EFFECT OF SIO2 AND TIO2 ADDITION ON THE EXAGGERATED GRAIN-GROWTH OF BATIO3

The exaggerated grain growth (sometimes referred to as secondary recry stallization) during sintering of BaTiO3 was studied with two differen t 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 g rain growth was observed to occur more rapidly in the SiO2-containing specimen than in the TiO2-containing specimen. Once the initial fine-g rained structure was completely replaced by the exaggeratedly grown gr ains, the TiO2-containing specimen exhibited practically no more micro structural evolution. For the SiO2-containing specimen, on the other h and, a few grains continued to grow without limit. The observed unusua l growth has been explained in terms of twin-assisted growth mechanism . (C) 1997 Elsevier Science Limited.