STRUCTURAL AND VIBRATIONAL INVESTIGATIONS OF THERMAL-PROPERTIES OF TELLURITE GLASSES

To obtain quantitative details about the structure of binary tellurite glasses, the thermal properties have been measured. The thermal properties (linear thermal expansion coefficient a and transformation temperature T(g)) of a set of tellurite glasses containing rare earth oxides in the form (TeO2)0.9 (A(n)O(m))0.1 have been measured. The vitreous systems containing the rare earth cations are La, Ce, and Sm. The coefficient of thermal expansion in the range of 300-500 K and the transformation temperatures were determined to detect local structural changes that might be induced by the modifiers. The thermal properties alpha and T(g) are discussed in terms of (i) structure, by calculating the volume of structure unit, the average crosslink density, and the average stretching force constant of each glass system; (ii) vibrations, by correlating the mean long wavelength acoustic mode Gruneisen parameter gamma(el) and the expansion coefficient-alpha.