Thermal behaviour of Fe-doped silicate-phosphate glasses

Thermal behaviour and structure of glasses from the SiO2-P2O5-K2O-MgO-CaO system modified by Fe2O3 addition were studied by DSC, XRD and FTIR methods. It has been found that the replacement of MgO and CaO modifiers by Fe2O3 in the structural network of silicate-phosphate glass results in decrease of the glass transition temperature (T (g)) and heat capacity change (Delta C (p)) accompanying the glass transformation. Simultaneously, the ability for crystallization, its course and the type of the forming phases depend on the relative proportions between iron and phosphorus as components forming the silicate-phosphate structure. The type of the crystal phases forming in the course of heating the considered glass has been found to be in agreement with the character of the domains occurring in this glass, confirmed by FTIR examinations.