Sol-gel derived (La,Sr)CoO3 thin films on silica glass

(La-0.5,Sr-0.5)CoO3 (LSCO) films were prepared by a sol-gel method on silica grown by various methods such as thermal oxidation, plasma enhanced chemical vapor deposition (PECVD) and atmospheric pressure chemical vapor deposition (APCVD). Polyvinyl alcohol (PVA) was used as a wetting agent to improve the surface wetting behavior of the LSCO precursor solution onto the silica. The surface wetting of LSCO precursor solution on the silica prepared by PECVD or APCVD was progressively improved with adding PVA in the solution. At 5 wt.% of PVA addition, the surface wetting became uniform and the resulting microstructure of the crystallized LSCO films was homogeneous. Crystallization and densification of the LSCO films were improved by modifying the heating rate during crystallization. Dense and uniform LSCO films were obtained with a ramp rate of 2 degrees C/min to 400 degrees C for pyrolysis of PVA, followed by heating with a ramp rate of 10 degrees C/min to crystallization temperatures. (C) 1999 Elsevier Science S.A. All rights reserved.