STUDY ON ELECTRICAL DISSIPATION OF HIGH TEMPERATURE SUPERCONDUCTOR WHISKERS

高温超导晶须的耗散特性研究

• 批准号: 06650033
• 负责人: IWAMA Saburo
• 金额: $ 1.34万
• 依托单位: DAIDO INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650033/
• 关键词: HIGH TEMPERATURE SUPERCONDUCTOR WHISKER; BISMUTH-SYSTEM SUPERCONDUCTOR; ELECTRICAL DISSIPATION; TEMPERATURE DEPENDENCE OF ELECTRICAL RESISTANCE; CURRENT VOLTAGE CHARACTERISTICS

Superconductor whiskers of several millimeters in length can be grown by heat treatment at 880 degrees of melt-quenched Bi-system amorphous bulk for 3 days in an oxygen gas stream. These whiskers were identified to be the low temperature phase with a typical mole-ratio : Bi : Sr : Ca : Cu=2 : 2 : 1 : 2, and found to grow along a-direction of the perovskite unit cell from the crystallographic observation using transmission electron microscope. The high temperature phase cannot be detected in the X-ray diffraction patterns of whiskers grown on the bulk with a nominal starting composition of 2223. Steps and also islands with a size of a few microns were frequently observed on a flat surface of the whiskers, the shape of those becoming narrower toward the top.Electrical resistance of whiskers decreases with decreasing the temperature, and drops to zero with two steps in general. The critical onset temperatures of these two resistance drops were 107K and 75K.This suggests that one whisker is composed of two phases of (2223) and (2212). The difference between the low- and the high-temperature phases is the number of CuO2 layrs in a half unit cell, as is known to be 2 in the former and 3 in the latter. From crystallographic consideration the both structures may coexist in a whisker, which involves some imperfections in a single crystal.A new cryostat system (Oxford : DN1710) equipped with the top range temperature controller (Oxford : ITC503) was constructed. The instruments to measure the electrical properties were improved, and preliminary experiments on current-voltage characteristics of bulk superconductors were carried out.

在880度的熔体淬火bi系非晶体中，在氧气流中热处理3天，可以生长出几毫米长的超导体晶须。通过透射电镜晶体学观察发现，这些晶须为低温相，具有典型的摩尔比：Bi: Sr: Ca: Cu= 2:2:1: 2，并沿钙钛矿单体电池a方向生长。在标称起始成分为2223的晶须上生长的x射线衍射图中无法检测到高温相。在胡须的平坦表面上经常观察到几微米大小的台阶和岛屿，这些形状越来越窄。晶须电阻随温度的降低而减小，一般分两步降至零。这两种电阻下降的临界起始温度分别为107K和75K。这表明一个晶须由（2223）和（2212）两相组成。低温相和高温相之间的区别是半单元电池中CuO2层的数量，已知前者为2层，后者为3层。从晶体学的角度来看，这两种结构可能共存于一个晶须中，这涉及到单晶中的一些缺陷。构建了一个新的低温恒温系统（Oxford: DN1710），配备了最高范围温度控制器（Oxford: ITC503）。对测量电性能的仪器进行了改进，对块状超导体的电流-电压特性进行了初步实验。

项目成果

M. S. Raven, E. E. Inametti, S. Iwama, Y. M. Wang, B. G. Murray: "Epitaxial growth and critical currents in (013)/(103)and(110)oriented YBa_2Cu_3O_xfilms" Physical Review B. 52. 6845-6853 (1995)

M. S. Raven、E. E. Inametti、S. Iwama、Y. M. Wang、B. G. Murray：“(013)/(103) 和 (110) 取向 YBa_2Cu_3O_xfilms 中的外延生长和临界电流” 物理评论 B. 52. 6845-6853 (1995)

S. Iwama, T. Okuda: "Effects of hidrogen peroxide peroxide on Bi-system superconductor powder formed by spray pyrolysis" Jpn. J. Appl. Phys. (in preparing).

S. Iwama，T. Okuda：“过氧化氢对喷雾热解形成的双系统超导粉末的影响”Jpn。

S.Iwama, T.Okuda: "Effects of hidrogen peroxide on Bi-system superconductor formed by spray pyrolysis" Jpn.J.Appl.Phys.(in preparing).

S.Iwama，T.Okuda：“过氧化氢对喷雾热解形成的双系超导体的影响”Jpn.J.Appl.Phys.（准备中）。

M.S.Raven, E.E.Inametti, S.Iwama, Y.M.Wang, B.G.Murray: "Epitaxial growth and critical currents in (013) / (103) and (110) oriented YBa_2 Cu_30_X films" Physical Review B. Vol.52. 6845-6853 (1995)

M.S.Raven、E.E.Inametti、S.Iwama、Y.M.Wang、B.G.Murray：“(013) / (103) 和 (110) 取向 YBa_2 Cu_30_X 薄膜中的外延生长和临界电流”《物理评论 B》第 52 卷。

M. S. Raven, E. E. Inametti. S. Iwama, Y. M. Wang, B. G. Murray: "Epitaxial growth and critical currents in (013)/(103) and (110) oriented YBa_2Cu_3O_X films" Physical Review B. 52. 6845-6853 (1995)

M.S.雷文，E.E.伊纳梅蒂。