Preparation of nanocomposite thin films by sol-gel and photochemical metal-organic deposition of Ba0.5Sr0.5TiO3 and PbZr0.48Ti0.52O3

The process for generating nanocomposite films constructed from alternate thin film layers of Ba0.5Sr0.5TiO3 and PbZr0.48Ti0.52O3 by photochemical metal-organic deposition and sol-gel has been investigated. By spin coating the appropriate metal organic precursors to Ba-0.5 Sr0.5TiO3 followed by photolysis a single layer of amorphous Ba0.5Sr0.5TiO3, is produced. Subsequent spin coating of the appropriate metal organic precursors of PbZr0.48Ti0.52O3 and photolysis led to the formation of a layer of amorphous PbZr0.48Ti0.52O3 By repeating this procedure a material composed of alternating layers of BST and PZT was constructed. In an analogous process alternate coating and heating of the appropriate sol-gel precursors was used to make similar structures. These nanocomposite materials were formed as amorphous layered materials but could be made to crystallize by heat treatment. Heat treatment resulted in crystallization of the films although the resultant diffraction pattern was dependent upon the thickness of the layers. X-ray diffraction patterns of both BST and PZT were apparent in crystalline films formed from layers of more than 25 nm in thickness. The crystallization of films formed from layers less than 25 nm in thickness showed only a lattice constant intermediate between that expected for BST and PST consistent with the interdiffusion of these components. Atomic force microscopy indicated that the amorphous nanocomposite films were near featureless while the crystalline films had a much higher surface roughness. (C) 2000 Elsevier Science Ltd. All rights reserved.