Phase Stability of Cubic Pyrochlore Rare Earth Tantalate Pinning Additives in YBa2Cu3O7−δ Superconductor

Phase stability of cubic‐pyrochlore‐structured RE3TaO7 (RTO, where RE = rare earth elements) pinning additives in YBa2Cu3O7−δ (YBCO) superconductor and the pinning properties influenced by RTO addition into YBCO films were investigated. RTO completely reacts with YBCO and is converted to cubic‐double‐perovskite‐structured Ba2RETaO6 (BRETO), a more thermodynamically stable tantalate phase within YBCO. In RTO‐doped YBCO films, BRETO self‐assembled nanocolumns align along the c‐axis of the film and play a major role in the improvement of flux pinning and Jc performance over wide magnetic field and angular ranges.