Low temperature evolution of crystalline BaTiO₃ from alkali-metal free precursor using sol-gel process

Abstract

 Bulk structure and surface texture of BaTiO₃ materials synthesized at low temperature using sol-gel technique have been investigated. The materials were produced by the pyrolysis of an xerogel precursor of the tentative formula BaTiO_3-x(CH₃COO)_2x, which was prepared using 1:1 molar ratio of barium acetate and titanium oxyacetate solution. The present method avoids using alkali-metal hydroxides (as a hydrolyzing agent), and thus produces an alkali-metal free precursor. The decomposition course of the xerogel at the onset of formation of crystalline BaTiO₃ was probed applying thermogravimetry (TG), differential scanning calorimetery (DSC), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) techniques. Results indicated that most of the precursor weight loss occurs below 400°C, with the formation of titania rich intermediates. However, it was not until the temperature reached ≥600°C that well crystallized BaTiO₃ was produced. The specific surface area and porosity were assessed for BaTiO₃ produced at 600–1000°C using N₂ adsorption at liquid N₂ temperature.