Fabrication of bismuth titanate (Bi4Ti3O12) thin Films: Effect of annealing temperature on their structural and optical properties

Bismuth Titanate (Bi4Ti3O12) ceramics, so-called BiT, have many modern applications in microelectronics, sensors, and capacitors. In this study, the related solutions for fabricating BiT thin films were prepared and then coated on glass substrates by using the sol-gel technique and the spin coating instrument. The Xray diffraction patterns of our samples indicate that the crystalline phases of BiT are orthorhombic. Based on the transmission-spectra analysis, the samples are transparent in the visible spectrum, and their optical energy gaps are found to be 3.36 eV and 3.41 eV for the BiT thin films annealed at 600◦C and 650◦C, respectively. Other physical quantities such as refractive index, thickness, extinction coefficient and dielectric constant were estimated by swanepol’s method. The results show that as the annealing temperature rises the real part of the dielectric constant becomes larger indicating our samples are good dielectric materials