Some Factors Governing Ag+ and Cu+ Low Coordination in Chalcogenide Environments

Abstract

The factors influencing the low coordination of Cu+ and Ag+d10 cations in chalcogenides are analyzed by means of FLAPW band structure calculations. The study shows that the metal s/d orbital mixing is the predominant factor, in agreement with most previous research reports. It also quantitatively shows that the d10 cation polarization is reduced when the chalcogen electronegativity decreases, thus the coordination increases when going from the oxides to the tellurides. The calculation results make clear the fact that the d10 element low coordination can be raised for a given chalcogen by enhancing the polarization influence of the chalcogen through a charge transfer from an alkali metal. Finally, the shift in behavior from Cu+ to Ag+ is shown to be related to their different polarizabilities.