Critical current property in YBCO coated conductor fabricated by improved TFA-MOD process

We have investigated critical current property in YBa₂Cu₃O_7-δ (YBCO) coated conductor fabricated by improved metal organic deposition using trifluoroacetates (TFA-MOD) process optimizing conditions such as solution compositions. The electric field vs. current density (E-J) characteristic measurement was carried out at wide range of temperature, T, and magnetic field, B. Critical current density, J_c, reached 3.8 × 10¹⁰ A/m² at 77 K in self-field for 1.2 μm thick YBCO layer. In-field J_c is also improved by this new process. From the analysis of E-J characteristics, we have found out that the shape of statistical distribution of J_c in the new process becomes sharper than that of the previous one. These results indicate that the uniformity of YBCO layer is improved by the new process. Furthermore, analytical expression of E-J characteristics, which is based on a percolation model and a scaling law of the pinning force density, shows good agreement with the experimental results. This allows us to predict the critical current property at arbitrary conditions of T and B even if we couldnot have measured data. For example, it is predicted that J_c could be about 1 × 10¹⁰ A/m² at 4.2 K and 30 T parallel to the c-axis.