LOW-MELTING PBO-ZNO-P2O5 GLASSES

A series of lend zinc phosphate glasses containing 30-80 mol% P2O5, 0- 60%PbO and 0-60%ZnO have been prepared and characterised. The composit ion dependence of density, melting temperature(T-m), vitrification ran ge, thermal beahaviours (thermal expansion coefficient, glass transfor mation temperature T-g and softening temperature), chemical durability refraction index and Raman spectra is described These glasses can be prepared at relatively low temperatures (600-900 degrees C). Glasses w ith 40% or more P2O5 have lower T-g (<340 degrees C) and sensitive to water Glasses with 40% P2O5 or lower exhibit T-g of 340-400 degrees C and goon chemical durability, with a dissolution rate (R(w)) in 50 deg rees C deionised water at the order of 10(-8)-10(-9) g/cm(2) min. For example, a 50Pb0.10Zn0.40P(2)O(5) glass has T-g, T-m and R(w), of 338, 591 and 3.7x10(-9) g/cm(2)min, respectively. Details are also given o f structure of these glasses with Raman spectra.