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 X-ray diffraction patterns of our samples indicated that the crystalline phases of the BiT were orthorhombic. Based on the transmission-spectra analysis, the samples are transparent in a visible spectrum, and their optical energy gaps were found to be 3.36 eV and 3.41 eV for the BiT thin films annealed at 600 degrees C and 650 degrees C, respectively. Other physical quantities, such as refractive index, thickness, extinction coefficient, and dielectric constant, were estimated by Swanepoel's method. The results show that as the annealing temperature rises, the real part of the dielectric constant becomes larger, that is, our samples are good dielectric materials. (C) 2019 Sharif University of Technology. All rights reserved.