Low melting PbO-ZnO-P2O5 glasses

A series of lead zinc phosphate glasses containing 30-80 mol% P 2 O 5 , 0-60%PbO and 0-60%ZnO have been prepared and characterised. The composition dependence of density, melting temperature(T m ), vitrification range, thermal behaviours (thermal expansion coefficient, glass transformation temperature, Tg and softening temperature), chemical durability refraction index and Raman spectra is described. These glasses can be prepared at relatively low temperatures (600-900°C). Glasses with 40% or more P 2 O 5 have lower Tg (<340° C) and sensitive to water. Glasses with 40% P 2 O 5 or lower exhibit Tg of 340-400°C and good chemical durability with a dissolution rate (R w . ) in 50°C deionised water at the order of 10 -8 -10 -9 g/cm 2 min. For example, a 50PbO.1OZnO.40P 2 O 5 glass has Tg, T m and R w ., of 338, 591 and 3.7x10 -9 g/cm 2 min, respectively. Details are also given of structure of these glasses with Raman spectra.