Effect of SiO2 and TiO2 addition on the exaggerated grain growth of BaTiO3

The exaggerated grain growth (sometimes referred to as secondary recrystallization) during sintering of BaTiO3 was studied with two different liquid-forming additive oxides, TiO2 and SiO2. The liquid phase was distributed inhomogeneously by placing a small amount of TiO2 and SiO2, respectively, on top of the BaTiO3 powder compact. The exaggerated grain growth was observed to occur more rapidly in the SiO2-containing specimen than in the TiO2-containing specimen. Once the initial fine-grained structure was completely replaced by the exaggeratedly grown grains, the TiO2-containing specimen exhibited practically no more microstructural evolution. For the SiO2-containing specimen, on the other hand, a few grains continued to grow without limit. The observed unusual growth has been explained in terms of twin-assisted growth mechanism. (C) 1997 Elsevier Science Limited.