FIRST-PRINCIPLES STUDY OF THE OXYGEN-VACANCY IN FERROELECTRIC PEROVSKITES

Through first-principles pseudopotential total energy calculations, th e nature of atomic relaxations around oxygen-vacancy defects in the fe rroelectric perovskite PbTiO3 is examined. A tail-to-tail polarization leading to an antiphase-polarization is one of the patterns that emer ges from atomic relaxations around an oxygen vacancy and that its stab ility is enhanced by charge trapping. The role of oxygen vacancies in fatigue and aging will be discussed based on the calculational results .