High performance of YBCO coated conductors using advanced TFA-MOD method

In order to shorten the calcination time in the metal-organic deposition (MOD) process using metal trifuluoroacetete (TFA), a new combination of starting materials was developed using F-free salt of Cu and TFA salts of Y and Ba as called "New solution". Moreover, a new process temperature profile for this solution was developed as an advanced TFA-MOD process where the high heating rate was achieved. Consequently, the overall transport Ic value of 210 A and the Jc value of 1.5 MA/cm² (77 K, Self field) similar to Ic and Jc values using TFA for all salts were obtained. In order to obtain higher Jc performance, the effects of process parameters such as degree of in-plane alignment δφ of the buffer layer and P_H2O in the annealing process for the Jc characteristics were investigated. As a result, a YBCO film with 1.48 μm in thickness was fabricated on a CeO₂/IBAD-Gd ₂Zr₂O₇ layer buffered Hastelloy substrate with δφ = 4.7°. The overall Ic value of 292 A (77 K Self-field) corresponding to the Jc value of 2.0 MA/cm² was achieved. Moreover, the overall Jc value of 2.1 MA/cm² (77 K Self-field) for the YBCO film with 1.2 μm thickness was achieved by annealing under the P _H2O value of 13.5 vol% on a similar metal substrate even with δφ∼7°.