Modulated DSC and fragility studies on diborate glasses containing heavy metal ion

Glasses in a wide range of compositions in the system xPbO - (100-x) Na2B4O7 (10 ⤠x ⥠50) have been prepared and characterized using XRD and modulated differential scanning calorometry(DSC). Quantitative correlations are established between fragility, glass transition temperature and structure. Addition of PbO causes a change in short range order of the diborate matrix. The modification of diborate network with the addition of PbO, results in the formation of B-O-Pb covalent linkages. Density, molar volume and glass transition temperature exhibit composition dependent trends. The fragility increases with increase in concentration of PbO. Analysis of the modulated DSC data reveals the investigated glasses are fragile.