Dedensification During Sintering of BaTiO3 Caused by the Decomposition of Residual BaCO3

The dedensification of BaTiO3 by residual BaCO3 has been demonstrated. By changing compaction pressure or presintering time in H-2, samples with different relative densities were prepared. During subsequent sintering at 1350 degrees C in air, abnormal grain growth, which was suggested to be a cause of dedensification, was completely suppressed. As the presintering time or compaction pressure increased, the relative density of the presintered samples also increased. During sintering in air, however, the relative density of the samples decreased and large pores and cracks formed in the presintered samples with high relative density. This tendency intensified with increasing relative density of the presintered samples. These results indicate that the decomposition of residual BaCO3 caused the dedensification of BaTiO3. The dedensification effect of residual BaCO3 also critically depended upon the time for pore closure during sintering.