Preparation of BaTiO3 thin films using glycolate precursor

The translucent grease-like gel was obtained by heating the mixed solution of monohydrated barium hydroxide and titanium isopropoxide in ethylene glycol up to 145 degrees C, The gel consisted of EG (ca. 90%) and residual flake-like microcrystals with a characteristic low-angle X-ray diffraction peak (d = 1.187 nm). The thermal decomposition of the gel proceeded through three major stages, viz., (i) evolution of EG (similar to 200 degrees C), (ii) decomposition of EG moiety in microcrystal to form an amorphous carbonate (similar to 400 degrees C), and (iii) crystallization of cubic BaTiO3 with a grain size of 10 to 20 nm (similar to 600 degrees C). Spectroscopic and thermoanalytical techniques were used to characterize the glycolate precursor and the intermediate isolated at various stages. Smooth and transparent BaTiO3 films with 2-3 mu m thickness were obtained by painting the gel once on several substrates and heating up to above 600 degrees C, BaTiO3 films prepared were strongly oriented along the (110) plane. (C) 1997 Academic Press.