Boundary faceting-dependent densification in a BaTiO_3 model syste

摘要

The effect of boundary faceting on densification has been studied in a 5 mol. TiO_2-excess BaTiO_3 model system. It was possil inhibit grain growth during sintering in moderately reducing atmospheres after a hydrogen presintering treatment and, thus, to ex the effect of grain growth on densification. For a given oxygen partial pressure (Po_2) there was a saturated relative density decreased with increasing Po_2 and boundary faceting. The fraction of small pores was also higher in the samples sintered under Po_2 than in those sintered under low Po_2. These experimental observations demonstrate the presence of a critical driving force for sification in systems with faceted boundaries and its dependence on boundary faceting, i.e. the critical driving force is larger for sys with greater faceting. The result further confirms that a faceted boundary, either fully or partially faceted, is an imperfect atom soun densification;;this idea is in contrast to the conventional understanding.