Examination of a Structural Preference in Quaternary Alkali-Metal (A) Rare-Earth (R) Copper Tellurides by Combining Experimental and Quantum-chemical Means

Exploring the correlation between chemical bonding and structural distortions in TbCu0.33Te2

The design of solid-state materials requests a thorough understanding of the structural preferences among plausible structure models. Since the bond energy contributes to the formation energy of a given structure model, it also is decisive to determine the nature of chemical bonding for a given material. In this context, we were motivated to explore the correlation between chemical bonding and structural distortions within the low-dimensional tellurium fragments in TbCu0.33Te2. The ternary telluride was obtained from high-temperature solid-state reactions, while structure determinations based on x-ray diffraction experiments did not point to the presence of any structural distortion above 100 K. However, the results of first-principles-based computations indicate that a potential structural distortion within the low-dimensional tellurium fragments also correlates to an optimization of overall bonding.

Exploring the Interdependence between Electronically Unfavorable Situations and Pressure in a Chalcogenide Superconductor

The development of solids with the requested chemical and physical properties requires a thorough understanding of their electronic structures, as proper knowledge of the electronic structure of a given solid provides invaluable information regarding its properties. In this context, recent research on two competing sorts of electronic instabilities in chalcogenide superconductors stimulated us to explore the interdependence between these instabilities and another aspect, pressure, which was previously shown to influence the presence of a superconducting state in diverse solids. To accomplish our goal, we carried out pressure-dependent examinations of the electronic structures of two tellurides, YTe and YTe0.97, which were inspected as prototypes in our explorations based on quantum-chemical means. In addition to our pressure-dependent explorations of the electronic structures, we also performed chemical bonding analyses to reveal the subtle interplay between pressure and two sorts of electronically unfavorable situations.

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.