Analysis of fine structure and elucidation of joint mechanism at the heterojunction interface for high temperature superconducting wire

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04719
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26030:Composite materials and interfaces-related
• Research Institution: Muroran Institute of Technology
• Principal Investigator: Kanazawa Shintetsu 室蘭工業大学, 大学院工学研究科, 助教 (50584306)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: ヘテロ界面 / 超伝導接合 / 高温超伝導線材

Outline of Final Research Achievements

As planned, regarding the heterojunction between RE123 wires by the melt growth method using Yb123 bulk, the texture formation, crystal growth and structural change of the interface were investigated. In the interfacial texture formation, a part of junction structure as Gd123-Yb123 was detected, and a structure of Gd123-BaCuO2-Yb123 that via non-superconducting BaCuO2 phase was observed with a large amount. It is considered to be a reason of a low critical current of the joint. For the crystal growth at the hetero interface, the thickness of crystal growth of Yb123 phase was estimated to be below 1 μm. In the structural changes at the interface, solid-phase diffusion of Mo elements was measured and that may have a large effect on the critical current of the joint, and it is considered that changing of the wire structure is necessary to improve the critical current.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

本研究の溶融バルク成長法により、従来の拡散法で未解決となった機械強度の課題が大きく改善され、さらなる研究により臨界電流の改善が得られば、実用が検討されている有力な候補である。本研究成果により、接合メカニズムにおける接合組織と結晶成長の範囲、および構造変化に知見を深めることができ、今後の臨界電流の改善に向けた理論的な根拠を提供した。また、多分野のBi2223線材の接合の性能向上にも貢献している。