Optical and dielectric properties of CaBi4Ti4O15 films prepared from sol gel route

Calcium Bismuth Titanate (CBT) is the potential material for the high temperature piezoelectric and ferroelectric applications, and exhibits excellent property for the non-volatile FeRAM for various commercial applications. In the present study CBT thin films were prepared from sol gel technique using acetate precursor method and films were annealed over a wide temperature range (500degC-800degC). The crystallographic orientations of films were investigated using X-ray diffraction and confirmed the orthorhombic structure. Grain size of the prepared CBT film increases from 19nm to 94nm with the increases in annealing temperature from 500degC to 800degC. The transmittance of the films in the visible region decrease with the increases in annealing temperature. Raman spectroscopy study indicates the formation of single phase layered perovskite material at 700degC. Optical band gap of the CBT film annealed at 700degC was found to be minimum (3.4 eV). The dielectric constant measured at room temperature approach the bulk value for the CBT films annealed at 700degC temperature.