STRUCTURAL COMPARISON OF BA1-XKXBIO3 SUPERCONDUCTING THIN-FILMS

The microstructure of Ba1-xKxBiO3 (BKBO) thin films from three differe nt sources has been extensively compared by transmission electron micr oscopy studies. The three films were prepared independently in three d ifferent laboratories on three different substrates of (100) orientati on and displayed excellent superconducting properties. The observed mi crostructure is remarkably similar in the three films. They are epitax ial with (100) orientation through all their extension and no cracks h ave been observed. Their defect density is similar and the resulting e xtension of defect-free regions is of the order of 50-80 nm.