STRUCTURAL COMPARISON OF BA1-XKXBIO3 SUPERCONDUCTING THIN-FILMS

The microstructure of Ba1-xKxBiO3 (BKBO) thin films from three different sources has been extensively compared by transmission electron microscopy studies. The three films were prepared independently in three different laboratories on three different substrates of (100) orientation and displayed excellent superconducting properties. The observed microstructure is remarkably similar in the three films. They are epitaxial with (100) orientation through all their extension and no cracks have been observed. Their defect density is similar and the resulting extension of defect-free regions is of the order of 50-80 nm.