Exploring the subtle factors that control the structural preferences in Cu₇Te₄

In the quest for materials suited as components in future technologies, the copper-rich regions of the binary Cu-Te system have been of great interest. In this context, several explorative efforts were also focused on Cu₇Te₄which was reported to crystallize with different types of structure. To explore the structural preferences for two Cu₇Te₄structure models, both experimental as well as quantum-chemical means were employed. The crystal structures of both Cu₇Te₄types are composed of hexagonal closest packed layers of tellurium atoms, and differ in the respective distributions of the copper atoms between these layers. The analysis of the electronic structures was accomplished based on the densities-of-states, Mulliken charges, projected crystal orbital Hamilton populations, and electron localization functions of both structure models, and its outcome indicates that the factors that control the formation of a respective type of structure are rather subtle.