Ferroelectric properties of Bi4−xLaxTi3O12 (x = 0, 0.75) thin films prepared by sol–gel method

The Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol–gel method. The microstructure and ferroelectric properties of these films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth-layered perovskite structure and the single perovskite phase was obtained at 550 °C. The structures of Pt/Bi4Ti3O12/Pt and Pt/Bi3.25La0.75Ti3O12/Pt were fabricated. The 2Pr value of Bi3.25La0.75Ti3O12 thin films was much higher than that of Bi4Ti3O12 thin films. The Bi3.25La0.75Ti3O12 films showed fatigue-free behavior. The La doping effects on the crystal structure and ferroelectric properties of Bi4Ti3O12 films were investigated. The mechanism of improvement of ferroelectric properties was discussed.