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superconductivity of Nd_(1.85)Ce_(0.15)CuO_(4-y) by Electrochemical Oxidation

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Chinese Physics Letters 2000年第8期17卷 601-602页

作者： CHEN Ling CHE GUANG-CAN LI Hong DONG Cheng ZHOU Fang Huang Yu-zhen ZHAO Zhong-Xian National Laboratory for superconductivity Institute of PhysicsChinese Academy of SciencesBeijing 100080 National Laboratory for Solid State Ionics Institute of PhysicsChinese Academy of SciencesBeijing 100080

superconductivity of n-type superconductor Nd_(1.85)Ce_(0.15)CuO_(4-y)(NCCO)by electrochemical oxidation is re ported for the first time and the cyclic voltammogram curve for NCCO as working electrode is *** vestigations indicate that after oxidation,superconductivity of NCCO is improved:Tc is raised from 20 K up to 26 K,the superconducting volume fraction is increased *** valence electronic states of oxygen and copper in NCCO are studied by x-ray photoelectron *** is found that the Cu-2_(ps/2)peak shifts to the higher binding energy side about 0.4 e V,which indicates that the valence-state of copper ions is risen up after *** results imply that hole-carriers exist in n-type superconductor.

关键词： spectroscopy. copper Oxidation

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

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

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

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

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

superconductivity at 36 K in gadolinium-arsenide oxides GdO_(1-x)F_xFeAs

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 719-722页

作者： CHENG Peng, FANG Lei, YANG Huan, ZHU XiYu, MU Gang, LUO HuiQian, WANG ZhaoSheng & WEN HaiHu National Laboratory for superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China National Laboratory for superconductivity Institute of Physics Chinese Academy of Sciences Beijing China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China

In this paper we report the fabrication and superconducting properties of GdO1-xFxFeAs. It was found that when x is equal to 0.17, GdO0.83F0.17FeAs is a su-perconductor with the onset transition temperature Tcon ≈ 36.6 K. Resistivity anomaly near 130 K was observed for all samples up to x = 0.17, and such a phenomenon is similar to that of LaO1-xFxFeAs. Hall coefficient indicates that GdO1-xFxFeAs is conducted by electron-like charge carriers.

关键词： iron-based superconductor high-temperature superconductor

superconductivity in Ti-doped iron-arsenide compound Sr_4Cr_(0.8)Ti_(1.2)O_6Fe_2As_2

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Science China(Physics,Mechanics & Astronomy) 2009年第12期52卷 1876-1878页

作者： ZHU XiYu,HAN Fei,MU Gang,CHENG Peng,SHEN Bing,ZENG Bin & WEN HaiHu National Laboratory for superconductivity,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China Beijing Na-tional Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China National Laboratory for superconductivity Institute of Physics Chinese Academy of Sciences Beijing China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China

superconductivity was achieved in Ti-doped iron-arsenide compound Sr4Cr0.8Ti1.2O6Fe2As2 (abbreviated as Cr-FeAs-42622). The X-ray diffraction measurement shows that this material has a layered structure with the space group of P4/nmm,and with the lattice constants a = b = 3.9003  and c = 15.8376 . Clear diamagnetic signals in ac susceptibility data and zero-resistance in resistivity data were detected at about 6 K,confirming the occurrence of bulk superconductivity. Meanwhile we observed a supercon-ducting transition in the resistive data with the onset transition temperature at 29.2 K,which may be induced by the nonuniform distribution of the Cr/Ti content in the FeAs-42622 phase.

关键词： iron-based superconductor high-temperature superconductor Perovskite

superconductivity and normal state magnetoresistance in superconducting FeSe:Sb

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Science China(Physics,Mechanics & Astronomy) 2010年第7期53卷 1180-1186页

作者： CHU HaiFeng LI Jie LI Shao ZHANG Yu WANG Ning WANG Jia GAO YanLi DENG Hui SUN XiaoSong ZHENG DongNing National Laboratory for superconductivity Institute of Physics and National Laboratory for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100190China College of Materials Science and Engineering Sichuan UniversityChengdu 610064China

We prepared a series of β-FeSe samples with a nominal composition of Fe1.11Se1-xSbx(0≤x≤0.5).The X-ray diffraction,transport and magnetic measurements were performed on these samples to investigate the structure,the superconducting properties and the normal state transport and magnetic *** the X-ray diffraction data suggested that Sb atoms were not incorporated into the β-FeSe phase,the transport data showed observable changes of superconductivity,normal state resistivity and *** was represented by the increase in the superconducting transition temperature and the upper critical ***,for the samples with a low level of Sb content,a clear decrease of the normal state resistivity and a substantial increase of the residual resistance ratio were ***,the samples showed a significant increase of the normal state magnetoresistance that appeared not to follow the Kohler's *** results were discussed in the frame of reduction of excess Fe at interstitial sites of β-FeSe.

关键词： iron-based superconductor superconductivity magnetoresistance