Improvement of the Transport Properties in BiSrCaCuO Superconductors prepared by Melt-Casting Process and Development of Bi-2212 HTS Current Leads

熔铸工艺制备的 BiSrCaCuO 超导体输运性能的改善及 Bi-2212 HTS 电流引线的开发

• 批准号: 13650361
• 负责人: TSUKAMOTO Takehiko
• 金额: $ 2.3万
• 依托单位: Toyota National College of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650361/
• 关键词: Melt-Casting Process; Bi-2212 Bulk Superconductor; Effect of Li Addition; AC Transport Losses; Critical Current; Critical Temperature; Transport Properties; Current Lead; 臨界電流密度分布; n値; 交流損失; 導電特性; Li添加

The Bi-2212 bulk superconductors, with a proper amount of SrSO_4, were prepared by melt-casting process (MCP). Critical current in bulk Bi2212 bar (φ10.7mm) exceeded 50A at 77K. The weak links have been largely eliminated in the MCP sample. The enhancement of transport properties is due to the addition of lithium carbonate (Li_2CO_3). The maximum critical temperature occurs for the MCP sample Bi_2Sr_2CaCu_2Li_<0.2>O_y annealed at 800°C. And, we have investigated the ac transport losses and critical current density distribution of MCP samples. The ac losses are mainly ascribed the hysteresis loss of the superconductor. The ac loss value is about one-half of the theoretical value obtained by the theory of Norris. The local J_c value decreases significantly in going from the surface to the interior of the sample, which suppresses the extension of the flux-penetration-region to the interior under ac current transmission and lowers the loss generation compared with the calculated results obtained by the uniform J_c distribution. Present MCP Bi-2212 bulk superconductors seem to be promising as a current lead.

采用熔铸工艺(MCP)制备了添加适量SrSO_4的Bi-2212块体超导体，其临界电流在77K时超过了50A。 MCP 样品的传输性能增强是由于添加了碳酸锂 (Li_2CO_3)，MCP 样品出现了最高临界温度。 Bi_2Sr_2CaCu_2Li_<0.2>O_y在800°C下退火并且，我们研究了MCP样品的交流损耗和临界电流密度分布。交流损耗主要归因于超导体的磁滞损耗，交流损耗值约为1。 Norris 理论得到的理论值的一半，局部 J_c 值从样品表面到内部显着减小。与均匀 J_c 分布获得的计算结果相比，抑制了交流电流传输下磁通穿透区域向内部的扩展，并降低了损耗的产生，目前的 MCP Bi-2212 体超导体似乎有望作为电流引线。