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91.
本文研究了Nd-Fe(Co,Al,Ga)-B永磁合金的磁性能并且用Mssbauer谱仪等手段研究了Al,Co,Ga诸原子在上述合金中的晶位占据。选用粉末冶金方法研制出上述实用磁体,其磁性能是:Br=1.19T,jHG=1130kA/m,(BH)max=262kJ/m3,α(B,)=0.04％/℃,Tc=450—550℃。研究结果发现Al原子主要占据j2晶位;Ga原子优先占据j2和k2晶位;Co原子优先占据8 j2,16k2晶位。Co在四方相中占据上述晶位是造成永磁合金居里温度上升的原因。 相似文献
92.
The a-axis oriented YBa2Cu3Ox(YBCO) thin films could be grown on (100) SrTiO3(STO) substrates with STO buffer layers by dc and rf magnetron sputtering either by low-ering the deposition temperature, or by using a self-template technique. For the latter, the resistivity of the thin film at 290K along the substrate [001] direction is about four times larger than that in the [010] direction. The zero resistance temperatures Tc0 are 89 K in both directions. So high quality a-axis oriented YBCO thin films can be prepared by the self-template technique. Also the Tc0 increase monotonously with the reduction of the thickness of the YBCO seed layer. 相似文献
93.
In this paper, the preparation process of the tetragonal LaBaCaCu3O7-x (LBCCO) superconductor with Tc=84 K is repored. The superconductivity and structure of the LBCCO superconducting phase are investigated by means of X-ray diffraction (XRD), transmission electron microscope(TEM) and superconductivity measurements, The results indicate that the superconducting phase with Tc=82K in the LBCCO system has a tetragonal structure with a=0.3966nm, c=l.1838nm and space group P4/mmm. About 50% of the Ca and La atoms are located in 1d sites (i.e. Y site in the YBCO structure). It is confirmed that there is in fact no orthorhombic to tetragonal transition in this material. The relationship between the oxygen content and Tc is also presented. 相似文献
94.
This paper presents three different kinds of infrared (IR) spectra of oxide materials. The first one is the IR reflection spectra of Ti2Ba2Ca2Cu3O10 superconducting film at the incident angles 7°, 12° and 30°. The second one is the IR spectra of nonsuperconducting ceramic materials YBa2Cu3O6 and PrBa2Cu3O7. The third one is the IR spectra of superconductor YBa2Cu3O7-δ and of its film with the c-axis perpendicular to the film plane, as well as the changes in the spectra of these materials after annealing at different temperatures. It is found that in the spectra of high-Tc oxide superconductor, only the phonon modes along c-axis can be observed while the modes in a-b plane are absent. But in the spectra of nonsuperconductors the modes in a-b plane can be observed, particularly in the absorption spectra of the semiconductor YBa2Cu3O6, all eleven allowed IR active modes have been detected. We suggest that the above experimental phenomena may result from the fact that the phonon modes vibrating in the a-b plane of the high-Tc oxide superconducting materials are almost screened by the free carriers which can move only in a-b plane. 相似文献
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98.
Single crystal growth and characterizations of iron arsenide superconductor BaFe2-xNixAs2（0.0≤x≤0.12） 
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下载免费PDF全文 A series of big single crystals of BaFeFe2-xNixAs2 have been prepared by the FeAs self-flux method,with nominal nickel doping x = 0--0.12. The dimensions of thecleaved crystals are over 10~mm along ab plane and ～ 2~mmin maximum along the c direction. The measurements of x-raydiffraction, electrical resistance and magnetic property are carriedout on the crystals. For the undoped parent compoundBaFe2As2, both resistance and magnetization data displayan anomaly associated with spin density wave and/or structural phasetransition, with the transition temperatures at ～ 138~K. ForNi-doped BaFe2-xNixAs2 crystals, thesuperconducting critical temperature Tc ranges from 4.3~Kfor x=0.06 sample to 20~K for the optimally doped x=0.10crystal. 相似文献
99.
在超高真空（１０￣（－７）ｐａ）条件下用双源蒸镀法在单晶Ｓｉ和ＮａＣｌ衬底上制备了一系列Ｆｅ、Ｄｙ原子配比的成分调制多层膜。用卢瑟福背散时（ＲＢＳ）和俄歇能谱（ＡＥＳ）分析成分沿厚度的分布，并用掠入射ｘ射线衍射分析（ＸＲＤ）离子束混合前后的结构。结果表明，随Ａｒ离子剂量的增加混合量增加，在１０￣（１７）Ａｒ／ｃｍ￣２达到均匀混合，同时混合还诱发非晶化，平均成分约为Ｆｅ＿（６０）Ｄｙ＿（４０）的多晶膜完全转变为非晶态，Ｆｅ含量高于６０ａｔ％，有残余ｂｃｃ－Ｆｅ，反之，Ｄｙ含量高于４０ａｔ％，有残余ｈｃｐ－Ｄｙ． 相似文献
100.
本文通过透射电子显微镜观察、超导电性测量、Ｘ射线衍射、氧含量测定等手段研究了淬火和制备工艺对Ｂｉ（Ｐｂ）－２２２３相超导体超导电性、氧含量和微结构的影响．结果表明，随着淬火温度的提高，Ｔｃ（０）呈现一个不连续的变化，在１００－４００℃范围内，Ｔｃ（０）基本不变，在５００－６００℃，Ｔｃ（０）略有升高，在７５０℃．Ｔｃ（０）呈现一个极小值．在５００—６００℃淬火处理可以增加样品中的氧含量，具有Ｔｃ（０）近１１０Ｋ的Ｂｉ１．７Ｐｂ０．３Ｓｒ２Ｃａ２Ｃｕ３Ｏ１０＋６的最佳氧含量在δ＝０．１４—０．２９之间．在８００—８２０℃淬火处理可以改善样品晶粒间的弱连接状态，而样品的弱连接和微结构与阳离子和氧的组成及其制备工艺密切相关． 相似文献