COMPOSITIONAL DEPENDENCE OF CRYSTALLIZATION OF AS-TE GLASSES

Thermal crystallization studies have been carried out on bulk, semiconducting AsxTe100-x glasses of different compositions, using Differential Scanning Calorimetry. AsxTe100-x glasses with x < 40, are found to exhibit one glass transition and one crystallization. On the other hand, glasses with composition 40 less-than-or-equal-to x less-than-or-equal-to 50 show one glass transition and two crystallization reactions. It has been found that in glasses with x greater-than-or-equal-to 40, the two crystallization reactions progressively merge with an increase in arsenic concentration. Consequently AsxTe100-x glasses with x > 50 show only one crystallization. The composition dependence of crystallization temperatures and activation energies for crystallization estimated by Kissinger's method, show marked deviations at a composition x = 40. These observations can be explained in terms of the changes in the local structure of the material with composition.