Field-assisted sintering of undoped BaTiO3: Microstructure evolution and dielectric permittivity

We report, for first time, how electric fields influence the sintering of undoped BaTiO3, a ferroelectric material, and how this process affects the microstructure and the dielectric properties. Flash sintering is achieved at a furnace temperature of 688 °C under a field of 500 V cm−1, producing specimens that are 94% dense. As a consequence, the grain size is much finer than in conventional sintering, which is shown to influence the Curie temperature and dielectric permittivity. Data obtained at different strengths of the electrical field, and current limits imposed on the specimen are presented in the form of a “processing map” that separates the safe region, where sintering is uniform, from the fail region, where the current flow in the sample becomes localized. The map illustrates that ceramics can respond by different mechanisms, with the dominant mechanism changing with the strength of the electrical parameters.