Influence of Oxygen Vacancies on the Polarization Properties in Bi4Ti3O12 Ferroelectric Single Crystals
Measurements of the leakage-current and polarization properties in bismuth titanate (Bi4Ti3O12) along the a axis show that the crystals grown in air followed by air annealing at 700oC had a superior remanent polarization of 48 μC/cm2 as well as a low leakage current density of the order of 10-9 A/cm2. The annealing at a high oxygen partial pressure of 35MPa (700oC) resulted in a higher leakage current, indicating that electron holes arising from the incorporation of oxygen at oxygen vacancies act as detrimental carriers for electrical conduction at room temperature. A crystal growth under high-pressure oxygen atmosphere and subsequent annealing at a moderate oxygen partial pressure is proposed to be advantageous for suppressing the vacancy formation and for attaining a large remanent polarization as well as a high insulating property of the Bi4Ti3O12 system.
Keiichi Katayama, Kazumi Kato, Tadashi Takenaka, Masasuke Takata and Kazuo Shinozaki
Y. Noguchi et al., "Influence of Oxygen Vacancies on the Polarization Properties in Bi4Ti3O12 Ferroelectric Single Crystals", Key Engineering Materials, Vol. 320, pp. 19-22, 2006