Improvement in fatigue properties of ferroelectric Bi4Ti 3O12 thin films by heat treatment in O2 gas at high pressure

Fabrication of ferroelectric Bi₄Ti₃O₁₂ thin films was carried out by spin-coating pyrolysis process of metal naphthenates. The films were finally sintered at 800°C for 30 min in O₂ gas with the pressures ranging from 0.1 to 0.4 MPa. In any conditions, ferroelectric Bi₄Ti₃O₁₂ thin films with complete c-axis orientation were obtained. Remanent polarizations of the films were improved with increasing O₂ gas pressure in sintering while coercive fields were constant. The Bi₄Ti₃O₁₂ thin film sintered at the O₂ gas pressure of 0.4 MPa exhibited good ferroelectric properties: the remanent polarization of 2.1 μC/cm² and the coercive field of 66 kV/cm. The remanent polarization of the film sintered at 0.4 MPa was observed to be 95 % of the initial value after the polarization reversal of 1×10⁹ cycles while that of the film sintered at 0.1 MPa was reduced to about half of the initial one after 1×10⁷ cycles. Sintering at high O₂ gas pressure had a great influence on the improvement of fatigue properties of ferroelectric Bi₄Ti ₃O₁₂ thin films