Enhanced flux-pinning performance of YBCO films derived from a fluorine-free sol-gel process with ceria addition.

Abstract In this work, a facile and effective method which can significantly improve the flux-pinning performance of YBCO films was reported. YBCO/CeO 2 composite films were prepared on LaAlO 3 (LAO) single crystal substrates through a fluorine-free sol-gel approach with a certain amount of ceria addition. During the nucleation and growth of YBCO films, CeO 2 reacted with the barium-contained phase in YBCO precursors to generate the nanosized BaCeO 3 phase and thus the redundant Y 2 O 3 and CuO phases remained, leading to the wrong stacking of Cu atoms to form the stacking faults of Cu-O planes, which has been demonstrated by XRD, TEM, SEM and EDS results. The variation of critical current density (J c) and flux-pinning force (F p) with the percentage of ceria addition was investigated, and the results show that YBCO film with the amount of 5 mol% of ceria addition exhibits the highest J c and the strongest F p at the same temperature and applied magnetic fields. In addition, the stacking faults effectively reduced the degree of dependency of J c of YBCO film on the applied magnetic field especially at low temperature. [ABSTRACT FROM AUTHOR]