Evidence for Anomalous Grain Growth below the Eutectic Temperature in BaTiO3 Ceramics.

Anomalous grain growth can obviously occur by solid state mechanisms and is not dependent on the presence of a liquid phase as had been generally supposed. The formation of twinned crystals, which can grow preferentially in a dense matrix, is one necessary requirement. Microregions of more advanced shrinkage, containing at least one twin, are the nuclei for anomalous growth. Green density and shrinkage rate (rate of heating), together with the chemical composition, therefore, decisively influence the microstructure of barium titanate.