HRTEM Studies of Stress Assisted Sintered BaLa₄Ti₄O₁₅

The role of interfaces on the grain growth of polycrystals during sintering has been recently recalled into attention and important theoretical work has been developed, supported by experimental results on ceramic oxide materials [1,2]. It was shown that by controlling the nature of the interfaces one can tune the grain growth during sintering and, therefore, the subsequent control of related properties is envisaged. One way to control the interface nature is by changing the sintering conditions and there are several studies proving the importance of the sintering temperature, holding time, heating rate and atmosphere, but very few about the effect of an external pressure applied during the consolidation process [3,4]. In this work we are presenting a HRTEM study of BaLa4Ti4O15 (BLT) ceramics sintered under compressive stresses applied by Hot Pressing (HP) and Hot Isostatic Pressing (HIP) and the comparison with a free sintered sample. This study clearly reveals that the external pressure plays a role on the nature of the grain boundaries in BLT.