X-RAY-DIFFRACTION STUDIES ELUCIDATING HIGH-TEMPERATURE SUPERCONDUCTING PROPERTIES OF YBA2CU3O7-X THIN-FILMS

A quantitative evaluation of the influence of the amount of the crystallographically unoriented grains of YBa2 Cu3O7-x epitaxial films on the major high temperature superconducting (HTS) properties such as microwave surface resistance R(s) and critical current J(c) has been analyzed. The correlation is quite complex but it is clear that a very high percentage of [100] basal plane orientation, as determined by the X-ray (108) phi-scan, is essential to obtain the optimal HTS properties. The role of (005) rocking curves width and percentage of crystallographic orientation of YBa2Cu3O7-x grains decomposed into Y2BaCuO5 and BaCuO2 are also discussed. The optimal deposition temperature for thin films is analyzed in terms of the structural and HTS properties.