by means of the X-ray powder diffraction method. The R occupies the octahedral site and both A and Ti does the trigonalbipyramidal one in these compounds. Relation between lattice constants for the rhombic R(A1-xTix)O3+x/2 and the monoclinic In(A1-xTix)O3+x/2 are as follows, ah≈5 x bm, ch≈3 x cm x sin β and am=31/2 x bm, where ah and ch are the lattice constants as a hexagonal setting for R(A1-xTix)O3+x/2 and am, bm, cm and β are those of the monoclinic In(A1-xTix)O3+x/2. Crystal structural relationships among α-InGaO3 (hexagonal, high pressure form, space group: P63/mmc), InGaO3 (rhombic, hypothetical), (RAO3)n(BO)m and RAO3(ZnO)m (R: Lu-Ho, Y and In, A: Fe, Ga, and Al, B: divalent cation element, m, n: natural number), the orthorhombic-and monoclinic In(A1-xTix)O3+x/2 (A: Fe, Ga, Al, Cr and Mn) and the hexagonal-and rhombic R(A1-xTix)O3+x/2 (R: Lu-Sm and Y, A: Fe, Ga and Al) are schematically presented. We concluded that the crystal structures of both the α-InGaO3 (high pressure form, hexagonal, space group: P63/mmc) and the hypothetical InGaO3 (rhombic) are the key structures for constructing the crystal structures of these compounds having the cations with CN=5.

Electronic and optical properties of graphene-like InAs: An ab initio study

Science.gov (United States)

Sohrabi, Leila; Boochani, Arash; Ali Sebt, S.; Mohammad Elahi, S.

2018-03-01

The present work initially investigates structural, optical, and electronic properties of graphene-like InAs by using the full potential linear augmented plane wave method in the framework of density functional theory and is then compared with the bulk Indium Arsenide in the wurtzite phase. The lattice parameters are optimized with GGA-PBE and LDA approximations for both 2D- and 3D-InAs. In order to study the electronic properties of graphene-like InAs and bulk InAs in the wurtzite phase, the band gap is calculated by GGA-PBG and GGA-EV approximations. Moreover, optical parameters of graphene-like InAs and bulk InAs such as the real and imaginary parts of dielectric function, electron energy loss function, refractivity, extinction and absorption coefficients, and optical conductivity are investigated. Plasmonic frequencies of 2D- and 3D-InAs are also calculated by using maximum electron energy loss function and the roots of the real part of the dielectric function.

Optical emission of InAs nanowires

International Nuclear Information System (INIS)

Möller, M; De Lima Jr, M M; Cantarero, A; Chiaramonte, T; Cotta, M A; Iikawa, F

2012-01-01

Wurtzite InAs nanowire samples grown by chemical beam epitaxy have been analyzed by photoluminescence spectroscopy. The nanowires exhibit two main optical emission bands at low temperatures. They are attributed to the recombination of carriers in quantum well structures, formed by zincblende–wurtzite alternating layers, and to the donor–acceptor pair. The blue-shift observed in the former emission band when the excitation power is increased is in good agreement with the type-II band alignment between the wurtzite and zincblende sections predicted by previous theoretical works. When increasing the temperature and the excitation power successively, an additional band attributed to the band-to-band recombination from wurtzite InAs appears. We estimated a lower bound for the wurtzite band gap energy of approximately 0.46 eV at low temperature. (paper)

Optical emission of InAs nanowires

Science.gov (United States)

Möller, M.; de Lima, M. M., Jr.; Cantarero, A.; Chiaramonte, T.; Cotta, M. A.; Iikawa, F.

2012-09-01

Wurtzite InAs nanowire samples grown by chemical beam epitaxy have been analyzed by photoluminescence spectroscopy. The nanowires exhibit two main optical emission bands at low temperatures. They are attributed to the recombination of carriers in quantum well structures, formed by zincblende-wurtzite alternating layers, and to the donor-acceptor pair. The blue-shift observed in the former emission band when the excitation power is increased is in good agreement with the type-II band alignment between the wurtzite and zincblende sections predicted by previous theoretical works. When increasing the temperature and the excitation power successively, an additional band attributed to the band-to-band recombination from wurtzite InAs appears. We estimated a lower bound for the wurtzite band gap energy of approximately 0.46 eV at low temperature.

Surface morphology and electronic structure of halogen etched InAs (1 1 1)

Energy Technology Data Exchange (ETDEWEB)

Eassa, N., E-mail: nashwa.eassa@nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Murape, D.M. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Betz, R. [Department of Chemistry, Nelson Mandela Metropolitan University (South Africa); Neethling, J.H.; Venter, A.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)

2012-05-15

The reaction of halogen-based etchants with n-InAs (1 1 1)A and the resulting surface morphology and surface electronic structure are investigated using field emission scanning electron microscopy and Raman spectroscopy. Using the intensity ratio of the unscreened longitudinal optical (LO) phonon to the transverse optical (TO) phonon in the Raman spectrum, a significant reduction in band bending is deduced after exposure of the InAs surface to HCl:H{sub 2}O, Br-methanol and I-ethanol for moderate times and concentrations. These procedures also lead to smooth and defect-free InAs surfaces. The improvements in surface properties are reversed, however, if the concentrations of the etchants are increased or the etch time is too long. In the worst cases, pit formation and inverted pyramids with {l_brace}1 1 1{r_brace} side facets are observed. The influence of the etchant concentration and etch time on the morphological and electronic properties of the etched surfaces is reported.

Surface morphology and electronic structure of halogen etched InAs (1 1 1)

International Nuclear Information System (INIS)

Eassa, N.; Murape, D.M.; Betz, R.; Neethling, J.H.; Venter, A.; Botha, J.R.

2012-01-01

The reaction of halogen-based etchants with n-InAs (1 1 1)A and the resulting surface morphology and surface electronic structure are investigated using field emission scanning electron microscopy and Raman spectroscopy. Using the intensity ratio of the unscreened longitudinal optical (LO) phonon to the transverse optical (TO) phonon in the Raman spectrum, a significant reduction in band bending is deduced after exposure of the InAs surface to HCl:H 2 O, Br–methanol and I–ethanol for moderate times and concentrations. These procedures also lead to smooth and defect-free InAs surfaces. The improvements in surface properties are reversed, however, if the concentrations of the etchants are increased or the etch time is too long. In the worst cases, pit formation and inverted pyramids with {1 1 1} side facets are observed. The influence of the etchant concentration and etch time on the morphological and electronic properties of the etched surfaces is reported.

Tuning the magnetic phase transition and the magnetocaloric properties of La0.7Ca0.3MnO3 compounds through Sm-doping

Science.gov (United States)

Thanh, Tran Dang; Dung, Nguyen Thi; Van Dang, Nguyen; Bau, Le Viet; Piao, Hong-Guang; Phan, The Long; Huyen Yen, Pham Duc; Hau, Kieu Xuan; Kim, Dong-Hyun; Yu, Seong-Cho

2018-05-01

In this work, we point out that the width and the nature of the magnetic phase transition, TC value, and as well as magnetocaloric effect in La0.7-xSmxCa0.3MnO3 compounds can be easily modified through Sm-doped into La-site. With an increasing Sm concentration, a systematic decrease in the magnetization, TC, and magnetic entropy change (ΔSm) are observed. The Arrott-plot proveds that the samples with x = 0 and 0.1 undergoing a first-order phase transition. Meanwhile, sample x = 0.2 undergoes a second-order phase transition, which exhibits a high value of the relative cooling power (81.5 J/kg at ΔH = 10 kOe). An analysis of the critical behavior based on the modified Arrott plots method has been done for sample x = 0.2. The results proved a coexistence of the long- and short-range interactions in La0.5Sm0.2Ca0.3MnO3 compound.

Highly Chemoselective Reduction of Amides (Primary, Secondary, Tertiary) to Alcohols using SmI2/Amine/H2O under Mild Conditions

Science.gov (United States)

2014-01-01

Highly chemoselective direct reduction of primary, secondary, and tertiary amides to alcohols using SmI2/amine/H2O is reported. The reaction proceeds with C–N bond cleavage in the carbinolamine intermediate, shows excellent functional group tolerance, and delivers the alcohol products in very high yields. The expected C–O cleavage products are not formed under the reaction conditions. The observed reactivity is opposite to the electrophilicity of polar carbonyl groups resulting from the nX → π*C=O (X = O, N) conjugation. Mechanistic studies suggest that coordination of Sm to the carbonyl and then to Lewis basic nitrogen in the tetrahedral intermediate facilitate electron transfer and control the selectivity of the C–N/C–O cleavage. Notably, the method provides direct access to acyl-type radicals from unactivated amides under mild electron transfer conditions. PMID:24460078

Thermochromic effect at room temperature of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Boileau, A.; Capon, F.; Barrat, S.; Pierson, J. F. [Universite de Lorraine, Institut Jean Lamour, Departement CP2S, UMR CNRS 7198, Nancy, F-54042 (France); Laffez, P. [Groupe de Recherche Electronique, Materiaux, Acoustique, Nanoscience (GREMAN), Universite Francois Rabelais de Tours, UMR CNRS 7347, IUT de Blois, 15 rue de la Chocolaterie, Blois, F-41000 (France)

2012-06-01

Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thermochromic thin films were synthesized using dc reactive magnetron co-sputtering and subsequent annealing in air. The film structure was studied by x-ray diffraction analysis. To validate the thermochromic potentiality of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3}, electrical resistivity and infrared transmittance spectra were recorded for temperatures ranging from 77 K to 420 K. The temperature dependence of the optical band gap was estimated in the near infrared range. Upon heating, the optical transmission decreases in the infrared domain showing a thermochromic effect over a wide wavelength range at room temperature.

Thermal decomposition of RE(C2H5CO2)3·H2O (RE = Dy, Tb, Gd, Eu and Sm)

DEFF Research Database (Denmark)

Grivel, Jean-Claude

2014-01-01

The thermal decomposition of Dy(III), Tb(III), Gd(III), Eu(III), and Sm(III) propionate monohydrates was studied in argon by means of simultaneous differential thermal analysis and thermogravimetry, infrared-spectroscopy, X-ray diffraction, and optical microscopy. After dehydration, which takes......, an intermediate stage involving a RE2O(C2H5CO2)4 composition was evidenced in the case of the Eu- and Sm-propionates. For all compounds, further decomposition of RE2O2CO3 into the corresponding sesquioxides (RE2O3) is accompanied by the release of CO2. The thermal decomposition of Dy- and Tb-propionates occurs...

Two structure types based on Si6O15 rings: synthesis and structural and spectroscopic characterisation of Cs1.86K1.14DySi6O15 and Cs1.6K1.4SmSi6O15

International Nuclear Information System (INIS)

Wierzbicka-Wieczorek, Maria; Goeckeritz, Martin; Kolitsch, Uwe; Lenz, Christoph; Giester, Gerald

2015-01-01

The silicate Cs 1.86 K 1.14 DySi 6 O 15 represents a mixed tetrahedral-octahedral framework structure type based on roughly circular Si 6 O 15 rings and isolated DyO 6 octahedra. The silicate Cs 1.6 K 1.4 SmSi 6 O 15 has a layered atomic arrangement built from corrugated Si 6 O 15 layers containing four-, six- and eight-membered rings. The layers are connected by isolated SmO 6 octahedra to form a mixed tetrahedral-octahedral framework. This structure shows a close structural relationship to β-K 3 NdSi 6 O 15 and a less close one to dehydrated elpidite (Na 2 ZrSi 6 O 15 ). In both structures, Cs/K atoms occupy large voids. The silicates were obtained through high-temperature flux syntheses. Their crystal structures have been determined from single-crystal X-ray diffraction data. Cs 1.86 K 1.14 DySi 6 O 15 crystallises in R32 (no. 155) with a = 13.896(2), c = 35.623(7) Aa and V = 5957.2(17) Aa 3 , whereas Cs 1.6 K 1.4 SmSi 6 O 15 crystallises in Cmca (no. 64) with a = 14.474(3), b = 14.718(3), c = 15.231(3) Aa and V = 3244.7(11) Aa 3 . The Dy 3+ and Sm 3+ cations present in the silicates cause PL emission bands in the visible yellow-to-orange spectral range. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Investigation of the oxidative processes in intermetallic Sm Co5 powder during heat treatment

International Nuclear Information System (INIS)

Talijan, Nadezda M.; Milutinovic-Nikolic, Aleksandra; Stajic-Trosic, Jasna T.; Jovanovic, Zarko D.

1996-01-01

Understanding of the thermal stability of intermetallic Sm Co 5 powder is essential for designing the working atmosphere in all phases of the technological procedure in the production of sintered Sm Co 5 magnets to obtain maximal magnetic properties. The thermal stability of the Sm Co 5 powder with defined chemical composition and particle size was investigated in the interval from 20 to 900 deg C. Commercial Sm Co 5 powder was used in this experiment. The powder was milled in anhydrous toluene in an agate mortar to fine powder of quality used in the production of sintered magnets. All the experiments were carried out with powder of an average particle size of 7.23μm, established by SEM. THe thermal stability of the Sm Co 5 powder in static air atmosphere was investigated by thermogravimetric analysis (TGA) using a DuPont Thermal Analyzer. Investigation of the behaviour of Sm Co 5 powder during heating was carried out using new samples of Sm Co 5 powder for each of the investigated temperature cycles. It was found by TGA that up to 200 deg C, the oxidation of Sm Co 5 was negligible. X-ray diffraction of the thermogravimetric experimental residue of the Sm Co 5 powder, heated at 240 deg C, yielded only the presence of the Sm Co 5 phase. By X-ray diffraction different crystal forms were identified depending on the maximal heating temperature. The following phases were identified: Sm 2 O 3 , Co, Co O, Co 3 O 4 and Sm Co O 3 . According to TG and X-ray results, for each of the investigated temperatures, the corresponding chemical reactions were established. The experimental data from both the thermal and X-ray investigations confirm that the phases of pressing and aligning the Sm Co 5 powder, in the process of producing sintered Sm Co 5 magnets, may be performed without a protective atmosphere. (author)

Structural, optical absorption and photoluminescence spectral studies of Sm3+ ions in Alkaline-Earth Boro Tellurite glasses

Science.gov (United States)

Siva Rama Krishna Reddy, K.; Swapna, K.; Mahamuda, Sk.; Venkateswarlu, M.; Srinivas Prasad, M. V. V. K.; Rao, A. S.; Prakash, G. Vijaya

2018-05-01

Sm3+ ions doped Alkaline-Earth Boro Tellurite (AEBT) glasses were prepared by using conventional melt quenching technique and characterized using the spectroscopic techniques such as FT-IR, optical absorption, emission and decay spectral measurements to understand their utility in optoelectronic devices. From absorption spectra, the bonding parameters, nephelauxetic ratios were determined to know the nature of bonding between Sm3+ ions and its surrounding ligands. From the measured oscillator strengths, the Judd-Ofelt (J-O) intensity parameters were evaluated and in turn used to estimate various radiative parameters for the fluorescent levels of Sm3+ ions in AEBT glasses. The PL spectra of Sm3+ ions exhibit three emission bands corresponding to the transitions 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 in the visible region for which the emission cross-sections and branching ratios were evaluated. The decay spectral profiles measured for 4G5/2 → 6H7/2 transition showed single exponential for lower concentration and non-exponential for higher concentration of doped rare earth ion in the as prepared glasses. Conversion of decay spectral profiles from single to non-exponential have been analyzed using Inokuti-Hirayama (I-H) model to understand the energy transfer mechanism involved in the decay process. CIE Chromaticity coordinates were measured using emission spectral data to identify the exact region of emission from the as-prepared glasses. From the evaluated radiative parameters, emission cross-sections and quantum efficiencies, it was observed that AEBT glass with 1 mol% of Sm3+ ions is more suitable for designing optoelectronic devices.

Crossrelaxations and non-radiative energy transfer from ({sup 4}G{sub 5/2}) Sm{sup 3+} → ({sup 5}D{sub 0}) Eu{sup 3+}: B{sub 2}O{sub 3}–ZnO glasses

Energy Technology Data Exchange (ETDEWEB)

Naresh, V., E-mail: varna.naresh@gmail.com; Rudramadevi, B.H.; Buddhudu, S., E-mail: profsb_svuniv@hotmail.com

2015-05-25

Graphical abstract: The energy transfer process occurring from Sm{sup 3+} to Eu{sup 3+} in B{sub 2}O{sub 3}–ZnO (BZn) glasses is analyzed. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm{sup 3+} and Eu{sup 3+} has been demonstrated from the spectral overlap of Eu{sup 3+} absorption and Sm{sup 3+} emission, photoluminescence spectra, energy level diagram and lifetime measurements. The energy transfer mechanism in (Sm{sup 3+} + Eu{sup 3+}) co-doped glass is governed by dipole–dipole interaction. - Highlights: • Spectroscopic properties of individually doped Sm{sup 3+}, Eu{sup 3+} & co-doped (Sm{sup 3+} + Eu{sup 3+}) in BZn glasses were studied separately. • The effect of Eu{sup 3+} concentration on luminescence properties is explained from cross-relaxations. • Energy transfer from Sm{sup 3+} ({sup 4}G{sub 5/2}) to Eu{sup 3+} ({sup 5}D{sub 0}) has been explained from Foster–Dexter theory. • Dipole–dipole mechanism governs the energy transfer from Sm{sup 3+} to Eu{sup 3+}. - Abstract: The present paper reports on the results concerning to photoluminescence features of Eu{sup 3+}, Sm{sup 3+} ions and energy transfer process occurring from Sm{sup 3+} to Eu{sup 3+} doped in 45 B{sub 2}O{sub 3}–55 ZnO (BZn) glasses prepared by melt quenching technique. Luminescence quenching as a function of Eu{sup 3+} concentration in BZn glasses has been discussed. Among the studied concentrations, 0.5 mol% of Eu{sup 3+} is optimized because it has exhibited red emission transition {sup 5}D{sub 0} → {sup 7}F{sub 2}. With regard to Sm{sup 3+} glasses, orange emission at 602 nm ({sup 4}G{sub 5/2} → {sup 6}H{sub 7/2}) has been noticed on exciting with λ{sub exci} = 403 nm. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm{sup 3+} and Eu{sup 3+} has been explained from the spectral overlap of Eu{sup 3+} absorption and Sm{sup 3+} emission. The optimized concentration 0.5 mol% of Eu{sup 3+} is co

Preparation and quality control of {sup 153}Sm radiopharmaceuticals

Energy Technology Data Exchange (ETDEWEB)

Swasono, R Tamat; Widyastuti, W; Purwadi, B; Laksmi, I [Radioisotope Production Center - BATAN, Jakarta (Indonesia)

1998-10-01

The paper summarizes the preparation and quality control of {sup 153}Sm-EDTMP and three {sup 153}Sm-radiosynovectomy agents. Natural and enriched Sm{sub 2}O{sub 3} (98.7% {sup 152}Sm) irradiated in RSG-GAS 30 MW reactor yielded pure and high specific activity {sup 153}Sm. Labeling of EDTMP with {sup 153}Sm was carried out by mixing {sup 153}SmCl{sub 3} solution of pH 4.0 to an EDTMP solution at room temperature then pH adjustment to 8. The {sup 153}Sm-EDTMP complex was separated from the free {sup 153}Sm{sup +3} on a Chelex 100 column. Radiochemical purity was determined by thin layer chromatography using Cellulose sheets and pyridine: ethanol: water (1: 2: 4) mixture as solvent. The {sup 153}Sm-EDTMP has been shown to be stable for two weeks. Three particulate preparations of {sup 153}Sm used for the irradiation of chronic synovitis have been studied. They are hydroxyapatite particles, human serum albumin microspheres and ferric hydroxide macroaggregates. The {sup 153}Sm-ferric hydroxide macroaggregates were prepared in a single step by coprecipitation of {sup 153}Sm in the formation of Fe(OH){sub 3}. Preparation of {sup 153}Sm-labelled hydroxyapatite particles and {sup 153}Sm-labelled albumin microspheres were carried out by {sup 153}Sm labelling of previously prepared particles. Radiolabelling efficiency were greater than 95% for hydroxyapatite particles and macroaggregates and was lower than 20% for albumin microspheres. The particle sizes were inspected using an optical microscope with a haemocytometer and micrometric ocular. (author)

The study of structural and optical properties of (Eu, La, Sm) codoped ZnO nanoparticles via a chemical route

Energy Technology Data Exchange (ETDEWEB)

Lang, Jihui; Zhang, Qi; Han, Qiang; Fang, Yue; Wang, Jiaying; Li, Xiuyan; Liu, Yanqing [Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping, 136000 (China); Wang, Dandan [Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China); Yang, Jinghai, E-mail: jhyang1@jlnu.edu.cn [Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping, 136000 (China); Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China)

2017-06-15

The (Eu, La, Sm) ions were doped into ZnO nanoparticles by a chemical route, and the substitution of (Eu, La, Sm) for Zn{sup 2+} ions was proved by analytic techniques of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, transmission electron microscope (TEM), photoluminescence (PL) and UV–vis absorption spectroscopy. The results revealed that the codoping did not change the wurtzite structure of ZnO nanoparticles, but the diameter of the nanoparticles decreased with increasing the rare earth (RE) doping concentrations. The optical bandgaps calculated through UV–visible absorption spectroscopy were found to decrease from 3.26 to 3.14 eV with increasing the RE doping concentrations, which also proved by the slight shift of UV positions in PL spectra. The sharp red emissions located at 578.2, 590.1 and 615.7 nm were originated from the 4f-4f transitions in Eu{sup 3+} ions under excitation of 325 nm. And these red emissions of Eu{sup 3+} ions showed a strong correlation with the energy storage centers of oxygen vacancies in the samples which was introduced by the other RE ions of La{sup 3+} and Sm{sup 3+} codoping. - Highlights: • Doping of (Eu, La, Sm) ions into ZnO nanoparticles is realized by a chemical route. • Eu{sup 3+}-related red emissions from intra-4f follow a similar trend as broad defect emission. • Red emissions of Eu{sup 3+} enhance with RE codoping due to oxygen vacancies as energy storage centers. • The bandgap can be tuned by RE codoping, which shows a prospect for the visible utilization.

Jezdecké stezky v kraji Vysočina

OpenAIRE

Bendeová, Tereza

2014-01-01

This bachelor thesis discusses the topic of riding trails in the Vysočina region. At the beginning I discuss the role of equestrian tourism in the Czech Republic. There are briefly described origins and conditions of riding trails in the regions and also the list of the public support and grants for development of equestrian tourism. The next part focuses on chosen region and characterizes its natural and cultural heritage. There are also described several trails through the Vysočina region. ...

Phase transition of the orthorhombic fluorite-related compounds Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, Eu)

Energy Technology Data Exchange (ETDEWEB)

Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.j [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Doi, Yoshihiro; Nishimine, Hiroaki; Wakeshima, Makoto [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Sato, Mineo [Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan)

2009-12-04

Rare earth iridium oxides Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) were prepared and their structures were determined by X-ray diffraction measurements. At room temperature, Pr{sub 3}IrO{sub 7} crystallized in an orthorhombic superstructure of cubic fluorite with space group Cmcm. The differential thermal analysis (DTA) and specific heat measurements for Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) showed a phase transition at 262, 342, 420, and 485 K, respectively. At low temperatures, Ln{sub 3}IrO{sub 7} crystallized in a monoclinic structure with the space group P2{sub 1}/n. The transition temperatures increased with decreasing the ionic radius of rare earths, which indicates that the transition is stress-induced and occurs with the lattice contraction on cooling. These results for Ln{sub 3}IrO{sub 7} were compared with the phase transitions observed for Ln{sub 3}MoO{sub 7}, Ln{sub 3}RuO{sub 7}, Ln{sub 3}ReO{sub 7}, and Ln{sub 3}OsO{sub 7}.

The Neutronic Effect of Zr-rod and Sm2O3-disk in the Model of Kartini Reactor Fuel Element

International Nuclear Information System (INIS)

Edi-Trijono-Budisantoso; Bambang-Sumarsono; Tri-Wulan-Tjiptono

2000-01-01

The model of Kartini fuel element has been constructed using a variationof materials in it fuels. For basic model, the construction of fuel assemblyis a rod type fuel element with SS-304 cladding and UZrH (8.5 % wt U in 20 %enrichment) as a fuel meat and graphite reflector at the both ends of fuelmeat. By using is basic construction, the material then varied in 4 models asthe following: 1) The model with the Zr-rod in 5.76 mm diameter, is insertedat the axis of fuel meat; 2) The model with Sm 2 O 3 -disk in 1.28 mmthickness, is inserted at the both ends of fuel meat; 3) The compound ofmodel 1 and model 2; 4) The basic construction of cell without Zr-rod andSm 2 O 3 -disk. The neutronic-behavior of each model then calculated usingWIMSD4 and the result then represented as a graphics form of the correlationof parameters as the following: 1) The correlation between model and itneutron multiplication factor; 2) The comparison of neutron flux distributionfor each model. By the graphic can be concluded, that Zr-rod in the fuelelement can reduce power peaking factor to 82 % with the effect of neutronmultiplication factor reduced to 98 %, while the insertion of Sm 2 O 3 -disk atthe both ends of fuel meat can make neutron multiplication factor reduce to97 % but unfortunately the neutron peaking factor increase to 101 %. Theinsertion of Zr-rod in the axis of fuel meat, increase the safety margin offuel utilization, while the insertion of Sm 2 O 3 -disk at the both ends offuel meat can make it as the burn-able poison that maintain the neutronmultiplication factor stable for a long time utilization. (author)

Radiation damage in SmS, SmSsub(1-x)Psub(x) and SmB6

International Nuclear Information System (INIS)

Morillo, J.; Bordier, G.; de Novion, C.H.; Senateur, J.P.; Jun, J.

1984-08-01

Large conductivity increases under 21 K electron or neutron irradiations are observed in SmS and SmSsub(1-x)Psub(x). It is shown that they are related to Sm defects. A possible mechanism is 4f electron delocalization around radiation defects. In SmB 6 , the low temperature resistivity increase desappears under 21 K irradiation. The thermal stability of the defects is also investigated up to room temperature

Hall and thermoelectric evaluation of p-type InAs

Energy Technology Data Exchange (ETDEWEB)

Wagener, M.C., E-mail: magnus.wagener@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Wagener, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

2009-12-15

This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

Hall and thermoelectric evaluation of p-type InAs

International Nuclear Information System (INIS)

Wagener, M.C.; Wagener, V.; Botha, J.R.

2009-01-01

This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

Thermoelectric power of RFeAsO (R = Ce, Pr, Nd, Sm and Gd)

International Nuclear Information System (INIS)

Poddar, Asok; Mukherjee, Sanjoy; Samanta, Tanmay; Saha, Rajat S.; Mukherjee, Rajarshi; Dasgupta, Papri; Mazumdar, Chandan; Ranganathan, R.

2009-01-01

Thermoelectric powers of a series of compounds RFeAsO (R = Ce, Pr, Nd, Sm and Gd) have been reported for temperatures ranging from 77 K up to room temperature. The behavior of S(T) in this temperature range can be divided into three regions. Every region has been fitted with mathematical functions of T. The physical significance of separate terms in the mathematical functions has been discussed. Some kind of universality has been observed between different members of the series.

Thermoelectric power of RFeAsO (R = Ce, Pr, Nd, Sm and Gd)

Energy Technology Data Exchange (ETDEWEB)

Poddar, Asok, E-mail: asok.poddar@saha.ac.i [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, West Bengal (India); Mukherjee, Sanjoy [Department of Physics, The University of Burdwan, Golapbag, Burdwan 713 104, West Bengal (India); Samanta, Tanmay [Rishra High School, 15 Tilakram Dan Ghat Lane, Rishra, Hooghly, West Bengal (India); Saha, Rajat S.; Mukherjee, Rajarshi [Department of Physics, University of Burdwan, Golapbag, Burdwan 713 104, West Bengal (India); Dasgupta, Papri; Mazumdar, Chandan; Ranganathan, R. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, West Bengal (India)

2009-07-15

Thermoelectric powers of a series of compounds RFeAsO (R = Ce, Pr, Nd, Sm and Gd) have been reported for temperatures ranging from 77 K up to room temperature. The behavior of S(T) in this temperature range can be divided into three regions. Every region has been fitted with mathematical functions of T. The physical significance of separate terms in the mathematical functions has been discussed. Some kind of universality has been observed between different members of the series.

Chemical and biological evaluation of {sup 153}Sm and {sup 46/47}Sc complexes of indazolebisphosphonates for targeted radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Neves, Maria, E-mail: mneves@itn.p [Instituto Tecnologico e Nuclear, Sacavem (Portugal); Teixeira, Fatima C.; Antunes, Ines [INETI-Departamento de Tecnologia de Industrias Quimicas, Lisboa (Portugal); Majkowska, Agnieszka [Institute of Nuclear Chemistry and Technology, Warsaw (Poland); Gano, Lurdes [Instituto Tecnologico e Nuclear, Sacavem (Portugal); Santos, Ana Cristina [IBB-Instituto de Biofisica e Biomatematica, Coimbra (Portugal)

2011-01-15

Introduction: Novel 1-hydroxy-1,1-bisphosphonates derived from indazole and substituted at the C-3 position were labeled with the radionuclides {sup 46}Sc and {sup 153}Sm. Several parameters such as molar ligand concentration, pH, reaction time and temperature were studied. The radiolabelling yield, reaction kinetics and stability were assessed and radiocomplexes were evaluated by in vitro and in vivo experiments. Methods: The radionuclides {sup 46}Sc and {sup 153}Sm were obtained by neutron irradiation of natural Sc{sub 2}O{sub 3} and enriched {sup 152}Sm{sub 2}O{sub 3} (98.4%) targets at the neutron flux of 3x10{sup 14} n cm{sup -2} s{sup -1}. The radiolabelling yield, reaction kinetics and stability were accomplished by ascending instant thin layer chromatography. The radiocomplexes were submitted to in vitro experiments (hydroxyapatite binding and lipophilicity) and biodistribution studies in animal models. Results: The radionuclides {sup 46}Sc and {sup 153}Sm were produced with specific activities of 100 and 430 MBq mg{sup -1}, respectively. High radiochemical yields were achieved and the hydrophilic radiocomplexes have shown high degree of binding to hydroxyapatite. Biodistribution studies at 1, 3 and 24 h of the 4 radiocomplexes under study, have showed a similar biodistribution profile with a relatively high bone uptake, slow clearance from blood and a very slow rate of total radioactivity excretion from the whole animal body. Conclusion: We have developed a new class of indazolebisphosphonates complexes with radioisotopes of samarium and scandium. All complexes have shown high degree of binding to hydroxyapatite, which could be attributed to the ionized phosphonate groups. The bone uptake and the bone-to-muscle ratios were relatively low.

Spin effects in InAs self-assembled quantum dots

Directory of Open Access Journals (Sweden)

Brasil Maria

2011-01-01

Full Text Available Abstract We have studied the polarized resolved photoluminescence in an n-type resonant tunneling diode (RTD of GaAs/AlGaAs which incorporates a layer of InAs self-assembled quantum dots (QDs in the center of a GaAs quantum well (QW. We have observed that the QD circular polarization degree depends on applied voltage and light intensity. Our results are explained in terms of the tunneling of minority carriers into the QW, carrier capture by InAs QDs and bias-controlled density of holes in the QW.

Large anisotropy in colossal magnetoresistance of charge orbital ordered epitaxial Sm0.5Ca0.5MnO3 films

DEFF Research Database (Denmark)

Chen, Yunzhong; Sun, J.R.; Zhao, J.L.

2009-01-01

We investigated the structure and magnetotransport properties of Sm0.5Ca0.5MnO3 (SCMO) films epitaxially grown on (011)-oriented SrTiO3 substrates, which exhibited clear charge/orbital ordering transition. A significant anisotropy of ~1000 in the colossal magnetoresistance (CMR) effect was observ...

Tris-(hydroxyamino)triazines: high-affinity chelating tridentate O,N,O-hydroxylamine ligand for the cis-V(V)O2(+) cation.

Science.gov (United States)

Nikolakis, Vladimiros A; Exarchou, Vassiliki; Jakusch, Tamás; Woolins, J Derek; Slawin, Alexandra M Z; Kiss, Tamás; Kabanos, Themistoklis A

2010-10-14

The treatment of the trichloro-1,3,5-triazine with N-methylhydroxylamine hydrochloride results in the replacement of the three chlorine atoms of the triazine ring with the function -N(OH)CH(3) yielding the symmetrical tris-(hydroxyamino)triazine ligand H(3)trihyat. Reaction of the ligand H(3)trihyat with NaV(V)O(3) in aqueous solution followed by addition of Ph(4)PCl gave the mononuclear vanadium(V) compound Ph(4)P[V(V)O(2)(Htrihyat)] (1). The structure of compound 1 was determined by X-ray crystallography and indicates that this compound has a distorted square-pyramidal arrangement around vanadium. The ligand Htrihyat(2-) is bonded to vanadium atom in a tridentate fashion at the triazine ring nitrogen atom and the two deprotonated hydroxylamido oxygen atoms. The high electron density of the triazine ring nitrogen atoms, which results from the resonative contribution of electrons of exocyclic nitrogen atoms, leads to a very strong V-N bond. The cis-[V(V)O(2)(Htrihyat)](-) species exhibits high hydrolytic stability in aqueous solution over a wide pH range, 2.5-11.5, as was evidenced by potentiometry.

Emergence of Griffiths phase and glassy mixed phase in Sm0.5Ca0.5MnO3 nanomanganites

International Nuclear Information System (INIS)

Giri, S.K.; Yusuf, S.M.; Mukadam, M.D.; Nath, T.K.

2014-01-01

Graphical abstract: A detailed investigation on the effect of grain size on formation of Griffiths phase, and glassy mixed phase in CE-type antiferromagnetic Sm 0.5 Ca 0.5 MnO 3 manganite are carried out. A rigorous measurement of linear and non-linear ac magnetic susceptibilities, time dependent relaxation and aging phenomena in Sm 0.5 Ca 0.5 MnO 3 nanomanganite confirm the existence of a glassy mixed phase in the low temperature regime. The signature of Griffiths phase in nanosized manganite has been confirmed from the detailed ac and dc magnetization studies. The existence of Griffiths phase is verified through the anomalous behavior of the low field temperature dependent an inverse ac and dc magnetic susceptibility. Based on experimental results, the glassy phase of nanomanganites has been attributed to the phase separation effect and interaction between the ferromagnetic clusters. A phenomenological core/shell model has also been proposed based on the surface disorder to explain the observed Griffiths phase in these nanosized manganites. Fig. 1: (Left) The plot of inverse of ac susceptibility χ ac -1 measured at f = 1 Hz and H ac = 2 Oe as a function of temperature for S750 sample. Inset shows the same for S550 sample. (Right) A schematic of the proposed model to describe the magnetic state of the Sm 0.5 Ca 0.5 MnO 3 system at different average sizes. Highlights: • Effect of grain size on Griffiths phase and glassy mixed phase is discussed. • GP is confirmed by dc, linear and non-linear ac magnetization in nanomanganites. • Glassy mixed phase is discussed by time dependent relaxation and aging phenomena. • The existence of GP is verified through an inverse ac and dc magnetic susceptibility. • A phenomenological core/shell model has been proposed based on surface disorder. -- Abstract: A detailed investigation on the effect of grain size on formation of Griffiths phase (GP), and glassy mixed phase in CE-type antiferromagnetic Sm 0.5 Ca 0.5 MnO 3

20 CFR 668.710 - What planning documents must an INA grantee submit?

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false What planning documents must an INA grantee... Planning/Funding Process § 668.710 What planning documents must an INA grantee submit? Each grantee... participant services and expenditures covering the two-year planning cycle. We will, in consultation with the...

A soft lithographic approach to fabricate InAs nanowire field-effect transistors

DEFF Research Database (Denmark)

Madsen, Morten; Lee, S. H.; Shin, S.-H.

2018-01-01

-down approach and an epitaxial layer transfer process, using MBE-grown ultrathin InAs as a source wafer. The width of the InAs nanowires was controlled using solvent-assisted nanoscale embossing (SANE), descumming, and etching processes. By optimizing these processes, NWs with a width less than 50 nm were...

Analysis of energy transfer based emission spectra of (Sm{sup 3+}, Dy{sup 3+}): Li{sub 2}O–LiF–B{sub 2}O{sub 3}–CdO glasses

Energy Technology Data Exchange (ETDEWEB)

Naresh, V., E-mail: varna.naresh@gmail.com; Buddhudu, S., E-mail: profsb_svuniv@hotmail.com

2014-03-15

The present paper brings out the results concerning the preparation and optical properties of Sm{sup 3+} and Dy{sup 3+} each ion separately in four different concentrations (0.1, 0.5, 1.0 and 1.5 mol%) and also together doped (1 mol% Dy{sup 3+}+x mol% Sm{sup 3+}): Li{sub 2}O–LiF–B{sub 2}O{sub 3}–CdO (where x=0.1, 0.5, 1.0 and 1.5 mol%) glasses by a melt quenching method. Sm{sup 3+} doped base glasses have displayed an intense orange emission at 602 nm ({sup 4}G{sub 5/2}→{sup 6}H{sub 7/2}) with an excitation at 403 nm and Dy{sup 3+} doped glasses have shown two emissions located at 486 nm ({sup 4}F{sub 9/2}→{sup 6}H{sub 15/2}; blue) and 577 nm ({sup 4}F{sub 9/2}→{sup 6}H{sub 13/2}; yellow) with λ{sub exci}=387 nm. The co-doped (Dy{sup 3+}+Sm{sup 3+}) lithium fluoro-boro cadmium glasses have been excited with an excitation at 387 nm of Dy{sup 3+} which has resulted in with a significant reduction in Dy{sup 3+} emission, at the same time there exists an increase in the reddish-orange emission of Sm{sup 3+} due to an energy transfer from Dy{sup 3+} to Sm{sup 3+}. The non-radiative energy transfer from Dy{sup 3+} to Sm{sup 3+} is governed by dipole–quadrupole interactions as is explained in terms of their emission spectra, donor lifetime, energy level diagram and energy transfer characteristic factors. -- Highlights: • In co-doped (Dy{sup 3+}+Sm{sup 3+}): LFBCd glass, reddish-orange emission due to Sm{sup 3+} ({sup 4}F{sub 9/2}→{sup 6}H{sub J}) has been enhanced due to an energy transfer from Dy{sup 3+} ions in the glass. • This has been evidenced from a lowering trend in the emission transition lifetimes of donor (Dy{sup 3+}) ions with increasing acceptor (Sm{sup 3+}) concentration. • Energy transfer mechanism involved in Dy{sup 3+}→Sm{sup 3+} has been explained in terms of I–H luminescence decay curve analysis.

Structural characterization of PbTi03, Sm0.6Nd0.4NiO3 and NdMnO3 multifunctional Perovskite thin films

Directory of Open Access Journals (Sweden)

Rapenne L.

2012-06-01

Full Text Available Different multifunctional (PbTiO3, Sm0.6Nd0.4NiO3, NdMnO3 thin films were grown by metalorganic chemical vapor deposition (MOCVD technique on SrTiO3 and LaAlO3 substrates. TEM and X-ray diffraction measurements reveal that almost single crystalline thin films can be epitaxially grown on the top of substrates. The relationship between the crystallographic orientation of the films and those of the substrates were determined by reciprocal space mapping and TEM analyses. PbTi03 thin films appear to be under tensile or compressive strain according to the different mismatch of their cell parameter with those of the substrate. Relaxation mechanism as a function of the film thickness arises from coexistence of different type of domains and size and strain effect are analyzed. SmNiO3 thin films present diffuse scattering strikes and are less well organized when compared to PbTi03 thin films. Different domains are observed as well as an additional parasitic phase close to NiO. Its regular distribution can be associated to reduced transport properties. Preliminary observations on NdMnO3 thin films show that an amorphous phase is obtained during MOCVD that can be transformed in a single crystalline film by annealing. The films are under tensile or compressive strain according to the different mismatch of their cell parameter with those of the substrate. Magnetic properties are investigated.

New Ru(II) Complexes for Dual Photoreactivity: Ligand Exchange and 1O2 Generation

OpenAIRE

Knoll, Jessica D.; Albani, Bryan A.; Turro, Claudia

2015-01-01

Uncovering the factors that govern the electronic structure of Ru(II)–polypyridyl complexes is critical in designing new compounds for desired photochemical reactions, and strategies to tune excited states for ligand dissociation and 1O2 production are discussed herein. The generally accepted mechanism for photoinduced ligand dissociation proposes that population of the dissociative triplet ligand field (3LF) state proceeds through thermal population from the vibrationally cooled triplet meta...

Effect of ligand nature and geometry of its surrounding on electron absorption spectra of NpO22+ and PuO22+ compounds

International Nuclear Information System (INIS)

Sokolov, E.I.; Tebelev, L.G.; Melkaya, R.F.; Rykov, A.G.

1981-01-01

Electron absorption spectra of actinide compounds with the symmetry of the nearest surrounding of actinyl-ions as follows: Dsub(2h)-AnO 2 (NO 3 ) 2 xnH 2 O, AnO 2 (CH 3 COO) 2 x2H 2 O; Dsub(3h)-MAnO 2 (NO 3 ) 3 (M-K, Rb, Cs), NaAnO 2 (CH 3 COO) 3 , (NH 4 ) 4 AnO 2 (CO 3 ) 3 ; Dsub(4h)-Cs 2 AnO 2 Cl 4 , where An-U, Np, Pb, are measured at room temperature. It is established that position, intensity and form of absorption bands in neptunyl compound spectra are sensible equally to geometry of coordination sphere and to ligand nature. The character of the change of plutonyl compound spectra is the same as of neptunyl ones: it is determined both by surrounding geometry and chemical nature of ligands. It is shown that in the near infrared region ligand effect on plutonyl compound spectra with the symmetry of anion complex Dsub(3h) is weaker than in the visible region

Structures, magnetic, and thermal properties of Ln3MoO7 (Ln=La, Pr, Nd, Sm, and Eu)

International Nuclear Information System (INIS)

Nishimine, Hiroaki; Wakeshima, Makoto; Hinatsu, Yukio

2005-01-01

Ternary lanthanide-molybdenum oxides Ln 3 MoO 7 (Ln=La, Pr, Nd, Sm, Eu) have been prepared. Their structures were determined by X-ray diffraction measurements. They crystallize in a superstructure of cubic fluorite and the space group is P2 1 2 1 2 1 . The Mo ion is octahedrally coordinated by six oxygens and the slightly distorted octahedra share corners forming a zig-zag chain parallel to the b-axis. These compounds have been characterized by magnetic susceptibility and specific heat measurements. The La 3 MoO 7 shows complex magnetic behavior at 150 and 380K. Below these temperatures, there is a large difference in the temperature-dependence of the magnetic susceptibility measured under zero-field-cooled condition and under field-cooled condition. The Nd 3 MoO 7 show a clear antiferromagnetic transition at 2.5K. From the susceptibility measurements, both Pr 3 MoO 7 and Sm 3 MoO 7 show the existence of magnetic anomaly at 8.0 and 2.5K, respectively. The results of the specific heat measurements also show anomalies at the corresponding magnetic transition temperatures. The differential scanning calorimetry measurements indicate that two phase-transitions occur for any Ln 3 MoO 7 compound in the temperature range between 370 and 710K

Ln28Ti2O7 (Ln = La, Nd, Sm, Gd): a novel series of defective Ruddlesden–Popper phases formed by topotactic dehydration of HLnTiO4

OpenAIRE

Thangadurai, V; Subbanna, GN; Gopalakrishnan, J

1998-01-01

Topotactic dehydration of HLnTiO4 (Ln = La, Nd, Sm or Gd) around 480–500 °C yields a new series of metastable layered perovskite oxides, Ln28Ti2O7, that possess a defective Sr3Ti2O7 structure, where the cubooctahedral sites within the double-perovskite layers are most likely vacant.

Host-sensitized luminescence properties in CaNb2O6:Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) phosphors with abundant colors.

Science.gov (United States)

Li, Kai; Liu, Xiaoming; Zhang, Yang; Li, Xuejiao; Lian, Hongzhou; Lin, Jun

2015-01-05

A series of Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) ion doped CaNb2O6 (CNO) phosphors have been prepared via the conventional high-temperature solid-state reaction route. The X-ray diffraction (XRD) and structure refinement, diffuse reflection, photoluminescence (PL), and fluorescent decay curves were used to characterize the as-prepared samples. Under UV radiation, the CNO host present a broad emission band from about 355 to 605 nm centered around 460 nm originating from the NbO6 octahedral groups, which has spectral overlaps with the excitation of f-f transitions of Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) samples. They show both host emission and respective emission lines derived from the characteristic f-f transitions of activators, which present different emission colors owing to the energy transfer from the NbO6 group in the host to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) with increasing activator concentrations. The decreases of decay lifetimes of host emissions in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) demonstrate the energy transfer from the hosts to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+). The energy transfer mechanisms in CNO:Eu(3+)/Tb(3+)/Dy(3+) phosphors have been determined to be a resonant type via dipole-dipole mechanisms. For CNO:Sm(3+), the metal-metal charge transfer transition (MMCT) might contribute to the different variations of decay lifetimes and emission intensity from CNO:Eu(3+)/Tb(3+)/Dy(3+) samples. The best quantum efficiency is 71.2% for CNO:0.01/0.02Dy(3+). The PL properties of as-prepared materials indicate the promising application in UV-pumped white-emitting lighting diodes field.

Formation of nanogaps in InAs nanowires by selectively etching embedded InP segments.

Science.gov (United States)

Schukfeh, M I; Storm, K; Hansen, A; Thelander, C; Hinze, P; Beyer, A; Weimann, T; Samuelson, L; Tornow, M

2014-11-21

We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor-liquid-solid grown InAs nanowires with embedded InP segments of 10-60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap.

Formation of nanogaps in InAs nanowires by selectively etching embedded InP segments

International Nuclear Information System (INIS)

Schukfeh, M I; Hansen, A; Tornow, M; Storm, K; Thelander, C; Samuelson, L; Hinze, P; Weimann, T; Beyer, A

2014-01-01

We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor–liquid–solid grown InAs nanowires with embedded InP segments of 10–60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap. (paper)

Effect of growth temperature on the morphology and phonon properties of InAs nanowires on Si substrates

Directory of Open Access Journals (Sweden)

Lei Wen

2011-01-01

Full Text Available Abstract Catalyst-free, vertical array of InAs nanowires (NWs are grown on Si (111 substrate using MOCVD technique. The as-grown InAs NWs show a zinc-blende crystal structure along a < 111 > direction. It is found that both the density and length of InAs NWs decrease with increasing growth temperatures, while the diameter increases with increasing growth temperature, suggesting that the catalyst-free growth of InAs NWs is governed by the nucleation kinetics. The longitudinal optical and transverse optical (TO mode of InAs NWs present a phonon frequency slightly lower than those of InAs bulk materials, which are speculated to be caused by the defects in the NWs. A surface optical mode is also observed for the InAs NWs, which shifts to lower wave-numbers when the diameter of NWs is decreased, in agreement with the theory prediction. The carrier concentration is extracted to be 2.25 × 1017 cm-3 from the Raman line shape analysis. A splitting of TO modes is also observed. PACS: 62.23.Hj; 81.07.Gf; 63.22.Gh; 61.46.Km

Comparison of the elastic and inelastic scattering between 152Sm + 12C and 148Nd + 16O

International Nuclear Information System (INIS)

Zhao Kui; Lu Xiuqin; Cheng Yehao; Li Qingli; Li Min; Li Zhichang; Guo Jiyu; Li Shuyuan; Zhang Qinghua; Song Xiaobin; Jiang Chenglie

1994-01-01

Angular distributions of elastic and inelastic scattering have been measured for 152 Sm+ 12 C at 63.2 MeV and 148 Nd+ 16 O at 90.9 MeV. An evident interference pattern in the inelastic scattering has been observed for the first time in a strong Coulomb coupling system. (orig.)

An analysis on structural and magnetic properties of La{sub 1-x}RE{sub x}FeO{sub 3} (x = 0.0 and 0.5, RE = Nd, Sm and Gd) nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Blessington Selvadurai, A. Paul; Pazhanivelu, V.; Jagadeeshwaran, C.; Murugaraj, R. [Anna University, Department of Physics, Chennai (India); Gazzali, P.M. Mohammed; Chandrasekaran, G. [Pondicherry University, Department of Physics, Pudhucherry (India)

2017-01-15

La{sub 1-x}RE{sub x}FeO{sub 3} (x = 0.0 and 0.5, RE = Nd, Sm and Gd) is synthesised by sol-gel citrate combustion method. X-ray diffraction (XRD) and Raman spectra show orthorhombic phase with Pbnm symmetry, confirmed by profile fitting and Raman modes analysis for La{sub 1-x}R{sub x}FeO{sub 3} samples. The estimated crystallite size and the orthorhombic strain of La{sub 1-x}RE{sub x}FeO{sub 3} (x = 0.0 and 0.5, RE = Nd, Sm and Gd) from XRD data illustrate the role of ionic size substitution. The temperature- and field-dependent magnetisation M(T) and M(H) were measured using vibrating sample magnetometer. The M(H) curve parameters of La{sub 1-x}RE{sub x}FeO{sub 3}(x = 0.5, RE = Nd and Gd) exhibit a relation of M{sub r} ∝ (1)/(H{sub c}) and H{sub ex} ∝ H{sub C} at 20, 150 and 300 K. The M (T) curve of La{sub 0.5}Nd{sub 0.5}FeO{sub 3} and La{sub 0.5}Gd{sub 0.5}FeO{sub 3} indicates the paramagnetic-like behaviour, whereas the M (H) curve reveals the antiferromagnetic signature in them. The M (H) curve of La{sub 0.5}Sm{sub 0.5}FeO{sub 3} shows a strong AFM pinned ferromagnetism and ferromagnetism (FM) at 150 and 20 K, respectively. Further, field-cooled (FC) and zero-field-cooled (ZFC) measurement of La{sub 0.5}Sm{sub 0.5}FeO{sub 3} indicates a competitive interaction of AFM-FM, which is emphasised by a broad blocking temperature at ∝117 K in ZFC curve. The FM-like ordering of Sm{sup 3+} ions are observed below at ∝150 K in FC curve of La{sub 0.5}Sm{sub 0.5}FeO{sub 3}. In addition, the electron paramagnetic resonance spectra at room temperature show a high g value and a strong non-homogenous broadening for La{sub 0.5}Sm{sub 0.5}FeO{sub 3}. (orig.)

Metalorganic vapour epitaxial growth and infrared characterisation of InAsSb and InAs on InAs substrates

CSIR Research Space (South Africa)

Baisitse, TR

2006-07-01

Full Text Available Motivation for the research: Interest exists in III-V semiconducting materials (InAs, GaSb, InSb and related alloys) for the detection of infrared radiation; Such materials could be used as alternatives for future infrared detectors and various...

Wavelength tuning of InAs quantum dots grown on InP (100) by chemical-beam epitaxy

International Nuclear Information System (INIS)

Gong, Q.; Noetzel, R.; Veldhoven, P.J. van; Eijkemans, T.J.; Wolter, J.H.

2004-01-01

We report on an effective way to continuously tune the emission wavelength of InAs quantum dots (QDs) grown on InP (100) by chemical-beam epitaxy. The InAs QD layer is embedded in a GaInAsP layer lattice matched to InP. With an ultrathin GaAs layer inserted between the InAs QD layer and the GaInAsP buffer, the peak wavelength from the InAs QDs can be continuously tuned from above 1.6 μm down to 1.5 μm at room temperature. The major role of the thin GaAs layer is to greatly suppress the As/P exchange during the deposition of InAs and subsequent growth interruption under arsenic flux, as well as to consume the segregated surface In layer floating on the GaInAsP buffer layer

Positioning of self-assembled InAs quantum dots by focused ion beam implantation

International Nuclear Information System (INIS)

Mehta, M.

2007-01-01

Self-assembled quantum dots (QDs) are envisioned as building blocks for realization of novel nanoelectronic devices, for which the site-selective growth is highly desirable. This thesis presents a successful route toward selective positioning of self-assembled InAs QDs on patterned GaAs surface by combination of in situ focused ion beam (FIB) implantation and molecular beam epitaxy (MBE) technology. First, a buffer layer of GaAs was grown by MBE before a square array of holes with a pitch of 1-2 μm was fabricated by FIB implantation of Ga and In, ions respectively. Later, an in-situ annealing step followed by InAs deposition was performed. The InAs QDs were preferentially formed in the holes generated by FIB. The influence of ion dose, annealing parameters and InAs amount was investigated in this work. With optimized parameters, more than 50 % single dot occupancy per hole is achieved. Furthermore, the photoluminescence spectra from positioned QDs confirm their good optical quality. (orig.)

Luminescent Enhancement of Na+ and Sm3+ Co-doping Reddish Orange SrCa3Si2O8 Phosphors

Science.gov (United States)

Chun, Fengjun; Zhang, Binbin; Li, Wen; Liu, Honggang; Deng, Wen; Chu, Xiang; Osman, Hanan; Zhang, Haitao; Yang, Weiqing

2018-04-01

Reddish orange SrCa3Si2O8 phosphors, prepared by the facile solid state reaction method, are a luminescent enhancement of Na+ and Sm3+ co-doping luminescent material. Na+ was designed to compensate the charge imbalance of Sm3+ ion substituting for the Sr2+ ion of orthorhombic SrCa3Si2O8 crystals. The results suggest that Na+ can effectively enhance the luminescent intensity of the reddish orange light peaked at about 562 nm (4 G 5/2 → 6 H 5/2), 600 nm (4 G 5/2 → 6 H 7/2) and 645 nm (4 G 5/2 → 6 H 9/2) excited by the near ultraviolet excited light 404 nm (4 L 13/2 → 6 H 5/2). The energy transfer has been further verified by the florescence lifetime. Additionally, the luminescent lifetime τ of as-grown phosphors was separated into two parts, a rapid lifetime and a slow lifetime. The average lifetime results ranged from 2.098 to 1.329 ms which were influenced by the concentration of Sm3+ doping. The systematic researches of as-grown phosphors have clearly suggested a potential application for white-light-emitting diodes ( w-LEDs).

GaAs metal-oxide-semiconductor based non-volatile flash memory devices with InAs quantum dots as charge storage nodes

Energy Technology Data Exchange (ETDEWEB)

Islam, Sk Masiul, E-mail: masiulelt@gmail.com; Chowdhury, Sisir; Sarkar, Krishnendu; Nagabhushan, B.; Banerji, P. [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India); Mukherjee, Rabibrata [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302 (India)

2015-06-24

Ultra-thin InP passivated GaAs metal-oxide-semiconductor based non-volatile flash memory devices were fabricated using InAs quantum dots (QDs) as charge storing elements by metal organic chemical vapor deposition technique to study the efficacy of the QDs as charge storage elements. The grown QDs were embedded between two high-k dielectric such as HfO{sub 2} and ZrO{sub 2}, which were used for tunneling and control oxide layers, respectively. The size and density of the QDs were found to be 5 nm and 1.8×10{sup 11} cm{sup −2}, respectively. The device with a structure Metal/ZrO{sub 2}/InAs QDs/HfO{sub 2}/GaAs/Metal shows maximum memory window equivalent to 6.87 V. The device also exhibits low leakage current density of the order of 10{sup −6} A/cm{sup 2} and reasonably good charge retention characteristics. The low value of leakage current in the fabricated memory device is attributed to the Coulomb blockade effect influenced by quantum confinement as well as reduction of interface trap states by ultra-thin InP passivation on GaAs prior to HfO{sub 2} deposition.

The crystal structure and electrical properties of K{sub 2}NiF{sub 4}-type (Ca{sub 2−x}Sm{sub x})MnO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Taguchi, Hideki, E-mail: htaguchi@cc.okayama-u.ac.jp [The Graduate School of Natural Science and Technology (Science), Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama 700-8530 (Japan); Kido, Hiroyasu [Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Jyoto-Ku, Osaka 536-8553 (Japan); Kato, Masaki; Hirota, Ken [Department of Molecular Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, Kyo-Tanabe 610-0321 (Japan)

2015-04-15

Graphical abstract: The relationship between log ρ of K{sub 2}NiF{sub 4}-type (Ca{sub 2−x}Sm{sub x})MnO{sub 4} and 1000/T. - Highlights: • K{sub 2}NiF{sub 4}-type (Ca{sub 2−x}Sm{sub x})MnO{sub 4} was synthesized using a polymerized complex route. • The semiconductive samples had minimum values of ρ and E{sub a} at x = 0.1. • The log ρ–1/T curve of x = 0.3 consisted of two different lines at 315 K. • The 1/χ − T curve of x = 0.3 had a peak at 325 K. • These results indicated the presence of a charge-ordering transition at x = 0.3. - Abstract: K{sub 2}NiF{sub 4}-type (Ca{sub 2−x}Sm{sub x})MnO{sub 4} (0.02 ≤ x ≤ 0.3) was synthesized using a polymerized complex route. The crystal structure changed from tetragonal to orthorhombic at x = 0.3. A variation in the lattice parameters was explained by the Mn–O(2) distance, the Mn−O(2)−Mn angle, and the (Ca,Sm)–(Ca,Sm) distance. The samples were n-type semiconductors, and the minimum values of electrical resistivity (ρ) and an energy gap (E{sub g}) at x = 0.1 were accounted by electron transfer through an Mn−O(2)−Mn path and overlap between the Mnt{sub 2g} and Op{sub π} orbitals. In the sample (x = 0.3), the log ρ–1000/T curve consisted of two different lines that intersected at ca. 325 K, and a peak was observed at ca. 315 K in the magnetic susceptibility–temperature curve. These results indicated the presence of a charge-ordering (CO) transition at 315–325 K.

20 CFR 668.650 - Can INA grantees exclude segments of the eligible population?

Science.gov (United States)

2010-04-01

... eligible population? 668.650 Section 668.650 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION... population? (a) No, INA grantees cannot exclude segments of the eligible population. INA grantees must document in their Two Year Plan that a system is in place to afford all members of the eligible population...

H₃O_2-, O₂^2- and O₂•- bridging ligands in cobalt(III) complexes of an acyclic phenolate-hinged dinucleating ligand

DEFF Research Database (Denmark)

Ghiladi, Morten; Gomez, Jonnes T.; Hazell, A.

2003-01-01

The dicobalt(III) complex, [Co2(bpbp)(μ-H3O2)2](ClO4)3 (bpbp− = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-tert-butylphenolate), obtained by reaction of cobalt(II) perchlorate with Hbpbp under ambient conditions contains two μ-H3O2− bridging ligands. The H-bonded O⋯O distances in this motif are 2...

Growth-interruption-induced low-density InAs quantum dots on GaAs

International Nuclear Information System (INIS)

Li, L. H.; Alloing, B.; Chauvin, N.; Fiore, A.; Patriarche, G.

2008-01-01

We investigate the use of growth interruption to obtain low-density InAs quantum dots (QDs) on GaAs. The process was realized by Ostwald-type ripening of a thin InAs layer. It was found that the optical properties of the QDs as a function of growth interruption strongly depend on InAs growth rate. By using this approach, a low density of QDs (4 dots/μm 2 ) with uniform size distribution was achieved. As compared to QDs grown without growth interruption, a larger energy separation between the QD confined levels was observed, suggesting a situation closer to the ideal zero-dimensional system. Combining with an InGaAs capping layer such as In-rich QDs enable 1.3 μm emission at 4 K

Structural, magnetotransport and thermal properties of Sm substituted La{sub 0.7−x}Sm{sub x}Ba{sub 0.3}MnO{sub 3} (0≤x≤0.2) manganites

Energy Technology Data Exchange (ETDEWEB)

Modi, Anchit, E-mail: anchitmodi87@gmail.com [Department of Physics, Barkatullah University, Bhopal 462026 (India); Bhat, Masroor Ahmad; Pandey, Devendra K. [Department of Physics, Barkatullah University, Bhopal 462026 (India); Tarachand [UGC-DAE, Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India); Bhattacharya, Shovit [Technical Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Gaur, N.K. [Department of Physics, Barkatullah University, Bhopal 462026 (India); Okram, G.S. [UGC-DAE, Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India)

2017-02-15

In the present paper we studied the structural, magnetotransport and thermopower properties of a series of polycrystalline La{sub 0.7−x}Sm{sub x}Ba{sub 0.3}MnO{sub 3} (0≤x≤0.2) compounds which were synthesized by conventional solid state reaction techniques. The Rietveld refinement of the X-ray diffraction pattern predicts the formation of single-phase compositions and doping of La{sup 3+} by Sm{sup 3+} ion converted the chemical structure form rhombohedral (R-3C) to orthorhombic (Imma) The scanning electron microscopy show clean smooth and densified structure images be a sign of good crystalline nature of the samples. The temperature dependent electrical resistivity is measured by standard four-probe method between 5 and 300 K exhibits Metal–Insulator Transition MIT which shows the decreasing trend with increasing Sm doping content and metallic state (TT{sub p2}) are explained within the framework of variable range hopping (VRH) and small polaron hopping (SPH) models. The application of magnetic field suppresses the resistivity in entire temperature range and with increasing the Sm{sup 3+} content the samples showed very high magnetoresistance. The thermoelectric power (S) of the reported samples exhibit a crossover from positive to negative value and it increases in doped samples. The analysis of thermoelectric power data confirms the applicability of the small polaron hopping model in high temperature region and in low temperature fitted to an equation containing diffusion, magnon drag, phonon drag and electron-spin fluctuation term. An appropriate justification for the observed behavior is specified. - Highlights: • La{sub 0

Formation of anodic layers on InAs (111)III. Study of the chemical composition

Energy Technology Data Exchange (ETDEWEB)

Valisheva, N. A., E-mail: valisheva@thermo.isp.nsc.ru; Tereshchenko, O. E. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Prosvirin, I. P.; Kalinkin, A. V. [Russian Academy of Sciences, Boreskov Institute of Catalysis, Siberian Branch (Russian Federation); Goljashov, V. A. [Novosibirsk State University (Russian Federation); Levtzova, T. A. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Bukhtiyarov, V. I. [Russian Academy of Sciences, Boreskov Institute of Catalysis, Siberian Branch (Russian Federation)

2012-04-15

The chemical composition of {approx}20-nm-thick anodic layers grown on InAs (111)III in alkaline and acid electrolytes containing or not containing NH{sub 4}F is studied by X-ray photoelectron spectroscopy. It is shown that the composition of fluorinated layers is controlled by the relation between the concentrations of fluorine and hydroxide ions in the electrolyte and by diffusion processes in the growing layer. Fluorine accumulates at the (anodic layer)/InAs interface. Oxidation of InAs in an acid electrolyte with a low oxygen content and a high NH{sub 4}F content brings about the formation of anodic layers with a high content of fluorine and elemental arsenic and the formation of an oxygen-free InF{sub x}/InAs interface. Fluorinated layers grown in an alkaline electrolyte with a high content of O{sup 2-} and/or OH{sup -} groups contain approximately three times less fluorine and consist of indium and arsenic oxyfluorides. No distinction between the compositions of the layers grown in both types of fluorine-free electrolytes is established.

The atomic structure of protons and hydrides in Sm1.92Ca0.08Sn2O7-δ pyrochlore from DFT calculations and FTIR spectroscopy

DEFF Research Database (Denmark)

Bork, Nicolai Christian; Eurenius, K. E. J.; Rossmeisl, Jan

2012-01-01

A combined density functional theory and Fourier transform infrared spectroscopy study of the structure and specific site preference of protons and hydrides in the pyrochlore Sm1.92Ca0.08Sn2O7-δ is presented. Two protonic sites of particular high stability are identified, both located on O(1......) oxygen atoms closely associated with a Ca dopant. Further, the unexpected presence of Ho hydride defects in undoped, oxygen deficient Sm2Sn2O7 is reported. Finally, the stretching frequencies and relative intensities for these and other sites are calculated. The main features of the Fourier transform...

Sm/Ti co-substituted bismuth ferrite multiferroics: reciprocity between tetragonality and piezoelectricity.

Science.gov (United States)

Jha, Pardeep K; Jha, Priyanka A; Singh, Prabhakar; Ranjan, Rajeev; Dwivedi, R K

2017-10-04

BiFeO 3 (BFO) systems co-modified with Ti, Sm and Sm-Ti have been investigated for piezoelectricity together with dielectric and multiferroic properties. Structural studies revealed the coexistence of orthorhombic and rhombohedral (R3c) phases for x > 0.12. Impurity phases were shown to have hardly any effect on the remanent magnetization, which rather depends on the Fe-O-Fe bond angle. The dielectric loss was reduced considerably by substitution. A correlation between the piezoelectric coefficient and tetragonality was observed in these samples. BFO co-substituted with Sm-Ti exhibited a high piezoelectric coefficient with better ferroic properties, which revealed a unique combination of green piezoelectricity and multiferroicity.

Sm-153 EDTMP (ethylene diamine tetramethylene phosphonic acid) radiotherapeutic radiopharmaceutical

International Nuclear Information System (INIS)

Rehir Dahalan; Wan Anuar Wan Awang

1999-01-01

This work has utilized the technology used in the design of the diagnostic radiopharmaceuticals, which enabled optimum delivery of, the gamma emitting radionuclide to the target organs, enhancing the image of organ of interest. Optimal delivery of radiotherapeutic agents, minimizes the dose to the non target organs, whilst delivering destructive beta emitting radionuclide to target cancerous tissues with the hope of slowing down or completely ablating its growth. This work had been in establishing the parameters in the optimal production of Sm-153 using the MINT Research Reactor (MINTRR). This radionuclide, was then labeled to the ethylene diamine tetramethylene phosphoric acid (EDTMP) ligand, a bone-seeking complex. The results of this work have established the most suitable target form, the optimum labeling conditions and the necessary parameters to enhance the biodistribution of the Sm-153 EDTMP complex in the bone of the animal model, thus similarly in human. (author)

Structure and luminescent investigation of new Ln(III)-TTA complexes containing N-methyl-ε-caprolactam as ligand

Energy Technology Data Exchange (ETDEWEB)

Borges, Alex Santos, E-mail: alexb@ifes.edu.br [Coordenadoria de Química e Biologia, IFES, Vitória, ES 29040-780 (Brazil); Caliman, Ewerton Valadares [Coordenadoria de Engenharia Metalúrgica, IFES, Vitória, ES 29040-780 (Brazil); Dutra, José Diogo L. [Departamento de Química Fundamental, UFPE, Recife, PE 50590-470 (Brazil); Da Silva, Jeferson G. [Departamento de Farmácia, UFJF, Governador Valadares, MG 35010-17 (Brazil); Araujo, Maria Helena, E-mail: maria.araujo@pq.cnpq.br [Departamento de Química, UFMG, Belo Horizonte, MG 31270-901 (Brazil)

2016-02-15

The synthesis and photoluminescent properties of Ln(III)-TTA complexes (Ln=Eu(III) and Sm(III) ions; TTA=3-thenoyltrifluoroacetonate) with N-methyl-ε-caprolactam (NMC) are reported. The Ln complexes were characterized by elemental analysis, complexometric titration with EDTA and infrared spectroscopy. The molecular structures of the [Eu(TTA){sub 3}(NMC)(H{sub 2}O)] and [Sm(TTA){sub 3}(NMC)(H{sub 2}O)]·H{sub 2}O compounds were determined by single crystal X-ray crystallography. In these structures, the three TTA molecules are coordinated to the metal in anionic form as bidentate ligands, while the H{sub 2}O and NMC molecules are coordinated to the metal in neutral form as monodentated ligands. The coordination polyhedron around the Ln(III) atom can be described as square antiprismatic molecular geometry. The geometry of the [Eu(TTA){sub 3}(NMC)(H{sub 2}O)] complex was optimized with the Sparkle/RM1 model for Ln(III) complexes, allowing analysis of intramolecular energy transfer processes of the Eu(III) compound. The spectroscopic properties of the 4f{sup 6} intraconfigurational transitions of the Eu(III) complex were then studied experimentally and theoretically. The low value of emission quantum efficiency of {sup 5}D{sub 0} emitting level (η) of Eu(III) ion (ca. 36%) is due to the vibrational modes of the water molecule that act as luminescence quenching. In addition, the luminescence decay curves, the experimental intensity parameters (Ω{sub λ}), lifetimes (τ), radiative (A{sub rad}) and non-radiative (A{sub nrad}) decay rates, theoretical quantum yield (q{sub cal}) were also determined and discussed. - Highlights: • New Ln-TTA complexes with lactam were obtained and their luminescence investigated. • Jablonsky diagram for the Eu(III) complex shows the main channel for the IET process. • Data confirm the potentiality of the Eu(III) complex to produce red luminescence. • LUMPAC has provided useful information on the luminescence of the Eu

Awareness of the Vysočina Regional Food Labels With Context of Their Media Presence

Directory of Open Access Journals (Sweden)

Martina Chalupová

2016-01-01

Full Text Available The article presents results of research study that focused on the recognition of the Vysočina regional labels among the consumers in the region in connection with media analysis about the topic. Research among consumers was conducted in each district of Vysočina Region (Jihlava, Žďár nad Sázavou, Třebíč, Havlíčkův Brod and Pelhřimov by interviewing a sample of 819 respondents, selected by quota sampling methods. The research was aimed at analysing the ability of respondents to recognise and differentiate two existing regional labels VYSOČINA Regional Product®, Regional Food Vysočina Region and also nonexistent brand From Our Region Vysočina, created by authors. Data have been processed with correspondence analysis and showed that respondents connect different characteristics with the labels. Media analysis of the Vysočina regional labels revealed that media may help building awareness about the labels but they do not shape respondents’ views on them. Examining the link between the frequency of different types of information in media and their potential impact on the labels’ pereception by consumers have shown distorted image. Stronger consensus between research and media analysis have been examined only on importance of products’ origin, which can be viewed as a logical inference from the name of the labels.

Standard Missile-6 (SM-6)

Science.gov (United States)

2016-12-01

attack or Anti-Ship Cruise Missiles in flight. The SM-6 ERAM program is an evolutionary, capabilities based acquisition program that will use spiral ...Prior SAR Total O&S Estimates - Dec 2014 SAR 460.3 Programmatic/Planning Factors 0.0 Cost Estimating Methodology 0.0 Cost Data Update 0.0 Labor Rate

Heterobimetallic transition metal/rare earth metal bifunctional catalysis: a Cu/Sm/Schiff base complex for syn-selective catalytic asymmetric nitro-Mannich reaction.

Science.gov (United States)

Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

2010-04-07

The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)(2)/Sm(O-iPr)(3)/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)(3), we reoptimized the catalyst preparation method, and a catalyst derived from Sm(5)O(O-iPr)(13) showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)(3). The optimal system with Sm(5)O(O-iPr)(13) was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm(5)O(O-iPr)(13).

(18)O(2) label mechanism of sulfur generation and characterization in properties over mesoporous Sm-based sorbents for hot coal gas desulfurization.

Science.gov (United States)

Liu, B S; Wan, Z Y; Wang, F; Zhan, Y P; Tian, M; Cheung, A S C

2014-02-28

Using a sol-gel method, SmMeOx/MCM-41 or SBA-15 (Me=Fe, Co and Zn) and corresponding unsupported sorbents were prepared. The desulfurization performance of these sorbents was evaluated over a fixed-bed reactor and the effects of reaction temperature, feed and sorbent composition on desulfurization performance were studied. Samarium-based sorbents used to remove H2S from hot coal gas were reported for the first time. The results of successive sulfidation/regeneration cycles revealed that SmFeO3/SBA-15 sorbent was suitable for desulfurization of hot coal gas in the chemical industry. The formation of elemental sulfur during both sulfidation and regeneration processes depended strongly on the catalytic action of Sm2O2S species, which was confirmed for the first time via high sensitive time of flight mass spectrometer (TOF-MS) using 6%vol(18)O2/Ar regeneration gas and can reduce markedly procedural complexity. The sorbents were characterized using N2-adsorption, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), temperature-programmed reduction of H2 (H2-TPR), thermogravimetry (TG) and time-of-flight mass spectrometry (TOF-MS) techniques. Copyright © 2014 Elsevier B.V. All rights reserved.

Native oxide transport and removal during the atomic layer deposition of Ta{sub 2}O{sub 5} on InAs(100) surfaces

Energy Technology Data Exchange (ETDEWEB)

Henegar, Alex J.; Gougousi, Theodosia, E-mail: gougousi@umbc.edu [Department of Physics, UMBC, Baltimore, Maryland 21250 (United States)

2016-05-15

Atomic layer deposition (ALD) was used to deposit Ta{sub 2}O{sub 5} on etched and native oxide-covered InAs(100) using pentakis dimethyl amino tantalum and H{sub 2}O at 200–300 °C. The transport and removal of the native oxides during the ALD process was investigated using x-ray photoelectron spectroscopy (XPS). Depositions above 200 °C on etched surfaces protected the interface from reoxidation. On native oxide-covered surfaces, depositions resulted in enhanced native oxide removal at higher temperatures. The arsenic oxides were completely removed above 250 °C after 3 nm of film growth, but some of the As{sub 2}O{sub 3} remained in the film at lower temperatures. Angle-resolved and sputter depth profiling XPS confirmed indium and arsenic oxide migration into the Ta{sub 2}O{sub 5} film at deposition temperatures as low as 200 °C. Continuous removal of both arsenic and indium oxides was confirmed even after the deposition of several monolayers of a coalesced Ta{sub 2}O{sub 5} film, and it was demonstrated that native oxide transport is a prevalent component of the interface “clean-up” mechanism.

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

Energy Technology Data Exchange (ETDEWEB)

Mishra, A; Singh, M P; Singh, V K

1982-05-01

The nitrato-complexes, (Y(PyBzH)/sub 2/(NO/sub 3/)/sub 2/)NO/sub 3/.H/sub 2/O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole) are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm/sup -1/cm/sup 2/mol/sup -1/) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the positive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C/sub 2/v) and uncoordinated (D/sub 3/h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms.

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

International Nuclear Information System (INIS)

Mishra, A.; Singh, M.P.; Singh, V.K.

1982-01-01

The nitrato-complexes, [Y(PyBzH) 2 (NO 3 ) 2 ]NO 3 .H 2 O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole] are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm -1 cm 2 mol -1 ) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the terpositive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C 2 v) and uncoordinated (D 3 h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms. (author)

White-emission in single-phase Ba2Gd2Si4O13:Ce3 +,Eu2 +,Sm3 + phosphor for white-LEDs

Science.gov (United States)

Jiang, Xiumin; Zhang, Yuqian; Zhang, Jia

2018-03-01

To develop new white-light-emitting phosphor, a series of Ce3 +-Eu2 +-Sm3 + doped Ba2Gd2Si4O13 (BGS) phosphors were prepared by the solid-state reaction method, and their photoluminescence properties were studied. The Ce3 + and Eu2 + single-doped BGS show broad emission bands around in the region of 350-550 and 420-650 nm, respectively. By co-doping Ce3 +-Eu2 + into BGS, the energy transfer (ET) from Ce3 + to Eu2 + is inefficient, which could be due to the competitive absorption between the two activator ions. The Sm3 +-activated BGS exhibits an orangey-red emission in the region of 550-750 nm. To achieve white emission, the BGS:0.06Ce3 +,0.04Eu2 +,ySm3 + (0 ≤ y ≤ 0.18) phosphors were designed, in which the ET from Ce3 +/Eu2 + to Sm3 + was observed. The emission color can be tuned by controlling the Sm3 + concentration, and white emission was obtained in the BGS:0.06Ce3 +,0.04Eu2 +,0.06Sm3 + sample. The investigation of thermal luminescence stability for the typical BGS:0.06Ce3 +,0.04Eu2 +,0.06Sm3 + sample reveals that the emission intensities of both Eu2 + and Sm3 + demonstrate continuous decrease but the Ce3 + emission is enhanced gradually with increasing temperature. The corresponding reason has been discussed.

Solid-solid synthesis and structural phase transition process of SmF3

Science.gov (United States)

Yan, Qi-Cao; Guo, Xing-Min

2018-04-01

Mazes of contradictory conclusions have been obtained by previous researches about structural phase transition process of SmF3. In this paper, the single crystals of SmF3 (hexagonal and orthorhombic) were prepared by solid-solid synthesis, which have shown gradual changes in crystal growth modes with the increase temperature and holding time. Furthermore, we propose the phase transition process of in SmF3. Hexagonal symmetry of SmF3 (space group Pnma) was prepared firstly by heating Sm2O3 and NH4HF2 over 40 min at 270 °C. And then orthorhombic symmetry of SmF3 (space group P63mc) was obtained by heating hexagonal symmetry over 10 h at 650 °C. The reaction of SmF3 (hexagonal) = SmF3 (orthorhombic) is extremely sluggish at a low temperature (less than 650 °C), which was seen as a Mixed Grown Region.

INA's Preparations for Liberalised Energy Market and Privatisation

International Nuclear Information System (INIS)

Dragicevic, T.; Kolundzic, S.

2001-01-01

Before opening of the market, energy entities must carry out numerous preparations in order to be ready for challenges of a competitive environment. Some preparations refer to legal and organisational issues, but many of them encompass reengineering of business processes, cost reduction schemes and various improvement measures aimed at maintenance or acquisition of a competitive advantage. INA is actively pursuing some of the above measures, but now, by the end of 2001, we also have to deal with preparations for privatisation. These two processes have some important common elements, competitiveness being certainly one of them. INA must work toward improving its competitive strength in the gas sector, in refining, in marketing of oil products, but also in various supporting activities. However, there are constraints that we have to observe, mainly related to social issues.(author)

Ligand-Mediated Ring → Cube Transformation in a Catalytic Subnanocluster: Co4O4(MeCN)n with n = 1-6.

Science.gov (United States)

Luo, Sijie; Dibble, Collin J; Duncan, Michael A; Truhlar, Donald G

2014-08-07

We studied the Co4O4 subnanocluster and its MeCN-coated species using density functional theory, and we found that the Co4O4 core presents distinctive structures in bare and ligand-coated species. We propose a possible ligand-mediated ring → cube transformation mechanism during the ligand-coating process of the Co4O4 core due to the stronger binding energies of the MeCN ligands to the 3D distorted cube structure than to the 2D ring and ladder structures; theory indicates that three ligands are sufficient to stabilize the cube structure. Both ring and cube structures are ferromagnetic. Our finding is potentially useful for understanding the catalysis mechanism of Co4O4 species, which have important applications in solar energy conversion and water splitting; these catalysis reactions usually involve frequent addition and subtraction of various ligands and thus possibly involve core rearrangement processes similar to our findings.

Growth and characterization of Sm3+ doped cerium oxalate single crystals

Directory of Open Access Journals (Sweden)

Minu Mary C

2016-07-01

Full Text Available Single crystals of Sm3+ doped cerium oxalate decahydrate were synthesized using single diffusion gel technique and the conditions influencing the size, morphology, nucleation density and quality of the crystals were optimized. Highly transparent single crystals of average size 3 mm × 2 mm × 1 mm with well-defined hexagonal morphology were grown during a time period of two weeks. X-ray powder diffraction analysis revealed that the grown crystals crystallize in the monoclinic system with space group P21/c as identical with the pure cerium oxalate. The various functional groups of the oxalate ligand and the water of crystallization were identified by Fourier transform infrared spectroscopy. The photoluminescence spectrum of the Sm3+ doped cerium oxalate indicated that the Sm3+ ions are optically active in the cerium oxalate matrix. The crystal has a strong and efficient orange red emission with a wavelength peak at 595 nm and hence can be effectively used for optical amplification. Microhardness measurements of the crystal revealed that they belong to the soft material category.

A neodymium(III)-ammonium complex involving oxalate and carbonate ligands: (NH4)2[Nd2(C2O4)3(CO3)(H2O)].H2O.

Science.gov (United States)

Trombe, Jean-Christian; Galy, Jean; Enjalbert, Renée

2002-10-01

The title compound, diammonium aqua-mu-carbonato-tri-mu-oxalato-dineodymium(III) hydrate, (NH(4))(2)[Nd(2)(CO(3))(C(2)O(4))(3)(H(2)O)].H(2)O, involving the two ligands oxalate and carbonate, has been prepared hydrothermally as single crystals. The Nd atoms form a tetranuclear unit across the inversion centre at (1/2, 1/2, 1/2). Starting from this tetranuclear unit, the oxalate ligands serve to develop a three-dimensional network. The carbonate group acts as a bis-chelating ligand to two Nd atoms, and is monodentate to a third Nd atom. The oxalate groups are all bis-chelating. The two independent Nd atoms are ninefold coordinated and the coordination polyhedron of these atoms is a distorted monocapped antiprism.

Flux pinning landscape up to 25 T in SmBa2Cu3O y films with BaHfO3 nanorods fabricated by low-temperature growth technique

Science.gov (United States)

Tsuchiya, Yuji; Miura, Shun; Awaji, Satoshi; Ichino, Yusuke; Matsumoto, Kaname; Izumi, Teruo; Watanabe, Kazuo; Yoshida, Yutaka

2017-10-01

REBa2Cu3O y superconducting tapes are appropriate for high field magnet applications at low temperatures (i.e. below liquid nitrogen temperature). To clarify the morphology and the volume of the effective pinning center at low temperatures, we used a low-temperature growth technique to fabricate SmBa2Cu3O y (SmBCO) films with various amounts of BaHfO3 (BHO) nanorods onto MgO-buffered metal substrates produced by ion-beam-assisted deposition; we investigated their flux pinning properties using a 25 T cryogen-free superconducting magnet that was recently developed at Tohoku University. According to the microstructural analysis using transmission electron microscopy, the BHO nanorods have a content-dependent morphology and are aligned for the higher content. The inclined and discontinuous BHO nanorods were observed in SmBCO films with BHO contents up to 3.8 vol%; they show an excellent flux pinning force density (1.5 TN m-3 at 21 T and 4.2 K) even when the magnetic field is perpendicular to the films. Based on the effective mass model for the flux pinning, the random pinning centers are dominant at low temperatures. The correlated flux pinning is stronger for aligned nanorods; however, the random pinning center becomes weaker in the 4.5 vol% BHO-doped films. Therefore, the optimal BHO doping level is approximately 3.8 vol% in terms of the amplitude of the critical current density and the anisotropy from 4.2 K to 20 K because this provides the best mixture of correlated and random flux pinning centers.

Two New Families of Lanthanide Mixed-Ligand Complexes, Oxalate-Carbonate and Oxalate-Formate: Synthesis and Structure of [Ce(H 2O)] 2(C 2O 4) 2(CO 3)·2.5 H 2O and Ce(C 2O 4)(HCO 2)

Science.gov (United States)

Romero, S.; Mosset, A.; Trombe, J. C.

1996-12-01

Two new families of lanthanide complexes associating the ligands oxalate and carbonate or oxalate and formate have been prepared under autogenous pressure at 200°C using a pseudo-hydrothermal method. The two families have been extended to some lanthanides ( Ln): oxalate-carbonate Ln= Ce, Pr, Nd, and Eu; oxalate-formate Ln= La, Ce, and Sm. The starting suspension contains either oxalate or a mixture of oxalate and oxalic acid. The structures have been solved for the element cerium. In both cases, the structure is built up from cerium atoms sharing all their oxygen atoms with oxalate and carbonate or oxalate and formate ligands, thus forming a three-dimensional network. The cerium polyhedra share either faces or edges or corners. The coordination scheme of the oxalate ligands is variable: bischelating, bischelating and monodentate, or bischelating and bismonodentate. The carbonate group acts as a bischelating and bismonodentate ligand while the formate group is chelating and monodentate. The characterization of these two original families by infrared spectra and thermal behavior is presented for some pure phases. A tentative explanation of the synthesis of these two phases will be emphasized.

The influence of atmosphere on performance of pure-phase WZ and ZB InAs nanowire transistors.

Science.gov (United States)

Ullah, Abu Rifat; Joyce, Hannah J; Tan, Hoe; Jagadish, Chennupati; Micolich, Adam P

2017-09-21

We compare the characteristics of phase-pure MOCVD grown ZB and WZ InAs nanowire transistors in several atmospheres: air, dry pure N₂ and O₂, and N₂ bubbled through liquid H₂O and alcohols to identify whether phase-related structural/surface differences affect their response. Both WZ and ZB give poor gate characteristics in dry state. Adsorption of polar species reduces off-current by 2-3 orders of magnitude, increases on-off ratio and significantly reduces sub-threshold slope. The key difference is the greater sensitivity of WZ to low adsorbate level. We attribute this to facet structure and its influence on the separation between conduction electrons and surface adsorption sites. We highlight the important role adsorbed species play in nanowire device characterisation. WZ is commonly thought superior to ZB in InAs nanowire transistors. We show this is an artefact of the moderate humidity found in ambient laboratory conditions: WZ and ZB perform equally poorly in the dry gas limit yet equally well in the wet gas limit. We also highlight the vital role density-lowering disorder has in improving gate characteristics, be it stacking faults in mixed-phase WZ or surface adsorbates in pure-phase nanowires. © 2017 IOP Publishing Ltd.

Orange-red emitting Gd2Zr2O7:Sm3+: Structure-property correlation, optical properties and defect spectroscopy

Science.gov (United States)

Gupta, Santosh K.; Reghukumar, C.; Sudarshan, K.; Ghosh, P. S.; Pathak, Nimai; Kadam, R. M.

2018-05-01

Local structure analysis of dopant ion, understanding host to dopant energy transfer dynamics and defects characterization in a doped material which plays an important role in the designing a highly efficient opto-electronic material. In this connection a new Sm3+ doped Gd2Zr2O7 pyrochlore material was synthesized using gel-combustion technique and was characterized systematically using X-ray diffraction (XRD), time resolved photoluminescence spectroscopy (TRPLS), positron annihilation lifetime spectroscopy (PALS) and density functional theory (DFT) based ab-initio calculation. Based on DFT site selective energetics calculation and luminescence decay measurement, it was observed that the Sm3+ was distributed at both Gd3+ and Zr4+ site with higher Sm3+ fraction at the Gd3+ site. PALS was used to probe the presence of defects in the phosphor. In this work intense orange-red emission is realized through manipulating the energy transfer from host defect emission (oxygen vacancies) to Sm3+ which allows color emission from green in undoped to orange-red in doped samples. Effect of dopant concentration and annealing temperature was probed using TRPLS and PALS. These all information is highly important for researcher looking to achieve pyrochlore based phosphor materials with high quantum yield.

Luminescence enhancement in Eu3+, Sm3+ co-doped liy(MoO4)2 nano-phosphors by sol-gel process.

Science.gov (United States)

Zhou, Xianju; Wang, Guangchuan; Zhou, Tonghui; Zhou, Kaining; Li, Qingxu; Wang, Zhongqing

2014-05-01

A series of LiY(0.95-x)Eu(0.05)Sm(x)(MoO4)2 red light emitting phosphors were synthesized by sol-gel technique. The phase impurity and spectroscopic properties were characterized by X-ray Diffraction (XRD), Photo-Luminescence (PL) and Photo-Luminescence Excitation (PLE) spectra, respectively. It is found that the PLE spectra of the Eu3+, Sm3+ co-doped nanoparticles are enhanced and broadened as compared with the solely doped samples, which will make the co-doped phosphors match better with blue and/or UV GaN based LED chips. The red emission intensity of Eu3+ is largely enhanced by the energy transfer from Sm3+. The mechanism of the enhancement is clearly proven to be the increase in the quantum efficiency of 5D0 state of Eu3+ rather than the increase in the absorption of Eu3+. Meanwhile, the characteristic f-f transitions of Sm3+ are greatly reduced, resulting in little influence in the color purity of the co-doped phosphors. The present material is an amendatory promising red light emitting phosphor for white LEDs.

Isozyme-specific ligands for O-acetylserine sulfhydrylase, a novel antibiotic target.

Directory of Open Access Journals (Sweden)

Francesca Spyrakis

Full Text Available The last step of cysteine biosynthesis in bacteria and plants is catalyzed by O-acetylserine sulfhydrylase. In bacteria, two isozymes, O-acetylserine sulfhydrylase-A and O-acetylserine sulfhydrylase-B, have been identified that share similar binding sites, although the respective specific functions are still debated. O-acetylserine sulfhydrylase plays a key role in the adaptation of bacteria to the host environment, in the defense mechanisms to oxidative stress and in antibiotic resistance. Because mammals synthesize cysteine from methionine and lack O-acetylserine sulfhydrylase, the enzyme is a potential target for antimicrobials. With this aim, we first identified potential inhibitors of the two isozymes via a ligand- and structure-based in silico screening of a subset of the ZINC library using FLAP. The binding affinities of the most promising candidates were measured in vitro on purified O-acetylserine sulfhydrylase-A and O-acetylserine sulfhydrylase-B from Salmonella typhimurium by a direct method that exploits the change in the cofactor fluorescence. Two molecules were identified with dissociation constants of 3.7 and 33 µM for O-acetylserine sulfhydrylase-A and O-acetylserine sulfhydrylase-B, respectively. Because GRID analysis of the two isoenzymes indicates the presence of a few common pharmacophoric features, cross binding titrations were carried out. It was found that the best binder for O-acetylserine sulfhydrylase-B exhibits a dissociation constant of 29 µM for O-acetylserine sulfhydrylase-A, thus displaying a limited selectivity, whereas the best binder for O-acetylserine sulfhydrylase-A exhibits a dissociation constant of 50 µM for O-acetylserine sulfhydrylase-B and is thus 8-fold selective towards the former isozyme. Therefore, isoform-specific and isoform-independent ligands allow to either selectively target the isozyme that predominantly supports bacteria during infection and long-term survival or to completely block

Room-temperature sol–gel synthesis of organic ligand-capped ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zobel, Mirijam, E-mail: mirijam.zobel@fau.de; Chatterjee, Haimantee [Friedrich-Alexander University Erlangen-Nürnberg (FAU), Department of Physics, Lehrstuhl für Kristallographie und Strukturphysik (Germany); Matveeva, Galina; Kolb, Ute [Johannes Gutenberg-Universität, Institut für Physikalische Chemie (Germany); Neder, Reinhard B., E-mail: reinhard.neder@fau.de [Friedrich-Alexander University Erlangen-Nürnberg (FAU), Department of Physics, Lehrstuhl für Kristallographie und Strukturphysik (Germany)

2015-05-15

Powders of zinc oxide nanoparticles with individual particle sizes below 10 nm in diameter are readily produced in base-induced sol–gel processes from ethanolic solutions of zinc acetate dihydrate. These particles are covered with acetate molecules and without further stabilization, they grow when stored as a powder. Here, we present three organic ligands, which reproducibly stabilize individual particle sizes <5 nm within the agglomerated powders for extended periods of time, up to months. Citric acid and 1,5-diphenyl-1,3,5-pentanetrione result in average diameters of 3 nm, whereas dimethyl-L-tartrate stabilizes 2.1 nm. X-ray diffraction and pair distribution function analysis were used to investigate the structural properties of the particles. TEM data confirm the individual particle size and crystallinity and show that the particles are agglomerated without structural coherence. Besides the introduction of these novel ligands for ZnO nanoparticles, we investigated, in particular, the influence of each synthesis step onto the final nanoparticle size in the powder. Previous studies often reported the employed synthesis parameters, but did not motivate the reasoning for their choice based on detailed experimental observations. Herein, we regard separately the steps of (i) the synthesis of the colloids, (ii) their precipitation, and (iii) the drying of the resulting gel to understand the role of the ligands therein. ZnO particles only covered with acetate grow to 5 nm during the drying process, whereas particles with any of the additional ligands retain their colloidal size of 2–3 nm. This clearly shows the efficient binding and effect of the presented ligands.

Synthesis, structure, and polymorphism of A{sub 3}LnSi{sub 2}O{sub 7} (A=Na, K; Ln=Sm, Ho, Yb)

Energy Technology Data Exchange (ETDEWEB)

Latshaw, Allison M.; Yeon, Jeongho; Smith, Mark D.; Loye, Hans-Conrad zur, E-mail: zurloye@mailbox.sc.edu

2016-03-15

Four new members of the A{sub 3}LnSi{sub 2}O{sub 7} family, K{sub 3}SmSi{sub 2}O{sub 7}, Na{sub 3}HoSi{sub 2}O{sub 7}, and two polymorphs of Na{sub 3}YbSi{sub 2}O{sub 7}, are reported. K{sub 3}SmSi{sub 2}O{sub 7} crystallizes in the hexagonal space group P6{sub 3}/mcm, Na{sub 3}HoSi{sub 2}O{sub 7} and Na{sub 3}YbSi{sub 2}O{sub 7} crystallize in the hexagonal space group P6{sub 3}/m, and Na{sub 3}YbSi{sub 2}O{sub 7} crystallizes in the trigonal space group P31c. The Na{sub 3}YbSi{sub 2}O{sub 7} composition that crystallizes in P31c is a new structure type. The magnetic properties for the Ho and Yb analogs are reported. - Graphical abstract: The different structure types and polymorphs of the A{sub 3}LnSi{sub 2}O{sub 7} family reported. - Highlights: • Four new members of the A{sub 3}LnSi{sub 2}O{sub 7} family are presented. • Na{sub 3}YbSi{sub 2}O{sub 7} is reported as two polymorphs, one is a new structure type. • Crystals synthesized out of molten fluoride fluxes.

A robust NiO-Sm0.2Ce0.8O1.9 anode for direct-methane solid oxide fuel cell

KAUST Repository

Tian, Dong

2015-07-02

In order to directly use methane without a reforming process, NiO-Sm0.2Ce0.8O1.9 (NiO-SDC) nanocomposite anode are successfully synthesized via a one-pot, surfactant-assisted co-assembly approach for direct-methane solid oxide fuel cells. Both NiO with cubic phase and SDC with fluorite phase are obtained at 550 °C. Both NiO nanoparticles and SDC nanoparticles are highly monodispersed in size with nearly spherical shapes. Based on the as-synthesized NiO-SDC, two kinds of single cells with different micro/macro-porous structure are successfully fabricated. As a result, the cell performance was improved by 40%-45% with the new double-pore NiO-SDC anode relative to the cell performance with the conventional NiO-SDC anode due to a wider triple-phase-boundary (TPB) area. In addition, no significant degradation of the cell performance was observed after 60 hours, which means an increasing of long term stability. Therefore, the as-synthesized NiO-SDC nanocomposite is a promising anode for direct-methane solid oxide fuel cells.

InAs film grown on Si(111) by metal organic vapor phase epitaxy

International Nuclear Information System (INIS)

Caroff, P; Jeppsson, M; Mandl, B; Wernersson, L-E; Wheeler, D; Seabaugh, A; Keplinger, M; Stangl, J; Bauer, G

2008-01-01

We report the successful growth of high quality InAs films directly on Si(111) by Metal Organic Vapor Phase Epitaxy. A nearly mirror-like and uniform InAs film is obtained at 580 0 C for a thickness of 2 μm. We measured a high value of the electron mobility of 5100 cm 2 /Vs at room temperature. The growth is performed using a standard two-step procedure. The influence of the nucleation layer, group V flow rate, and layer thickness on the electrical and morphological properties of the InAs film have been investigated. We present results of our studies by Atomic Force Microscopy, Scanning Electron Microscopy, electrical Hall/van der Pauw and structural X-Ray Diffraction characterization

Channeling study of laser-induced defect generation in InP and InAs

International Nuclear Information System (INIS)

Burdel', K.K.; Kashkarov, P.K.; Timoshenko, V.Yu.; Chechenin, N.G.

1992-01-01

Damage production in InP and InAs single crystals induced by a ruby-laser pulse irradiation with τ p =20 ms in the energy density region W=0.05-1.0 J/cm 2 is studied by the channeling and Rutherford backscattering techniques. The defect generation threshold was determined to be equal to 0.2 J/cm 2 and 0.55 J/cm 2 for InP and InAs crystals, respectively. Stoichiometric defects in InP crystals were observed at W>=0.5 J/cm 2 . The temperature fields in InP and InAs under laser irradiation were calculated. The experimental observations are considered as a result of a selective evaporation of the components from the melt

Synthesis and luminescence properties of ZnAl{sub 2}O{sub 4}:RE{sup 3+} (RE = Eu, Sm) phosphors

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung Jin; Cho, Shin Ho [Silla University, Busan (Korea, Republic of)

2014-01-15

ZnAl{sub 2}O{sub 4}:RE{sup 3+} (RE = Eu or Sm) phosphor powders were synthesized with different concentrations of activator ions by using the conventional solid-state reaction method. The effects of the concentration of activator ions on the structural, morphological, and luminescent properties of zinc aluminate phosphors were investigated. The X-ray diffraction patterns revealed that the phosphors synthesized with different concentrations of activator ions showed mixed phases of ZnAl{sub 2}O{sub 4}, ZnO, and Al{sub 2}O{sub 3}. The crystallite size was estimated using the Scherrer formula, and the maximum size was obtained for 0.20 mol of Eu{sup 3+} ions. The emission spectra of of Eu{sup 3+}-doped ZnAl{sub 2}O{sub 4} phosphors under excitation at 303 nm exhibited one intense green band at approximately 520 nm and three weak bands centered at 590, 621, and 701 nm, respectively. The intensity of all the emission bands reached a maximum for 0.05 mol of Eu{sup 3+} ions. For the Sm{sup 3+}-doped ZnAl{sub 2}O{sub 4} phosphors, a broad emission band peak at 526 nm and several weak lines in the range 470 - 700 nm were observed. The results suggest that the luminescent intensity of the phosphors can be enhanced by controlling the amount of activator ions incorporated into the host lattice.

A two-dimensional layered Cd(II) coordination polymer with a three-dimensional supramolecular architecture incorporating mixed multidentate N- and O-donor ligands.

Science.gov (United States)

Huang, Qiu-Ying; Su, Ming-Yang; Meng, Xiang-Ru

2015-06-01

The combination of N-heterocyclic and multicarboxylate ligands is a good choice for the construction of metal-organic frameworks. In the title coordination polymer, poly[bis{μ2-1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole-κ(2)N(3):N(4)}(μ4-butanedioato-κ(4)O(1):O(1'):O(4):O(4'))(μ2-butanedioato-κ(2)O(1):O(4))dicadmium], [Cd(C4H4O4)(C9H8N6)]n, each Cd(II) ion exhibits an irregular octahedral CdO4N2 coordination geometry and is coordinated by four O atoms from three carboxylate groups of three succinate (butanedioate) ligands and two N atoms from two 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole (bimt) ligands. Cd(II) ions are connected by two kinds of crystallographically independent succinate ligands to generate a two-dimensional layered structure with bimt ligands located on each side of the layer. Adjacent layers are further connected by hydrogen bonding, leading to a three-dimensional supramolecular architecture in the solid state. Thermogravimetric analysis of the title polymer shows that it is stable up to 529 K and then loses weight from 529 to 918 K, corresponding to the decomposition of the bimt ligands and succinate groups. The polymer exhibits a strong fluorescence emission in the solid state at room temperature.

Influence of Sm2O3 microalloying and Yb contamination on Y211 particles coarsening and superconducting properties of IG YBCO bulk superconductors

Science.gov (United States)

Vojtkova, L.; Diko, P.; Kovac, J.; Vojtko, M.

2018-06-01

Single grain YBa2Cu3O7‑x (YBCO or Y123) bulk superconductors were produced by an infiltration growth process. The solid phase precursor was prepared by solid state synthesis from Y2O3 + BaCuO2 powders. The influence of the addition of Sm2O3 and YB contamination from the substrate on the microstructure and superconducting properties was analyzed. The dependences of Yb concentration on the distance from the bottom of the samples measured by energy dispersive spectroscopy microanalysis used in conjunction with scanning electron microscopy confirmed the contamination of the samples during the melting stage of the sample preparation. It is shown that the addition of Sm in low concentration and its combination with Yb from the substrate modify the coarsening of the Y211 particles as well as lead to the appearance of a secondary peak effect in the field dependences of the critical current density.

Investigations on optical properties of Sm3+ ion doped boro-phosphate glasses

Science.gov (United States)

Vijayakumar, R.; Suthanthirakumar, P.; Karthikeyan, P.; Marimuthu, K.

2015-06-01

The Sm3+ doped Boro-phosphate glasses with the chemical composition 60H3BO3+20Li2CO3+10ZnO+(10-x) H6NO4P+xSm2O3 (where x= 0.1, 0.5, 1 and 2 in wt%) have been prepared by melt quenching technique. The prepared glasses were characterized through optical absorption and luminescence spectral measurements. The band gap energies corresponding to the direct and indirect allowed transitions and the Urbach's energy values were estimated from the absorption spectra. Judd-Ofelt intensity parameters have been derived to predict the radiative properties of the various emission transitions. In order to identify the emission color of the prepared glasses, the emission intensities were analyzed using CIE 1931 color chromaticity diagram. The energy transfer process takes place between Sm3+-Sm3+ ions through cross-relaxation mechanism have also been investigated and the results were discussed and reported.

Negative pressure driven phase transformation in Sr doped SmCoO₃.

Science.gov (United States)

Arshad Farhan, M; Javed Akhtar, M

2010-02-24

Atomistic computer simulation techniques based on energy minimization procedures are utilized for the structural investigation of perovskite-type SmCoO(3). A reliable potential model is derived which reproduces both cubic as well as orthorhombic phases of SmCoO(3). We observe a negative chemical pressure induced structural phase transformation from distorted perovskite (orthorhombic) to perfect perovskite (cubic) due to the substitution of Sr(2 + ) at the Sm(3 + ) sites. However, external hydrostatic pressure shows isotropic compression and no pressure-induced structural transformation is observed up to 100 GPa. To maintain the electroneutrality of the system, charge compensation is through oxygen vacancies which results in the brownmillerite-type structure. A defect model is proposed, which is consistent with experimental results. The solution energies for divalent and trivalent cations are also calculated. These results show that the cations having ionic radii less than 0.75 Å will occupy the Co sites and those with ionic radii larger than 0.75 Å will substitute at the Sm sites.

Profound Understanding of Effect of Transition Metal Dopant, Sintering Temperature, and pO2 on the Electrical and Optical Properties of Proton Conducting BaCe0.9Sm0.1O3-δ.

Science.gov (United States)

Handal, Hala T; Hassan, Azfar; Leeson, Ryan; Eloui, Sherif M; Fitzpatrick, Martin; Thangadurai, Venkataraman

2016-01-19

This study reports the effect of transition metal (TM) substitution on the electrical and optical properties of BaCe0.9Sm0.1O3-δ (BCS). Concentrations of 5-10 mol % of each of Fe and Co have been doped for the B-site of BCS by citric acid autocombustion method. Powder X-ray diffraction has revealed the formation of an orthorhombic perovskite-type structure. FTIR confirmed a distortion in the lattice upon TM-doping in BCS. Scanning electron microscopy (SEM) images of 1400 °C sintered samples have manifested a higher densification in BaCe0.8Sm0.1Co0.1O3-δ (BCSC10) with a grain size ∼11 μm compared to the parent compound BCS (∼2 μm). Thermogravimetric (TG) analysis showed a water uptake in case of BaCe0.85Sm0.1Co0.05O3-δ (BCSC5), while BaCe0.85Sm0.1Fe0.05O3-δ (BCSF5) did not show a noteworthy uptake of water. TG has also proved that the incorporation of Fe and Co in BCS did not improve the chemical stability in CO2 at elevated temperature. The band gap estimated using Kubelka-Munk model based on the diffuse reflectance data was found to be the lowest for BCSC5 (2.47 eV). However, it increases upon lowering oxygen partial pressure (pO2), which was interpreted by a band structure modifications. Among the samples investigated, BCSC10 sintered at 1400 °C showed the highest electrical conductivity of 0.02 S cm(-1) in air at 600 °C, while its proton mobility appears to be negligible under the investigated humidity atmosphere.

Study of the R-(Zr,W)-(O,N) (R = Y, Nd, Sm, Gd, Yb) oxynitride system

Energy Technology Data Exchange (ETDEWEB)

Tessier, Franck, E-mail: Franck.Tessier@univ-rennes1.fr [UMR CNRS 6226 ' Sciences Chimiques de Rennes' , equipe ' Verres et Ceramiques' , Universite de Rennes 1, 35042 Rennes cedex (France); Maillard, Pascal [UMR CNRS 6226 ' Sciences Chimiques de Rennes' , equipe ' Verres et Ceramiques' , Universite de Rennes 1, 35042 Rennes cedex (France); Orhan, Emmanuelle [Laboratoire Science des Procedes Ceramiques et Traitements de Surface, UMR CNRS 6638, Universite de Limoges, 123 Avenue Albert Thomas, 87060 Limoges cedex (France); Chevire, Francois [UMR CNRS 6226 ' Sciences Chimiques de Rennes' , equipe ' Verres et Ceramiques' , Universite de Rennes 1, 35042 Rennes cedex (France)

2010-02-15

The replacement of tantalum by the couple Zr/W within the RTa-O-N systems (R = Y, Nd, Sm, Gd, Yb), enables the preparation of novel oxide and oxynitride phases in the R-Zr-W-O-N system. R{sub 2}Zr{sub 2-x}W{sub x}O{sub 7+x} oxides exhibit the fluorite-type (x < 0.9) and scheelite (x {approx} 1) structures. Corresponding oxynitride compositions are of the fluorite-type and show different colors, for example in the case of ytterbium: pale yellow (x = 0.2 or 0.25), green (x = 0.5-0.8) and brown for the tungsten-rich samples (x = 0.9, 1). Photocatalytic activity measurements have been performed to investigate the overall water splitting behavior of these colored phases.

ions (RE = La, Pr, Nd, Sm, Gd and Dy)

Indian Academy of Sciences (India)

) zirconia), tendency of phase transformation (tetragonal to monoclinic () zirconia) and lattice strain were studied with mechanical property e.g. tensile strength of sol–gel derived ZrO2–2 mol% RE2O3 (RE = La, Pr, Nd, Sm, Gd and Dy) spun ...

Dilatometric and dielectric behaviour of Sm modified PCT ceramics

International Nuclear Information System (INIS)

Singh, Sarabjit; Thakur, O.P.; Prakash, Chandra; Raina, K.K.

2005-01-01

Samarium modified PCT ceramics with composition (Pb 0.76-x Sm x Ca 0.24 )(Ti 0.98 Mn 0.02 )O 3 ; x=0-0.08 in steps of 0.02 were prepared by conventional mixed-oxide method. Detailed dilatometric studies were carried out for green specimens in order to study sintering behaviour. Change in the dilatometric behaviour is correlated with the XRD results of powders calcined at different temperatures. Dielectric constant was observed to increase with increasing Sm concentration, which has been attributed to reduced tetragonality and better densification on Sm substitution. SEM micrographs have revealed the grain size of the samples. Ferroelectric hysteresis behaviour was studied for all the compositions

Oxovanadium (iv) complexes with n/o- and o-donor ligands: their synthesis, characterization, semiempirical study and alkaline phosphatase activity (abstract)

International Nuclear Information System (INIS)

Munawar, K.S.; Ali, S.; Khan, A.N.

2011-01-01

Various N/O- and O-donor ligands and their oxovanadium complexes have been synthesized and characterized by different techniques such as FTIR, elemental analysis, thermogravimetery and conductometry. The IR data show the bidentate nature of the ligands and reveals hexa-coordinated geometry in the solid state which is also confirmed by semi-empirical study. Conductance measurements reveal the non-electrolytic nature of the complexes. These complexes have been checked for their alkaline phosphatase activity in the presence and absence of inhibitor which shows that by the addition of inhibitor the activity of enzyme decreases and at higher concentration it is completely inhibited. (author)

Structural, luminescence and biological studies of trivalent lanthanide complexes with N,N Prime -bis(2-hydroxynaphthylmethylidene)-1,3-propanediamine Schiff base ligand

Energy Technology Data Exchange (ETDEWEB)

Taha, Ziyad A., E-mail: tahaz33@just.edu.jo [Department of Applied Chemistry, Faculty of Arts and Sciences, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110 (Jordan); Ajlouni, Abdulaziz M. [Department of Applied Chemistry, Faculty of Arts and Sciences, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110 (Jordan); Al Momani, Waleed [Department of Allied Medical Sciences, Al Balqa Applied University (Jordan)

2012-11-15

New eight lanthanide metal complexes were prepared. These complexes were characterized by elemental analysis, molar conductivity measurements, spectral analysis ({sup 1}H NMR, FT-IR, UV-vis), luminescence and thermal gravimetric analysis. All Ln(III) complexes were 1:1 electrolytes as established by their molar conductivities. The microanalysis and spectroscopic analysis revealed eight-coordinated environments around lanthanide ions with two nitrate ligands behaving in a bidentate manner. The other four positions were found to be occupied with tetradentate L{sub III} ligand. Tb-L{sub III} and Sm-L{sub III} complexes exhibited characteristic luminescence emissions of the central metal ions and this was attributed to efficient energy transfer from the ligand to the metal center. The L{sub III} and Ln-L{sub III} complexes showed antibacterial activity against a number of pathogenic bacteria. - Highlights: Black-Right-Pointing-Pointer Ln(III) ion adopts an eight-coordinate geometry. Black-Right-Pointing-Pointer Luminescence spectra of Sm-L{sub III} and Tb-L{sub III} complexes display the metal centered line emission. Black-Right-Pointing-Pointer Energy transfer process from L{sub III} to Sm in Sm-L{sub III} complex is more efficient than to Tb in Tb-L{sub III} complex. Black-Right-Pointing-Pointer Ln(III) complexes may serve as models for biologically important species.

Influence of rare-earth additives (La, Sm and Dy on the microstructure and dielectric properties of doped BaTiO3 ceramics

Directory of Open Access Journals (Sweden)

Paunović Vesna

2010-01-01

Full Text Available A series of La/Mn, Sm/Mn and Dy/Mn codoped BaTiO3 samples were prepared by the conventional solid state procedure with dopant concentrations ranging from 0.1 up to 2.0 at%. The specimens were sintered at 1320°C and 1350°C in an air atmosphere for two hours. The low doped samples demonstrated a mainly uniform and homogeneous microstructure with average grain sizes ranging from 0.3 μm to 5.0 μm. The appearance of secondary abnormal grains in the fine grain matrix and core-shell structure were observed in highly doped La/BaTiO3 and Dy/BaTiO3 sintered at 1350°C. The low doped samples, sintered at 1350°C, display a high value of dielectric permittivity at room temperature, 6800 for Sm/BaTiO3, 5900 for Dy/BaTiO3 and 3100 for La/BaTiO3. A nearly flat permittivity-response was obtained in specimens with 2.0 at% additive content. Using a modified Curie-Weiss law the Curie-like constant C⁄ and a critical exponent γ were calculated. The obtained values of γ pointed out the diffuse phase transformation in heavily doped BaTiO3 samples.

New Ru(II) complexes for dual photoreactivity: ligand exchange and (1)O2 generation.

Science.gov (United States)

Knoll, Jessica D; Albani, Bryan A; Turro, Claudia

2015-08-18

Uncovering the factors that govern the electronic structure of Ru(II)-polypyridyl complexes is critical in designing new compounds for desired photochemical reactions, and strategies to tune excited states for ligand dissociation and (1)O2 production are discussed herein. The generally accepted mechanism for photoinduced ligand dissociation proposes that population of the dissociative triplet ligand field ((3)LF) state proceeds through thermal population from the vibrationally cooled triplet metal-to-ligand charge transfer ((3)MLCT) state; however, temperature-dependent emission spectroscopy provides varied activation energies using the emission and ligand exchange quantum yields for [Ru(bpy)2(L)2](2+) (bpy = 2,2'-bipyridine; L = CH3CN or py). This suggests that population of the (3)LF state proceeds from the vibrationally excited (3)MLCT state. Because the quantum yield of ligand dissociation for nitriles is much more efficient than that for py, steric bulk was introduced into the ligand set to distort the pseudo-octahedral geometry and lower the energy of the (3)LF state. The py dissociation quantum yield with 500 nm irradiation in a series of [Ru(tpy)(NN)(py)](2+) complexes (tpy = 2,2':6',2″-terpyridine; NN = bpy, 6,6'-dimethyl-2,2'-bipyridine (Me2bpy), 2,2'-biquinoline (biq)) increases by 2-3 orders of magnitude with the sterically bulky Me2bpy and biq ligands relative to bpy. Ultrafast transient absorption spectroscopy reveals population of the (3)LF state within 3-7 ps when NN is bulky, and density functional theory calculations support stabilized (3)LF states. Dual activity via ligand dissociation and (1)O2 production can be achieved by careful selection of the ligand set to tune the excited-state dynamics. Incorporation of an extended π system in Ru(II) complexes such as [Ru(bpy)(dppn)(CH3CN)2](2+) (dppn = benzo[i]dipyrido[3,2-a:2',3'-c]phenazine) and [Ru(tpy)(Me2dppn)(py)](2+) (Me2dppn = 3,6-dimethylbenzo[i]dipyrido[3,2-a:2',3'-c]phenazine) introduces

New Ru(II) Complexes for Dual Photoreactivity: Ligand Exchange and 1O2 Generation

Science.gov (United States)

Knoll, Jessica D.; Albani, Bryan A.; Turro, Claudia

2016-01-01

CONSPECTUS Uncovering the factors that govern the electronic structure of Ru(II)–polypyridyl complexes is critical in designing new compounds for desired photochemical reactions, and strategies to tune excited states for ligand dissociation and 1O2 production are discussed herein. The generally accepted mechanism for photoinduced ligand dissociation proposes that population of the dissociative triplet ligand field (3LF) state proceeds through thermal population from the vibrationally cooled triplet metal-to-ligand charge transfer (3MLCT) state; however, temperature-dependent emission spectroscopy provides varied activation energies using the emission and ligand exchange quantum yields for [Ru(bpy)2(L)2]2+ (bpy = 2,2′-bipyridine; L = CH3CN or py). This suggests that population of the 3LF state proceeds from the vibrationally excited 3MLCT state. Because the quantum yield of ligand dissociation for nitriles is much more efficient than that for py, steric bulk was introduced into the ligand set to distort the pseudo-octahedral geometry and lower the energy of the 3LF state. The py dissociation quantum yield with 500 nm irradiation in a series of [Ru(tpy)(NN)(py)]2+ complexes (tpy = 2,2′:6′,2″-terpyridine; NN = bpy, 6,6′-dimethyl-2,2′-bipyridine (Me2bpy), 2,2′-biquinoline (biq)) increases by 2–3 orders of magnitude with the sterically bulky Me2bpy and biq ligands relative to bpy. Ultrafast transient absorption spectroscopy reveals population of the 3LF state within 3–7 ps when NN is bulky, and density functional theory calculations support stabilized 3LF states. Dual activity via ligand dissociation and 1O2 production can be achieved by careful selection of the ligand set to tune the excited-state dynamics. Incorporation of an extended π system in Ru(II) complexes such as [Ru(bpy)(dppn)(CH3CN)2]2+ (dppn = benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine) and [Ru(tpy)(Me2dppn)(py)]2+ (Me2dppn = 3,6-dimethylbenzo[i]dipyrido[3,2-a:2′,3�

Bi2(Sr, Ln)2CuOz (Ln = Nd, Sm) phases: stability, crystal growth and superconducting properties

International Nuclear Information System (INIS)

Faqir, H.; Kikuchi, M.; Syono, Y.; Mansori, M.; Satre, P.; Sebaoun, A.; Vacquier, G.

2000-01-01

Bi 2 (Sr,Ln) 2 CuO z (Ln = Nd, Sm) single crystals were successfully grown by a self-flux method from stoichiometric and (Bi, Cu)-rich melts. Thermal analysis and thermogravimetry were used to determine stability and the melting sequence of Bi 2 (Sr,Ln) 2 CuO z phases in air. As-grown crystals of the ideal Bi 2 (Sr,Ln) 2 CuO z phase, of dimensions 1x0.5x0.03 mm 3 , exhibit superconducting behaviour with critical temperature T c = 21 K for the Bi 1.9 Sr 1.6 Nd 0.6 CuO z crystal and Tc = 14 K for the Bi 1.8 Sr 1.6 Sm 0.6 CuO z crystal. The compositions of these crystals were homogeneous and close to the stoichiometric composition. We report on the growth of Bi 2 Sr 2-x Sm x CuO z single crystals of large dimensions 9x3x0.03 mm 3 using Bi 2 Sr 1.5 Sm 0.5 CuO z as precursor and Bi 2 CuO 4 as flux. (author)

The influence of atmosphere on the performance of pure-phase WZ and ZB InAs nanowire transistors

Science.gov (United States)

Ullah, A. R.; Joyce, H. J.; Tan, H. H.; Jagadish, C.; Micolich, A. P.

2017-11-01

We compare the characteristics of phase-pure MOCVD grown ZB and WZ InAs nanowire transistors in several atmospheres: air, dry pure N2 and O2, and N2 bubbled through liquid H2O and alcohols to identify whether phase-related structural/surface differences affect their response. Both WZ and ZB give poor gate characteristics in dry state. Adsorption of polar species reduces off-current by 2-3 orders of magnitude, increases on-off ratio and significantly reduces sub-threshold slope. The key difference is the greater sensitivity of WZ to low adsorbate level. We attribute this to facet structure and its influence on the separation between conduction electrons and surface adsorption sites. We highlight the important role adsorbed species play in nanowire device characterisation. WZ is commonly thought superior to ZB in InAs nanowire transistors. We show this is an artefact of the moderate humidity found in ambient laboratory conditions: WZ and ZB perform equally poorly in the dry gas limit yet equally well in the wet gas limit. We also highlight the vital role density-lowering disorder has in improving gate characteristics, be it stacking faults in mixed-phase WZ or surface adsorbates in pure-phase nanowires.

Molecular electrophosphorescence in (Sm, Gd)-β-diketonate complex blend for OLED applications

International Nuclear Information System (INIS)

Reyes, R.; Cremona, M.; Teotonio, E.E.S.; Brito, H.F.; Malta, O.L.

2013-01-01

In this work the preparation and characterization of the triple-layer organic light-emitting diode (OLED) using a mixture of the samarium and gadolinium β-diketonate complexes [Sm 0.5 Gd 0.5 (TTA) 3 (TPPO) 2 ] as emitting layer is reported. The OLED's devices contain 1-(3-methylphenyl)-1,2,3,4-tetrahydroquinoline-6-carboxyaldehyde-1, 1'-diphenylhydrazone (MTCD) as hole-transporting layer and tris(8-hydroxyquinoline aluminum) (Alq 3 ) as electron transporting layer. The electroluminescence spectrum present emission narrow bands from the 4 G 5/2 → 6 H J transitions (where J=5/2, 7/2 and 9/2) characteristic of the Sm 3+ ion. These sharp lines are overlapped with a broad band attributed to the electrophosphorescence from the T 1 →S 0 transition in the ligand TTA. The intramolecular energy transfer is discussed and applied on the change of the emission color of the organic LEDs at different bias voltages. - Highlights: ► Samarium and gadolinium complexes. ► OLED with complex blend (Sm,Gd). ► Electrophosphorescence emission detection. ► Application in OLED changing the color emission.

Comparison in the electronic structure of YBa{sub 2}Fe{sub 3}O{sub 8} insulator with YBa{sub 2}Cu{sub 3}O{sub 7} and SmFeAsO{sub 0.8}F{sub 0.2} superconductors

Energy Technology Data Exchange (ETDEWEB)

Zhang, Y.; Guan, X.Y. [Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Superconductivity R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Pan, M. [Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Superconductivity R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Zhang, H. [Department of Physics, Peking University, Beijing 100871 (China); Zhao, Y., E-mail: yzhao@home.swjtu.edu.cn [Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Superconductivity R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)

2013-10-15

Highlights: • The electronic structure of YBa{sub 2}Fe{sub 3}O{sub 8}, YBa{sub 2}Cu{sub 3}O{sub 7} and SmFeAsO{sub 0.8}F{sub 0.2} were investigated by XPS. • The core-level and valence-band structures of these systems are different. • The density of states at Fermi level is related to the superconductivity. -- Abstract: The electronic structure and chemical states of relevant elements of YBa{sub 2}Fe{sub 3}O{sub 8} are investigated using X-ray photoemission spectroscopy (XPS), compared with those of YBa{sub 2}Cu{sub 3}O{sub 7} and SmFeAsO{sub 0.8}F{sub 0.2} superconductors. The typical differences and similarities in core-level and valence-band structures of these systems have been detected, strongly suggesting that the superconductivity have the finite density of states around Fermi level. Several features of O1s, Y3d, Ba3d, and Fe2p core lines in XPS spectra are also carefully compared and analyzed.

Infrared luminescence and thermoluminescence of lithium borate glasses doped with Sm3+ ions

Directory of Open Access Journals (Sweden)

Anjaiah J.

2015-03-01

Full Text Available Thermoluminescence (TL characteristics of X-ray irradiated pure and doped with Sm3+ ions Li2O-MO-B2O3 (where MO=ZnO, CaO, CdO glasses have been studied in the temperature range of 303 to 573 K. All the pure glasses exhibited single TL peaks at 382 K, 424 K and 466 K. When these glasses were doped with Sm3+ ions no additional peaks have been observed but the glow peak temperature of the existing glow peak shifted gradually towards higher temperatures with gain in intensity of TL light output. The area under the glow curve was found to be maximum for Sm3+ doped glasses mixed with cadmium oxide as a modifier. The trap depth parameters associated with the observed TL peaks have been evaluated using Chen’s formulae. The possible use of these glasses in radiation dosimetry has been described. The results clearly showed that samarium doped cadmium borate glass has a potential to be considered as a thermoluminescence dosimeter.

Luminescence and energy transfer studies on Sm3+/Tb3+codoped telluroborate glasses for WLED applications

Science.gov (United States)

Uma, V.; Vijayakumar, M.; Marimuthu, K.; Muralidharan, G.

2018-01-01

A new series of Sm3+/Tb3+ codoped telluroborate glasses have been prepared by conventional melt quenching technique with the chemical composition (40-x-y)B2O3+15TeO2+15Li2O+15LiF+15NaF+xTb2O3+ySm2O3 (where x = 0, 0.5; y = 0, 0.05, 0.1, 0.25, 0.5, 1 and 2 wt%). The structural and optical behaviour of the prepared glasses were investigated through Fourier transform infrared spectroscopy (FTIR), optical absorption, photoluminescence and lifetime measurements. The fundamental vibrational units of the borate and tellurite network have been identified through FTIR spectra. Nephelauxetic ratio (βbar) and bonding parameter (δ) values indicate that the Smsbnd O bonds are ionic in nature. The characteristic emissions of terbium (543 nm, green) and samarium (645 nm, orange-red) were observed while exciting the Tb3+ ions. Higher magnitude of asymmetric intensity ratio (AIR) values confirms the higher asymmetry around the Sm3+ ion site. Decay profiles of Tb3+ ions (5D4 state) and Sm3+ ions (4G9/2 state) exhibit double exponential nature. The nature of interaction between the donor (Tb3+) and acceptor (Sm3+) has been analyzed through Inokuti-Hirayama (IH) model. Energy transfer from Tb3+ to Sm3+ ions is dominated by dipole-dipole type interaction. TBLT0.5S glass possess the better colour coordinates (0.41, 0.45) and colour correlated temperature (CCT) value (3524 K) and the same is suggested for eye safe warm white light emitting applications.

Reactive ion etching of GaSb, (Al,Ga)Sb, and InAs for novel device applications

International Nuclear Information System (INIS)

LaTulipe, D.C.; Frank, D.J.; Munekata, H.

1991-01-01

Although a variety of novel device proposals for GaSb/(Al,Ga)Sb/InAs heterostructures have been made, relatively little is known about processing these materials. The authors of this paper have studied the reactive ion etching characteristics of GaSb, (Al,Ga)Sb, and InAs in both methane/hydrogen and chlorine gas chemistries. At conditions similar to those reported elsewhere for RIE of InP and GaAs in CH 4 /H 2 , the etch rate of (Al,Ga)Sb was found to be near zero, while GaSb and InAs etched at 200 Angstrom/minute. Under conditions where the etch mechanism is primarily physical sputtering, the three compounds etch at similar rates. Etching in Cl 2 was found to yield anistropic profiles, with the etch rate of (Al,Ga)Sb increasing with Al mole fraction, while InAs remains unetched. Damage to the InAs stop layer was investigated by sheet resistance and mobility measurements. These etching techniques were used to fabricate a novel InAs- channel FET composed of these materials. Several scanning electron micrographs of etching results are shown along with preliminary electrical characteristics

Formation of SmFe5(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

International Nuclear Information System (INIS)

Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

2010-01-01

SmFe 5 (0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe 5 structure forming an alloy compound of Sm(Fe,Cu) 5 . The Sm(Fe,Cu) 5 film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

Purification of the spliced leader ribonucleoprotein particle from Leptomonas collosoma revealed the existence of an Sm protein in trypanosomes. Cloning the SmE homologue.

Science.gov (United States)

Goncharov, I; Palfi, Z; Bindereif, A; Michaeli, S

1999-04-30

Trans-splicing in trypanosomes involves the addition of a common spliced leader (SL) sequence, which is derived from a small RNA, the SL RNA, to all mRNA precursors. The SL RNA is present in the cell in the form of a ribonucleoprotein, the SL RNP. Using conventional chromatography and affinity selection with 2'-O-methylated RNA oligonucleotides at high ionic strength, five proteins of 70, 16, 13, 12, and 8 kDa were co-selected with the SL RNA from Leptomonas collosoma, representing the SL RNP core particle. Under conditions of lower ionic strength, additional proteins of 28 and 20 kDa were revealed. On the basis of peptide sequences, the gene coding for a protein with a predicted molecular weight of 11.9 kDa was cloned and identified as homologue of the cis-spliceosomal SmE. The protein carries the Sm motifs 1 and 2 characteristic of Sm antigens that bind to all known cis-spliceosomal uridylic acid-rich small nuclear RNAs (U snRNAs), suggesting the existence of Sm proteins in trypanosomes. This finding is of special interest because trypanosome snRNPs are the only snRNPs examined to date that are not recognized by anti-Sm antibodies. Because of the early divergence of trypanosomes from the eukaryotic lineage, the trypanosome SmE protein represents one of the primordial Sm proteins in nature.

Measurement of the elastic tensor of SmScO3 and NdScO3 using resonant ultrasound spectroscopy with ab initio calculations

Directory of Open Access Journals (Sweden)

K. A. Pestka II

2011-09-01

Full Text Available The complete elastic tensors of SmScO3 and NdScO3 were measured using resonant ultrasound spectroscopy (RUS in combination with ab-initio calculations. Measurement of the elastic tensor of these recently synthesized single crystal RE scandates is essential for understanding dynamic lattice applications including phonon confinement, strain induced thin film growth and superlattice construction. On average, the experimental elastic constants differed by less than 5% of the theoretical values, further validating the accuracy of modern ab-initio calculations as a means of estimating the initial elastic constants used in RUS measurements.

Distinguishing a SM-like MSSM Higgs boson from SM Higgs boson ...

Indian Academy of Sciences (India)

We explore the possibility of distinguishing the SM-like MSSM Higgs boson from the SM Higgs boson via Higgs boson pair production at future muon collider. We study the behavior of the production cross-section in SM and MSSM with Higgs boson mass for various MSSM parameters tan and A. We observe that at fixed ...

Past and Present Development of INA's Liberalisation and Privatisation

International Nuclear Information System (INIS)

Lesic, A.; Stimac, B.

2001-01-01

The paper deals with the historical development aspects of the Croatian oil and gas industry INA. It describes the period from the very start of oil and gas production to the data of establishment of the Croatian state and afterwards. Some important milestones and political and economic events that impacted the development of the Croatian oil industry are described and commented, including changes toward liberalisation and privatisation of the oil and gas sector. The paper emphasises the role of INA in the Croatian economy and proposes some solutions for the liberalisation process and privatisation of the company that could prevent undesirable effects of privatisation and protect the interests of Croatia in the energy sector which is one of the main sectors of economy having influence on other production and service sectors and their competitiveness.(author)

Conductive atomic force microscopy study of InAs growth kinetics on vicinal GaAs (110)

International Nuclear Information System (INIS)

Tejedor, Paloma; Diez-Merino, Laura; Beinik, Igor; Teichert, Christian

2009-01-01

Conductive atomic force microscopy has been used to investigate the effect of atomic hydrogen and step orientation on the growth behavior of InAs on GaAs (110) misoriented substrates. Samples grown by conventional molecular beam epitaxy exhibit higher conductivity on [110]-multiatomic step edges, where preferential nucleation of InAs nanowires takes place by step decoration. On H-terminated substrates with triangular terraces bounded by [115]-type steps, three-dimensional InAs clusters grow selectively at the terrace apices as a result of a kinetically driven enhancement in upward mass transport via AsH x intermediate species and a reduction in the surface free energy.

The presence of INA proteins on the surface of single cells of Pseudomonas syringae R10.79 isolated from rain

Science.gov (United States)

Šantl-Temkiv, Tina; Ling, Meilee; Holm, Stine; Finster, Kai; Boesen, Thomas

2016-04-01

One of the important open questions in atmospheric ice nucleation is the impact of bioaerosols on the ice content of mix phase clouds (DeMott and Prenni 2010). Biogenic ice nuclei have a unique capacity of facilitating ice formation at temperatures between -1 and -10 °C. The model biogenic ice nuclei are produced by a few species of plant-surface bacteria, such as Pseudomonas syringae, that are commonly transported through the atmosphere. These bacterial species have highly specialized proteins, the so-called ice nucleation active (INA) proteins, which are exposed at the outer membrane surface of the cell where they promote ice particle formation. The mechanisms behind the onset of INA protein synthesis in single bacterial cells are not well understood. We performed a laboratory study in order to (i) investigate the presence of INA proteins on single bacterial cells and (ii) understand the conditions that induce INA protein production. We previously isolated an INA-positive strain of Pseudomonas syringae from rain samples collected in Denmark. Bacterial cells initiated ice nucleation activity at temperatures ≤-2°C and the cell fragments at temperatures ≤-8°C (Šantl-Temkiv et al 2015). We determined the amino-acid sequence of the INA protein and used the sequence to produce custom-made antibodies (GenScript, Germany). These antibodies were used to specifically stain and visualize the INA protein on the surfaces of single cells, which can then be quantified by a technique called flow cytometry. The synthesis of INA proteins by individual cells was followed during a batch growth experiment. An unusually high proportion of cells that were adapting to the new conditions prior to growth produced INA proteins (~4.4% of all cells). A smaller fraction of actively growing cells was carrying INA proteins (~1.2 % of all cells). The cells that stopped growing due to unfavorable conditions had the lowest fraction of cells carrying INA proteins (~0.5 % of all cells). To

New AMS method to measure the atom ratio {sup 146}Sm/{sup 147}Sm for a half-life determination of {sup 146}Sm

Energy Technology Data Exchange (ETDEWEB)

Kinoshita, N. [Tandem Accelerator Complex, Research Facility Center for Science and Technology, University of Tsukuba (Japan); Paul, M., E-mail: paul@vms.huji.ac.il [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Alcorta, M. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Bowers, M.; Collon, P. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670 (United States); Deibel, C.M. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 46624 (United States); DiGiovine, B. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Goriely, S. [Universite Libre de Bruxelles, CP-226, Brussels 1050 (Belgium); Greene, J.P.; Henderson, D.J.; Jiang, C.L. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Kashiv, Y. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670 (United States); Kay, B.P.; Lee, H.Y.; Marley, S.T. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Nakanishi, T. [Faculty of Chemistry, Institute of Science and Engineering, Kanazawa University (Japan); Pardo, R.C.; Patel, N.; Rehm, K.E. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Robertson, D. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670 (United States); and others

2013-01-15

The extinct p-process nuclide {sup 146}Sm (t{sub 1/2} = 103 {+-} 5 Myr) is known to have been present in the Early-Solar System and has been proposed as an astrophysical chronometer. {sup 146}Sm is also intensely used to date meteorite and planetary differentiation processes, enhancing the importance of an accurate knowledge of the {sup 146}Sm half-life. We are engaged in a new determination of the {sup 146}Sm half-life in which the {sup 146}Sm/{sup 147}Sm atom ratio is determined by accelerator mass spectrometry at the ATLAS facility of Argonne National Laboratory. In order to reduce systematic errors in the AMS determination of the {sup 146}Sm/{sup 147}Sm ratios (in the range of 10{sup -7}-10{sup -9}), {sup 146}Sm and {sup 147}Sm ions were alternately counted in the same detector in the focal plane of a gas-filled magnet, respectively in continuous-wave and attenuated mode. Quantitative attenuation is obtained with the 12 MHz pulsed and ns-bunched ATLAS beam by chopping beam pulses with an RF sweeper in a ratio (digitally determined) down to 1:10{sup 6}. The experiments and preliminary results are discussed.

Spin-glass-like behaviour in IrSr2RECu2O8 (RE=Sm and Eu)

International Nuclear Information System (INIS)

Santos-Garcia, A.J. dos; Duijn, J. van; Alario-Franco, M.A.

2008-01-01

We report the results of magnetic and specific heat measurements on the 1212-type compounds IrSr 2 RECu 2 O 8 with RE=Sm and Eu, prepared by high-pressure and high-temperature synthesis. The magnetic susceptibility of these compounds shows a large difference in the temperature dependence of the magnetization measured under zero-field-cooled and field-cooled conditions below 87 and 71 K, respectively, and upon further cooling below ∼10 K substantial maxima are observed too. Further AC susceptibility measurements support a glassy behaviour in lower magnetic transitions whereas the specific heat measurements do not show the typical long-range ordering commonly displayed in ferro, ferri or antiferromagnetic transitions. Hysteresis loops suggest the presence of magnetic clusters in the otherwise paramagnetic zone, indicating that these compounds probably display a reentrant spin-glass transition. Results are presented and discussed. - Graphical abstract: IrSr 2 RECu 2 O 8 with RE=Sm and Eu were prepared by high-pressure and high-temperature synthesis. Both samples adopt a M-1212-type perovskite structure and a microdomain texturing of the long c-axis is observed by TEM. A very interesting magnetic behaviour is observed in these materials. A 'cluster by cluster freezing' model is proposed, instead of the classical individual spin freezing one to explain the spin-glass-like behaviour that seems to coexist with weak ferromagnetism in both compounds

Standard enthalpy of formation of Sm6UO12 acid dissolution calorimetry

International Nuclear Information System (INIS)

Venkata Krishnan, R.; Jogeswararao, G.; Ananthasivan, K.

2016-01-01

The standard molar enthalpies of formation of Δ f (298 K) of Sm 6 UO 12 have been determined by using an indigenously developed isoperibol acid solution calorimeter. The water equivalent of this calorimeter was determined by electrical calibration. The accuracy of measurement were determined by using standard materials KCl and tris(hydroxyl methyl) amino-methane (TRIS) and was found to be within ±2%. The enthalpies of solution at 298 K of Sm 2 O 3 , UO 3 and Sm 6 UO 12 were measured by using this calorimeter. From these experimental results the enthalpies of formation of Sm 6 UO 12 at 298 K were computed by using Hess's law of summation. (author)

Tune color of single-phase LiGd(MoO4)2-X(WO4)X: Sm3+, Tb3+ via adjusting the proportion of matrix and energy transfer to create white-light phosphor

Science.gov (United States)

Wu, Hongyue; Yang, Junfeng; Wang, Xiaoxue; Gan, Shucai; Li, Linlin

2018-03-01

A series of LiGd(MO4)2: Sm3+, Tb3+ (M = Mo, W) phosphors was prepared by a conventional solid state reaction method. Powder X-Ray diffraction (XRD) analysis reveals that the compounds are of the same structure type. Their luminescent properties have been studied. The optimal doping concentrations are 8% for Sm3+ and 18% for Tb3+ in the LiGd(MoO4)2 host. Sm3+ and Tb3+ have different sensitivity to the Mo/W ratio. For LiGd(MoO4)2-X(WO4)X: Sm3+ (X = 0, 0.4, 0.8, 1.2, 1.6, 2.0), the strongest emission intensity is 1.766 times than that of the weakest, while 171 times for LiGd(MoO4)2-X(WO4)X: Tb3+. The experimental results show that Mo/W ratio strong influences on the properties of LiGd(MoO4)2-X(WO4)X: Tb3+. With the increasing of WO42- groups concentration, the shape of characteristic excitation peaks of Tb3+ is almost the same and the excitation intensity gradually increase. Moreover, the energy transfer from Tb3+ to Sm3+ has been realized in the co-doped phosphors. The experimental analysis and theoretical calculations reveal that the quadrupole-quadrupole interaction is the dominant mechanism for the Tb3+→Sm3+ energy transfer. Therefore, luminous intensity can be adjusted by different sensitivities to matrix composition and energy transfer from Tb3+→Sm3+. By this tuning color method, white-light-emitting phosphor has been prepared. The excitation wavelength is 378 nm, and this indicates that the white-light-emitting phosphor could be pumped by near-UV light.

Metal complexes with 1,5- and 1,8-dihydroxy-9,10-anthraquinones: electronic absorption spectra and structure of ligands

International Nuclear Information System (INIS)

Fajn, V.Ya.; Zajtsev, B.E.; Ryabov, M.A.

2004-01-01

By spectrophotometric, quantum-chemical, and correlation methods it is determined that in complexes of metals (Nd, Pr, Sm, Th, UO 2 2+ , V) with 1,5-dihydroxy-9,10-anthraquinone ligand could be in 7 excited states differing not only by ionization degree but primary contribution of tautomeric 9,10-, 1,10-, and 1,5-anthraquinoid structures. On all known complexes with 1,8-dihydroxy-9,10-anthraquinone containing once ionized ligand the last has 1,10-anthraquinoid structure; for complexes containing twofold ionized ligand 9,10-anthraquinoid structure of ligand is the most characteristic. Known complexes are classified in accordance with structure of ligands [ru

Tripodal (N-alkylated) CMP(O) and malonamide ligands: synthesis, extraction of metal ions, and potentiometric studies

International Nuclear Information System (INIS)

Janczewski, D.; Reinhoudt, D.N.; Verboom, W.; Malinowska, E.; Pietrzak, M.; Hill, C.; Allignol, C.

2007-01-01

Tripodal ligands build on the C-pivot (9b-e, 13b-d, and 17a-d) and tri-alkyl-benzene platforms (10a,b, 11, 12, 14a,b, and 18a,b) bearing (N-alkylated) carbamoyl-methyl-phosphine oxide (CMPO), carbamoyl-methyl-phosphonate (CMP), and malonamide moieties were synthesized. Extraction studies with Am 3+ and Eu 3+ show that in general there is a positive influence of the N-alkyl substituents in C-pivot CMP(O) ligands on the D(distribution) coefficients. The tri-alkyl-benzene CMPO ligands 10a,b, 11, and 12 have considerably larger D coefficients than the corresponding C-pivot analogues 9a-e, although hardly having any selectivity, while N-alkylation gives rise to smaller D coefficients. Although less effective the extraction behavior of the C-pivot CMP analogues 13b-d shows more or less the same trend as the corresponding CMPO ligands 9b-e upon substitution of the carboxamide N-atom with different alkyl chains. The different malonamide ligands 17a-d and 18a,b are bad extractants, while N-alkylation makes them even worse. Potentiometric studies of CMP(O) and malonamide ligands in polymeric membranes on Pb 2+ , Cu 2+ , Ca 2+ , Mg 2+ , Na + , and K + salts revealed that N-alkyl substituents increase the stability constants of ion-ionophore complexes compared to unsubstituted ligands. In polymeric membrane electrodes the ligands induce a selectivity pattern that differs significantly from the so-called Hofmeister series, giving the highest selectivity coefficients for UO 2 2+ among all examined cations (Pb 2+ , Cu 2+ , Ca 2+ , Mg 2+ , Na + , K + ). (authors)

GaAs structures with InAs and As quantum dots produced in a single molecular beam epitaxy process

International Nuclear Information System (INIS)

Nevedomskii, V. N.; Bert, N. A.; Chaldyshev, V. V.; Preobrazhenskii, V. V.; Putyato, M. A.; Semyagin, B. R.

2009-01-01

Epitaxial GaAs layers containing InAs semiconductor quantum dots and As metal quantum dots are grown by molecular beam epitaxy. The InAs quantum dots are formed by the Stranskii-Krastanow mechanism, whereas the As quantum dots are self-assembled in the GaAs layer grown at low temperature with a large As excess. The microstructure of the samples is studied by transmission electron microscopy. It is established that the As metal quantum dots formed in the immediate vicinity of the InAs semiconductor quantum dots are larger in size than the As quantum dots formed far from the InAs quantum dots. This is apparently due to the effect of strain fields of the InAs quantum dots upon the self-assembling of As quantum dots. Another phenomenon apparently associated with local strains around the InAs quantum dots is the formation of V-like defects (stacking faults) during the overgrowth of the InAs quantum dots with the GaAs layer by low-temperature molecular beam epitaxy. Such defects have a profound effect on the self-assembling of As quantum dots. Specifically, on high-temperature annealing needed for the formation of large-sized As quantum dots by Ostwald ripening, the V-like defects bring about the dissolution of the As quantum dots in the vicinity of the defects. In this case, excess arsenic most probably diffuses towards the open surface of the sample via the channels of accelerated diffusion in the planes of stacking faults.

Oxygen Atom Exchange between H2O and Non-Heme Oxoiron(IV) Complexes: Ligand Dependence and Mechanism.

Science.gov (United States)

Puri, Mayank; Company, Anna; Sabenya, Gerard; Costas, Miquel; Que, Lawrence

2016-06-20

Detailed studies of oxygen atom exchange (OAE) between H2(18)O and synthetic non-heme oxoiron(IV) complexes supported by tetradentate and pentadentate ligands provide evidence that they proceed by a common mechanism but within two different kinetic regimes, with OAE rates that span 2 orders of magnitude. The first kinetic regime involves initial reversible water association to the Fe(IV) complex, which is evidenced by OAE rates that are linearly dependent on [H2(18)O] and H2O/D2O KIEs of 1.6, while the second kinetic regime involves a subsequent rate determining proton-transfer step between the bound aqua and oxo ligands that is associated with saturation behavior with [H2(18)O] and much larger H2O/D2O KIEs of 5-6. [Fe(IV)(O)(TMC)(MeCN)](2+) (1) and [Fe(IV)(O)(MePy2TACN)](2+) (9) are examples of complexes that exhibit kinetic behavior in the first regime, while [Fe(IV)(O)(N4Py)](2+) (3), [Fe(IV)(O)(BnTPEN)](2+) (4), [Fe(IV)(O)(1Py-BnTPEN)](2+) (5), [Fe(IV)(O)(3Py-BnTPEN)](2+) (6), and [Fe(IV)(O)(Me2Py2TACN)](2+) (8) represent complexes that fall in the second kinetic regime. Interestingly, [Fe(IV)(O)(PyTACN)(MeCN)](2+) (7) exhibits a linear [H2(18)O] dependence below 0.6 M and saturation above 0.6 M. Analysis of the temperature dependence of the OAE rates shows that most of these complexes exhibit large and negative activation entropies, consistent with the proposed mechanism. One exception is complex 9, which has a near-zero activation entropy and is proposed to undergo ligand-arm dissociation during the RDS to accommodate H2(18)O binding. These results show that the observed OAE kinetic behavior is highly dependent on the nature of the supporting ligand and are of relevance to studies of non-heme oxoiron(IV) complexes in water or acetonitrile/water mixtures for applications in photocatalysis and water oxidation chemistry.

24/7 SM slavery.

Science.gov (United States)

Dancer, Peter L; Kleinplatz, Peggy J; Moser, Charles

2006-01-01

This study describes the nature of 24/7 SM slavery as practiced within the SM (sadomasochistic) community. These SM participants, who attempt to live full-time in owner-slave roles, represent a small proportion of those with SM interests. SM slaves have not been studied systematically to determine if and how they differ from other SM practitioners. An online questionnaire was used to obtain responses from individuals who self-identified as slaves. A total of 146 respondents participated, 53% female and 47% male, ranging in age from 18 to 72. We explored the depth of their relationships, how well they approximated "slavery," and how their relationships were structured to maintain distinct roles. Data showed that in long-term SM slave relationships, a power differential exists which extends beyond time-limited SM or sexual interactions. Owners and slaves often use common, daily life experiences or situations, such as the completion of household chores, money management, and morning or evening routines, to distinguish and maintain their respective roles. In addition, contrary to the perception of total submission, results revealed that slaves exercise free will when it is in their best interests to do so. These relationships were long-lasting and satisfying to the respondents.

On the evolution of InAs thin films grown by molecular beam epitaxy on the GaAs(001) surface

International Nuclear Information System (INIS)

Grabowski, Jan

2010-01-01

Semiconductor nanostructures are currently of high interest for a wide variety of electronic and optoelectronic applications. A large number of devices, in particular for the optical data transmission in the long-wavelength range, essential in modern communication, are based on InAs/GaAs quantum dot (QD) structures. Though the properties of the InAs/GaAs QDs have been extensively studied, only little is known about the formation and structure of the wetting layer (WL) yet. In the present work, the pathway of the InAs WL evolution is studied in detail. For this purpose, InAs thin films in the range of one monolayer (ML) are deposited on the GaAs(001) surface by molecular beam epitaxy (MBE) and studied by reflection high energy electron diffraction (RHEED) and in particular by scanning tunneling microscopy (STM). The InAs thin films are grown in both typical growth regimes, on the GaAs-c(4 x 4) and the GaAs-β2(2 x 4) reconstructed surface, in a variety of thicknesses starting from submonolayers with 0.09 ML of InAs up to 1.65 ML of InAs exceeding the critical thickness for QD growth. In principle, three growth stages are found. At low InAs coverages, the indium adsorbs in agglomerations of typically eight In atoms at energetically preferable surface sites. In the STM images, the signatures of these In agglomerations appear with a clear bright contrast. A structural model for the initial formation of these signatures is presented, and its electronic and strain related properties are discussed. At an InAs coverage of about 0.67ML the initial surface transforms into a (4 x 3) reconstructed In 2/3 Ga 1/3 As ML and the detailed structure and strain properties of this surface are unraveled. On top of the InGaAs ML further deposited InAs forms a second layer, characterized by a typical zig-zag alignment of (2 x 4) reconstructed unit cells, with an alternating α2/α2-m configuration. In contrast to the previous surface reconstructions, where structural strain is

On the evolution of InAs thin films grown by molecular beam epitaxy on the GaAs(001) surface

Energy Technology Data Exchange (ETDEWEB)

Grabowski, Jan

2010-12-14

Semiconductor nanostructures are currently of high interest for a wide variety of electronic and optoelectronic applications. A large number of devices, in particular for the optical data transmission in the long-wavelength range, essential in modern communication, are based on InAs/GaAs quantum dot (QD) structures. Though the properties of the InAs/GaAs QDs have been extensively studied, only little is known about the formation and structure of the wetting layer (WL) yet. In the present work, the pathway of the InAs WL evolution is studied in detail. For this purpose, InAs thin films in the range of one monolayer (ML) are deposited on the GaAs(001) surface by molecular beam epitaxy (MBE) and studied by reflection high energy electron diffraction (RHEED) and in particular by scanning tunneling microscopy (STM). The InAs thin films are grown in both typical growth regimes, on the GaAs-c(4 x 4) and the GaAs-{beta}2(2 x 4) reconstructed surface, in a variety of thicknesses starting from submonolayers with 0.09 ML of InAs up to 1.65 ML of InAs exceeding the critical thickness for QD growth. In principle, three growth stages are found. At low InAs coverages, the indium adsorbs in agglomerations of typically eight In atoms at energetically preferable surface sites. In the STM images, the signatures of these In agglomerations appear with a clear bright contrast. A structural model for the initial formation of these signatures is presented, and its electronic and strain related properties are discussed. At an InAs coverage of about 0.67ML the initial surface transforms into a (4 x 3) reconstructed In{sub 2/3}Ga{sub 1/3}As ML and the detailed structure and strain properties of this surface are unraveled. On top of the InGaAs ML further deposited InAs forms a second layer, characterized by a typical zig-zag alignment of (2 x 4) reconstructed unit cells, with an alternating {alpha}2/{alpha}2-m configuration. In contrast to the previous surface reconstructions, where

Alloy formation during InAs nanowire growth on GaAs(111)

Energy Technology Data Exchange (ETDEWEB)

Davydok, Anton; Saqib, Muhammad; Biermanns, Andreas; Pietsch, Ullrich [Festkoerperphysik, Universitaet Siegen (Germany); Rieger, Torsten; Grap, Thomas; Lepsa, Mihail [Peter Gruenberg Institut 9, Forschungszentrum Juelich (Germany); JARA - Fundamentals of Future Information Technology (Germany)

2012-07-01

The growth of semiconductor nanowires has attracted significant interest in recent years due to the possible fabrication of novel semiconductor devices for future electronic and opto-electronic applications. A possible way to obtain nanowires is the growth in molecular beam epitaxy on the (111)B oriented surface of the desired substrate, covered by a thin oxide layer. A crucial parameter in this method is the initial thickness of the oxide layer, often determined by an etching procedure. In this contribution, we report on the structural investigation of InAs nanowires grown on GaAs substrates covered by different oxide-layers using X-ray diffraction. In this contribution, we report on the structural investigation of InAs nanowires grown via an In droplet on GaAs substrates covered by different oxide layers using X-ray diffraction. Using a combination of symmetric and asymmetric X-ray diffraction, we observe that for growth on a defective oxide layer, alloy formation takes place and a large amount of InGaAs is formed, whereas for growth on an initially smooth oxide layer, only pure InAs is formed.

Distinguishing a SM-like MSSM Higgs boson from SM Higgs boson at muon collider

International Nuclear Information System (INIS)

Singhal, Jai Kumar; Singh, Sardar; Nagawat, Ashok K.

2007-01-01

We explore the possibility of distinguishing the SM-like MSSM Higgs boson from the SM Higgs boson via Higgs boson pair production at future muon collider. We study the behavior of the production cross-section in SM and MSSM with Higgs boson mass for various MSSM parameters tanβ and m A . We observe that at fixed CM energy, in the SM, the total cross-section increases with the increase in Higgs boson mass whereas this trend is reversed for the MSSM. The changes that occur for the MSSM in comparison to the SM predictions are quantified in terms of the relative percentage deviation in cross-section. The observed deviations in cross-section for different choices of Higgs boson masses suggest that the measurements of the cross-section could possibly distinguish the SM-like MSSM Higgs boson from the SM Higgs boson. (author)

The Material Supply Adjustment Process in RAMF-SM, Step 2

Science.gov (United States)

2016-06-01

I N S T I T U T E F O R D E F E N S E A N A L Y S E S The Material Supply Adjustment Process in RAMF-SM, Step 2 Eleanor L. Schwartz James S...5564 The Material Supply Adjustment Process in RAMF-SM, Step 2 Eleanor L. Schwartz James S. Thomason, Project Leader This page is intentionally blank...9 1. Inputs and Outputs .......................................................................................10 2. Specific Steps of the PEAP

Angle Integrated Photoemission Study of SmO0.85F0.15FeAs

International Nuclear Information System (INIS)

Hong-Wei, Ou; Jia-Feng, Zhao; Yan, Zhang; Da-Wei, Shen; Bo, Zhou; Le-Xian, Yang; Cheng, He; Fei, Chen; Min, Xu; Yan, Chen; Dong-Lai, Feng; Tao, Wu; Xian-Hui, Chen

2008-01-01

The electronic structure of the new superconductor SmO 1-x F x FeAs (x = 0.15) is studied by angle-integrated photoemission spectroscopy. Our data show a sharp feature very close to the Fermi energy, and a relative flat distribution of the density of states between 0.5eV and 3eV binding energy, which agrees well with the band structure calculations considering an antiferromagnetic ground state. No noticeable gap opening is observed at 12K below the superconducting transition temperature, indicating the existence of large ungapped regions in the Brillouin zone. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Formation of SmFe{sub 5}(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

Energy Technology Data Exchange (ETDEWEB)

Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: yabuhara@futamoto.elect.chuo-u.ac.j [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

2010-01-01

SmFe{sub 5}(0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe{sub 5} structure forming an alloy compound of Sm(Fe,Cu){sub 5}. The Sm(Fe,Cu){sub 5} film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

Tripodal (N-alkylated) CMP(O) and malonamide ligands: synthesis, extraction of metal ions, and potentiometric studies

Energy Technology Data Exchange (ETDEWEB)

Janczewski, D.; Reinhoudt, D.N.; Verboom, W. [Twente Univ., Lab. of Supramolecular Chemistry and Technology, Mesa Research Institute for Nanotechnology, Enschede (Netherlands); Malinowska, E.; Pietrzak, M. [Warsaw Univ. of Technology, Dept. of Analytical Chemistry, Faculty of Chemistry (Poland); Hill, C.; Allignol, C. [CEA Valrho, 30 - Marcoule (France)

2007-01-15

Tripodal ligands build on the C-pivot (9b-e, 13b-d, and 17a-d) and tri-alkyl-benzene platforms (10a,b, 11, 12, 14a,b, and 18a,b) bearing (N-alkylated) carbamoyl-methyl-phosphine oxide (CMPO), carbamoyl-methyl-phosphonate (CMP), and malonamide moieties were synthesized. Extraction studies with Am{sup 3+} and Eu{sup 3+} show that in general there is a positive influence of the N-alkyl substituents in C-pivot CMP(O) ligands on the D(distribution) coefficients. The tri-alkyl-benzene CMPO ligands 10a,b, 11, and 12 have considerably larger D coefficients than the corresponding C-pivot analogues 9a-e, although hardly having any selectivity, while N-alkylation gives rise to smaller D coefficients. Although less effective the extraction behavior of the C-pivot CMP analogues 13b-d shows more or less the same trend as the corresponding CMPO ligands 9b-e upon substitution of the carboxamide N-atom with different alkyl chains. The different malonamide ligands 17a-d and 18a,b are bad extractants, while N-alkylation makes them even worse. Potentiometric studies of CMP(O) and malonamide ligands in polymeric membranes on Pb{sup 2+}, Cu{sup 2+}, Ca{sup 2+}, Mg{sup 2+}, Na{sup +}, and K{sup +} salts revealed that N-alkyl substituents increase the stability constants of ion-ionophore complexes compared to unsubstituted ligands. In polymeric membrane electrodes the ligands induce a selectivity pattern that differs significantly from the so-called Hofmeister series, giving the highest selectivity coefficients for UO{sub 2}{sup 2+} among all examined cations (Pb{sup 2+}, Cu{sup 2+}, Ca{sup 2+}, Mg{sup 2+}, Na{sup +}, K{sup +}). (authors)

Molecular electrophosphorescence in (Sm, Gd)-{beta}-diketonate complex blend for OLED applications

Energy Technology Data Exchange (ETDEWEB)

Reyes, R., E-mail: fisicaplic@hotmail.com [Facultad de Ingenieria Quimica y Textil, Universidad Nacional de Ingenieria, UNI, Av. Tupac Amaru 210, Lima 31, Peru (Peru); Cremona, M. [DIMAT - Divisao de Metrologia de Materiais, Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial, INMETRO, Duque de Caxias, RJ (Brazil); Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, PUC-Rio, C.P. 38071, Rio de Janeiro, RJ, CEP 22453-970 (Brazil); Teotonio, E.E.S. [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, UFPB, C.P. 5093, Joao Pessoa, PB, CEP 5805-970 (Brazil); Brito, H.F. [Instituto de Quimica, Universidade de Sao Paulo, USP, C.P. 26077, Sao Paulo, SP, CEP 05599-970 (Brazil); Malta, O.L. [Departamento de Quimica Fundamental, CCEN, Universidade Federal de Pernambuco, Cidade Universitaria, Recife, PE, CEP 50670-901 (Brazil)

2013-02-15

In this work the preparation and characterization of the triple-layer organic light-emitting diode (OLED) using a mixture of the samarium and gadolinium {beta}-diketonate complexes [Sm{sub 0.5}Gd{sub 0.5}(TTA){sub 3}(TPPO){sub 2}] as emitting layer is reported. The OLED's devices contain 1-(3-methylphenyl)-1,2,3,4-tetrahydroquinoline-6-carboxyaldehyde-1, 1'-diphenylhydrazone (MTCD) as hole-transporting layer and tris(8-hydroxyquinoline aluminum) (Alq{sub 3}) as electron transporting layer. The electroluminescence spectrum present emission narrow bands from the {sup 4}G{sub 5/2}{yields}{sup 6}H{sub J} transitions (where J=5/2, 7/2 and 9/2) characteristic of the Sm{sup 3+} ion. These sharp lines are overlapped with a broad band attributed to the electrophosphorescence from the T{sub 1}{yields}S{sub 0} transition in the ligand TTA. The intramolecular energy transfer is discussed and applied on the change of the emission color of the organic LEDs at different bias voltages. - Highlights: Black-Right-Pointing-Pointer Samarium and gadolinium complexes. Black-Right-Pointing-Pointer OLED with complex blend (Sm,Gd). Black-Right-Pointing-Pointer Electrophosphorescence emission detection. Black-Right-Pointing-Pointer Application in OLED changing the color emission.

Structural and electrical properties of Sm{sup 3+} substituted PZT ceramics

Energy Technology Data Exchange (ETDEWEB)

Pandey, S.K. [Solid State Physics Laboratory, Timarpur, Delhi 110 054 (India)], E-mail: 628@ssplnet.org; Thakur, O.P.; Bhattacharya, D.K. [Solid State Physics Laboratory, Timarpur, Delhi 110 054 (India); Prakash, Chandra [DRDO Bhawan, DHQ, New Delhi 110 011 (India); Chatterjee, Ratnamala [Department of Physics, Indian Institute of Technology, New Delhi 110 016 (India)

2009-01-22

Samarium modified lead zirconate titanate (PSZT: Pb{sub 1-x}Sm{sub x}(Zr{sub 0.65}Ti{sub 0.35})O{sub 3}: x = 0, 0.02, 0.04, 0.06) ceramics were synthesized by solid state ceramic route. XRD shows single-phase formation with rhombohedral structure up to x = 0.04. With Sm-substitution, the grain size first increases up to x = 0.02 and then decreases. A metal/ferroelectric/metal (MFM) structure was made by depositing gold electrode on the flat surfaces for electrical measurements. All samples show normal ferroelectric behaviour, however, a squareness of P-E loop (polarization vs. electric field) was observed to increase with Sm content. Higher electromechanical coupling coefficients (K{sub p} and K{sub t}) have been achieved for the PZT with 6 mol% Sm substitution and having fine grain size.

Formation of the InAs-, InSb-, GaAs-, and GaSb-polished surface

Science.gov (United States)

Levchenko, Iryna; Tomashyk, Vasyl; Stratiychuk, Iryna; Malanych, Galyna; Korchovyi, Andrii; Kryvyi, Serhii; Kolomys, Oleksandr

2018-04-01

The features of the InAs, InSb, GaAs, and GaSb ultra-smooth surface have been investigated using chemical-mechanical polishing with the (NH4)2Cr2O7-HBr-CH2(OH)CH2(OH)-etching solutions. The etching rate of the semiconductors has been measured as a function of the solution saturation by organic solvent (ethylene glycol). It was found that mechanical effect significantly increases the etching rate from 1.5 to 57 µm/min, and the increase of the organic solvent concentration promotes the decrease of the damaged layer-removing rate. According to AFM, RS, HRXRD results, the treatment with the (NH4)2Cr2O7-HBr-ethylene glycol solutions produces the clean surface of the nanosize level (R a < 0.5 nm).

Competitive emissions of InAs (QDs)/GaInAsP/InP grown by GSMBE

Energy Technology Data Exchange (ETDEWEB)

Yuan, Xiaowen [Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Wuhan (China); Chinese Academy of Sciences, National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Shanghai (China); Wang, Qi; Li, Senlin; Chen, C.Q. [Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Wuhan (China); Sun, Liaoxin; Luo, X.D.; Zhang, Bo [Chinese Academy of Sciences, National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Shanghai (China)

2015-04-01

In this letter, the optical properties of InAs (QDs)/GaInAsP on InP substrate grown by gas source molecular beam epitaxy are investigated. By measuring and analyzing the photoluminescence spectra of InAs (QDs)/GaInAsP/InP at different temperatures and excitation powers, the origin of each emission is verified. And it is found that, with the temperature increasing, the emission intensity of GaInAsP wetting layers decreases firstly (T < 150 K) and then increases from 160 K to room temperature. By analyzing the experimental results of three samples with different QDs' sizes, a competitive emission between InAs QDs and GaInAsP wetting layers is confirmed. (orig.)

Secondary ligand-directed assembly of Co(II) coordination polymers based on a pyridine carboxylate ligand

International Nuclear Information System (INIS)

Cao, Ke-Li; Zhang, Yi-Ping; Cai, Yi-Ni; Xu, Xiao-Wei; Feng, Yun-Long

2014-01-01

To investigate the influence of hydrogen bonds and secondary ligands on the structures and properties of the resulting frameworks, five new Co(II) compounds have been synthesized by the reactions of Co(II) salts and 3,5-bis(pyridin-4-ylmethoxy)benzoic acid (HL) with four rationally selected dicarboxylic acid ligands. Without secondary ligand, we got one compound [CoL 2 (H 2 O) 2 ] n ·2nH 2 O (1), which possesses a 1D chain structure. In the presence of ancillary ligands, namely, 1,3-adamantanedicarboxylic acid (H 2 adbc), terephthalic acid (H 2 tpa), thiophene-2,5-dicarboxylic acid (H 2 tdc) and 1,4-benzenedithioacetic acid (H 2 bdtc), four 3D structures [Co 2 L 2 (adbc)] n ·nH 2 O (2), [Co 2 L 2 (tpa)] n (3), [Co 2 L 2 (tdc)] n (4), [Co 2 L 2 (bdtc)(H 2 O)] n (5) were obtained, respectively. It can be observed from the architectures of 1–5 that hydrogen bonds and secondary ligands both have great effects on the spatial connective fashions, resulting in the formation of various dimensional compounds. The XRPD, TGA data of title polymers and the magnetic properties for 2 and 5 have also been investigated. - Graphical abstract: The structural differences show that the ancillary ligands have great effects on the spatial connective fashions, resulting in the formation of various dimensional compounds. - Highlights: • Five new Co(II) coordination polymers have been synthesized by solvothermal reactions based on 3,5-bis(pyridin-4-ylmethoxy)benzoic acid (HL). • The long-flexible ligand (HL) is a good candidate to produce interpenetrating architectures. • The secondary dicarboxylic acid ligands play important roles in the spatial connective fashions and the formation of various dimensional compounds. • The magnetism studies show that both 2 and 5 exhibit antiferromagnetic interactions

Elastic properties and electron transport in InAs nanowires

Energy Technology Data Exchange (ETDEWEB)

Migunov, Vadim

2013-02-22

The electron transport and elastic properties of InAs nanowires grown by chemical vapor deposition on InAs (001) substrate were studied experimentally, in-situ in a transmission electron microscope (TEM). A TEM holder allowing the measurement of a nanoforce while simultaneous imaging nanowire bending was used. Diffraction images from local areas of the wire were recorded to correlate elastic properties with the atomic structure of the nanowires. Another TEM holder allowing the application of electrical bias between the nanowire and an apex of a metallic needle while simultaneous imaging the nanowire in TEM or performing electron holography was used to detect mechanical vibrations in mechanical study or holographical observation of the nanowire inner potential in the electron transport studies. The combination of the scanning probe methods with TEM allows to correlate the measured electric and elastic properties of the nanowires with direct identification of their atomic structure. It was found that the nanowires have different atomic structures and different stacking fault defect densities that impacts critically on the elastic properties and electric transport. The unique methods, that were applied in this work, allowed to obtain dependencies of resistivity and Young's modulus of left angle 111 right angle -oriented InAs nanowires on defect density and diameter. It was found that the higher is the defect density the higher are the resistivity and the Young's modulus. Regarding the resistivity, it was deduced that the stacking faults increase the scattering of the electrons in the nanowire. These findings are consistent with the literature, however, the effect described by the other groups is not so pronounced. This difference can be attributed to the significant incompleteness of the physical models used for the data analysis. Regarding the elastic modulus, there are several mechanisms affecting the elasticity of the nanowires discussed in the thesis. It

Time evolution studies of laser induced chemical changes in InAs nanowire using Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Pal, Suparna; Aggarwal, R.; Kumari Gupta, Vandna; Ingale, Alka [Laser Physics Application Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India)

2014-07-07

We report the study of time evolution of chemical changes on the surface of an InAs nanowire (NW) on laser irradiation in different power density regime, using Raman spectroscopy for a time span of 8–16 min. Mixture of metastable oxides like InAsO{sub 4,} As{sub 2}O{sub 3} are formed upon oxidation, which are reflected as sharp Raman peaks at ∼240–254 and 180–200 cm{sup −1}. Evidence of removal of arsenic layer by layer is also observed at higher power density. Position controlled laser induced chemical modification on a nanometer scale, without changing the core of the NW, can be useful for NW based device fabrication.

Effect of Co substitution on magnetic ground state in Sm0.5Ca0.5MnO3

International Nuclear Information System (INIS)

Xu, Xiaolong; Li, Yu; Hou, Feifei; Cheng, Qian; Su, Runzhou

2015-01-01

Highlights: • Polycrystalline Sm 0.5 Ca 0.5 Mn 1−x Co x O 3 were prepared by standard solid-state reaction. • The orthorhombic deformation and normalized slope were calculated for each sample. • Critical slowing down model and dynamic scaling equation are applied in some samples. • Canted antiferromagnetic state via spin glass state, changes to ferrimagnetic state. - Abstract: The effect of cobalt doping on the structural and magnetic properties of polycrystalline Sm 0.5 Ca 0.5 Mn 1−x Co x O 3 (0 ⩽ x ⩽ 0.20) has been studied. Powder X-ray diffraction (XRD), dc magnetization and ac susceptibility measurements have been performed. The orthorhombic deformation caused by the Jahn–Teller (JT) effect can be counterbalanced by Co 3+ doping. Meanwhile, antiferromagnetic (AFM), spin glass (SG) and phase separation (PS) ferrimagnetic states appear, successively, with the increase of x. The critical slowing down model and the dynamic scaling equation were applied in some samples. The existence of two distinct length scales for SG and finite FM (ferromagnetic) order is the source of the progressive deviation which exists in the dynamic scaling fitting for x = 0.05. Moreover, the small peaks at ∼8 K in χ″(T) curves are believed to be induced by the canted moments of Mn ions as observed in Nd 2/3 Ca 1/3 MnO 3

Investigations on optical properties of Sm{sup 3+} ion doped boro-phosphate glasses

Energy Technology Data Exchange (ETDEWEB)

Vijayakumar, R.; Suthanthirakumar, P.; Karthikeyan, P.; Marimuthu, K., E-mail: mari-ram2000@yahoo.com [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram – 624302 (India)

2015-06-24

The Sm{sup 3+} doped Boro-phosphate glasses with the chemical composition 60H{sub 3}BO{sub 3}+20Li{sub 2}CO{sub 3}+10ZnO+(10−x) H{sub 6}NO{sub 4}P+xSm{sub 2}O{sub 3} (where x= 0.1, 0.5, 1 and 2 in wt%) have been prepared by melt quenching technique. The prepared glasses were characterized through optical absorption and luminescence spectral measurements. The band gap energies corresponding to the direct and indirect allowed transitions and the Urbach’s energy values were estimated from the absorption spectra. Judd-Ofelt intensity parameters have been derived to predict the radiative properties of the various emission transitions. In order to identify the emission color of the prepared glasses, the emission intensities were analyzed using CIE 1931 color chromaticity diagram. The energy transfer process takes place between Sm{sup 3+}−Sm{sup 3+} ions through cross-relaxation mechanism have also been investigated and the results were discussed and reported.

Calorimetric investigation on the Pb-Sm and Sn-Sm alloys

International Nuclear Information System (INIS)

Berrada, A.-E.-A.; Claire, Y.; Chafik el Idrissi, M.; Castanet, R.

1997-01-01

The integral enthalpy of formation of the Sm-Pb and Sm-Sn melts at 1203 K, h f , was determined by direct reaction calorimetry (drop method) in the Pb and Sn rich sides with the help of a high-temperature Tian-Calvet calorimeter. The results can be fitted respectively with reference to the mole fraction of samarium, x, as follows: f /kJmol -1 =x(1-x)(-109.8 -372.0.7x) with 0 Sm f /kJmol -1 =x(1- x)(-277.0+105.4x) with 0 Sm -1 respectively. Such negative values suggest the existence of a strong short-range order in the liquid state. The stoichiometry and the thermal stability of these associations needs additional thermodynamic determinations concerning mainly the free enthalpy of formation. It will be determined by Knudsen-effusion combined with mass spetrometry in a further work. (orig.)

Ferroelectric, magnetic and structural studies of the Bi4LaSmFe2Ti3O18 multiferroic material

International Nuclear Information System (INIS)

Alarcón-Suesca, C.E.; Cardona-Vásquez, J.A.; Salcedo-Fontecha, J.P.; Vargas-Jiménez, A.; Landínez-Téllez, D.A.; Roa-Rojas, J.

2014-01-01

We report the synthesis and characterization of the new Bi 4 LaSmFe 2 Ti 3 O 18 ferroelectric ceramic. X-ray characterization reveals reflections for layered perovskite Aurivillius system. Rietveld analyses of the powder pattern shows that Bi 4 LaSmFe 2 Ti 3 O 18 crystallizes in orthorhombic structure, which corresponds to the space group F2/mm (#42), with lattice parameters a=5.4240(16) Ǻ, b=5.4078(23) Ǻ and c=50.2440(12) Ǻ. Scanning electron microscopy (SEM) reveals the formation of dense material with plate-like morphology. Electric polarization curves were measured by means of a radiant ferroelectric tester, at room temperature in bulk samples and exhibit an intrinsic ferroelectric response, even at low applied fields. Measurements of the magnetization as a function of temperature after Zero field cooling and field cooling were carried out by using a MPMS Quantum Design SQUID magnetometer. We found an effective magnetic moment of 7.95 µB, which is 95.8% in agreement with the expected value calculated from Hund's rules. Magnetization curves as the function of applied fields reveal an incipient hysteretic behavior at room temperature

Highly stable [mambf6-n(o/h2o)n(ligand)2(solvent)x]n metal organic frameworks

KAUST Repository

Eddaoudi, Mohamed; Adil, Karim; Belmabkhout, Youssef; Shekhah, Osama; Bhatt, Prashant M.; Cadiau, Amandine

2016-01-01

Provided herein are metal organic frameworks having high selectivity and stability in the present of gases and vapors including H2S, H2O, and CO2. Metal organic frameworks can comprise metal nodes and N-donor organic ligands. Further provided

Steric modulation of coordination number and reactivity in the synthesis of lanthanoid(III) formamidinates.

Science.gov (United States)

Cole, Marcus L; Deacon, Glen B; Forsyth, Craig M; Junk, Peter C; Konstas, Kristina; Wang, Jun

2007-01-01

Reactions of a range of the readily prepared and sterically tunable N,N'-bis(aryl)formamidines with lanthanoid metals and bis(pentafluorophenyl)mercury (Hg(C6F5)2) in THF have given an extensive series of tris(formamidinato)lanthanoid(III) complexes, [Ln(Form)3(thf)n], namely [La(o-TolForm)3(thf)2], [Er(o-TolForm)3(thf)], [La(XylForm)3(thf)], [Sm(XylForm)3], [Ln(MesForm)3] (Ln=La, Nd, Sm and Yb), [Ln(EtForm)3] (Ln=La, Nd, Sm, Ho and Yb), and [Ln(o-PhPhForm)3] (Ln=La, Nd, Sm and Er). [For an explanation of the N,N'-bis(aryl)formamidinate abbreviations used see Scheme 1.] Analogous attempts to prepare [Yb(o-TolForm)3] by this method invariably yielded [{Yb(o-TolForm)2(mu-OH)(thf)}2], but [Yb(o-TolForm)3] was isolated from a metathesis synthesis. X-ray crystal structures show exclusively N,N'-chelation of the Form ligands and a gradation in coordination number with Ln3+ size and with Form ligand bulk. The largest ligands, MesForm, EtForm and o-PhPhForm give solely homoleptic complexes, the first two being six-coordinate, the last having an eta1-pi-Ar--Ln interaction. Reaction of lanthanoid elements and Hg(C6F5)2 with the still bulkier DippFormH in THF resulted in C--F activation and formation of [Ln(DippForm)2F(thf)] (Ln=La, Ce, Nd, Sm and Tm) complexes, and o-HC6F4O(CH2)4DippForm in which the formamidine is functionalised by a ring-opened THF that has trapped tetrafluorobenzyne. Analogous reactions between Ln metals, Hg(o-HC6F4)2 and DippFormH yielded [Ln(DippForm)2F(thf)] (Ln=La, Sm and Nd) and 3,4,5-F3C6H2O(CH2)4DippForm. X-ray crystal structures of the heteroleptic fluorides show six-coordinate monomers with two chelating DippForm ligands and cisoid fluoride and THF ligands in a trigonal prismatic array. The organometallic species [Ln(DippForm)2(C[triple chemical bond]CPh)(thf)] (Ln=Nd or Sm) are obtained from reaction of Nd metal, bis(phenylethynyl)mercury (Hg(C[triple chemical bond]CPh)2) and DippFormH, and the oxidation of [Sm(DippForm)2(thf)2] with Hg

Sol-Gel Synthesis of La(0.6)Sr(0.4)CoO(3-x) and Sm(0.5)Sr(0.5)CoO(3-x) Cathode Nanopowders for Solid Oxide Fuel Cells

Science.gov (United States)

Bansal, Narottam P.; Wise, Brent

2011-01-01

Nanopowders of La(0.6)Sr(0.4)CoO(3-x) (LSC) and Sm(0.5)Sr(0.5)CoO(3-x) (SSC) compositions, which are being investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFC) with La(Sr)Ga(Mg)O(3-x) (LSGM) as the electrolyte, were synthesized by low-temperature sol-gel method using metal nitrates and citric acid. Thermal decomposition of the citrate gels was followed by simultaneous DSC/TGA methods. Development of phases in the gels, on heat treatments at various temperatures, was monitored by x-ray diffraction. Solgel powders calcined at 550 to 1000 C consisted of a number of phases. Single perovskite phase La(0.6)Sr(0.4)CoO(3-x) or Sm(0.5)Sr(0.5)CoO(3-x) powders were obtained at 1200 and 1300 C, respectively. Morphological analysis of the powders calcined at various temperatures was done by scanning electron microscopy. The average particle size of the powders was approx.15 nm after 700 C calcinations and slowly increased to 70 to 100 nm after heat treatments at 1300 to 1400 C.

Etching and oxidation of InAs in planar inductively coupled plasma

Energy Technology Data Exchange (ETDEWEB)

Dultsev, F.N., E-mail: fdultsev@thermo.isp.nsc.ru [Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, Novosibirsk 630090 (Russian Federation)

2009-10-15

The surface of InAs (1 1 1)A was investigated under plasmachemical etching in the gas mixture CH{sub 4}/H{sub 2}/Ar. Etching was performed using the RF (13.56 MHz) and ICP plasma with the power 30-150 and 50-300 W, respectively; gas pressure in the reactor was 3-10 mTorr. It was demonstrated that the composition of the subsurface layer less than 5 nm thick changes during plasmachemical etching. A method of deep etching of InAs involving ICP plasma and hydrocarbon based chemistry providing the conservation of the surface relief is proposed. Optimal conditions and the composition of the gas phase for plasmachemical etching ensuring acceptable etch rates were selected.

Etching and oxidation of InAs in planar inductively coupled plasma

Science.gov (United States)

Dultsev, F. N.; Kesler, V. G.

2009-10-01

The surface of InAs (1 1 1)A was investigated under plasmachemical etching in the gas mixture CH 4/H 2/Ar. Etching was performed using the RF (13.56 MHz) and ICP plasma with the power 30-150 and 50-300 W, respectively; gas pressure in the reactor was 3-10 mTorr. It was demonstrated that the composition of the subsurface layer less than 5 nm thick changes during plasmachemical etching. A method of deep etching of InAs involving ICP plasma and hydrocarbon based chemistry providing the conservation of the surface relief is proposed. Optimal conditions and the composition of the gas phase for plasmachemical etching ensuring acceptable etch rates were selected.

Etching and oxidation of InAs in planar inductively coupled plasma

International Nuclear Information System (INIS)

Dultsev, F.N.; Kesler, V.G.

2009-01-01

The surface of InAs (1 1 1)A was investigated under plasmachemical etching in the gas mixture CH 4 /H 2 /Ar. Etching was performed using the RF (13.56 MHz) and ICP plasma with the power 30-150 and 50-300 W, respectively; gas pressure in the reactor was 3-10 mTorr. It was demonstrated that the composition of the subsurface layer less than 5 nm thick changes during plasmachemical etching. A method of deep etching of InAs involving ICP plasma and hydrocarbon based chemistry providing the conservation of the surface relief is proposed. Optimal conditions and the composition of the gas phase for plasmachemical etching ensuring acceptable etch rates were selected.

Growth and electrical characterization of Zn-doped InAs and InAs{sub 1-x}Sb{sub x}

Energy Technology Data Exchange (ETDEWEB)

Venter, A., E-mail: andre.venter@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth (South Africa); Shamba, P.; Botha, L.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth (South Africa)

2009-06-01

The electrical properties of Zn doped InAs and InAsSb layers grown on semi-insulating GaAs by metal organic vapour phase epitaxy, using dimethyl zinc as the p-type dopant source, have been studied. The influence of dopant flow rate, V/III ratio and substrate orientation on the electrical properties of these InAs and InAs{sub 1-x}Sb{sub x} layers have been studied at a few appropriate growth temperatures. A promising group V source, tertiary butyl arsenic was used as an alternative to arsenic hydride in the case of InAs growth. The electrical properties of the InAs and InAs{sub 1-x}Sb{sub x} epitaxial layers were mainly studied by the Hall effect. However, surface accumulation in these materials results in deceptive Hall results being extracted. A two layer model (assuming the layer to consist of two parallel conducting paths viz. surface and bulk) has therefore been used to extract sensible transport properties. In addition, conventional Hall measurements ignores the high electron to hole mobility ratio in InAs and InAsSb leading to erroneous transport properties.

Sensing Responses Based on Transfer Characteristics of InAs Nanowire Field-Effect Transistors

Science.gov (United States)

Savelyev, Igor; Blumin, Marina; Wang, Shiliang; Ruda, Harry E.

2017-01-01

Nanowire-based field-effect transistors (FETs) have demonstrated considerable promise for a new generation of chemical and biological sensors. Indium arsenide (InAs), by virtue of its high electron mobility and intrinsic surface accumulation layer of electrons, holds properties beneficial for creating high performance sensors that can be used in applications such as point-of-care testing for patients diagnosed with chronic diseases. Here, we propose devices based on a parallel configuration of InAs nanowires and investigate sensor responses from measurements of conductance over time and FET characteristics. The devices were tested in controlled concentrations of vapour containing acetic acid, 2-butanone and methanol. After adsorption of analyte molecules, trends in the transient current and transfer curves are correlated with the nature of the surface interaction. Specifically, we observed proportionality between acetic acid concentration and relative conductance change, off current and surface charge density extracted from subthreshold behaviour. We suggest the origin of the sensing response to acetic acid as a two-part, reversible acid-base and redox reaction between acetic acid, InAs and its native oxide that forms slow, donor-like states at the nanowire surface. We further describe a simple model that is able to distinguish the occurrence of physical versus chemical adsorption by comparing the values of the extracted surface charge density. These studies demonstrate that InAs nanowires can produce a multitude of sensor responses for the purpose of developing next generation, multi-dimensional sensor applications. PMID:28714903

Geometric factors in the magnetoresistance of n-doped InAs epilayers

KAUST Repository

Sun, Jian

2013-11-27

We investigate the magnetoresistance (MR) effect in n-doped InAs and InAs/metal hybrid devices with geometries tailored to elucidate the physical mechanism and the role of geometry in the MR. Despite the isotropic Fermi surface in InAs, we observe a strong intrinsic MR in the InAs epilayer due to the existence of a surface conducting layer. Experimental comparison confirms that the extraordinary MR in the InAs/metal hybrids outperforms the orbital MR in the Corbino disk in terms of both the MR ratio and the magnetic field resolution. The results also indicate the advantage of a two-contact configuration in the hybrid devices over a four-contact one with respect to the magnetic field resolution. This is in contrast to previously reported results, where performance was evaluated in terms of the MR ratio and a four-contact configuration was found to be optimal. By applying Kohler\\'s rule, we find that at temperatures above 75 K the extraordinary MR violates Kohler\\'s rule, due to multiple relaxation rates, whereas the orbital MR obeys it. This finding can be used to distinguish the two geometric effects, the extraordinary MR and the orbital MR, from each other.

Critical surface phase of α2(2 × 4) reconstructed zig-zag chains on InAs(001)

Energy Technology Data Exchange (ETDEWEB)

Guo, Xiang [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); Zhou, Xun [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); School of Physics and Electronics Science, Guizhou Normal University, Guizhou, Guiyang 550001 (China); Wang, Ji-Hong [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); Luo, Zi-Jiang [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); School of Education Administration, Guizhou University of Finance and Economics, Guizhou, Guiyang 550004 (China); Zhou, Qing; Liu, Ke; Hu, Ming-Zhe [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); Ding, Zhao, E-mail: zding@gzu.edu.cn [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China)

2014-07-01

The critical condition for InAs(001) surface phase transition has been studied, the surface phase transition of InAs(001) showed discontinuity with hysteresis cycle as a function of substrate temperature. A mixed reconstruction surface and zig-zag chain α2(2 × 4) reconstruction surface have been observed by scanning tunneling microscopy. Considering the interaction and dynamics of surface arsenic atoms, the zig-zag chains of α2(2 × 4) reconstruction were found to be actually caused by the selective adsorption and desorption of surface arsenic dimers, they played a critical role in the surface phase transition between (2 × 4) and (4 × 2). - Highlights: • Discontinuous surface phase transition phenomena on the flat InAs(001) surface • Nanoscale InAs(001) surface observed by scanning tunneling microscopy • “Zig-Zag” chains of α2(2 × 4) reconstruction • Critical role in the surface phase transition between (2 × 4) and (4 × 2)

Critical surface phase of α2(2 × 4) reconstructed zig-zag chains on InAs(001)

International Nuclear Information System (INIS)

Guo, Xiang; Zhou, Xun; Wang, Ji-Hong; Luo, Zi-Jiang; Zhou, Qing; Liu, Ke; Hu, Ming-Zhe; Ding, Zhao

2014-01-01

The critical condition for InAs(001) surface phase transition has been studied, the surface phase transition of InAs(001) showed discontinuity with hysteresis cycle as a function of substrate temperature. A mixed reconstruction surface and zig-zag chain α2(2 × 4) reconstruction surface have been observed by scanning tunneling microscopy. Considering the interaction and dynamics of surface arsenic atoms, the zig-zag chains of α2(2 × 4) reconstruction were found to be actually caused by the selective adsorption and desorption of surface arsenic dimers, they played a critical role in the surface phase transition between (2 × 4) and (4 × 2). - Highlights: • Discontinuous surface phase transition phenomena on the flat InAs(001) surface • Nanoscale InAs(001) surface observed by scanning tunneling microscopy • “Zig-Zag” chains of α2(2 × 4) reconstruction • Critical role in the surface phase transition between (2 × 4) and (4 × 2)

Strategisch management (SM)

NARCIS (Netherlands)

Nagel, A.P.; Vercouteren, W.J.J.C.; Hoek, van der N.; Lohman, T.A.M.; Vermeulen, N.

1996-01-01

Kernbegrippen die bij de discussie van strategisch management (SM) aan de orde komen, zijn productinnovatie op ondernemingsniveau (oftewel strategische productinnovatie, SPI) en technologiestrategie. In dit artikel wordt een raamwerk van SM geintroduceerd. Daartoe worden de verschillende fasen van

Pathogenic and Ice-Nucleation Active (INA) Bacteria causing Dieback of Willows in Short Rotation Forestry

Energy Technology Data Exchange (ETDEWEB)

Nejad, Pajand

2005-03-01

To find out whether bacteria isolated from diseased plant parts can be the main causal agent for the dieback appearing in Salix energy forestry plantations in Sweden during the last few years, and if the joint effects of bacteria and frost injury are synergistic, extensive sampling of shoots from diseased Salix plants was performed. We performed several laboratory and greenhouse investigations and used evaluation techniques on the functions of the Ice-Nucleation Active (INA) bacteria. We carried out a comparison between spring and autumn bacterial communities isolated from within (endophytically) and surface (epiphytically) plant tissues of Salix viminalis. Seasonal variation of bacteria in willow clones with different levels of frost sensitivity and symptoms of bacterial damage was also investigated. We further focussed on possible effect of fertilisation and nutrient availability on the bacterial community in relation to plant dieback in Estonian willow plantations. The identification and detection of INA bacteria which cause damage in combination with frost to willow (Salix spp) plants in late fall, winter and spring was performed using BIOLOG MicroPlate, biochemical tests, selective INA primers and 16S rDNA analysis. To distinguish the character for differentiation between these bacteria morphologically and with respect to growing ability different culture media were used. We studied the temperature, at which ice nucleation occurred for individual bacteria, estimated the population of INA bacteria, effect of growth limiting factors, and evaluated the effect of chemical and physical agents for disruption and possible inhibition of INA among individual bacterial strains. The concentration of carbon, nitrogen and phosphorus on INA is discussed. We demonstrate that among the bacterial isolates recovered from the willow plantations, there were many that were capable of ice nucleation at temperatures between -2 and -10 deg C, many that were capable of inducing a

Electronic Structures of Strained InAs x P1-x by Density Functional Theory.

Science.gov (United States)

Lee, Seung Mi; Kim, Min-Young; Kim, Young Heon

2018-09-01

We investigated the effects of strain on the electronic structures of InAsxP1-x using quantum mechanical density functional theory calculations. The electronic band gap and electron effective mass decreased with the increase of the uniaxial tensile strain along the [0001] direction of wurtzite InAs0.75P0.25. Therefore, faster electron movements are expected. These theoretical results are in good agreement with the experimental measurements of InAs0.75P0.25 nanowire.

InAs migration on released, wrinkled InGaAs membranes used as virtual substrate

International Nuclear Information System (INIS)

Filipe Covre da Silva, S; Lanzoni, E M; De Araujo Barboza, V; Deneke, Ch; Malachias, A; Kiravittaya, S

2014-01-01

Partly released, relaxed and wrinkled InGaAs membranes are used as virtual substrates for overgrowth with InAs. Such samples exhibit different lattice parameters for the unreleased epitaxial parts, the released flat, back-bond areas and the released wrinkled areas. A large InAs migration towards the released membrane is observed with a material accumulation on top of the freestanding wrinkles during overgrowth. A semi-quantitative analysis of the misfit strain shows that the material migrates to the areas of the sample with the lowest misfit strain, which we consider as the areas of the lowest chemical potential of the surface. Material migration is also observed for the edge-supported, freestanding InGaAs membranes found on these samples. Our results show that the released, wrinkled nanomembranes offer a growth template for InAs deposition that fundamentally changes the migration behavior of the deposited material on the growth surface. (paper)

Electron microscopy of GaAs-based structures with InAs and As quantum dots separated by an AlAs barrier

International Nuclear Information System (INIS)

Nevedomskiy, V. N.; Bert, N. A.; Chaldyshev, V. V.; Preobrazhenskiy, V. V.; Putyato, M. A.; Semyagin, B. R.

2013-01-01

Electron microscopy studies of GaAs-based structures grown by molecular beam epitaxy and containing arrays of semiconductor InAs quantum dots and metal As quantum dots are performed. The array of InAs quantum dots is formed by the Stranski-Krastanov mechanism and consists of vertically coupled pairs of quantum dots separated by a GaAs spacer 10 nm thick. To separate the arrays of semiconductor and metal quantum dots and to prevent diffusion-induced mixing, the array of InAs quantum dots is overgrown with an AlAs barrier layer 5 or 10 nm thick, after which a GaAs layer is grown at a comparatively low temperature (180°C). The array of As quantum dots is formed in an As-enriched layer of the low-temperature GaAs by means of post-growth annealing at 400–760°C for 15 min. It is established that the AlAs barrier layer has a surface profile corresponding to that of a subbarrier layer with InAs quantum dots. The presence of such a profile causes the formation of V-shaped structural defects upon subsequent overgrowth with the GaAs layer. Besides, it was obtained that AlAs layer is thinned over the InAs quantum dots tops. It is shown that the AlAs barrier layer in the regions between the InAs quantum dots effectively prevents the starting diffusion of excess As at annealing temperatures up to 600°C. However, the concentration of mechanical stresses and the reduced thickness of the AlAs barrier layer near the tops of the InAs quantum dots lead to local barrier breakthroughs and the diffusion of As quantum dots into the region of coupled pairs of InAs quantum dots at higher annealing temperatures

Single-photon generation with InAs quantum dots

International Nuclear Information System (INIS)

Santori, Charles; Fattal, David; Vuckovic, Jelena; Solomon, Glenn S; Yamamoto, Yoshihisa

2004-01-01

Single-photon generation using InAs quantum dots in pillar microcavities is described. The effects on performance of the excitation wavelength and polarization, and the collection bandwidth and polarization, are studied in detail. The efficiency and photon state purity of these devices have been measured, and issues affecting these parameters are discussed. Prospects for improved devices are also discussed

Correlation between the Montreal Cognitive Assessment-Indonesian Version (Moca-INA) and the Mini-Mental State Examination (MMSE) in Elderly.

Science.gov (United States)

Rambe, Aldy Safruddin; Fitri, Fasihah Irfani

2017-12-15

As the rapid growth of the elderly population and the increased prevalence of Alezheimer's Disease and related disorders, there is an increasing need for effective cognitive screening. The Mini Mental State Examination (MMSE) is the most frequently used screening test of cognitive impairment because of its convenience. The Montreal Cognitive Assessment-Indonesian Version (MoCA-INA) has been validated and recently been used as a cognitive screening tool. The aim of this study was to compare the MMSE and MoCA-INA scores and to determine the correlation between the MMSE and MoCA-INA scores in elderly. This was a cross-sectional study including 83 elderly subjects from November 2016 until June 2017. We performed MMSE and MoCA-INA for assessment of cognitive function and the time between each test was at least 30 minutes. The study included 83 subjects which were consisted of 46 (55.4%) males and 37 (44.6%) females. The mean age was 69.19 ± 4.23 ranging from 65 to 79 years old. The average MMSE scores was 24.96 ± 3.38 (range 14 to 30). The average MoCA-INA scores was 21.06 ± 4.56 (range 5 to 30). The Pearson correlation coefficient between the scores was 0.71 (p<0.005). There were no significant differences of both scores based on history of hypertension, diabetes mellitus and previous stroke, but there was a significant difference in MMSE scores based on level of education. The MoCA-INA score showed a good correlation with the MMSE score. Both tests showed comparable results but MoCA-INA showed lower average with wider range of scores.

Detection of antifungal properties in Lactobacillus paracasei subsp. paracasei SM20, SM29, and SM63 and molecular typing of the strains.

Science.gov (United States)

Schwenninger, Susanne Miescher; von Ah, Ueli; Niederer, Brigitte; Teuber, Michael; Meile, Leo

2005-01-01

Lactobacilli isolated from different food and feed samples such as raw milk, cheese, yoghurt, olives, sour dough, as well as corn and grass silage, were screened for their antifungal activities. Out of 1,424 isolates tested, 82 were shown to be inhibitory to different yeasts (Candida spp. and Zygosaccharomyces bailii) and a Penicillium sp., which were previously isolated from spoiled yoghurt and fruits. Carbohydrate fermentation patterns suggested that a substantial portion, 25%, belonged to the Lactobacillus casei group, including L. casei, L. paracasei, and L. rhamnosus. The isolates SM20 (DSM14514), SM29 (DSM14515), and SM63 (DSM14516) were classified by PCR using species-specific primers to target the corresponding type strains (L. casei, L. paracasei, and L. rhamnosus) as controls. Further molecular typing methods such as randomly amplified polymorphic DNA, pulsed-field gel electrophoresis, and sequencing analysis of the 16S rRNA gene allowed classifying strains SM20, SM29, and SM63 as L. paracasei subsp. paracasei in accordance with the new reclassification of the L. casei group proposed by Collins et al.

Surface Preparation of InAs (110 Using Atomic Hydrogen

Directory of Open Access Journals (Sweden)

T.D. Veal

2002-06-01

Full Text Available Atomic hydrogen cleaning has been used to produce structurally and electronically damage-free InAs(110 surfaces.  X-ray photoelectron spectroscopy (XPS was used to obtain chemical composition and chemical state information about the surface, before and after the removal of the atmospheric contamination. Low energy electron diffraction (LEED and high-resolution electron-energy-loss spectroscopy (HREELS were also used, respectively, to determine the surface reconstruction and degree of surface ordering, and to probe the adsorbed contaminant vibrational modes and the collective excitations of the clean surface. Clean, ordered and stoichiometric  InAs(110-(1×1 surfaces were obtained by exposure to thermally generated atomic hydrogen at a substrate temperature as low as 400ºC.  Semi-classical dielectric theory analysis of HREEL spectra of the phonon and plasmon excitations of the clean surface indicate that no electronic damage or dopant passivation were induced by the surface preparation method.

Coercivity Recovery Effect of Sm-Fe-Cu-Al Alloy on Sm2Fe17N3 Magnet

Science.gov (United States)

Otogawa, Kohei; Asahi, Toru; Jinno, Miho; Yamaguchi, Wataru; Takagi, Kenta; Kwon, Hansang

2018-03-01

The potential of a Sm-Fe-Cu-Al binder for improvement of the magnetic properties of Sm2Fe17N3 was examined. Transmission electron microscope (TEM) observation of a Sm-Fe-Cu-Al alloy-bonded Sm2Fe17N3 magnet which showed high coercivity revealed that the Sm-Fe-Cu-Al alloy had an effect of removing the surface oxide layer of the Sm2 Fe17N3 grains. However, the Sm-Fe-Cu-Al binder was contaminated by carbon and nitrogen, which originated from the organic solvent used as the milling medium during pulverization. To prevent carbon and nitrogen contamination, the Sm-Fe- Cu-Al alloy was added directly on the surface of the Sm2Fe17N3 grains by sputtering. Comparing the recovered coercivity per unit amount of the added binder the uncontaminated binder-coated sample had a higher coercivity recovery effect than the milled binder-added sample. These results suggested that sufficient addition of the contamination-free Sm-Fe-Cu-Al binder has the possibility to reduce the amount of binder necessary to produce a high coercive Sm2Fe17N3 magnet.

Magnetic Ligand Fishing as a Targeting Tool for HPLC-HRMS-SPE-NMR: α-Glucosidase Inhibitory Ligands and Alkylresorcinol Glycosides from Eugenia catharinae.

Science.gov (United States)

Wubshet, Sileshi G; Brighente, Inês M C; Moaddel, Ruin; Staerk, Dan

2015-11-25

A bioanalytical platform combining magnetic ligand fishing for α-glucosidase inhibition profiling and HPLC-HRMS-SPE-NMR for structural identification of α-glucosidase inhibitory ligands, both directly from crude plant extracts, is presented. Magnetic beads with N-terminus-coupled α-glucosidase were synthesized and characterized for their inherent catalytic activity. Ligand fishing with the immobilized enzyme was optimized using an artificial test mixture consisting of caffeine, ferulic acid, and luteolin before proof-of-concept with the crude extract of Eugenia catharinae. The combination of ligand fishing and HPLC-HRMS-SPE-NMR identified myricetin 3-O-α-L-rhamnopyranoside, myricetin, quercetin, and kaempferol as α-glucosidase inhibitory ligands in E. catharinae. Furthermore, HPLC-HRMS-SPE-NMR analysis led to identification of six new alkylresorcinol glycosides, i.e., 5-(2-oxopentyl)resorcinol 4-O-β-D-glucopyranoside, 5-propylresorcinol 4-O-β-D-glucopyranoside, 5-pentylresorcinol 4-O-[α-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside, 5-pentylresorcinol 4-O-β-D-glucopyranoside, 4-hydroxy-3-O-methyl-5-pentylresorcinol 1-O-β-D-glucopyranoside, and 3-O-methyl-5-pentylresorcinol 1-O-[β-D-glucopyranosyl-(1→6)]-β-D-glucopyranoside.

Oxygen infrared spectra of oxyhemoglobins and oxymyoglobins. Evidence of two major liganded O2 structures

International Nuclear Information System (INIS)

Potter, W.T.; Tucker, M.P.; Houtchens, R.A.; Caughey, W.S.

1987-01-01

The dioxygen stretch bands in infrared spectra for solutions of oxy species of human hemoglobin A and its separated subunits, human mutant hemoglobin Zurich (β63His to Arg), rabbit hemoglobin, lamprey, hemoglobin, sperm whale myoglobin, bovine myoglobin, and a sea worm chlorocruorin are examined. Each protein exhibits multiple isotope-sensitive bands between 1160 and 1060 cm -1 for the liganded 16 O 2 , 17 O 2 , and 18 O 2 . The O-O stretch bands for each of the mammalian myoglobins and hemoglobins are similar, with frequencies that differ between proteins by only 3-5 cm -1 . The spectra for the lamprey and sea worm hemoglobins exhibit greater diversity. For all proteins an O-O stretch band expected to occur near 1125 cm -1 for 16 O 2 and 17 O 2 , but not 18 O 2 , appears split by ∼25 cm -1 due to an unidentified perturbation. The spectrum for each dioxygen isotope, if unperturbed, would contain two strong bands for the mammalian myoglobins (1150 and 1120 cm -1 ) and hemoglobins (1155 and 1125 cm -1 ). Two strong bands separated by ∼30 cm -1 for each oxy heme protein subunit indicate that two major protein conformations (structure) that differ substantially in O 2 bonding are present. The two dioxygen structures can result from a combination of dynamic distal and proximal effects upon the O 2 ligand bound in a bent-end-on stereochemistry

S,O-Ligand-Promoted Palladium-Catalyzed C-H Functionalization Reactions of Nondirected Arenes

NARCIS (Netherlands)

Naksomboon, K.; Valderas, C.; Gomez-Martinez, M.; Alvarez-Casao, Y.; Fernández Ibáñez, M.A.

Pd(II)-catalyzed C-H functionalization of non directed arenes has been realized using an inexpensive and easily accessible type of bidentate S,O-ligand. The catalytic system shows high efficiency in the C-H olefination reaction of electron-rich and electron-poor arenes. This methodology is

Highly stable [mambf6-n(o/h2o)n(ligand)2(solvent)x]n metal organic frameworks

KAUST Repository

Eddaoudi, Mohamed

2016-10-13

Provided herein are metal organic frameworks having high selectivity and stability in the present of gases and vapors including H2S, H2O, and CO2. Metal organic frameworks can comprise metal nodes and N-donor organic ligands. Further provided are methods of making metal organic frameworks.

Magnetic properties of cyano-bridged Ln3+-M3+ complexes. Part I: trinuclear complexes (Ln3+ = La, Ce, Pr, Nd, Sm; M3+ = FeLS, Co) with bpy as blocking ligand.

Science.gov (United States)

Figuerola, Albert; Ribas, Joan; Llunell, Miquel; Casanova, David; Maestro, Miguel; Alvarez, Santiago; Diaz, Carmen

2005-10-03

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to eight trinuclear complexes: trans-[M(CN)4(mu-CN)2{Ln(H2O)4(bpy)2}2][M(CN)6].8H2O (M = Fe3+ or Co3+, Ln = La3+, Ce3+, Pr3+, Nd3+, and Sm3+). The structures for the eight complexes [La2Fe] (1), [Ce2Fe] (2), [Pr2Fe] (3), [Nd2Fe] (4), [Ce2Co] (5), [Pr2Co] (6), [Nd2Co] (7), and [Sm2Co] (8) have been solved; they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular 3D architecture through hydrogen bonding and pi-pi stacking interactions. A stereochemical study of the nine-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. No significant magnetic interaction was found between the lanthanide(III) and the iron(III) ions.

Effect of temperature on the luminescence of Sm{sup 3+} ions in YAM crystals

Energy Technology Data Exchange (ETDEWEB)

Kaczkan, M. [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland); Boruc, Z., E-mail: z.boruc@stud.elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland); Turczyński, S. [Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warsaw (Poland); Malinowski, M. [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland)

2014-11-05

Highlights: • Different concentration Sm{sup 3+}-doped Y{sub 4}Al{sub 2}O{sub 9} crystals are fabricated by μ-pulling down method. • Thermally activated {sup 4}F{sub 3/2} → {sup 6}H{sub 5/2} emission of Sm{sup 3+} in YAM is studied. • Temperature dependent quenching mechanism of the {sup 4}G{sub 5/2} luminescence is proposed. - Abstract: The spectroscopic features of samarium Sm{sup 3+} activated Y{sub 4}Al{sub 2}O{sub 9} (YAM) crystals are presented and discussed. Temperature sensing properties of Sm{sup 3+}:YAM phosphor was demonstrated over the 300–1200 K range. Temperature dependent luminescence spectra and decay curves for the {sup 4}G{sub 5/2} level of Sm{sup 3+} in YAM were measured. Ratio of the fluorescence intensities arising from the two close lying {sup 4}F{sub 3/2} and {sup 4}G{sub 5/2} levels (with energy separation of ΔE ∼ 1000 cm{sup −1}) followed a straight line pattern, which confirms the Boltzmann distribution of the population, and can be used to measure temperature. The lifetime for the {sup 4}G{sub 5/2} level in 1% Sm doped sample decreases from 1.65 to 0.08 ms with heating from room temperature to 1200 K. This behavior of decays is discussed in terms of radiative and multiphonon decays as well as cross-relaxation dependence on temperature.

Soil Moisture Active Passive Mission L4_SM Data Product Assessment (Version 2 Validated Release)

Science.gov (United States)

Reichle, Rolf Helmut; De Lannoy, Gabrielle J. M.; Liu, Qing; Ardizzone, Joseph V.; Chen, Fan; Colliander, Andreas; Conaty, Austin; Crow, Wade; Jackson, Thomas; Kimball, John;

Mechanochemical synthesis of magnetically hard anisotropic RFe{sub 10}Si{sub 2} powders with R representing combinations of Sm, Ce and Zr

Energy Technology Data Exchange (ETDEWEB)

Gabay, A.M., E-mail: gabay@udel.edu; Hadjipanayis, G.C.

2017-01-15

Alloy synthesis consisting of mechanical activation followed by annealing was explored as a method of manufacturing medium-grade permanent magnet materials with a reduced content of the critical rare earth elements. Four R{sub x}Fe{sub 10}Si{sub 2} alloys with R=Sm, Sm{sub 0.7}Zr{sub 0.3}, Sm{sub 0.3}Ce{sub 0.3}Zr{sub 0.4} and Ce{sub 0.6}Zr{sub 0.4} (nominal compositions) were prepared from mixtures of Sm{sub 2}O{sub 3}, CeO{sub 2}, ZrO{sub 2}, Fe{sub 2}O{sub 3} and Si powders in the presence of a reducing agent Ca and a CaO dispersant. The collected alloy particles typically consisted of few joined submicron crystals. For R=Sm, X-ray diffraction analysis reveals a significant amount of the unwanted Th{sub 2}Zn{sub 17}-type compound forming alongside the desired ThMn{sub 12}-type 1:12 compound. A more pure 1:12 phase could be obtained for R=Ce{sub 0.6}Zr{sub 0.4}, but it exhibited a room-temperature coercivity of less than 1 kOe. The most pure 1:12 phase and the highest values of the coercivity (10.8 kOe) and calculated maximum energy product (13.8 MGOe) were obtained for R=Sm{sub 0.7}Zr{sub 0.3} processed at 1150 °C. The calculated maximum energy products of the Sm{sub 0.3}Ce{sub 0.3}Zr{sub 0.4}Fe{sub 10}Si{sub 2} particles, with half of their rare earths constituents represented by the relatively abundant Ce, was 10.1 MGOe. - Highlights: • 30% Zr substitution for Sm improves prospects of the alloys as permanent magnets. • Pure ThMn{sub 12}-type structure could only be obtained in the Zr-substituted alloys. • Obtained powders exhibit better properties than nanocrystalline Sm(Fe,M){sub 12} alloys. • If fully dense, alloy containing only 2.3 at% Sm would energy product of 10 MGOe.

Influência da heparina sódica na ocorrência de laminite eqüina induzida por sobrecarga de carboidratos

OpenAIRE

Martins Filho,L.P.; Fagliari,J.J.; Moraes,J.R.E.; Sampaio,R.C.; Oliveira,J.A.; Lacerda Neto,J.C.

2008-01-01

Avaliou-se a eficiência da infusão intravenosa de heparina sódica (100UI/kg/8h, a partir de 24h após o fornecimento de carboidrato, até completar 48h) no controle da laminite eqüina experimentalmente induzida por sobrecarga de carboidrato (17,6g de amido de milho/kg de peso corpóreo). Foram utilizados 15 eqüinos adultos, distribuídos em três grupos experimentais: GI (grupo-controle); GII (grupo laminite) e GIII (grupo laminite+heparina). Posteriormente ao fornecimento de carboidrato, os anima...

Comparison of effective relative dielectric permittivities obtained by three independent ways for CeO2-Sm2O3 films prepared by EB-PVD (+IBAD) techniques

International Nuclear Information System (INIS)

Kundracik, F.; Neilinger, P.; Hartmanova, M.; Nadazdy, V.; Mansilla, C.

2011-01-01

Ceria, as material with relatively high dielectric permittivity, ε r , and ability to form films on the Si substrate, is a candidate for the gate dielectrics in the MOS devices. Doping with suitable e.g. trivalent rare earth oxides and suitable treatment after deposition (preparation) can improve their properties, e.g. ionic conductivity, dielectric permittivity and mechanical hardness. In this work, the dielectric properties of CeO 2 + Sm 2 O 3 films prepared by electron beam physical vapour deposition (EB-PVD) and some of them simultaneously also by the Ar + ionic beam assisted deposition (IBAD) techniques are analysed. (authors)

Interactions between alkaline earth cations and oxo ligands. DFT study of the affinity of the Mg²+ cation for phosphoryl ligands.

Science.gov (United States)

da Costa, Leonardo Moreira; de Mesquita Carneiro, José Walkimar; Paes, Lilian Weitzel Coelho

2011-08-01

DFT (B3LYP/6-31+G(d)) calculations of Mg(2+) affinities for a set of phosphoryl ligands were performed. Two types of ligands were studied: a set of trivalent [O = P(R)] and a set of pentavalent phosphoryl ligands [O = P(R)(3)] (R = H, F, Cl, Br, OH, OCH(3), CH(3), CN, NH(2) and NO(2)), with R either bound directly to the phosphorus atom or to the para position of a phenyl ring. The affinity of the Mg(2+) cation for the ligands was quantified by means of the enthalpy for the substitution of one water molecule in the [Mg(H(2)O)(6)](2+) complex for a ligand. The enthalpy of substitution was correlated with electronic and geometric parameters. Electron-donor groups increase the interaction between the cation and the ligand, while electron-acceptor groups decrease the interaction enthalpy.

A study on sintering aids for Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} electrolyte

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xinge; Deces-Petit, Cyrille; Yick, Sing; Robertson, Mark; Kesler, Olivera; Maric, Radenka; Ghosh, Dave [Institute for Fuel Cell Innovation, National Research Council Canada, 3250 East Mall, Vancouver, BC (Canada V6T 1W5)

2006-11-08

In this study, an addition of Co oxide or Cu oxide to Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} (SDC) was studied to improve the sinterability of SDC. It has been found that both Co and Cu oxide are very effective as sintering aids, and the SDC sintering temperature can be reduced from 1400{sup o}C without aids to below 1000{sup o}C with only 1at.% of either Cu oxide or Co oxide. As compared to the pure SDC, a slight decrease of ionic conductivity was observed in SDC with Cu sintering aid. There is no obvious effect on electrochemical property of SDC with Co sintering aid under 2.5at.%. (author)

Fe-contacts on InAs(100) and InP(100) characterised by conversion electron Mössbauer spectroscopy

DEFF Research Database (Denmark)

Damsgaard, Christian Danvad; Gunnlaugsson, H.P; Weyer, G.

2005-01-01

We have grown 4 nm thin films of Fe-57 on InAs(100) and InP(100) surfaces by use of MBE and studied the samples by Fe-57 conversion electron Mossbauer spectroscopy. In the case of InAs, the Mossbauer spectrum showed a sextet due to alpha-Fe and a further magnetically split component with slightly...

Synthesis and structure of unprecedented samarium complex with bulky bis-iminopyrrolyl ligand via intramolecular C=N bond activation

Energy Technology Data Exchange (ETDEWEB)

Das, Suman; Anga, Srinivas; Harinath, Adimulam; Panda, Tarun K. [Department of Chemistry, Indian Institute of Technology, Hyderabad (India); Pada Nayek, Hari [Department of Applied Chemistry, Indian Institute of Technology, (ISM) Dhanbad, Jharkhand (India)

2017-12-29

An unprecedentate samarium complex of the molecular composition [{κ"3-{(Ph_2CH)N=CH}{sub 2}C{sub 4}H{sub 2}N}{κ"3-{(Ph_2CHN=CH)(Ph_2CHNCH)C_4H_2N}Sm}{sub 2}] (2), which was isolated by the reaction of a potassium salt of 2,5-bis{N-(diphenylmethyl)-iminomethyl}pyrrolyl ligand [K(THF){sub 2}{(Ph_2CH)N=CH}{sub 2}C{sub 4}H{sub 2}N] (1) with anhydrous samarium diiodide in THF at 60 C through the in situ reduction of imine bond is presented. The homoleptic samarium complex [[κ{sup 3}-{(Ph_2CH)-N=CH}{sub 2}C{sub 4}H{sub 2}N]{sub 3}Sm] (3) can also be obtained from the reaction of compound 1 with anhydrous samarium triiodide (SmI{sub 3}) in THF at 60 C. The molecular structures of complexes 2 and 3 were established by single-crystal X-ray diffraction analysis. The molecular structure of complex 2 reveals the formation of a C-C bond in the 2,5-bis{N-(diphenylmethyl)iminomethyl}pyrrole ligand moiety (Ph{sub 2}Py{sup -}). However, complex 3 is a homoleptic samarium complex of three bis-iminopyrrolyl ligands. In complex 2, the samarium ion adopts an octahedral arrangement, whereas in complex 3, a distorted three face-centered trigonal prismatic mode of nine coordination is observed around the metal ion. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

On the processing of InAs and InSb photodiode applications

Energy Technology Data Exchange (ETDEWEB)

Odendaal, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Auret, F.D. [Department of Physics, University of Pretoria, Lynnwood road, Hillcrest, Pretoria 0002 (South Africa)

2008-07-01

In this paper, potential methods for the surface passivation of InSb and InAs material, covering both compositional extremes of the promising narrow band gap semiconductor InAsSb, are evaluated. Surface states, mostly due to dangling bonds and exposure to the atmosphere, create generation-recombination centres that negatively influence the dark current, stability, efficiency and related noise characteristics of photosensitive devices fabricated from these materials. The effect of various surface treatments, including sulphuric acid based etching, lactic acid based etching, KOH anodising and Na{sub 2}S anodising, on the relative number of surface states is deduced by evaluating the capacitance versus voltage characteristics of metal-insulator-semiconductor structures fabricated on InAs and InSb. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

On the processing of InAs and InSb photodiode applications

International Nuclear Information System (INIS)

Odendaal, V.; Botha, J.R.; Auret, F.D.

2008-01-01

In this paper, potential methods for the surface passivation of InSb and InAs material, covering both compositional extremes of the promising narrow band gap semiconductor InAsSb, are evaluated. Surface states, mostly due to dangling bonds and exposure to the atmosphere, create generation-recombination centres that negatively influence the dark current, stability, efficiency and related noise characteristics of photosensitive devices fabricated from these materials. The effect of various surface treatments, including sulphuric acid based etching, lactic acid based etching, KOH anodising and Na 2 S anodising, on the relative number of surface states is deduced by evaluating the capacitance versus voltage characteristics of metal-insulator-semiconductor structures fabricated on InAs and InSb. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The role of strain-driven in migration in the growth of self-assembled InAs quantum dots on InP

CERN Document Server

Yoon, S H; Lee, T W; Hwang, H D; Yoon, E J; Kim, Y D

1999-01-01

Self-assembled InAs quantum dots (SAQDs) were grown on InP by metalorganic chemical vapor deposition. The amount of excess InAs and the aspect ratio of the SAQD increased with temperature and V/III ratio. It is explained that the As/P exchange reaction at the surface played an important role in the kinetics of SAQD formation. Insertion of a lattice-matched InGaAs buffer layer suppressed the excess InAs formation, and lowered the aspect ratio. Moreover, the dots formed on InGaAs buffer layers were faceted, whereas those on InP were hemispherical, confirming the effect of the As/P exchange reaction. The shape of InAs quantum dots on InGaAs buffer layers was a truncated pyramid with four [136] facets and base edges parallel to directions.

Determining the mechanism of dehydration of primary, secondary, and tertiary alcohols by means of deuterium uptake on deuterated catalysts (BPO4, Ca3(PO4)2 and Sm2O3)

International Nuclear Information System (INIS)

Thomke, K.

1977-01-01

In order to gain insight into the mechanisms of dehydration (E1, E2, E1cB) of α- and β-substituted ethanols, the uptake of deuterium on deuterated catalysts [BPO 4 , Ca 3 (PO 4 ) 2 , Sm 2 O 3 ] into the alcohols and the thus formed olefines was measured. For that purpose microcatalytic and mass-spectrometric techniques were used. Most of the examined alcohols showed E1 on BPO 4 , E2 (sometimes mingled with E1) on Ca 3 (PO 4 ) 2 , and E1cB on Sm 2 O 3 . The common mechanism for ethanol on BPO 4 , for 2-propanol on Ca 3 (PO 4 ) 2 , and for 2-ethyl-2-propanol on Sm 2 O 3 was E2, i.e. that the OH-group and the β-proton were split off simultaneously. This can be explained by a decrease of the strength of the α-C-OH-bound caused by α-methyl-substitution on the one hand and by an increase of basicity of the catalyst on the other hand. (orig.) 891 HK [de

The Crystal structure of InAs nanorods grown onto Si[111] substrate

Energy Technology Data Exchange (ETDEWEB)

Davydok, Anton; Biermanns, Andreas; Pietsch, Ullrich [Festkoerperphysik, Universitaet Siegen, Walter-Flex-Str. 3,57072, Siegen (Germany); Breuer, Steffen; Dimakis, Manos; Geelhaar, Lutz [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

2011-07-01

Nanowires are of particular interest due to the ability to synthesize heterostructures in the nanometer range. It was found that nearly any AIIIBV semiconductor material can be grown as NWs onto another AIIIBV or group IV [111] substrate independent from lattice mismatch. We presented an X-ray characterization of InAs NRs on Si [111] grown by assist free MBE method. Lattice mismatch of this materials is 11%. For study of strain realizing we concentrated our research on initial stages of growth process investigating samples set with different growth time. Using synchrotron radiation we have performed experiments in symmetrical and asymmetrical out-of plane scattering geometry and grazing-incidence diffraction. Combining the results we were able to characterize the transition between silicon silicon substrate and InAs NWs. We find in-plane lattice mismatch of -0.18% close to the interface compared to InAs bulk material. With help of micro-focus setup we are able measure structural parameters of single NWs to determine the strain accomodation as function of NW size. In particular using asymmetric wurzite-sensitive reflections under coherent beam illumination we could quantify the number of stacking faults. In the talk we present details of the analysis and first simulation results.

Doping dependent nonlinear Hall effect in SmFeAsO1-xFx

International Nuclear Information System (INIS)

Riggs, Scott C; Kemper, J B; Stegen, Z; Boebinger, G S; McDonald, R D; Balakirev, F F; Kohama, Y; Migliori, A; Chen, H; Liu, R H; Chen, X H

2009-01-01

We report the Hall resistivity, ρ xy , of polycrystalline SmFeAsO 1-x F x for four different fluorine concentrations from the onset of superconductivity through the collapse of the structural phase transition. For the two more highly doped samples, ρ xy is linear in magnetic field up to 50 T with only weak temperature dependence, reminiscent of a simple Fermi liquid. For the lightly doped samples with x xy (H) being both nonlinear in magnetic field and strongly temperature-dependent even though the Hall angle is small. The onset temperature for this nonlinear regime is in the vicinity of the structural phase (SPT)/magnetic ordering (MO) transitions. The temperature dependence of the Hall resistivity is consistent with a thermal activation of carriers across an energy gap. The evolution of the energy gap with doping is reported. (fast track communication)

Study of LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) double perovskites as new cathode material for IT-SOFC

Energy Technology Data Exchange (ETDEWEB)

Chavez, E; Mueller, M; Mogni, L; Caneiro, A, E-mail: mogni@cab.cnea.gov.a [Centro Atomico Bariloche-CNEA, Instituto Balseiro. Av. Bustillo 9500, S. C. de Bariloche 8400 (Argentina)

2009-05-01

Oxides with double perovskites structures of general composition LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) were synthesized by solid state reaction with the purpose to evaluate new materials to be used as cathodes in intermediate temperature solid oxide fuel cell (IT-SOFC). A preliminary study about electrochemical properties was performed by impedance spectroscopy between 500 and 800 deg. C under atmosphere of pure O{sub 2}. Symmetrical cells were obtained by spray deposition of LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) at both sides of a dense ceramic electrolyte. The impedance spectroscopy measurements as a function of temperatures show a hysteresis loop which could be associated to a tetragonal/orthorhombic phase transition. The existence of this transition was corroborated by high temperature X-Ray diffraction and Differential Scanning Calorimetry measurements.

The investigation of alloy formation during InAs nanowires growth on GaAs (111)B substrate

Energy Technology Data Exchange (ETDEWEB)

Saqib, Muhammad; Biermanns, Andreas; Davydok, Anton; Pietsch, Ullrich [Festkoerperphysik, Universitaet Siegen, Walter-Flex-Str. 3, Siegen 57072 (Germany); Rieger, Torsten; Grap, Thomas; Lepsa, Mihail [Peter Gruenberg Institute (PGI-9), Forschungzentrum Juelich, Juelich 52425 (Germany)

2013-07-01

A possible way to obtain nanowires is the growth in molecular beam epitaxy (MBE) on the (111) oriented surface of the desired substrate, covered by a thin oxide layer. A crucial parameter in this method is the initial thickness of the oxide layer, often determined by an etching procedure. In this contribution, we report on the structural investigation of two different series (etched and unetched) of NWs samples. Vertically aligned InAs nanowires (NWs) doped with Si were self-assisted grown by molecular beam epitaxy on GaAs [111]B substrates covered with a thin SiO{sub x} layer. Using a combination of symmetric and asymmetric X-ray diffraction we study the influence of Si supply on the growth process and nanostructure formation. We find that the number of parasitic crystallites grown between the NWs increases with increasing Si flux. In addition, we observe the formation of a Ga{sub 0.2}In{sub 0.8}As alloy if the growth is performed on samples covered by a defective (etched) oxide layer. This alloy formation is observed within the crystallites and not within the nanowires. The Gallium concentration is determined from the lattice mismatch of the crystallites relative to the InAs nanowires. No alloy formation is found for samples with faultless oxide layers.

Effect of mixing RE elements (Nd, Sm, Gd, Eu, Y, Yb) on the RE2BaCuO5/Nd4-2xBa2+2xCu2-xO10-2x phases in RE cuprate high-Tc superconductors

International Nuclear Information System (INIS)

Langhorn, J.B.; Black, M.A.; McGinn, P.J.

1999-01-01

The phases RE 2 BaCuO 5 /RE 4 Ba 2 Cu 2 O 10 phases (where RE is a mixture of Nd, Sm, Gd, Eu, Y and Yb) have been synthesized in an oxygen atmosphere and subsequently characterized. The mixing of RE elements which inherently form the RE 2 BaCuO 5 phase through the peritectic decomposition of REBa 2 Cu 3 O 7-x (RE123) (i.e. Sm, Gd, Eu, Y, Yb), was observed to give homogeneous mixing of the elements in the 211 phase. In contrast it was found that on mixing Nd with other RE elements a mixture of the Nd 4-2x Ba 2+2x Cu 2-x O 10-2x (Nd422) and RE 2 BaCuO 5 (RE211) phases resulted. It was also observed that on mixing Nd with other REs a finite amount of the RE is substituted into the Nd422 phase and Nd into the RE211. (author)

Temperature dependence of spin and orbital magnetic moments of Sm 4f electrons in (Sm, Gd)Al2

International Nuclear Information System (INIS)

Qiao, S.; Kimura, A.; Adachi, H.; Iori, K.; Miyamoto, K.; Xie, T.; Namatame, H.; Taniguchi, M.; Tanaka, A.; Muro, T.; Imada, S.; Suga, S.

2005-01-01

X-ray magnetic circular dichroism studies were carried out on (Sm, Gd)Al 2 , a ferromagnet without net magnetization at a certain compensation temperature. For Sm 4f electrons, the following understandings were obtained: the magnitude of expectation value of orbital magnetic moment (m L Sm ) is always larger than that of spin one (m S Sm ), so the cancellation of total spin and orbital magnetic moments cannot be achieved only by Sm 4f electrons and the contributions from Gd ions and conduction electrons are important; when the temperature decreases, the magnitude of both m L Sm and m S Sm increases and the gross magnetic moment due to the Sm 4f electrons monotonically deviates from zero. These results tell us that the temperature dependence of magnetic moments related with the electrons other than Sm 4f ones may play important roles in the subtle adjustment of the total spin and orbital magnetic moments to the zero magnetization at the compensation temperature

Dielectric spectroscopy of the SmQ* phase

Science.gov (United States)

Perkowski, P.; Bubnov, A.; Piecek, W.; Ogrodnik, K.; Hamplová, V.; Kašpar, M.

2011-11-01

Liquid crystal possessing two biphenyl moieties in the molecular core and lateral chlorine substitution far from the chiral chain has been studied by dielectric spectroscopy. On cooling from the isotropic phase, the material possesses the frustrated smectic Q* (SmQ*) and SmCA* phases. It has been confirmed by dielectric spectroscopy that the SmQ* phase can be related to the SmCA* anti-ferroelectric phase. However, only one relaxation process has been observed in the SmQ* phase, while in the SmCA*, two relaxations are clearly detectable. It seems that the mode found in the SmQ* can be connected with high-frequency anti-phase mode observed in the SmCA* phase. Its relaxation frequency is similar to PH relaxation frequency, but is weaker. The same relaxation has been observed even a few degrees above the SmQ*-Iso phase transition. Another explanation for the mode detected in SmQ* and isotropic phases can be molecular motions around short molecular axis.

Preparation and structure characterization of SmCo5(0001) epitaxial thin films grown on Cu(111) underlayers

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

2009-01-01

SmCo 5 (0001) epitaxial films were prepared on Cu(111) single-crystal underlayers formed on Al 2 O 3 (0001) substrates at 500 deg. C. The nucleation and growth mechanism of (0001)-oriented SmCo 5 crystal on Cu(111) underlayer is investigated and a method to control the nucleation is proposed. The SmCo 5 epitaxial thin film formed directly on Cu underlayer consists of two types of domains whose orientations are rotated around the film normal by 30 deg. each other. By introducing a thin Co seed layer on the Cu underlayer, a SmCo 5 (0001) single-crystal thin film is successfully obtained. Nucleation of SmCo 5 crystal on Cu underlayer seems controllable by varying the interaction between the Cu underlayer and the SmCo 5 layer

Effects of substrate temperature and Cu underlayer thickness on the formation of SmCo5(0001) epitaxial thin films

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

2010-01-01

SmCo 5 (0001) epitaxial thin films were prepared on Cu(111) underlayers heteroepitaxially grown on Al 2 O 3 (0001) single-crystal substrates by molecular beam epitaxy. The effects of substrate temperature and Cu underlayer thickness on the crystallographic properties of SmCo 5 (0001) epitaxial films were investigated. The Cu atoms of underlayer diffuse into the SmCo 5 film and substitute the Co sites in SmCo 5 structure forming an alloy compound of Sm(Co,Cu) 5 . The ordered phase formation is enhanced with increasing the substrate temperature and with increasing the Cu underlayer thickness. The Cu atom diffusion into the SmCo 5 film is assisting the formation of Sm(Co,Cu) 5 ordered phase.

Optical isotype shifts of 146Sm and 151Sm

International Nuclear Information System (INIS)

Eastham, D.A.; Walker, P.M.; Griffith, J.A.R.; Evans, D.E.; England, J.G.; Grant, I.S.

1984-01-01

We have measured the optical isotope shifts of 146 Sm and 151 Sm by laser resonance fluorescence. From these measurements the changes in the mean square nuclear radii are: delta 2 > (A=144 to 146)=0.266(10) fm 2 , and delta 2 > (A=151 to 152)=0.262(10) fm 2 . These results, together with those of the stable isotopes, show that the average nuclear expansion of samarium can be accounted for by the liquid drop model with deformations. (orig.)

99mTc-MIBI/123I-Na subtraction scanning for localized parathyroid adenoma in patients with asymptomatic/mild primary hyperparathyroidism

International Nuclear Information System (INIS)

Tanaka, Yuji; Funahashi, Hiroomi; Imai, Tsuneo

1996-01-01

Primary hyperparathyroidism is most commonly detected as a mild elevation of the serum calcium concentration. In the present study, the utility of 99m Tc-methoxyisobutylisonitrile (MIBI) imaging before initial surgery was evaluated for localizing abnormal parathyroid glands in patients with asymptomatic and mild primary hyperparathyroidism. The results were compared with those of thallium-technetium subtraction scanning (TTSS). 99m Tc-MIBI/ 123 I-Na subtraction scanning was performed in 11 patients, and TTSS was performed in 10 of them. The sensitivity was 100% and the positive predictive value was 92% for 99m Tc-MIBI/ 123 I-Na, while the sensitivity was 50% and the positive predictive value was 100% for TTSS. The smallest gland detected weighed 85 mg in 99m Tc-MIBI/ 123 I-Na, and 570 mg in TTSS. There was a difference between the median weight of adenomas which were detected by 99m Tc-MIBI/ 123 I-Na (754 mg), and those which were detected by TTSS (1,195 mg). These results suggest that TTSS parathyroid scintigraphy could give way to 99m Tc-MIBI/ 123 I-Na parathyroid scintigraphy for improved detection of low-weight abnormal parathyroid glands. (author)

InP and InAs nanowires hetero- and homojunctions: energetic stability and electronic properties.

Science.gov (United States)

Dionízio Moreira, M; Venezuela, P; Miwa, R H

2010-07-16

We performed an ab initio total energy investigation, within the density functional theory, of the energetic stability and the electronic properties of hydrogenated InAs/InP nanowire (NW) heterojunctions, as well as InAs and InP homojunctions composed of different structural arrangements, zinc-blend (zb) and wurtzite (w). For InAs/InP NW heterojunctions our results indicate that w and zb NW heterojunctions are quite similar, energetically, for thin NWs. We also examined the robustness of the abrupt interface through an atomic swap at the InAs/InP interface. Our results support the formation of abrupt (non-abrupt) interfaces in w (zb) InAs/InP heterojunctions. Concerning InAs/InP NW-SLs, our results indicate a type-I band alignment, with the energy barrier at the InP layers, in accordance with experimental works. For InAs or InP zb/w homojunctions, we also found a type-I band alignment for thin NWs, however, on increasing the NW diameter both InAs and InP homojunctions exhibit a type-II band alignment.

InP and InAs nanowires hetero- and homojunctions: energetic stability and electronic properties

International Nuclear Information System (INIS)

Dionizio Moreira, M; Venezuela, P; Miwa, R H

2010-01-01

We performed an ab initio total energy investigation, within the density functional theory, of the energetic stability and the electronic properties of hydrogenated InAs/InP nanowire (NW) heterojunctions, as well as InAs and InP homojunctions composed of different structural arrangements, zinc-blend (zb) and wurtzite (w). For InAs/InP NW heterojunctions our results indicate that w and zb NW heterojunctions are quite similar, energetically, for thin NWs. We also examined the robustness of the abrupt interface through an atomic As↔P swap at the InAs/InP interface. Our results support the formation of abrupt (non-abrupt) interfaces in w (zb) InAs/InP heterojunctions. Concerning InAs/InP NW-SLs, our results indicate a type-I band alignment, with the energy barrier at the InP layers, in accordance with experimental works. For InAs or InP zb/w homojunctions, we also found a type-I band alignment for thin NWs, however, on increasing the NW diameter both InAs and InP homojunctions exhibit a type-II band alignment.

High uniformity of self-organized InAs quantum wires on InAlAs buffers grown on misoriented InP(001)

International Nuclear Information System (INIS)

Wang Yuanli; Jin, P.; Ye, X.L.; Zhang, C.L.; Shi, G.X.; Li, R.Y.; Chen, Y.H.; Wang, Z.G.

2006-01-01

Highly uniform InAs quantum wires (QWRs) have been obtained on the In 0.5 Al 0.5 As buffer layer grown on the InP substrate 8 (convolutionsign) off (001) towards (111) by molecular-beam epitaxy. The quasi-periodic composition modulation was spontaneously formed in the In 0.5 Al 0.5 As buffer layer on this misoriented InP (001). The width and period of the In-rich bands are about 10 and 40 nm, respectively. The periodic In-rich bands play a major role in the sequent InAs QWRs growth and the InAs QWRs are well positioned atop In-rich bands. The photoluminescence (PL) measurements showed a significant reduction in full width at half maximum and enhanced PL efficiency for InAs QWRs on misoriented InP(001) as compared to that on normal InP(001)

Determination of standard molar Gibbs energy of formation of Sm6UO12(s)

International Nuclear Information System (INIS)

Sahu, Manjulata; Dash, Smruti

2015-01-01

The standard molar Gibbs energies of formation of Sm 6 UO 12 (s) have been measured using an oxygen concentration cell with yttria stabilized zirconia as solid electrolyte. Δ f G o m (T) for Sm 6 UO 12 (s) has been calculated using the measured and required thermodynamic data from the literature. The calculated Gibbs energy expression in the temperature range 899 to 1127 K can be given as: Δ f G o m (Nd 6 UO 12 , s,T)/(±2.3) kJ∙ mol -1 = -6681 +1.099 (T/K) (899-1127 K)(T/K). (author)

Electrical and Plasmonic Properties of Ligand-Free Sn(4+) -Doped In2 O3 (ITO) Nanocrystals.

Science.gov (United States)

Jagadeeswararao, Metikoti; Pal, Somnath; Nag, Angshuman; Sarma, D D

2016-03-03

Sn(4+) -doped In2 O3 (ITO) is a benchmark transparent conducting oxide material. We prepared ligand-free but colloidal ITO (8 nm, 10 % Sn(4+) ) nanocrystals (NCs) by using a post-synthesis surface-modification reaction. (CH3 )3 OBF4 removes the native oleylamine ligand from NC surfaces to give ligand-free, positively charged NCs that form a colloidal dispersion in polar solvents. Both oleylamine-capped and ligand-free ITO NCs exhibit intense absorption peaks, due to localized surface plasmon resonance (LSPR) at around λ=1950 nm. Compared with oleylamine-capped NCs, the electrical resistivity of ligand-free ITO NCs is lower by an order of magnitude (≈35 mΩ cm(-1) ). Resistivity over a wide range of temperatures can be consistently described as a composite of metallic ITO grains embedded in an insulating matrix by using a simple equivalent circuit, which provides an insight into the conduction mechanism in these systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystal-phase intergradation in InAs nanostructures grown by van der Waals heteroepitaxy on graphene

Science.gov (United States)

Choi, Ji Eun; Yoo, Jinkyoung; Lee, Donghwa; Hong, Young Joon; Fukui, Takashi

2018-04-01

This study demonstrates the crystal-phase intergradation of InAs nanostructures grown on graphene via van der Waals epitaxy. InAs nanostructures with diverse diameters are yielded on graphene. High-resolution transmission electron microscopy (HR-TEM) reveals two crystallographic features of (i) wurtzite (WZ)-to-zinc blende (ZB) intergradation along the growth direction of InAs nanostructures and (ii) an increased mean fraction of ZB according to diameter increment. Based on the HR-TEM observations, a crystal-phase intergradation diagram is depicted. We discuss how the formation of a WZ-rich phase during the initial growth stage is an effective way of releasing heterointerfacial stress endowed by the lattice mismatch of InAs/graphene for energy minimization in terms of less in-plane lattice mismatching between WZ-InAs and graphene. The WZ-to-ZB evolution is responsible for the attenuation of the bottom-to-top surface charge interaction as growth proceeds.

Facile in-situ reduction: Crystal growth and magnetic studies of reduced vanadium (III/IV) silicates CaxLn1-xVSiO5 (Ln = Ce-Nd, Sm-Lu, Y)

Science.gov (United States)

Abeysinghe, Dileka; Smith, Mark D.; Morrison, Gregory; Yeon, Jeongho; zur Loye, Hans-Conrad

2018-04-01

A series of lanthanide containing mixed-valent vanadium (III/IV) silicates of the type CaxLn1-xVSiO5 (Ln = Ce-Nd, Sm-Lu, Y) was synthesized as high quality single crystals from a molten chloride eutectic flux, BaCl2/NaCl. Utilizing Ca metal as the reducing agent, an in-situ reduction of V5+ to V3+/4+ as well as of Ce4+ to Ce3+ was achieved. The structures of 14 reported isostructural compounds were determined by single crystal X-ray diffraction. They crystallize in the tilasite (CaMgAsO4F) structure type in the monoclinic space group C2/c. The extended structure contains 1D chains of VO6 octahedra that are connected to each other via SiO4 groups and (Ca/Ln)O7 polyhedra. The magnetic susceptibility and the field dependent magnetization data were measured for CaxLn1-xVSiO5 (Ln = Ce-Nd, Sm, Gd-Lu, Y), and support the existence of antiferromagnetic behavior at low temperatures.

Optical properties of Sm3+ -doped TeO2sbnd WO3sbnd GeO2 glasses for solid state lasers

Science.gov (United States)

Subrahmanyam, T.; Gopal, K. Rama; Suvarna, R. Padma; Jamalaiah, B. Chinna; Rao, Ch Srinivasa

2018-03-01

Sm3+ -doped oxyfluoride tellurite-tungsten (TWGSm) glasses were prepared by conventional melt quenching method. The optical properties were investigated through photoluminescence excitation, emission and luminescence decay analysis. The optical band gap energy was determined as ∼3.425 eV for 1.0 mol% of Sm3+ -doped TWGSm glass. Upon 404 nm excitation, the TWGSm glasses emit luminescence through 4G5/2 → 6H5/2 (563 nm), 4G5/2 → 6H7/2 (600 nm), 4G5/2 → 6H9/2 (645 nm) and 4G5/2 → 6H11/2 (705 nm) transitions. The Judd-Ofelt analysis was performed using absorption spectrum and obtained radiative parameters were used to estimate the laser characteristics of present glasses. The concentration of Sm3+ has been optimized as 1.0 mol% for efficient luminescence. The luminescence decay of 4G5/2 emission level was studied by monitoring the emission and excitation wavelengths at 600 and 404 nm, respectively. The experimental lifetime of 4G5/2 level was decrease with increase of Sm3+ concentration. The 1.0 mol% of Sm3+ -doped TWGSm glass could be the best choice for solid state visible lasers to emit orange luminescence.

3D coordination polymers with nitrilotriacetic and 4,4'-bipyridyl mixed ligands: structural variation based on dinuclear or tetranuclear subunits assisted by Na-O and/or O-H...O interactions.

Science.gov (United States)

Lü, Xing-Qiang; Jiang, Ji-Jun; Chen, Chun-Long; Kang, Bei-Sheng; Su, Cheng-Yong

2005-06-27

The reactions of Cu(II) with the mixed nitrilotriacetic acid (H3NTA) and 4,4'-bipyridyl (4,4'-bpy) ligands in different metal-to-ligand ratios in the presence of NaOH and NaClO4 afforded two complexes, Na3[Cu2(NTA)2(4,4'-bpy)]ClO4 x 5H2O (1) and [Cu2(NTA) (4,4'-bpy)2]ClO4 x 4H2O (2). The two complexes have been characterized by elemental analysis, IR, XRD, and single-crystal X-ray diffraction. 1 contains a basic doubly negatively charged [Cu2(NTA)2(4,4'-bpy)]2- dinuclear unit which was further assembled via multiple Na-O and O-H...O interactions into a three-dimensional (3D) pillared-layer structure. 2 features a two-dimensional (2D) undulated brick-wall architecture containing a basic doubly positively charged [Cu4(NTA)2(4,4'-bpy)2]2+ tetranuclear unit. The 2D network possesses large cavities hosting guest molecules and was further assembled via O-H...O hydrogen bonds into a 3D structure with several channels running in different directions.

Ligand identification using electron-density map correlations

International Nuclear Information System (INIS)

Terwilliger, Thomas C.; Adams, Paul D.; Moriarty, Nigel W.; Cohn, Judith D.

2007-01-01

An automated ligand-fitting procedure is applied to (F o − F c )exp(iϕ c ) difference density for 200 commonly found ligands from macromolecular structures in the Protein Data Bank to identify ligands from density maps. A procedure for the identification of ligands bound in crystal structures of macromolecules is described. Two characteristics of the density corresponding to a ligand are used in the identification procedure. One is the correlation of the ligand density with each of a set of test ligands after optimization of the fit of that ligand to the density. The other is the correlation of a fingerprint of the density with the fingerprint of model density for each possible ligand. The fingerprints consist of an ordered list of correlations of each the test ligands with the density. The two characteristics are scored using a Z-score approach in which the correlations are normalized to the mean and standard deviation of correlations found for a variety of mismatched ligand-density pairs, so that the Z scores are related to the probability of observing a particular value of the correlation by chance. The procedure was tested with a set of 200 of the most commonly found ligands in the Protein Data Bank, collectively representing 57% of all ligands in the Protein Data Bank. Using a combination of these two characteristics of ligand density, ranked lists of ligand identifications were made for representative (F o − F c )exp(iϕ c ) difference density from entries in the Protein Data Bank. In 48% of the 200 cases, the correct ligand was at the top of the ranked list of ligands. This approach may be useful in identification of unknown ligands in new macromolecular structures as well as in the identification of which ligands in a mixture have bound to a macromolecule

Effects of Zn doping on crystal structure, Raman spectra and superconductivity of SmBa2Cu3O7−δ systems

International Nuclear Information System (INIS)

Xue, Renzhong; Dai, Haiyang; Chen, Zhenping; Li, Tao; Xue, Yuncai

2013-01-01

Highlights: ► Zn ions affect significantly the lattice parameter of the SmBa 2 Cu 3−x Zn x O 7−δ (SBCZO) ceramic. ► Raman spectra of SBCZO samples obviously change with increasing Zn doping content. ► The superconducting transition temperature decreases with increasing Zn content. ► Induced lattice disorder and local magnetic moment in CuO 2 planes are related to suppression of T c . -- Abstract: Polycrystalline SmBa 2 Cu 3−x Zn x O 7−δ (SBCZO) (x = 0.0–0.4) samples are prepared by the usual solid-state reaction technique. The effects of Zn doping on the structure, the grain morphology, Raman spectra and electronic transport properties of SBCZO systems have been investigated. The orthorhombic structure of the samples does not change remarkably. The samples become denser and grain boundary becomes unclear with the increase of Zn content. Raman spectra exhibit different features with increasing Zn content which shows that Zn ions act as strong scattering centers to the charge carriers in the CuO 2 planes, enhance the disorder of the CuO 2 planes and increase oxygen depletion in Cu-O chains. The measurements of the resistivity show that the superconducting transition temperature T c decreases rapidly and the superconducting transition width increases gradually with increasing Zn contents. Furthermore, the changes of the samples’ normal state resistivity from metallic to semi-conducting behavior show the increase of heterogeneities with increasing Zn content which causes inter-grain or intra-grain disorders. All the results suggest that lattice disorder in the CuO 2 planes, the oxygen content change in Cu-O chains and local weak superconductivity regions due to the substitution of Zn for Cu are related to the suppression of T c in the SBCZO systems