A new process with the promise of high J_c in oxide superconductors

We report a new process which promises high critical current density in oxide superconductors. The process consists of three stages. Firstly a YBa₂Cu₃O_x sample is rapidly heated and quenched from the Y₂O₃ plus liquid region. Subsequently the quenched sample is reheated to the Y₂BaCuO₅ plus liquid region, and then slowly cooled with a temperature gradient in flowing oxygen. The process enables us to grow a superconducting phase unidirectionally and to suppress the second phase intrusion, leading to the production of well textured YBa₂Cu₃O_x which yields a high J_c value in the presence of magnetic fields. It is also found that Bean's critical state is realized in such high J_c samples.