Cerium Oxide Buffer Layers on Perovskite-Type Substrates for Preparation of $c$ -Axis-Oriented ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$ Films by Fluorine-Free Metalorganic Deposition

c -axis-oriented epitaxial YBa 2 Cu 3 O 7-delta (YBCO) superconducting films were prepared on perovskite-type single crystal substrates, i.e., SrTiO 3 , LaAlO 3 , NdGaO 3 and YAlO 3 with cerium oxide (CeO 2 ) buffer layers by fluorine-free metalorganic deposition (MOD) at relatively low heating rates. The YBCO films on these CeO 2 -buffered substrates exhibited high critical current densities with an average of 3-5 MA/cm 2 at 77.3 K. Using CeO 2 buffer layers we could avoid the occurrence of undesired a -axis-oriented grains of YBCO on these substrates despite employing lower heating rates. The lattice constants of YBCO films, CeO 2 buffer and substrates were compared. It was found that both the YBCO films and CeO 2 buffer were elastically deformed.