Lead phosphate-tellurite glasses in the compositional series (100-x) [0.5PbO-0.5P2O5]-xTeO2 (X-series) and 50PbO-(50-y)P2O5-yTeO2 (Y-series) with x=0-80mol% TeO2 were studied. The incorporation of TeO2 structural units into the lead metaphosphate glass results in a substantial decrease in their molar volume while the density increases in both compositional series. All prepared glasses exhibit good chemical durability against water corrosion. The additions of TeO2 to the starting 50PbO-50P2O5 glass composition lead only to small changes of their thermal expansion coefficient within the range of 15.6-17.3ppm degreesC1. Glass transition temperature and dilatometric softening temperature reveal a maximum for the glass with x=50mol% and y=25 mol% TeO2. DTA measurements showed that most of the glasses studied crystallise on heating in the temperature range of 380 - 550 degrees C. The lowest tendency towards crystallisation was observed for the samples containing 20-50mol% TeO2 in the compositional series (100-x)[0.5PbO-0.5P2O5]-xTeO2. Raman spectra indicated that the replacement of phosphate structural units by tellurite units is accompanied by the depolymerisation of phosphate chains and gradual transformation of Q2 to Q1 and Q0 phosphate units.
