Barium Carbonate Phase on the Surfaces of Barium Titanate Particles and in Situ Transmission Electron Microscopy Observation of Its Decomposition

A BaCO 3 phase is found on the surfaces of hydrothermally synthesized BaTiO 3 particles; it occurs as aggregates or small protuberances. A small proportion of the phase decomposes to BaO crystallites when heated by a convergent electron beam in a transmission electron microscope. The BaO and BaCO 3 crystallites disappear when they are irradiated successively by the convergent electron beam. The BaO crystallites and the BaCO 3 phase sublimate and/or react with BaTiO 3 crystals whose surface layers are deficient in Ba 2+ ions.