YBCO growth on textured NiW substrates by TFA-MOD method

For production of low cost coated conductor tapes, the TFA-MOD (metal organic deposition using trifluoroacetates) process is one of the promising methods and textured NiW alloy substrates are expected to be a candidate for their substrates. However, the superconducting properties obtained on the NiW substrates are not high enough due to lack of understandings on YBCO grain growth on the NiW. In this work, MOD growth conditions such as molar ratio (Ba/Y) of the starting solution, the crystallization temperature and P (O2) (O2 partial pressure) especially on the NiW substrates were studied. Compositional effects of the starting solution on Ic values have a trend having the highest value at Ba/Y = 1.5, which is similar to those on IBAD substrates, though the Ic values of YBCO on NiW are lower. One of the differences between YBCO layers on NiW and IBAD could be explained by the significant difference in a-axis oriented grain growth. The higher temperature and/or the lower PO2 were required to suppress the nucleation for a-axis oriented grain growth on the NiW. 1 m-long RTR production exhibited the end-to-end Ic value of 221 A/cm w, which could be improved further by the optimization of the process conditions