Control of in-field performance of 25 mol.% Zr-added REBCO superconductor tapes

The relation between the c-axis lattice parameter of REBa2Cu3O7−δ (REBCO and RE = Gd, Y) superconductors with 25 mol.% Zr addition and the critical current density (Jc) was determined at (77 K, 0  T), (30 K, 3 T (B||c)), and (30 K, 9 T (B||c)). In this work, heavily doped Zr-added REBCO films with the thickness of 0.9 µm were fabricated by metal organic chemical vapor deposition (MOCVD) using a roll-to roll process. An increase in REBCO c-axis lattice parameter and a decrease in elastic mismatch strain relative to self-assembled BZO nanocolumns were observed with increasing (Ba + Zr)/Cu content. The optimum c-axis lattice parameter for achieving the highest Jc in magnetic field was found to be temperature and field dependent, with optimum values of 11.74, 11.76 and 11.78 Å at (77 K, 0 T), (30 K, 3 T (B||c)), and (30 K, 9 T (B||c)), respectively.