Correlation between nonbridging oxygens and the thermal and optical properties of the TeO 2 –Li 2 O–MoO 3 glassy system

In this work, the correlation between the number of nonbridging oxygen (NBO) atoms and the thermal and optical properties of TeO 2 –Li 2 O–MoO 3 glasses was studied. Samples containing (100 − x )TeO 2 – x (Li 2 O–MoO 3 ) with x = 10, 15, 20, and 25 mol% were investigated by Raman and Fourier transform infrared (FTIR) spectroscopies. From the optical absorption measurements, the band gap energies were determined. The Raman and FTIR results showed that with increasing x , the TeO 4 units transform into TeO 3+1 units and then into TeO 3 units, while the Mo coordination changes from 4 → 6. This transformation corresponds to a decrease in the total number of NBO with increasing x in this glass matrix. The decrease in the NBO is also confirmed by the increase in band gap energies and the decrease in the optical basicity, indicating a more polymerized network with increasing x .