Studies on Bi-Based Oxide High-Temperature Superconductors Synthesized by a Diffusion Process for Conductor Application

扩散法合成铋基氧化物高温超导体的导体应用研究

基本信息

批准号：
09650770
负责人：
YAMADA Yutaka
金额：
$ 2.11万
依托单位：
Tokai University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Bi_2Sr_2CaCu_2O_<8+x> (Bi-22 12) superconductors have been synthesized by the diffusion reaction between a high melting point Sr-Ca-Cu oxide substrate and a low melting point Bi-Cu oxide coating layer with Ag2O addition. The Bi-22 12 diffusion layer, formed around both outside and inside of the cylindrical tube of 20/16mm in outerfmner diameter, shows dense and oriented structure with plate-like grains. The transport Jc of the diffusion layer, about 150mum in thickness, exceeds 20,000 A/cm_2 at 4.2K under self-field. The transport Ic of the whole tube is estimated to be about 4,000 A.Post annealing in Ar gas atmosphere improves Tc of the diffusion specimen by about 10K.Therefore, the transport Ic increases at temperatures higher than 40K in comparison with that of the as diffused specimen. The contact resistivity of the bulk ends is in order of 1-10 n(2cm2 between at 4.2K and 65K up to 3T.Consequently, the joule heating in the current terminals of the specimen is expected to be as small as 1mW for the transport current of 1,000 A.Present Bi-22 12 oxide cylinders with large transport Ic and Jc as well as low contact resistance may be promising as current leads and conductors.Furthermore, Bi-2212 oxide superconducting layer has been synthesized around cylinder by the dip-coating and subsequent diffusion reaction between Sr_2CaCu_3 oxide substrate and Bi_2Cu_<0.136> eutectic oxide. The transport Jc of the diffusion layer, about 120mum in thickness, is as high as 25,000 A/cm_2 at 25K under self-field. The dip-coating process is more simple for the fabrication of Bi-22 12 oxide layer compared with the conventional slurry-coating process.

通过高熔点Sr-Ca-Cu氧化物基底和添加Ag2O的低熔点Bi-Cu氧化物涂层之间的扩散反应合成了Bi_2Sr_2CaCu_2O_<8+x>（Bi-22 12）超导体。 Bi-22 12 扩散层形成于外径为20/16mm的圆柱管的内外两侧，呈致密、定向的板状晶粒结构。厚度约150μm的扩散层的传输Jc在4.2K自场下超过20,000 A/cm_2。整个管子的传输 Ic 估计约为 4,000 A。Ar 气氛中的后退火将扩散样品的 Tc 提高了约 10K。因此，与扩散样品相比，传输 Ic 在温度高于 40K 时增加标本。块体端部的接触电阻率在 4.2K 至 65K 之间为 1-10 n(2cm2，最高可达 3T)。因此，样品电流端子中的焦耳热预计将小至 1mW，以便于运输电流为 1,000 A。目前具有大传输 Ic 和 Jc 以及低接触电阻的 Bi-22 12 氧化物圆柱体可能有望作为电流引线和此外，通过Sr_2CaCu_3氧化物基底和Bi_2Cu_<0.136>共晶氧化物之间的浸涂和随后的扩散反应，在圆柱体周围合成了Bi-2212氧化物超导层，扩散层的传输Jc，厚度约为120μm。自场下25K时高达25,000 A/cm_2 浸涂工艺更简单。 Bi-22 12 氧化层的制备与传统浆料涂覆工艺的比较。