Enhancement of remnant polarization in multilayered Bi4Ti3O12/(Bi3.25La0.75)Ti3O12 films obtained by chemical solution deposition

Enhancement of remnant polarization was observed in artificially multilayered Bi4Ti3O12 (BT)/(Bi3.25La0.75)Ti3O12 (BLT) films. The multilayer were prepared on platinum coated silicon substrate by chemical solution deposition and compared with the single-phase BT, BLT and (Bi3.5La0.5)Ti3O12 films. The multilayered film with a stacking periodicity of 60 nm BLT/30 nm BT shows a remnant polarization (2Pr) of about 61 μC/cm2, which is much higher than those of the single-phase films. In addition, the multilayered films show a good fatigue-endurance character. After post-annealing the multilayered films at 700 °C for a long time (20 h), its remnant polarization decreased to a value close to the corresponding uniform film. Some possible mechanisms behind the polarization enhancement were proposed.