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Morphological evolution of CdS films prepared by chemical bath deposition

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Rare Metals 2013年第4期32卷 380-389页

作者： Xing-Yu Peng Hong-Wei Gu Teng Zhang Fei Qu Fa-Zhu Ding Hong-Yan Wang Key laboratory of Applied superconductivity Institute of Electrical Engineering Chinese Academy of Sciences

In this article, the growth process of chemical bath deposited CdS films was systematically investigated. The structural, optical, and morphological properties were investigated by X-ray diffraction （XRD）, transmission electron microscope （TEM）, UV-Vis spectrophotometer, scanning electron microscope （SEM）, respectively. CdS nanocubes with size of less than 500 nm and nanocrystal-lites with diameter of less than 5 nm forming in reaction solution are observed. According to the TEM results and the SEM morphological evolution of CdS films, a crystal-lite-by-crystallite growth mechanism is proposed to eluci-date the growth process of chemical bath deposited CdS films based on the present growth mechanism.

关键词： CdS Chemical bath deposition Growthmechanism Crystallite-by-crystallite

Superconducting magnetic energy storage for stabilizing grid integrated with wind power generation systems

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 400-411页

作者： Poulomi MUKHERJEE V. V. RAO Applied superconductivity laboratory Cryogenic Engineering Centre Indian Institute of TechnologyKharagpur

Due to the interconnection of various renewable energies and adaptive technologies, voltage quality and frequency stability of modern power systems are becoming erratic. Superconducting magnetic energy storage(SMES),for its dynamic characteristic, is very efficient for rapid exchange of electrical power with grid during small and large disturbances to address those *** addition,SMES plays an important role in integrating renewable sources such as wind generators to power grid by controlling output power of wind plant and improving the stability of power *** application of SMES in various power system operations depends on the proper location in the power system, exact energy and power ratings and appropriate controllers. In this paper, an effort is given to explain SMES device and its controllability to mitigate the stability of power grid integrated with wind power generation systems.

关键词： Power fluctuation Power quality Low voltage ride through Superconducting magnetic energy storage Superconductors Wind energy

Synthesis, characterization and thermostability of tris(2,2,6,6-tetramethyl-3,5- heptanedionato)yttrium(Ⅲ)

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Journal of Rare Earths 2012年第10期30卷 1041-1047页

作者：张腾古宏伟丁发柱屈飞戴少涛 Key laboratory of Applied superconductivity Institute of Electrical EngineeringChinese Academy of Sciences

The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high temperature superconductor YBa2Cu3O7-δ （YBCO） preparation. In this technique, the purity, evaporation characteristics and thermostability of adopted precursors will de- cide the quality and reproducible results of YBCO film. In the present report, tris（2,2,6,6-tetramethyl-3,5-heptanedionato）yttrium（III）（Y（TMHD）3） was synthesized by the interaction of yttrium nitrate hydrate with TMHD in methanol solution, and its structure was identified by FTIR, 1H NMR, 13C NMR and EI-MS spectroscopy. Subsequently, the thermal property and the kinetics of decomposition were system- atically investigated by non-isothermal thermogravimetric analysis methods （TGA） at different heating rates in streams of N2, and the average apparent activation energy of evaporation process was evaluated by the Ozawa, Kissinger and Friedman methods. The possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 88.9 kJ/mol.

关键词： Y(TMHD)3 metal-organic chemical vapor deposition (MOCVD) synthesis thermostability rare earths

Influence of oxygen pressure on critical current density and magnetic flux pinning structures in YBa_2 Cu_3 O_(7-x) fabricated by chemical solution deposition

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Chinese Physics B 2011年第2期20卷 478-481页

作者：丁发柱古宏伟张腾戴少涛肖立业 Key laboratory of Applied superconductivity Institute of Electrical EngineeringChinese Academy of Sciences

This paper studies the effect of oxygen partial pressure on the fabrication of YBa2Cu307-x films on （00/） LaAIO3 substrates by metalorganic deposition using trifluoroacetates （TFA-MOD）. As the oxygen partial pressure increases to 1500 Pa, a great increase in the superconducting properties is observed at high magnetic fields parallel to the YBCO c axis. The cross-sectional transmission electron microscope images show that a high density of stacking faults in the size range of 10-15 nm may act as flux pinning centres to enhance the critical current density of the YBCO films

关键词： YBCO oxygen pressure stacking fault TFA-MOD

Synthesis, characterization, and thermostability of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)barium(Ⅱ)

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Rare Metals 2013年第1期32卷 67-74页

作者： Teng Zhang Hong-Wei Gu Fa-Zhu Ding Fei Qu Shao-Tao Dai Key laboratory of Applied superconductivity Institute of Electrical Engineering Chinese Academy of Sciences

The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high-tem- perature superconductor YBa2Cu307_6（YBCO） preparation. In this technique, it is a challenge to obtain barium precursors with high volatility. In addition, the purity, evaporation characteristics, and thermostability of adopted precursors in whole process will decide the quality and reproducible results of YBCO film. In the present report, bis（2,2,6,6-tetramethyl- 3,5-heptanedionato）barium（II）（Ba（TMHD）2） was synthe- sized, and its structure was identified by PTIR, 1H NMR, 13C NMR, and ESI-MS spectroscopy. Subsequently, the thermal properties and the kinetics of decomposition were systemati- cally investigated by nonisothermal thermogravimetric anal- ysis methods. Based on the average apparent activation energy evaluated by the Ozawa, Kissinger, and Friedman methods, the volatilization process was discussed, and all results show that Ba（TMHD）2 is unstable and highly sensitive to the change of temperature during the whole evaporation process. There- fore, it is very important to choose suitable volatilization technology and conditions for avoiding Ba（TMHD）2 break- down （or thermal aging） during MOCVD process. Subse- quently, the possible conversion function is estimated through the Coats-Redfern method to characterize the evaporation patterns and follows a phase boundary reaction mechanism by the contracting surface equation with average activation energy of 118.7 ***1-1.

关键词： Ba(TMHD)2 Metal-organic chemical vapordeposition (MOCVD) Synthesis Thermostability

Rapid preparation of Mg(B_(1-x)C_x)_2 superconductor using hybrid microwave method

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Chinese Physics B 2008年第3期17卷 1124-1129页

作者：郭娟董成高红闻海虎杨立红曾富陈红 National laboratory for superconductivity Institute of PhysicsChinese Academy of SciencesBeijing & National Laboratory for Condensed Matter Physics

The crystal structure and the superconductivity for samples Mg（B1-xCx）2 （0〈 x 〈0.09） prepared by a hybrid microwave synthesis have been investigated. The starting material B10C is also obtained by using the microwave method. The carbon can distribute uniformly in the Mg（B1-xCx）2 samples because boron and carbon are mixed on an atomic scale in the staring material B10C. The dependences of both lattice parameters and superconducting transition temperature Tc on carbon content accord with those reported in the literature. The upper critical field He2 at 20 K can be enhanced from about 4.3 T for x = 0 to 10 T for x = 0.05. The critical current density Jc of Mg（B0.95 C0.05）2 is 1.05×10^4 A/cm^2 at 20 K and 1 T.

关键词： microwave synthesis MgB2 superconductor carbon doping

Temperature dependent phonon modes and ionicity of LiGaO_2 single crystal

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Chinese Physics B 2008年第9期17卷 3313-3317页

作者：马继云方煦 M. Kamran 赵华英毕聪志赵柏儒邱祥冈 National laboratory for superconductivity Institute of PhysicsChinese Academy of Sciences and Beijing National Laboratory for Condensed Matter Physics

This paper reports that polarized far-infrared reflectivity measurements have been done on LiGaO2 single crystal along two crystalline taxes at different temperatures. The temperature dependent frequencies of the longitudinal and transverse optical phonon have been obtained from the real part of optical conductivity and the loss function respectively. A small Drude component is observed at frequency below 300 cm^-1 which could arise from Li ions or oxygen deficiencies. The ionicity of LiGaO2 has been studied from the analysis of the Born effective charge of different ions.

关键词： infrared optical conductivity LiGaO2 single crystal phonon

Structural and physical properties of undoped and nickel-doped BaFe_(2-x)Ni_xAs_2(x = 0,0.04) single crystals

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Chinese Physics B 2010年第8期19卷 469-473页

作者：李正才陆伟董晓莉周放赵忠贤 National laboratory for superconductivity Institute of Physics and Beijing National Laboratory for Condensed Matter PhysicsChinese Academy of Sciences

Single crystals of undoped and nickel-doped BaFe2-xNixAs2 （x = 0, 0.04） have been grown by FeAs self-flux method. The maximum dimension of the crystal is as large as - 1 cm along ab plane. The crystalline topography of a cleaved crystal surface is examined by scanning electron microscope （SEM）. By x-ray powder diffraction （XRD） experiments using pure silicon as an internal standard, precise unit cell parameters （tetragonal at room temperature） are determined： a = 3.9606（4） A^°. （1 A^°=0.1 nm）, c = 13.015（2） A^°. for BaFe1.96Ni0.04As2 and a = 3.9590（5） A^°, c = 13.024（1） A^°for BaFe2As2. DC magnetization and transport measurements are performed to check superconducting transition （Tc = 15 K for x = 0.04） and other subtle anomalies. For BaFe1.96Ni0.04As2 crystal, the resistance curve at normal state shows two distinct anomalies associated with spin and structure transitions, and its magnetization data above - 91 K exhibit a linear temperature dependence due to spin density wave （SDW） instability.

关键词： BaFe2-xNixAs2 single crystal superconductivity x-ray diffraction

Floating-zone growth and property characterizations of high-quality La_(2-x)Sr_xCuO_4 superconductor crystals

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Chinese Physics B 2009年第7期18卷 2893-2897页

作者：慎晓丽李正才申彩霞陆伟董晓莉周放赵忠贤 National laboratory for superconductivity Institute of Physics and Beijing National Laboratory for Condensed Matter PhysicsChinese Academy of Sciences

We have grown underdoped （х = 0.11, 0.12） and optimally doped （x = 0.16）La2-хSrхCuO4 single crystals by the traveling-solvent floating-zone *** order to prepare good quality cuprate crystals,we have made much effort to optimize the preparation *** example,we haveadopted the sol-gel route to prepare a highly fine and homogeneous La2-хSrхCuO4 precursor powder for fabricating a very dense ceramic feed rod used for the floating-zone growth,and we have also used quite a slow growth rate. The high quality of the grown crystals has been verified by double-crystal x-ray rocking curves,with the full-width-at-half-maximum being only 113-150 arcseconds, which are the best data reported so far for La2-хSrхCuO4 *** superconducting critical temperatures of the grown crystals are 30, 31 and 38.5 K for х = 0.11, 0.12 and 0.16 samples, respectively,according to magnetic measurements.

关键词： floating-zone crystal growth sol-gel chemistry x-ray rocking curves superconductivity