Network structure of molybdenum lead phosphate glasses: Infrared spectra and constants of elasticity

Molybdenum lead phosphate glasses doped with La2O3 of the system xMoO(3)-5La(2)O(3)-50P(2)O(5)-(45-x)PbO, with 0 <= x <= 25 mol%, have been synthesized and studied by FTIR, ultrasonic and differential scanning calorimetry (DSC) in order to investigate the role of MoO3 content on their atomic structure. The constants of elasticity and Debye temperatures of the glasses have been investigated using sound velocity measurements at 4 MHz. According to the IR analysis, the vibrations of the phosphate structural units are shifted towards higher wavenumbers associated with the formation of bridging oxygens. The change in density with MoO3 content reveals that the molybdate units are less dense than the lead units. The observed compositional dependence of the constants of elasticity is interpreted in terms of the effect of MoO3 on the different phosphate bonds. It is assumed that MoO3 plays the role of a former by increasing the ultrasonic velocity and the constants of elasticity of the phosphate glasses. (C) 2010 Elsevier B.V. All rights reserved.