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 °C by the CRH method. A rapid densification of the samples between 1000 and about 1230 °C with the formation of a continuous interconnected porosity, and a negligible grain growth took place. Above 1230 °C 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.