STRUCTURE AND ELECTRICAL-CONDUCTIVITY OF AGTAS3

Single crystals of the compound AgTaS3 have been prepared through reac tions of the elements with halide mixtures. The structure of AgTaS3 ha s been analyzed by single-crystal X-ray diffraction methods. AgTaS3 cr ystallizes in the space group D-2h(17)-Cmcm of the orthorhombic system with four formula units in a cell of dimensions a=3.378(2), b=14.070( 5), c=7.756(3) Angstrom. The structure of AgTaS3 consists of two-dimen sional (2)(infinity)[TaS3-] layers separated by Ag+ cations, The layer is composed of Ta-centered bicapped trigonal prisms stacked on top of each other by sharing triangular faces. These chains are linked to fo rm the infinite two-dimensional (2)(infinity)[TaS3-] slabs. These laye rs are held together through van der Waals interactions, and Ag+ ions reside in the distorted octahedral sites between the layers, The tempe rature dependence of the electrical conductivity along the needle axis of AgTaS3 shows the typical behavior of an extrinsic semiconductor. ( C) 1997 Academic Press.