THE (FE,NB)NB2SE10 FAMILY - RESISTIVITY AND MAGNETIC MEASUREMENTS

The physical properties (electric and magnetic) of (FeNb)Nb//2Se//1//0, (Fe, V, Nb)Nb//2Se//1//0, (Cr, Nb) Nb//2Se//1//0 and (Fe, Ta, Nb) (Nb, Ta)Se//1//0 are reported and a discussion is given in relation to their structural type. These four compounds exhibit two types of chains within the unit cell, running in a direction parallel to the monoclinic b axis (FeNb//3Se//1//0 structural type): a trigonal prismatic chain (NbSe//3 like) where C. D. W. s occurs at low temperature (as example FeNb//3Se//1//0), and an octahedral chain along which the disorder of the distribution of metallic atoms seems to be a key factor governing the transport properties; indeed, it creates a random potential causing the localization of the conduction electrons.