Electron spin resonance and optical absorption spectra of Cu 2+ ions in xNaI(30 - x)Na 2O70B 2O 3 glasses

Abstract

Electron spin resonance (ESR) and optical absorption spectra of xNaI(30 - x)Na 2O70B 2O 3 glasses containing 1 mol% CuO have been investigated at room temperature. The optical absorption spectra of all the glass samples exhibited a broad asymmetric absorption band which correspond to the d—d transitions bands due to Cu 2+ ions. From the ESR spectra the spin-Hamiltonian parameters were evaluated. It was observed that the ground state of Cu 2+ is d x 2 - y 2 orbital and the site symmetry around Cu 2+ ions is tetragonally distorted octahedral. The bonding co-efficients were evaluated using the optical and ESR data to obtain information about Cu 2+-ligand bond nature. The basicity of σ-type symmetry was independent of the glass composition while the π-type basicity was found to vary as a function of the glass composition.