Optical and EPR Spectroscopy of Manganese Ions in Fluorozirconate Glasses

The EPR and luminescence spectra of fluorozirconate and fluorochlorozirconate glasses doped with various manganese compounds were studied to determine the oxidation state of manganese ions and the structure of their distribution. The luminescence spectra of both the fluorozirconate and the fluorochlorozirconate glasses showed the presence of only Mn2+ ions due to the T-4(1)(G) -> (6)A(1) transition, regardless of the oxidation state of the manganese ions in the initial dopant compound. In the fluorozirconate glasses, Mn2+ ions have a green emission band at 550 nm, which is shifted to the red region to 615 nm after the substitution of chlorine for a part of the fluorine in the glass. The ratio of the content of free manganese ions to the content of ions in clusters in the synthesized glasses was investigated. It was determined that manganese ions in the glasses are mainly aggregated to form clusters, and an increase in the activator concentration leads to a decrease of the fraction of free ions. The differences in luminescence and EPR spectra between the fluorozirconate and fluorochlorozirconate glasses are explained by a change in the structure of the local environment of the manganese ions.