Magnesium Fluoride Borate Glasses for Low Phonon Energy

An oxyflouroborate glass series of composition 75B2O3-5Al2O3–(20-x) Li2O–xMgF2 (where x = 0, 5, 10, and 15 mol.%) was prepared using the normal melt-quenching technique. The physical properties (density, molar volume, and different optical behaviors) of the glass system were investigated via different techniques and discussed with the substitution of Li2O for MgF2. Also, the absorption coefficient, both direct and indirect optical energy gaps, and the optical exciton energy gap were studied. Furthermore, IR spectroscopy was used as a structural probe of the nearest-neighbor environment in the glass network. The results elucidate that the replacement of Li2O with MgF2 leads to both a blueshift in absorption cutoff and a decrease in the direct energy gap. More liberation of Mg+2 ions produces more localized states during transition, which decreases the values of band gap energy. The addition of MgF2 has a clear impact on lowering the glass phonon energy, which makes this glass promising for fiber amplifiers that operate at certain telecommunications wavelength bands and for upconversion fiber lasers. These results show the capability of using oxyflouroborate glass series to be applicable in optical amplifier laser components.