Electron paramagnetic resonance and optical absorption studies of Fe(III) ions in alkali barium borate glasses

Abstract

Electron paramagnetic resonance (EPR) and optical absorption studies of Fe(III) ions doped in 20 M 2O+(25− x) BaO+55B 2O 3+ xFe 2O 3 (M=Li, Na or K, 0.25≤ x≤10) glasses were carried out. The EPR spectra have resonances at g=10±0.5, g=6.4±0.1, g=4.2±0.1 and g=2.0±0.1. The EPR spectra of x=0.5 mol% of Fe 2O 3 in sodium–barium borate glass sample was studied at various temperatures. The linewidths were found to be unaffected by temperature changes, while the intensity increases with decrease in temperature. From the concentration dependence of the g=4.2 and g=2.0 resonances in sodium–barium borate glasses it was observed that clusters of iron are formed for Fe 2O 3 contents >3 mol%. The optical absorption spectrum of Fe(III) ions in such a glass exhibits six bands characteristic of Fe(III) ions in octahedral symmetry. From the analysis of the bands, the crystal-field parameter D q and the Racah interelectronic repulsion parameters B and C were estimated.