Ferroelectric Phase Transition in Some Perovskite-Type Oxide Mixtures

Abstract

In some perovskite oxides, addition of a small amount of other perovskite oxide induces a strong reduction of ferroelectric phase transition temperature. We apply the vibronically coupled two-band model to these mixtures and show that the transition temperature lowering is caused by the band width broadening which surpasses the effect of the band gap narrowing.