Optical Absorption Characteristics of Copper Ions in Some Binary Alkali Borate Glasses

Abstract

From the optical absorption spectra of cupric ions existing in binary lithium, sodium and potassium borate glasses, it was deduced that the cupric ions are in octahedral coordination with the surrounding oxygen ligands. No evidence for coordinations other than octahedral was found. There is strong tetragonal distortion which causes the characteristic band in the region of 12,500 Cm⁻¹ to be broad and asymmetric. The distortion was measured by the formula of alkali content. It increased very slightly with increasing alkali content up to 16 mol.%, beyond which it appreciably increased. The weak absorption band in the region of 22,500 Cm⁻¹, for which markedly different attributions were proposed, is suggested to be associated with cuprous, ions.