MISFIT LAYER COMPOUNDS (MX)(N)(TX(2))(M) [M=SN, PB, BI, RARE-EARTH, T = TRANSITION METAL, X=S, SE, 1.08-LESS-THAN-N-LESS-THAN-1.25, M=1, 2]

The misfit layered compounds (MX)(n) (TX(2))(m) with M = Sn, Pb, Bi, Ln; T= Ti, V, Cr, Nb, Ta; X= S, Se; m= 1, 2 result from an alternate stacking of NaCl like MX slabs and TX(2) sandwiches. The in-plane a parameters of both sublattices are incommensurate, hence the structural misfit and complicated formulations like (LaS)(1.14)NbS2. In the case of M= Ln there is a partial electronic transfer from MX to TX(2) which leads to consider these phases as infinite two-dimensional intercalation compounds. Some of the compounds are highly anisotropic superconductors, ah have very striking physical properties. An interplay between MX and TX(2) layers allow to vary the number of each of them. In the case of the bilayer compounds (MX)(n)(TX(2))(2) it is possible to practice ''second order'' intercalation reactions between successive TX(2) layers.