Synthesis, structure, and properties of barium cobalt sulfide (Ba6Co25S27) a perovskite-like superstructure of Co8S6 and Ba6S clusters

Abstract

Abstract : We have prepared single crystals of a new ternary barium cobalt sulfide, Ba6Co25S27 by cooling a melt containing BaS, CoS and Co from 975 deg C. The structure, determined by single crystal X-ray diffraction, is cubic (Pm3M) with a = 10.033(3)A, Z=l, and R= 2.6%, Rw= 2.4%. The structure contains an octahedrally coordinated cobalt atom, nearly cubic clusters of eight cobalt atoms, and an unusual arrangement of barium atoms. The electric resistivity and magnetic susceptibility measurements show that Ba6Co25S27 is a poor metal with a resistance minimum at 8K, and Pauli paramagnetic with a small Curie contribution indicating that either the Co8 cluster or the octahedrally coordinated cobalt atom has a magnetic moment. Solid State Sulfides, Electrical and magnetic Properties, Metal Clusters.