Superstructures and Chemical Bonding in Rare Earth Metal Polytellurides RETe2‐δ (RE=La−Nd; Sm−Tm; 0≤δ≤0.2)

Abstract

AbstractPolychalcogenides REX2‐δ (X=S, Se, Te; 0≤δ≤0.2) of trivalent rare earth metals RE have been investigated in recent years to shed light on the structural diversity as a function of compositional, metric, thermodynamic, and electronic situation. Whereas the former aspects have comparable influence on the structures of all polychalcogenides REX2‐δ, the bonding situation was assumed different for tellurides due to tellurium's higher tendency to delocalize electrons. The crystal structures generally contain puckered [REX] double slabs and planar [X] layers, the latter hosting different distortions from a square‐like arrangement. The distortion patterns of sulfides and selenides can be understood by a Zintl‐type approach; they are dominated by localization of valence electrons in mono‐ (X2−) or dinuclear (X22−) anions only. This review discusses crystal structures of some rare‐earth metal polytellurides RETe2‐δ (0≤δ≤0.2) and bonding features in the chalcogenide layers and relates them to their sulfide and selenide counterparts.