Structure cristalline et proprietes physiques de Cu 0.65VS 2

Abstract

A second form of compounds Cu xVS 2 is described here. As in Cu 0.75VS 2 (1) the structure of Cu 0.65VS 2 is related to the CdI 2-type. In Cu 0.75VS 2, Cu atoms are ordered in tetrahedral sites between the CdI 2-type subunits, whereas in the Cu 0.65VS 2, Cu atoms are partially disordered and occupy 4 different sites. Both structures differ from one another in vanadium atoms arrangements: In Cu 0.75VS 2, V-atoms form triangular clusters while in Cu 0.65VS 2 they form zigzag chains perpendicular to the hexagonal axis. The physical properties show a metallic type behaviour. Resistivity decreases with temperature with low 300 K/4.2 K ratio according to a disordered nature of the compound. Magnetic susceptibility shows a Pauli paramagnetism with an additionnal Curie-Weiss term due to a relatively large amount of paramagnetic impureties (0,9 % V 3+ atoms). The observed low temperature localisation of the 3d electrons in Cu 0.75VS 2 disappears in the case of Cu 0.65VS 2.