DEDENSIFICATION AND ANOMALOUS GRAIN-GROWTH DURING SINTERING OF UNDOPED BARIUM-TITANATE

Dedensification (up to 10% of the theoretical density in some instance s) occurs at temperatures of >1320 degrees C during the sintering of c ommercial undoped BaTiO3 powders. The expansion of the rigid, intercon nected network of large, rounded grains that grow by the Ostwald ripen ing effect can explain the dedensification that is observed. The isotr opic anomalous grain growth results from the appearance of a liquid ph ase at approximate to 1320 degrees C and induces tensile stresses on t he residual porous fine-grained matrix. No dedensification was observe d at temperatures of <1320 degrees C, despite anisotropic anomalous gr ain growth.