Structure cristalline et proprietes physiques de Cu0.75 VS2 |
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Authors: | N. Le Nagard G. Collin O. Gorochov |
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Affiliation: | Laboratoire de Chimie Minérale Structurale Laboratoire Associé au C.N.R.S. n° 200 Faculté des Sciences Pharmaceutiques et Biologiques de Paris V 4, avenue de l''Observatoire - 75270 Paris - Cedex 06, France |
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Abstract: | A new compound with composition Cu0.75 VS2 has been prepared. Its preparation, X-Ray structure, electrical and magnetic properties are reported. The structure is related to the CdI2-type, as in the case of the previously described CuxTiS2 (1); in Cu0.75 VS2, Cu atoms are ordered in tetrahedral sites between the CdI2-type subunits, whereas in CuxTiS2 Cu atoms are disordered in two independent sites. The vanadium atoms are shifted with respect to the titanium sites which leads a monoclinic distortion of the hexagonal cell. The relation between the CdI2 unit cell and the true monoclinic cell of Cu0.75 VS2 is: In Cu0.75 VS2, vanadium atoms occupy two independent sites, three vanadium atoms forming a triangular cluster (V2—V3 distances are 2.91 Å and V3—V3 are 2.92 Å) while one vanadium atom is isolated ( and . The physical properties exhibit a transition at 50°K approximately, the magnetic susceptibility being temperature-independent above and temperature dependent below the transition (Curie-Weiss behavior). Resistivity and Hall measurements confirm the metallic nature of the compound and show the existence of the low temperature transition. The observed properties could be interpreted as a result of the low temperature localisation of the 3d electron of V1. |
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