Structure properties for the superconductor MgCNi3 under high pressure with synchrotron radiation

The recent discovery of superconductivity at 39 K in the superconductor MgB2[1] shows that intermetallic compounds with simple structure types are worth serious reconsideration as sources of new superconducting mate-rials. Subsequent to this discovery, He et al. observed a new intermetallic superconductor MgCNi3[2] at about 8 K. The perovskite crystal structure for MgCNi3 is shown in Fig. 1, with the atomic positions: Mg: 1a (0,0,0), C: 1b (0.5,0.5,0.5) and Ni: 3c (0,0.5,0.5). This mater…     

Quasi-particle injection into YBa2Cu3O7-δ micro-bridge

The perspectives of fast three-terminal (3T) super- conducting devices with considerable gain have triggered many research activities on suppression of superconductivity; especially on that in high-Tc superconductors[1—3] and many achievements have been obtained. Unfortunately, certain factors such as current superposition and heating are overlooked in some experiments, thus leaving much room for improvement. With YBCO micro-bridges, we have looked at quasiparticle injections in the forms o…     

Space qualification mechanical tests of HTS filters for satellite application

High performance high-temperature superconducting （HTS） filters have been designed and constructed for satellite application. The filters are actually a superconducting integration of an 8-pole band-pass filter with an adjustable band-stop filter onto a single piece of LaAIO3 substrate （with dimension of 0.5x45x20 mm3）. Typical results of the filters, i.e., Filters A （made by YBCO） ＆ B （made by TBCCO） will be reported. The measured responses of Filter A showed excellent specifications, e.g., an insertion loss less than 0.1 dB, a return loss better than -22.5 dB in pass-band, band-edge steepness greater than 12 dB/MHz and out-of-band rejection at a certain band deeper than -110 dB. To satisfy the requirement of rocket launch and space operation, three filters of the above design have undergone mechanical environmental simulation tests for space qualification. Detailed analysis of the response curves of Filter B measured before and after the tests showed that no noticeable change in the performance can be found. All the filters passed the rigorous ground simulation tests, which is the first time in China for HTS devices and provided a solid foundation for satellite applications of high-temperature superconductors in the near future.     

超导体相变的热力学描述

本文从教学的角度,对超导体的相变问题用热力学理论作一些讨论。     

超导涡旋系统的非平衡态相变

利用三维各向异性XY模型和电阻分流结动力学,研究了较强钉扎势下第二类层状超导体涡旋系统的非平衡态相变.结果发现,平衡态的涡旋玻璃相可在电流驱动下转变为运动玻璃相.在低温下系统经历了三次相变:随电流的增加,系统首先从运动涡旋玻璃相转变为运动Bragg玻璃相,再转变为运动Smectic相,最后融化为运动液体相.     

(CuTe)O_3对YBa_2Cu_3O_y织构生长的影响

用熔融织构法生长YBa_2 Cu_3(CuTe)xOy 系列,实验结果表明,生长过程中(CuTe)O_3 的参与有助于YBa_2 Cu_3 Oy 织构的形成,Te 可能具有俘获O 的能力.     

单相和多相Y-Ba-Cu-O超导化合物的制备

本文报导单相和多相Y-Ba-Cu-O化合物超导体的制备工艺及其超导电性.X射线分析及电子显微镜观察表明,名义配比Y:Ba:Cu=1:2:3的样品为单相,其他配比成分的样品呈多相,但在一定配比范围内均呈现超导电性.它们的零电阻温度均在90K附近.