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Microstructure and Microstructural Evolution in BaTi03 Films Fabricated Using the Combinatorial Precursor Method

Published

Author(s)

Leonid A. Bendersky, C J. Lu, J J. Scott, Ichiro Takeuchi, K S. Chang

Abstract

Pulsed laser deposition (PLD) of Ti0(sub2) and BaF(sub2) layers at room temperature and subsequent annealing in flowing oxygen were used to form homogeneous expitaxial BaTi0(sub3) films on LaAlO(sub3). This oxide film synthesis method, known as the precursor technique, is frequently used for making combinatorial libraries. In this paper, we have investigated the microstructures of the films at different stages of annealing using cross-sectional transmission electron microscopy, high-resolution imaging, and electron energy loss spectroscopy. It was shown that epitaxial BaTiO(sub3) thin films with large grains could be formed on a LaAlO(sub3) substrate. Their formation process consists of the following stages: at 200 degress C, the BaF(Sub2) layer is partially oxidized; at 400 degress C, the amorphouse TiO(Sub 2) layer crystallizes, further transformation of BaF(Sub 2) into BaO takes place, and interdiffusion begins; at 700 degress C, the formation of a polycrystalline structure with different Ba-Ti-phases occurs, epitaxial BaTiO(sub 3) grains nucleate on the film/substrate interface and significant interdiffusion takes place; at 900 degress C, the interdiffusion is completed, and the epitaxial BaTiO(sub 3) grains coalesce and grow. The presence of non-epitaxial polycrystalline regions in fully annealed films can be explained as: (a) stoichiometric transient regions not yet consumed by recrystallization of BaTi0(sub3); non-stoichiometric regions resulting from inhomogeneous deposition of BaF(sub 2).
Citation
Journal of Materials Research
Volume
17
Issue
No. 10

Keywords

BaTiO(Sub 3), combinatorial chemistry, PLD, TEM, thin films

Citation

Bendersky, L. , Lu, C. , Scott, J. , Takeuchi, I. and Chang, K. (2002), Microstructure and Microstructural Evolution in BaTi0<sub>3</sub> Films Fabricated Using the Combinatorial Precursor Method, Journal of Materials Research (Accessed June 14, 2024)

Issues

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Created October 1, 2002, Updated February 17, 2017