Structural and Optical properties of P2O5-ZnO-Na2O-Li2O glasses

The transparent glasses of composition 40P2O5-20ZnO-(40-x)Na2O-xLi2O have been prepared using conventional melt quenching technique (where 0 ≤ x ≤ 25 Li2O mol. %). The prepared glass samples were characterized by x-ray diffraction (XRD), differential thermal analysis (DTA), UV-VIS optical absorption and Fourier transform infrared spectroscopy (FTIR). The differential thermal analysis (DTA) studies showed that the glass transition temperature (Tg) decreases from 558K to 546.7K as the content of Li2O increases to 25 mol.% Li2O . The density and oxygen packing density measurements are found to be increase while the molar volume decreases with increasing of Li2O content. The FTIR studies revealed that these glasses consist of Q3, Q2, Q1 and Q0 structural units. Absorbance of investigated glasses was measured and used to estimate their optical absorption coefficient and optical energy gap. The optical studies revealed that the indirect optical band gap (Eg) decreases from 3.33-2.64 eV and Urbach energy increases from 0.46-2.4eV with increase of  Li2O content from zero to 25 mol.% Li2O.