Suppression of Acceptor Solubilities in BaTiO ₃ Densified in Highly Reducing Atmospheres

Abstract

The solubilities of acceptor impurities are strongly suppressed when BaTiO 3 is densified in highly reducing atmospheres. This is evidenced by a shift in the minimum in the equilibrium electrical conductivity to higher oxygen activities, a decrease in the ionic contribution to the conductivity, and a decrease in the leakage current and the rate of leakage current degradation under temperature–voltage stress. The normal solubility is restored by subsequent anneals in air that result in substantial grain growth, and the properties then revert to those of BaTiO 3 sintered in air. The solubility suppression is attributed to a mass‐action interaction between the processes that generate oxygen vacancies, those that result from the compensation of acceptor centers, and those that result from reduction.