The effect of tungsten ions on the structure of PbO-As2O3 glasses

PbO-As2O3 glasses containing different concentrations of WO3 (ranging from 0 to 1 mol%) were prepared. A number of studies, namely, differential thermal analysis, IR spectra, optical absorption, ESR, elastic properties (Young's modulus E, shear modulus G and microhardness H) and dielectric properties (dielectric constant Ε, loss tan δ, and ac conductivity σac, over a range of frequency and temperature and breakdown strength), were carried out on these glasses as a function of tungsten ion concentration. An anomaly has been observed in all the properties of these glasses when the WO3 concentration is about 0.4 mol%. The studies indicate the presence of W5+O3- complexes in the glass matrix when the concentration of WO3 is more than 0.4 mol%. The analysis of results suggests that the stability of the PbO-As2O3 glass network is enhanced if a small concentration of WO3 (about 0.4 mol%) is present in the glass matrix.