Optimization of Process Parameters for Calcination in TFA-MOD Method

We have investigated the influence of the H₂O vapour inlet temperature in the calcination on both the microstructure and superconducting properties of YBa₂Cu₃O_7-x, (YBCO) films fabricated by the TFA-MOD method, from the viewpoint of the process control in the reel-to-reel system. Low critical current (J_c) values were obtained in the films prepared by introducing the H₂O vapour at temperatures less than 200degC. XRD measurements and cross-sectional TEM observations suggest that the YBCO films calcined with the H₂O vapour inlet temperature below 200degC revealed a random orientation without the epitaxial growth of the YBCO phase grains. Consequently, it is necessary to introduce H₂O vapour from temperatures higher than 250degC in calcination for fabrication of high performance YBCO tapes. In reel-to-reel system, it is important that the humidity management in a low temperature range in the furnace.