Volume and thermal studies for tellurite glasses

Binary tellurite glass systems of the forms TeO2(100 - x) - xA (n) O (m) where A (n) O (m) = La2O3 or V2O5 and x = 5, 7.5, 10, 12.5, 15, 17.5, and 20 mol% for La2O3 and 10, 20, 25, 30, 35, 40, 45, and 50 mol% for V2O5 were prepared. Density and molar volume of each glass were measured and calculated. The compressibility model has been used to find the difference volume V (d) due to the exchange of one formula unit between Te and both of La and V in the binary glass system and the mean volume V (A) per formula unit in the present binary glass in order to check whether or not it is independent of the percentage of the modifier for a glass series and also different from series to another. Differential scanning calorimetric at different heating rates was used to gain some insight into the thermal stability and calorimetric behavior of the present binary transition metal and rare-earth tellurite glasses. The glass transformation temperature T (g) and glass crystallization temperature T (c) were recorded at different heating rates to calculate both of the glass transition activation and the glass crystallization activation energies by using different methods.