Sintering behaviour and microstructural evolution of agglomerated spherical particles of high-purity barium titanate

Densification and grain growth of high-purity BaTiO3 spherical particle compacts have been studied in the temperature range of 25-1300 degreesC by the CRH method. A rapid densification of the samples between 1000 and about 1230 degreesC with the formation of a continuous interconnected porosity, and a negligible grain growth took place. Above 1230 degreesC grains grew rapidly and the interconnected porosity progressively collapsed into isolated pores. Measurements of grain size as a function of density showed that the grain-growth behaviour change took place at about 92% of theoretical density, which coincides with the end of the intermediate-stage sintering. From the present experimental results it can be tentatively stated, for the first time in barium titanate, that a linear correlation between density and grain size in the intermediate-stage of sintering exists. In the final-stage of sintering a bloating or desintering feature was present as consequence of the loss of carbon dioxide from the barium carbonate in the barium titanate environment. (C) 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.