Structural and Optical Properties of Sol-Gel Derived Barium Titanate Thin Film

Ferroelectric barium titanate ( BaTiO 3) films have been prepared from barium acetate and titanium (IV) isopropoxide precursors by the sol-gel technique. The structural and optical properties of films annealed at different temperatures have been investigated. The as-fired films were found to be amorphous and crystallized to the tetragonal phase after annealing at 700°C for one hour in air. The lattice constants "a" and "c" were found to be 3.996 Å and 4.040 Å respectively. The X-ray density of the crystalline film was about 6.00 g · cm -3. The amorphous film showed very high transparency (~95%), which decreased slightly after crystallization (~90%). The band gap and the refractive index of the amorphous and crystalline films were estimated. The influences of porosity on the optical properties of films have also been investigated. The optical dispersion data are also analyzed in the light of the single oscillator model, and are discussed.