Thermomechanical properties and stability of mixed strontium-zinc borophosphate glasses

Borophosphate glasses of the SrO-ZnO-B2O3-P2O5 system were prepared in 3 compositional series of 25ZnO-25SrO-xB(2)O(3)-(50 - x)P2O5, (58.3 - x) ZnO-xSrO-16.6B(2)O(3)-33.33P(2)O(5) and (50 - x)ZnO-20B(2)O(3)-30P(2)O(5) and the changes in their thermomechanical and thermal properties with changes in their composition were investigated. The thermal expansion coefficient alpha decreases with increasing B2O3 content, whereas the values of glass transformation temperature T-g and dilatation softening temperature T-d increase. The replacement of ZnO by SrO increases both T-g and T-d. From the DSC results the value of the the Hruby's criterion K-gl was calculated and changes in the glass-forming tendency with changes in glass composition were discussed. (C) 2000 Kluwer Academic Publishers.