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Abstract :
[en] Ferecrystals are a new family of compounds first synthesized in 2007 by the
group of D. Johnson at the University of Oregon. These materials consist
of inter-growths of dichalcogenide and chalcogenide layers, and can be written
as [(M X)_{1+δ} ]_m [T X_2 ]_n where M = Sn, Pb, Sb, Ni and some rare earths; T = Ti,
V, Cr, Nb and Ta; X= S and Se. The integers m and n denote the numbers of
consecutive formula unit layers in the different components of the inter-growth.
The δ parameter reflects the difference of the in-plane cell constants between
components of the inter-growth. This family of nanostructured materials shows
promising properties for thermoelectric devices. The compounds studied here
are [(SnSe)_1.29 ]_{234} [M oSe_2 ]_1 . We performed structural characterisation and
examined the transfer of charge at the interface between the two materials. We
show that there is a depletion of charge at the interface between the two compo-
nents of the heterostructures and that structural distortions of the SnSe layers
in the supercell are similar to those observed in slab calculations.
