Fabrication of YBCO coated conductor by TFA-MOD method in route of dissolving Y211 and Ba3Cu5O8 powders in TFA

Abstract

We fabricated YBCO coated conductors using a new TFA-MOD method and evaluated the phase formation, texture evolution, and critical properties as a function of the firing temperature and oxygen heat treatment time, in order to explore its possible application in CCs fabrication. In the fabrication process, Y2Ba1Cu1Ox and Ba3Cu5O8 powders were used as precursors, instead of Y-, Ba- and Cu-based acetate or organics, and dissolved in trifluoroacetic acid followed by firing and oxygen heat treatment.We observed that for the films fired at 725°C, BaF2 and other second phases formed and Tc was measured to be 66.5K. In contrast, when the film was fired at 775°C, strong and sharp (00l) diffraction peaks of YBCO were observed, without the formation of the BaF2 phase. In addition, X-ray pole-figure analysis indicated that a strong biaxial texture was developed and the full-width at half-maximums of in-plane and out-of-plane textures were 4.38° and 4.26°, respectively. The critical temperature and current were also increased to 85.3K and 35.8A/cm-width, respectively, at 77K when the oxygen heat treatment time was increased to 20h. Microstructure observation indicated that a crack-free surface was obtained and that there was no a-axis grain growth.