Low temperature synthesis and ferroelectric properties of La substituted Bi4Ti3O12 thin films by sol–gel

Bi4−xLaxTi3O12 (BLT) thin films were prepared on p-Si substrates by using sol–gel method. The effect of La content and annealing temperature on structure, morphology, dielectric and ferroelectric properties of BLT films were investigated. Even at low temperatures ranging from 500 to 650 °C, the BLT thin films were uniform and crack free as well as exhibited no preferred orientation analyzed by X-ray diffraction and atomic force microscope. La content and annealing temperature affect greatly on the preferred orientation and ferroelectric properties of BLT thin films. The Bi3.25La0.75Ti3O12 thin films annealed at as low as 600 °C showed excellent dielectric and ferroelectric properties with a dielectric constant of 288, a dielectric loss of 1.57%, a remanent polarization of 17.5 μC/cm2 and a coercive field of 102 kV/cm, which are better than those of Bi4Ti3O12 thin films prepared using the same processing. The low processing temperature and the large remanent polarization of BLT are favorable for device application.