Study on the Percolation Process of Clusters in Multiphase Superconductor

多相超导体团簇渗流过程研究

基本信息

批准号：
02650519
负责人：
YOSHIDA Katsukuni
金额：
$ 1.41万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

In order to reveal the problem of how the behavior of constituent phases in multiphase superconductors characterizes the superconducting properties, an experimental study was made of the network structure of the crystalline clusters of the high T_2 oxide of Bi-(Pb)-Sr-Ca-Cu-0 systems(By systems), to which oxide Ag_2O was doped. We investigated this problem in particular reference to the percolation process of the clusters, where the superconducting junction between adjacent crystallines plays an important role. Main results are sunynarized as follows. 1. A small amount of doped Ag, which was produced by dissolving Ag_2O during the sintering the above Bi compound, exerts a considerable deteriorating effect on the superconducting properties. This effect implies that the superconducting junction between crystallines is largely affected by the presence of nonsuperconducting compound like Ca_2PO_4, formation of which is easily controlled by such doping. 2. The X rgy diffraction does not show any change in the structure of the superconducting crystalline itself, and only demonstrates that the most amount of the doped Ag precipitates as a pure metallic phase. 3. The superconducting properties are remarkably affected also by the process of heat treatment(furnace cooled, air cooled or quenched to liquid nitrogen)after the sintering fabrication of the samples. The faster cooling makes the superconducting properties worse. The heat treatment also strongly controls the crystalline interface. 4. The magneto resistance appearing below the transition temperature T@CCc@DD shows a large hysteresis for the samples with inferior superconducting properties. 5. The samples with good qualities exhibit a large diamagnetic susceptibility characteristic of the intergrain superconducting. 6. The above properties was discussed in terms of the percolation process by modeling a Josephson network.

为了揭示多相超导体中组成相的行为如何表征超导体特性的问题，对BI-（PB）-SR-CA-CA-CU-0系统的高T_2氧化物的晶体簇的网络结构进行了实验研究，该结构是氧化物AG_2O的氧化物AG_2O。我们研究了这个问题，特别是指簇的渗滤过程，在该簇中，相邻晶体之间的超导连接起着重要作用。主要结果被固定在如下。 1。少量的掺杂Ag，是通过在上述BI化合物烧结过程中溶解AG_2O产生的，对超导特性产生了相当大的恶化影响。这种效果意味着晶体之间的超导连接在很大程度上受到非渗透化合物（如Ca_2po_4）的存在，其形成很容易受到这种掺杂的控制。 2。X射线衍射没有显示超导晶体本身的结构的任何变化，并且仅表明掺杂的Ag量最多会作为纯金属相沉淀。 3。在烧结样品烧结后，超导特性也受到热处理过程（冷却，空气冷却或淬火至液氮）的过程。更快的冷却使超导性能变得更糟。热处理还强烈控制晶体界面。 4。出现在过渡温度t@ccc@dd下方的磁电阻显示出具有较低超导特性的样品的较大滞后。 5。具有良好品质的样品表现出较大的磁化性敏感性的特征。 6。通过对约瑟夫森网络进行建模来讨论上述属性。