Optical Transmittance and Band Gap of Ferroelectric BaTi2O5 Bulk Glass

Abstract

Optical transmittance and reflectance on ferroelectric BaTi2O5 glasses prepared recently by a containerless synthesis technique are measured at room temperature in the wavelength range 190–800 nm. The fundamental absorption edge located around 340 nm demonstrates the colourless and transparent character of the glass. The optical band gap of 3.32eV has been estimated. The tail of the optical absorption near the fundamental absorption edge is found to follow the Urbach rule. Our analysis of the experimental spectra supports an indirect allowed interband transition between the valence band formed by O-2p orbitals and the conduction band formed by Ti-3d orbitals.