Effect of TiO2 on the chemical durability and optical properties of Mo-based phosphate glasses

The phosphate glasses belonging to the 20Li(2)O-(40-x)Li2MoO4-xTiO(2)-40P(2)O(5) (0 <= x <= 10 mol%) system were prepared via melt quenching route at 900 +/- 15 degrees C. The prepared samples are characterized by X Ray diffraction and differential scanning calorimetry to check possible crystalline residues and the glassy state. The structural properties of these glasses were investigated by some physical parameters such as density, molar volume, and glass transition temperature (T-g). Density values, molar volume values, and T-g values were found to depend strongly on the chemical composition of the glasses. The density decreased from 3.68 +/- 0.01 g/cm(3) to 3.27 +/- 0.01 g/cm(3), and Tg increased from 372 +/- 2 degrees C to 407 +/- 2.C with the TiO2 content increased from 0 mol% to 10 mol%. The structural approach is verified by Infrared (IR) and Raman spectroscopies. The chemical durability tests on the glasses have shown that the compositions containing pyrophosphate (Q(1)) and orthophosphate (Q(0)) units are more water resistant. The optical properties have been evaluated by determining some parameters, like optical band gap energy (E-g) and Urbach energy (Delta E) and their values are determinate. These parameters vary in opposite; E-g decreased from 2.12 eV to 1.35 eV and.. increased from 0.38 eV to 0.48 eV with increasing in TiO2 mol %.