La-modified bismuth titanate thin films prepared by Sol-Gel process

Abstract

The lead-free ferroelectric lanthanum modified bismuth titanate (Bi_4-xLa_xTi₃O₁₂, BLT-10x) thin films were prepared by sol-gel method using tetrabyl titanate, bismuth nitrate and lanthanum nitrate. Polycrystalline BLT-5 thin films were obtained at relatively low annealing temperatures of 600-650°C. The intensity of XRD peaks of BLT-5 thin films was increased with the increase of annealing temperature. The typical cohesive electric field (E_c) and remnant polarization (P_r) for BLT-5 thin films annealed at 650°C were E_c=65kV/cm, P_r=11.2μC/cm². The affection of heat treatment on the crystalline and electric properties of BLT-5 thin films was also discussed.