Development of rare-earth free superconducting wire consisting of ubiquitous elements

含稀土元素的氧化物超导线材是下一代各种能源应用的关键技术。然而，这些线材中含有低克拉克数的稀土元素。本研究旨在研制一种高克拉克数的Ae-CuO(AE=碱土)超导线材，并对生长Ae-CuO外延薄膜进行了基础性研究。然而，薄膜的晶体结构是正交的，这意味着薄膜中有许多氧空位。为了向薄膜中引入氧气，薄膜在沉积后在臭氧气氛中进行了热处理。结果表明，经臭氧处理的薄膜为四方结构，发现氧引入了薄膜中。

Oxide superconducting wires including a rare-earth element is key technology for various energy applications in next generation. However, these wires include the rare-earth element of low Clarke number. In this study, we aimed to develop a high-Clarke-number AE-Cu-O (AE=alkaline earth) superconducting wire and investigated the fundamental study to grow the AE-Cu-O epitaxial film.We successfully fabricated Sr-Cu-O and Ba-Cu-O epitaxial thin films by pulsed laser deposition method. However, the crystal structure of the films was orthorhombic and this means that there are many oxygen vacancies within the films. In order to introduce oxygen into the films, the films were annealed at ozone atmosphere after the deposition. As a result, the ozone-annealed films showed a tetragonal structure and we found that the oxygen was introduced into the films.