Study on the formation of YBCO phase and texture transformation of Ag substrate during the heat treatment of TFA-MOD process

Abstract

The YBCO films were directly deposited on cold-rolled Ag substrates by MOD (metal-organic deposition) method. The formation of YBCO phase and change of Ag textures were studied during firing precursor films. It was found that YBCO phase starts to be formed at 800°C when Ag {110}<110>texture (most suitable texture for YBCO epitaxial growth) appears. With the increase of firing temperature, pure YBCO phase is obtained and Ag {110}<110>texture gradually becomes stronger. The textures of both {110}<110>texture in Ag substrate and biaxial orientation in YBCO film were optimized after holding the film at 900°C for 30 minutes. Finally, the YBCO film deposited directly on cold rolled Ag substrate has a good biaxial texture, a smooth and dense surface as well as high critical current density of 1.5×104A/cm2. The results show that cold-rolled Ag can be used as a substrate material to directly deposit YBCO film without any buffer layers by MOD method.