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41.
T.T. Thuy 《Journal of solid state chemistry》2010,183(9):2154-2160
A water based cerium oxide precursor solution using nitrilo-tri-acetic-acid (NTA) and acetic acid as complexing agents is described in detail. This precursor solution is used for the deposition of epitaxial CeO2 layers on Ni-5at%W substrates by dip-coating. The influence of the complexation behavior on the formation of transparent, homogeneous solutions and gels has been studied. It is found that ethylenediamine plays an important role in the gelification. The growth conditions for cerium oxide films were Ar-5% gas processing atmosphere, a solution concentration level of 0.25 M, a dwell time of 60 min at 900 °C and 5-30 min at 1050 °C. X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM), pole figures and spectroscopic ellipsometry were used to characterize the CeO2 films with different thicknesses. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) was used to determine the carbon residue level in the surface of the cerium oxide film, which was found to be lower than 0.01%. Textured films with a thickness of 50 nm were obtained. 相似文献
42.
LIU Chi-Biao ZHAO Zhen YANG Xiang-Guang YE Xing-Kai WU Yue Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun Jilin China 《中国化学》1996,14(6):516-524
Superconductor mixed oxides were often used as catalysts at higher temperature in gas phase oxidations, and considered not suitable for lower temperature reactions in the liquid-solid phase; here the catalysis of YBa2Cu3O7+x and Y2BaCuO5+x in the phenol hydroxylation at lower temperature with H2O2 as oxygen donor was studied, and found that the superconductor YBaCu3O7±x has no catalytic activity for phenol hydroxylation, but Y2BaCuO5±x does, even has better catalytic activity and stability than most previously reported ones. With the studies of catalysis of other simple metal oxides and perovskite-like mixed oxides, a radical substitution mechanism is proposed and the experimental facts are explained clearly, and draw a conclusion that the perovskite-like mixed oxides with (AO)(ABO3) and (AO)2(ABO3) structure have better catalytic activity than the simple per-ovskite oxides with (ABO3)3 structure alone, and (AO) structure unit is the key for the mixed oxides to have the phenol hydroxylation activity. 相似文献
43.
IntroductionTheresistivityρ(T)ofsuperconductorsisdescribedasfollows[1]:κ(T<Tc)ρ(T)=ρ∥=AT(T>Tc,(abplane)ρ⊥=BT(T>Tc,(caxis)(1)HereA<B.Expression(1)accuratelysummariesuptheresistivitythroughmeasuringtheanisotropyconductivityofasinglecrystalofYBa2Cu3O(7-… 相似文献
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P. Calvani S. Lupi M. Ortolani L. Baldassarre C. Mirri R. Sopracase U. Schade Y. Takano T. Tamegai 《Infrared Physics & Technology》2008,51(5):429-432
We show how coherent synchrotron radiation (CSR) allows one to measure the slight increase in the reflectivity of a BCS superconductor as it is cooled below Tc. In fact, by CSR coupled to a conventional interferometric apparatus, one can obtain a signal-to-noise ratio 103 in the sub-THz range. We apply this technique to the measurement of the optical gap in boron-doped diamond and in CaAlSi, a superconductor isostructural to MgB2. In the latter compound we are also able to determine a slight anisotropy between the gap in the hexagonal planes and that along the orthogonal c axis. 相似文献
47.
Layer-structured crystals of β-MNCl (M=Zr,Hf) could be electron-doped by reactions with different alkali metal azides RN3 (R=Li,Na,K,Rb), and controlling the amounts with the molar ratios of azides to β-MNCl. All the prepared compounds show superconductivity with the same transition temperatures at 13.5 K for β-ZrNCl and 23.5 K for β-HfNCl. However the different alkali metal azides RN3 show different reactivity with β-MNCl, and the properties of the products such as superconducting fractions, the lattice constant, and stability against thermal or air, are very dependent on the kinds of alkali metals used. Based on the the results of SQUID measurements, it can be concluded that NaN3 and KN3 are the best react agents for β-ZrNCl and β-HfNCl respectively. 相似文献
48.
Abstract High-pressure neutron-diffraction experiments using the time-of-flight (TOF) method are presented. We first introduce the helium-gas pressure system at Argonne's Intense Pulsed Neutron Source (IPNS) with the Special Environment Powder Diffractometer (SEPD). The results for TIBa2CuO6+8, and La2?x, Srx, CuO4–8 are briefly reviewed. We then introduce the present situation in Japan. We have been developing a high-pressure system on high-resolution powder diffractometer (HRP) which was much improved recently and renamed VEGA at KEK. The best resolution of 0.45% was obtained at VEGA. The preliminary results for YBa2, Cu4O8, and HgBa2, CuO4+8, are presented and compared with the SEPD data. 相似文献
49.
通过对Y_(0.9)Eu_(0.1)Ba_2Cu_3O_(7-y)样品Jc(H)关系以及磁通蠕动行为的系统研究,发现:当T>40K时,其Jc值随磁场的增大呈现非单调变化.作者认为,Jc(H)的这种非单调性起源于集体磁通蠕动的维度转变. 相似文献
50.
中国第一组超导电缆并网运行试验 总被引:1,自引:0,他引:1
中国第一组超导电缆于2004年4月19日在昆明普吉220kV变电站并网成功,并开始向用户供电.本文详细地描述了该电缆并网前后部分试验,如:超导电缆直流电阻测量、超导电缆通流试验、温度、压力和流量的在线监测、绝缘电阻和介损损耗测试等.所有试验结果均显示该电缆技术指标达到实际并网运行要求.超导电缆并网运行成功,标志着我国已经掌握了超导电缆开发能力.本文所提出的超导电缆并网运行试验方法和试验结果为我国进一步开发超导电缆提供了宝贵的经验. 相似文献