High-temperature-superconductor coated conductors: technical progress in Japan

TLDR

High‑Jc Y‑123 superconducting wires, essential for strong‑field liquid‑nitrogen‑temperature performance, require coated‑conductor processing to overcome weak linking and have spurred worldwide efforts toward practical coated‑superconducting wires. This review focuses on Japan’s most outstanding achievements in high‑temperature‑superconductor coated conductors. Researchers have pursued textured substrates of sufficient length via multiple methods, with or without buffer layers, and fabricated epitaxial Y‑123 thin films from vapor, liquid, or solid phases using diverse techniques.

Abstract

It is now a widespread view that a high-Jc superconducting wire with a high performance under strong magnetic fields at liquid-nitrogen temperature needs to be realized by the material Y-123. However, because of the weak linking nature of this material, the fabrication of the wire must be based on a coated-conductor process to achieve a highly textured Y-123 thin film on a long starting wire tape. Various attempts to obtain a textured substrate with sizable length have been made by various methods, with or without the aid of buffer layers. Approaches to the fabrication of an epitaxial thin film of Y-123 have also been made from vapour, liquid, or solid phases by different methods. Therefore, combinations of these proposed processes in each category have led to several promising on-going worldwide approaches to achieve the realization of practical coated superconducting wires in the near future. This review focuses on the most outstanding achievements in Japan.