Superconductivity recovery of vacuum annealed HTS GdBCO CC

The superconducting properties of high temperature superconducting (HTS) GdBCO coated conductor (CC) tape (Ag/GdBCO/Buffer-layers/Stainless Steel) were investigated, specifically a series of samples prepared by vacuum heat treatment (200^o C to 600^o C), using a Quantum Design PPMS-14. The critical current density Jc value was obtained by applying the modified Bean model to the irreversible magnetization Mirr(H) data which was estimated from the magnetization M(H) loop. The reduction rates of lnJc and Tc values according to the increase of the vacuum annealing temperature Tan were d(lnJc)/dTan =-0.016 A/(cm²∙^o C) and dTc/dTan =-0.24, respectively. We examined the effect of recovery temperature Tre (475^o C to 700^o C) and recovery duration time t (0.5 h to 24 h) on the restoration of previously completely lost superconductivity in samples that subsequently received heat treatment in an O2 gas flow space. All samples were fully restored to superconductivity by heat treatment in an O2 gas flow space. The recovery temperatures Tre (475^o C to 700^o C) and recovery duration times t (0.5 h to 24 h) were both independent of the superconductivity recovery characteristics.