Optical properties of a near- axis tilt grain boundary in

Abstract

The electronic structure and the optical properties of a near- grain boundary in are studied by means of first-principles calculations based on a structural model constructed by Kenway. Results on the orbital-resolved partial density of states are presented for the grain boundary model and also for a perfect bulk supercell model containing the same number of atoms. An effective-charge calculation indicates an increased ionic character for atoms in the grain boundary region which is attributed to the distorted bonding pattern and a decrease in coordination number. The calculated optical properties show very similar results for the grain boundary model and the bulk supercell model. The electron energy-loss spectra are consistent with the recent experimental data on the near- grain boundary obtained by spatially resolved valence electron energy-loss spectroscopy.