Microstructure transition from normal to abnormal grains for BaTiO3

Quantitative characterization on the microstructure evolution during sintering of barium titanate has been conducted. The microstructure of the specimens sintered at 1320–1360 °C exhibits a typical mixture of normal and abnormal grains. The size of normal grains and abnormal grains differs by two orders of magnitude. No grain with an intermediate size is observed. A “pseudo-abnormal” region composing of many partially oriented normal grains is found instead. The formation of such pseudo-abnormal regions may help the transition from fine normal grains to coarse abnormal grains.