Crystal structure and ferroelectricity of nanocrystalline barium titanate thin films

The nanocrystalline thin films of barium titanate (BaTiO3) have been deposited on the Pt/Ti/SiO2/Si substrates by RF magnetron sputtering at 500degreesC. The XRD result shows only single perovskite structure phase of BaTiO3 and the intensity of reflection decreases with decreasing film thickness. The film deposited at 500degreesC has a thickness of 45.0 nm and is composed of granular crystallites of about 30.0 nm in size. The crystallite size decreases with decreasing film thickness. The structure changes from tetragonal to pseudocubic. The remnant polarization (P-r) and coercive field (E-c) of the 450.0 nm thick BaTiO3 films are 5 muC/cm(2) and 1.5 kV/cm, respectively, exhibiting ferroelectricity, being one-eighth and 10 times of the bulk values, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.