CaF₂–Al₂O₃ multicomponent borate glasses doped with MnO₂: physical and spectroscopic characterization

The motive of this work is to investigate the physical characteristics and spectroscopic features of multicomponent MnO₂-doped Bismuth Borate glasses. The chemical formula for the glasses was (30-x) CaF₂–xAl₂O₃–10Bi₂O₃–59B₂O₃–1MnO₂, with x ranging from 3 to 15 mol% in steps of 3 mol%. The glasses were synthesized using the traditional melt-quenching method. The amorphous nature of the glass samples was confirmed by the XRD and SEM patterns. The density of the glass specimens decreased while molar volume showed a trend opposite to density. The optical bandgap of the glasses grew when the Al₂O₃ content increased, as shown in UV–Vis spectra. The values of optical energy gap are varied from 2.712 eV to 2.868 eV. A characteristic property of glass: Urbach energy ranging from 0.223 to 0.315 eV. The local structure of the glasses was investigated using Raman spectroscopy, which showed a mostly borate network. The FTIR spectra showed recognizable absorption bands that corresponded to glass constituents such as Borate, Bismuth, Aluminium, Calcium and Manganese. The EPR spectra showed that the Mn²⁺ particle was bound to its environment via ionic bonds. Well-resolved six-line hyperfine signal pattern was observed at g (Lande’s g factor) = 2.018.