Preparation of BaTiO3Thin Films Using Glycolate Precursor

Abstract

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°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 (∼200°C), (ii) decomposition of EG moiety in microcrystal to form an amorphous carbonate (∼400°C), and (iii) crystallization of cubic BaTiO3with a grain size of 10 to 20 nm (∼600°C). Spectroscopic and thermoanalytical techniques were used to characterize the glycolate precursor and the intermediate isolated at various stages. Smooth and transparent BaTiO3films with 2–3 μm thickness were obtained by painting the gel once on several substrates and heating up to above 600°C. BaTiO3films prepared were strongly oriented along the (110) plane.