Bonding and electrical conduction in amorphous thallium-tellurium alloys

Abstract

The band structures of model structures for Tl₂Te, Tl₂Te₂ and Tl₂Te₃ have been calculated in an attempt to determine the density of electronic states for these alloys. Tellurium lone pairs form the upper valence band once intermolecular interactions are included, while Te-Te antibonding states, if present, form the lowest conduction band. It is pointed out that an ionic model similar to that used to describe the composition dependence of the conductivity of a-Mg _x Bi_1−x alloys is not appropriate for a-Tl _x Te_1−x alloys because of the possibility that a range of polymer molecules exists at all compositions.