ELECTRONIC-STRUCTURE AND PROPERTIES OF ANIONIC MIXED-VALENCE AND LAYERED CRTE3 - THE QUESTION OF EXTENDED TELLURIUM BONDING IN TRANSITION-METAL TELLURIDES

CrTe3 is a layered material whose tellurium sublattice contains Te, Te2, and Te3 entities. Our magnetic susceptibility measurements are consistent with a + 3 oxidation state for Cr. This indicates three different oxidation states for the tellurium atoms, i.e., Te2-, Te2-2, and Te2-3. Conductivity measurements show this material to be a semiconductor with an activation energy of 0.35 eV. Our tight-binding band structure calculations indicate that it is a Mott-Hubbard semiconductor rather than a regular one. A study of the Te···Te overlap populations suggests that CrTe3 is a new transition metal telluride with a polymerized tellurium network. Analysis of this additional bonding within the tellurium sublattice in this phase and in related tellurides leads to a classification of the transition metal ditellurides taking into account both dimensionality and degree of polymerization. © 1992.