Electron Spin Resonance and optical absorption spectroscopic studies of manganese centers in aluminium lead borate glasses

Electron Spin Resonance (ESR) and optical absorption studies of 5Al2O3 + 75H3BO3 + (20−x)PbO + xMnSO4 (where x = 0.5, 1,1.5 and 2 mol% of MnSO4) glasses at room temperature have been studied. The ESR spectrum of all the glasses exhibits resonance signals with effective isotropic g values at ≈2.0, 3.3 and 4.3. The ESR resonance signal at isotropic g ≈ 2.0 has been attributed to Mn2+ centers in an octahedral symmetry. The ESR resonance signals at isotropic g ≈ 3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn2+ ions. The zero-field splitting parameter (zfs) has been calculated from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits an intense band in the visible region and it has been attributed to 5Eg → 5T2g transition of Mn3+centers in an octahedral environment. The optical band gap and the Urbach energies have been calculated from the ultraviolet absorption edges.

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► We report for the first time the optical absorption and EPR in this glass system.
► The Gibbs free energy is new and interesting in this glass system.
► The optical results are interesting.
► Our optical results are supported by recent literature on oxide glasses.
► The relaxation times are useful for knowing the environment of dopants in glasses.