Theoretical prediction of physical parameters of GexSb20−x Te80 (x = 11, 13, 15, 17, 19) bulk glassy alloys

Abstract

Physical properties of Ge x Sb 20−x Te 80 (x = 11, 13, 15, 17, 19) bulk glassy alloys are examined theoretically. Lone pair electrons are calculated using an average coordination number ( r ) and the number of valence electrons, and are found to decrease with an addition of Ge. Mean bond energy ( E ) is proportional to glass transition temperature (T g ) and shows maxima near the chemical threshold. Cohesive energy of the system is calculated using chemical bond approach. A linear relation is found between cohesive energy, band gap (calculated theoretically and confirmed experimentally) and average heat of atomization. All these parameters are increasing with an increase in Ge content. A relation between average single bond energy and photon energy is discussed. Compactness of the structure is measured from the calculated density of the glass. An attempt is made to discuss the results in terms of structure of the glass or equivalently with average coordination number.

Theoretically Predicted Deviation in Physical Properties of Ge-Bi-S Chalcogenide Alloys With Compositional Variations

“…The increase in C.E and band gap of the system is attributed to the increase in average bond energy of the system because of the formation of Ge-S bond on the expense of Bi-S and S-S bonds. A similar trend of increase in CE with an increase in Ge content is observed for other chalcogenide glasses [50].…”

“…The density is an important physical parameter and is related to the change in atomic weight, atomic volume of the elements constituting the system [68]. The density is a measure of the rigidity of a system; theoretically was calculated by [69]:…”