Structure and DC conductivity of lead sodium ultraphosphate glasses

Glasses of (0.40−x)Na2O−xPbO−0.60P2O5 system with (0⩽x⩽0.40) molar fraction have been prepared with a conventional melting procedure. Their physical, thermal and spectroscopic studies such as density, molar volume, glass transition temperature, ionic conductivity and infrared spectroscopy have been investigated. The density and thermal stability of theses glasses increase with the substitution of PbO for Na2O. The ionic conductivity increases substantially with increasing concentration of sodium oxide and diminishes with increasing PbO content. Fourier-transform infrared spectroscopy reveals the formation of POPb bonds in theses glasses. The formation of POPb bonds which replace PO−…Na+ bonds is in accordance with variations of glass transition temperature (Tg), molar volume (Vm) and ionic conductivity (σ). The former bonds are the origin of the partial glass-forming ability of Pb2+.