Phase Formation and Microstructure of BaTiO₃Ceramics Prepared by Direct Current Arc Discharge Process

Abstract

BaTiO 3 (BT) ceramics are prepared above 2000 C by direct current arc discharge plasma process in argon atmosphere. The results show the formation of the perovskite structure. However, the coexisting of tetragonal phase and hexagonal phase is found in the structure. It is also found that a small amount of BaTi 4 O 9 compound appears. With the sintering temperature increasing, the structure becomes more homogeneous because of interdiffusion of constituent ions and phase transition. The hexagonal phase gradually disappears and BaTi 4 O 9 compound could also be traced.

Formation mechanism and microstructure evolution of Ba2Ti9O20 ceramics by reaction sintering method

“…Due to the local enrichment of titanium caused by the local inhomogeneity of barium, there might be a small amount of highly anisotropic metastable phase on the ceramic surface. The reasons of grain melting might be originated from the existence of metastable phases or impurities and materials with high anisotropy in interfacial energy . Therefore, the grain melting phenomenon caused by the local inhomogeneous distribution of barium on the Ba 2 Ti 9 O 20 grain surface was an important reason for the roughness of ceramic surface.…”

“…The reasons of grain melting might be originated from the existence of metastable phases or impurities and materials with high anisotropy in interfacial energy. 27 Therefore, the grain melting phenomenon caused by the local inhomogeneous distribution of barium on the Ba 2 Ti 9 O 20 grain surface was an important reason for the roughness of ceramic surface. The densification of ceramics was usually accompanied by migration of substances.…”