Abnormal grain growth in barium titanate doped with alumina

Abstract

The effect of additions of <= 1 mol% Al2O3 on abnormal grain growth in BaTiO3 sintered for periods of <= 60 min at 1350 degrees C has been studied. Addition of <= 0.2 mol% Al2O3 caused an increase in the nucleation and growth rates of abnormal grains, with further additions causing a decrease. This behavior is explained by interface-controlled growth. Dopant adsorption reduces both the edge free energy and the step velocity of a grain, causing the nucleation and growth rates of abnormal grains to increase, pass through a maximum, and then decrease with increasing dopant concentration.