Density andT g of glasses of the As-Al-Te system

Abstract

Results of measurements of the density and the glass transition temperature (Tg) on 25 glass compositions of the As-Al-Te system are reported and discussed. A linear increase of density and a decrease of Tg are seen with increasing As content across the AsAlTe4-As2Te3 tie-line compositions. In the density-composition and mean atomic volume-composition dependences for the AsxAl5Te95-x? AsxAl8Te92-x and AsxAl12Te88-x glasses, a change in slope is seen at the respective tie-line compositions, indicating chemical ordering in these glasses. When he dependence of density on the average coordination number Z are considered, the effects of chemical ordering are obscured; instead, the effects of topological nature emerge, with changes in slope at the topological thresholds of Z ? 2.40 and Z ? 2.67. The results further indicate that the dependence of mean atomic volume v on Z is controlled by the Te content in these glasses. Due to this, the generally observed features in the dependence of v on Z for chalcogenide glasses, namely a minimum in v to Z ? 2.40, a peak in v for Z ? 2.67 and a decrease of v for Z amp;gt; 2.67, are suppressed.