Characterization of Fe3 + doped mixed alkali zinc borate glasses — Physical and spectroscopic investigations

The glasses of 19.9ZnO + xLi2O + (30 − x)Na2O + 50B2O3 (5 ≤ x ≤ 25) (ZLNB) doped with 0.1 mol% of paramagnetic Fe2O3 impurity are prepared by melt quench technique. Physical parameters of all the glasses are evaluated and they reveal a non-linear behavior with respect to the composition. Powder XRD pattern has not revealed any crystalline peak which indicates its amorphous nature. The optical band gap and Urbach energies exhibited the mixed alkali effect. All the prepared glass samples are found to be strong and stable in structure with low values of Urbach energy which lie between 0.010 and 0.022 eV. Electron paramagnetic resonance exhibited three resonance signals around g values at 2.06, 4.24 and 8.34 in the all Fe3 + doped glasses. The optical absorption spectrum of the samples exhibited three bands which are characteristic of Fe3 + in distorted octahedral symmetry. The crystal field parameter (Dq) and Racah inter electronic repulsion parameters (B, C) are evaluated. The FT-IR spectra of Fe3 + doped glasses exhibited characteristic vibrations of BO3 and BO4 units.

► Various physical and structural parameters are evaluated and correlated. ► Mixed alkali effect is observed in all physical and structural studies. ► EPR and optical studies confirmed distorted octahedral site symmetry. ► The glasses are observed to be moderately covalent in nature.