CHARACTERIZATION OF LAYERED TRANSITION-METAL DICHALCOGENIDES WITH OCTAHEDRAL COORDINATION

The lattice constants of nonstoichiometric CdI2-type transition-metal dichalcogenides exhibit a characteristic feature. One of the body-diagonal lengths of the hexagonal lattice is kept nearly constant over the homogeneity range. This body-diagonal direction involves the full-layer metal-chalcogen bonds. The heats of formation of various CdI2-type transition-metal dichalcogenides are correlated to the reduced length which is derived from that body-diagonal and the ideal ionic radii. The ΔHof values of the CdI2-type transition-metal dichalcogenides can be estimated from the following empilical formula within the error of about 10kcal/mole. ΔHof = 1030 LR - 144 (kcal/mole). LR: Reduced length. © 1978.