Comparison study of the flux pinning enhancement of YBCO superconductor with BZO and BZO + Y2O3 mixed phase additions

摘要

Adding nanophase defects to YBa2Cu3O_(7-δ) (YBCO) superconductor thin films is well-known to enhance flux pinning, resulting in an increase in current density (J_(ct)). While many previous studies focused on single phase additions, the addition of several phases simultaneously shows promise in improving current density by combining different pinning mechanisms. This paper compares the effect of the addition of two insulating, nonreactive phases of barium zirconium oxide (BZO) and yttrium oxide Y2O3, both as a single addition of BZO and as a double addition in conjunction with Y2O3. Processing parameters vary the target composition volume percent of BZO from 2-6 vol. %, while maintaining 3 vol. % Y2O3, and the remaining vol. % YBCO. Pulsed laser deposition produced thin films on LaAlO3 (LAO) and SrTiO3 (STO) substrates at various deposition temperatures. Comparison of strong and weak flux pinning mechanisms, current densities, critical temperatures, and microstructures of the resulting films will be presented. Films produced from the 2 vol. % BZO + 3 vol. Y2O3 doped YBCO target at a deposition temperature of 825 °C attained the highest current density. The addition of second phase Y2O3 impacted the film microstructure, resulting in more isotropic behavior when compared to the YBCO films doped with only BZO.