姜万涛
,
许战立
,
陈政
,
赵晓鹏
功能材料
通过纳米复合掺杂的方法,在BSCCO超导体中引入了均匀排布的纳米ZnO缺陷.研究并比较了不同掺杂方法对超导体性能以及ZnO在超导体中分布状态的影响.测试结果表明,不同掺杂方法所制备的样品均有明显的超导现象;经HRSEM表征,纳米复合掺杂所得样品中ZnO缺陷呈线状均匀排布,粒径约为100 nm.
关键词:
超导
,
纳米复合
,
掺杂
,
BSCCO
,
ZnO
周方兵
,
邹贵生
,
郭伟
,
吴爱萍
,
任家烈
,
白海林
,
宋秀华
低温物理学报
采用超导粉末作中间层对BSCCO带材进行连接是比较有效的方法.超导粉末中间层中Bi-2223超导相的含量影响着连接的效果,超导相含量为88.5%的中间层连接所得到的接头的连接效率比含量为55%的中间层连接的接头的连接效率高18个百分点.另外在超导粉末中间层中添加适量的金属Ag可以有效的降低中间层的熔点,增加中间层的粘性,减少连接的缺陷,提高连接的质量.
关键词:
BSCCO
,
中间层
,
扩散连接
Physica C-Superconductivity and Its Applications
The major limitations of Bi-system superconductor application are the intergrain weak links and weak flux pinning capability. In order to promote the practical application of Bi-system superconductor, effective flux pinning centers must be artificially introduced into HTS to enhance the flux pinning capability. With those goals, we have investigated the effects of nanometer-sized ZrO2 addition on flux pinning capability of the bulk Pb-doped Bi-2223 by using of X-ray diffraction (XRD), DC resistivity, rho, AC susceptibility, c, and magnetic hysteresis loops measurements. We have prepared samples by Bi,Bi1.8Pb0.4Sr2Ca2.2Cu3O10+y (nano-ZrO2)(x) with x range from 0 to 0.5. The results show that, with the increasing of x-, the T-c (onset) drops down gradually. However, the measurements of the critical current density, J(c), show that appropriate amount-doped nano-ZrO2 greatly enhance the values of J(c) under magnetic fields. According to the results of XRD patterns, there are slight reflection peaks of ZrO2-related nonsuperconducting compounds. It is believed that these nonsuperconducting ZrO2-related compounds act as effective flux pinning centers. (C) 2000 Elsevier Science B.V. All rights reserved.
关键词:
nano-ZrO particles;superconductivity;Pb-doped BSCCO;critical-current densities;microstructure;composites;wires
Ieee Transactions on Applied Superconductivity
The SEM observation on the surface morphologies of quenched Bi-2223/Ag tapes after various sintering time indicates that Bi-2223 grains nucleated on the partially melted Bi-2212 grains at the initial stage of reaction and some of them were in the form of twin grains. Then they grew into plate-like grains with the growth of the twin grains and the consumption of the mother Bi-2212 grains. Remarkably, at the growth fronts of Bi-2223 grains the growth steps show the existence of preferential growing sites, which played an important role during the whole growing process of Bi-2223 grains. The appearance of preferential growing sites Is thought to be related to the inhomogeneously distributed chemical composition and liquid phase in the reaction system. Based on the microstructure observation and kinetic analysis, it is suggested that both the intercalation process and the two dimensional diffusion controlled nucleation and growth process might be responsible for the nucleation of Bi-2223 phase, but with only the later accounting for the 2223 grain growth.
关键词:
Bi-2223/Ag tapes;grain growth;nucleation;phase formation;mechanism;kinetics
Superconductor Science & Technology
The phase assemblage and particle sizes of precursor powders have been optimized in a sequence for fabricating Ag/BSCCO-2223 composite tapes. Firstly, an optimal calcination temperature was determined based on the experimental results. Then, the precursors calcined at the optimal temperature were ball-milled for different dwell times to obtain varied particle sizes. The effects of both the phase assemblages and particle sizes of the precursor powder on the phase formation, microstructure and transport J(c) of Bi-2223/Ag tapes have been investigated. The results show that the precursor phase assemblage has a large impact on the reaction routes, microstructure, and Jc property. Meanwhile, a fine powder is beneficial for the grain growth, alignment, and Jc enhancement in fully reacted tapes. The best J(c) was achieved in the tape made from the powder after optimizing the phase assemblage and particle size.
关键词:
critical-current density;superconducting tapes;phase assemblage;ag/bi-2223 tapes;particle-size;grain-size;microstructure;calcination;parameters;j(c)
