Solubility of TiO ₂ in BaTiO ₃

Abstract

Scanning electron microscopy and electron probe micro‐analysis were used to investigate the microstructure of both slow‐cooled and quenched polycrystalline BaTiO 3 specimens with a small excess of TiO 2 (Ba/Ti=0.995 to 0.999) or of BaO (Ba/Ti=1.002 and 1.005). The electron micrographs of polished and etched TiO 2 ‐excess BaTiOs samples, and of fracture surfaces of quenched samples, showed a second phase in the grain boundaries and triple‐point regions, whereas no second phase was observed in samples having Ba/Ti=1.000. Microprobe analysis of the second phase gave compositions near that of the reported adjacent phase of higher TiO 2 content, Ba 6 Ti 17 O 40 . The results indicate that the solubility of TiO 2 in BaTiO 3 is <0.1 mol%.