The rate-determining mechanism in the sintering of undoped nonstoichiometric barium titanate

High-purity undoped nonstoichiometric BaTiO3 powder of TiO2-excess and BaO-excess has been pressureless-sintered in the range of 1215–1340°C using conventional tube furnace. Low temperature sintering of the TiO2-excess composition results in the characteristic plate-like grains grown along the {111} plane. Surface energy anisotropy is proposed to account for the anomalous microstructural development and low final sintered density. The activation enthalpy values (ΔH) deduced from isothermal sintering are 522±130 and 396±16 kJ mol for the TiO2-excess and BaO-excess composition, respectively. The rate-determining mechanism for the solid-state sintering of the undoped nonstoichiometric BaTiO3 powder is discussed.