Structure Determination and Physical Properties of the Misfit Layered Compound (Pb2FeS3)0.58NbS2

A crystal structure study of the layered misfit compound (Pb2FeS3)0.58NbS2has been performed using the composite approach. The structure can be described on the basis of a regular alternation of [Pb2FeS3] and [NbS2] slabs stacked along thecdirection. The [Pb2FeS3] part has a thickness of three layers, the central FeS layer being sandwiched between the two external PbS layers. Thus, Pb atoms on the exterior sides of this part are in a squared-pyramidal sulfur coordination, while Fe atoms in the central zone are octahedrally and tetrahedrally surrounded by sulfur atoms. From bond valence calculations, Fe atoms are found in the +III oxidation state whatever their environment. This is corroborated by a M?ssbauer study. Magnetic and electrical properties complete this study.