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.