Effect of the liquid-phase characteristic on the microstructures and dielectric properties of donor- (niobium) and acceptor- (magnesium) doped barium titanate

Changes in the microstructure and dielectric properties with the variation of the donor/acceptor ratio in BaTiO3 ceramics were investigated. In donor-rich specimens, a liquid that appeared during sintering did not penetrate into grain boundaries. However, in the acceptor-rich specimens, the grains were separated by a liquid film during sintering. The much higher mobility of the liquid film than that of the grain boundaries was suggested to cause extensive grain growth in acceptor-rich BaTiO3. The macroscopic homogenization of dopants because of grain growth in acceptor-rich specimens resulted in changes in the dielectric properties.