Effects of Zn doping on superconducting properties of melt textured Y–Ba–Cu–O bulk superconductors

Abstract

Zn doping which may induce a second peak effect in YBa2Cu3O7−δ (YBCO) has been opted as a regular technique to improve the trapped field and flux pinning stability of YBCO bulk superconductors for practical applications, such as quasi-permanent or maglev magnets. Here, the effects of Zn doping on the flux trapping performance of single domain YBCO bulk superconductors have been systematically investigated. The doping amount x varies from 0 to 1.0 mol%. We analyzed the critical transition temperature (T c), critical current density (J c), trapped field (B t) and the flux relaxation at various temperatures, and measured in addition the levitation force (F L) for comparison. The doping amount of 0.6 mol% has been proven to be the optimal value, which enhances self-field J c by 243.3% at 30 K with an obvious secondary peak effect, resulting in great improvements in trapped field and flux stability. The holistic and local superconducting performances exhibit good agreement, demonstrating Zn-doping an effective method to improve flux pinning properties for practical applications.