Floppy to rigid transition and chemical ordering in Ge [sbnd]Sb(As) [sbnd]Se glasses

Abstract

The dependence of mean atomic volume and the glass transition temperature on the average coordination number, lt;igt;Zlt;/igt;, have been examined for glasses of the Ge-Sb(As)-Se systems, in the light of recent models proposed for network glasses. The results indicate the occurrence of additional features at lt;igt;Zlt;/igt; values other than the topological thresholds of amp;sime;2.40 and amp;sime;2.67. These additional features are attributed to effects of chemical ordering. The occurrence of these features in addition to those due to the two topological effects, namely, the floppy to rigid transition and the structural transition, leads to the conclusion that the effects of the chemical ordering and the effects which have topological origin coexist in these glasses