The influence of anions on the products of BaTiO₃ under hydrothermal conditions

Abstract

Tetragonal BaTiO₃ has been prepared from a reactive titanium source, tetrabutyl titanate, with barium acetate in alkaline aqueous solution at temperatures as low as 200–240 °C. Various methods, such as X-ray diffraction, differential scanning calorimetry and scanning electron microscopy have been used to investigate the effects of alkalinity, anions, reactivity of the titanium source and degrees of fill, on the particle sizes and morphologies of BaTiO₃ generated hydrothermally. The most appropriate KOH concentration is about 1.0 mol l⁻¹ in which BaTiO₃ is the stablest phase in the BaO-TiO₂ system. Compared with chloride and nitrate ions, the acetate ion accelerates the formation of large-grained particles of BaTiO₃ more prominently. A more reactive titanium source and a higher fill can promote the formation of tetragonal BaTiO₃.