Grain-growth behavior during stepwise sintering of barium titanate in hydrogen gas and air

Abstract

To study the effect of oxygen partial pressure on grain growth in BaTiO3, TiO2-excess samples have been sintered in air with and without a prior H-2 heat treatment. Without prior H-2 treatment, abnormal grain growth occurs below and above the eutectic temperature (T-e). An introduction of H, treatment before air sintering, however, increases the average grain size and suppresses the formation of abnormal grains during subsequent air sintering below and above T-e. This H-2 treatment effect has been explained in terms of a decrease of the driving force for the growth of faceted grains below a critical value for formation of abnormal grains. The observed grain-growth behavior under various atmospheres demonstrates the possibility of having various microstructures via control of oxygen partial pressure and initial grain size.