Electron Spin Resonance (ESR) and Optical Absorption Spectra of a Manganese Doped Soda-Lime-Silicate Glass System

Abstract

A (65-x)SiO₂:10CaO:25Na₂O:xMnO₂ glass system with 0 ≤ x ≤ 0.5 mol% was prepared and investigated by X-ray diffraction, optical absorption and ESR spectroscopies. The XRD pattern of undoped glass confirmed the formation of an amorphous vitreous structure. The optical absorption spectra exhibited a predominant broad band around 500 nm and its increase was clearly observed from 0.1 mol% of MnO₂. This band corresponded to an allowed transition from ⁵E_g→⁵T_2g, of Mn³⁺ ions. When the MnO₂ concentration was increased, the absorption band due to Mn³⁺ ions dominated. The ESR spectra results exhibited resonance signals at g ≈ 2.0 with a sextet of hyperfine lines and less intensity at g ≈ 4.3. The group of hyperfine lines at g ≈ 2.0 represented Mn²⁺ ions in octahedral symmetry. However, these lines were broader and disappeared for higher MnO₂ concentrations. This behavior indicated the reduction of Mn²⁺ ions in the glass system as the concentration of MnO2 was increased by increasing the Mn³⁺ ions.