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Grain coarsening during the sintering of BaTiO3 specimens prepared with excess SiO2-rich liquid has been investigated. At 1310°C, the grains were angular and a few grains having a double-twin grew extensively. At 1350°C, on the other hand, the grains were spherical and uniform grain coarsening was observed. The observed difference in coarsening behavior is discussed in terms of the coarsening mechanism and the atomic structure of interfaces.

The exaggerated growth behavior of β-Si3N4 grains during post sintering heat treatment at 1900 °C has been investigated. The specimens were sintered at 1760 °C with slow and rapid heating rates, respectively, and the exaggerated growth behavior was observed to occur only in the rapidly heated specimens. The results were explained in terms of the growth mechanism, similar to two-dimensional nucleation and growth. Practical implication of the results is that the fracture toughness of β-Si3N4 ceramics can be improved by adopting rapid heating to the sintering temperature.