Grain‐Growth Behavior during Stepwise Sintering of Barium Titanate in Hydrogen Gas and Air

To study the effect of oxygen partial pressure on grain growth in BaTiO 3 , TiO 2 ‐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 2 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.