Redox competition and stability: rare earth misfit layer compounds as an example

Recent studies of the electronic structure of the rare earth misfit layer c ompounds (LnS)(1+x)TS2 (Ln = rare earth, T = Ti, V, Cr, Nb, Ta) allow one t o present a model which explains their stability. Two redox competitions, o ne between the [LnS] and the [TS2] slabs, and the second between the T nd a nd S 3p bands, are found to govern the stabilization of these compounds. Th is study shows how the modification of the electronic structure of each sla b, by moving along the rare earth or the transition elements, defines a nar row stability range for the misfit layer structure. (C) 1999 Academie des s ciences / Editions scientifiques et medicales Elsevier SAS.