Barium titanate($BaTiO_3$) is widely used as various electronic components because of its excellent dielectric properties and chemical stability. Since the electrical properties of $BaTiO_3$ vary considerably with microsturcture, its grain growth and densification behaviors have been much studied to control the resultant microstructure. Recently, it was reported that the grain boundary structure changed with sintering atmosphere: facted in air and defaceted in $H_2$.
In the present investigation, the effect of sintering atmosphere on the densification and grain growth in $BaTiO_3$ has been studied. When $TiO_2$-excess-$BaTiO_3$ was sintered at 1300℃ in air, almost all the grain boundaries were faceted and abnormal grain growth occured due to the presence of {111}-twin lamellae. The relative density of the samles incresed slowly as sintering time increased. In contrast, when the samples were sintered in $H_2$, the grain boundaries were smoothly curved and all grains grew normally. The relative density of the $H_2$-sintered sample also increased slowly similar to the densification of air-sintered sample. However, when the samples were heat-treated at 1250℃ in $H_2$ and then sintered at 1300℃ in air, the densification was enhanced and the abnormal grain growth was suppressed. In the samples sintered in $H_2$ after a heat-treatment in $H_2$, a normal grain growth occured and the densification rate was low.
From the observation, it can be concluded that the densification of $BaTiO_3$ is enhanced when its grain boundaries are faceted and the abnormal grain growth is suppressed.
