Structures and Chemical Compositions of Chevrel Phase Compounds

Abstract

In the last decade a number of ternary molybdenum chalcogenides named Chevrel phase compounds, M_xMo₆X₈ (M=metal ion ; X=S, Se and Te), have been investigated. Many of these compounds show properties as superconductors with high upper critical fields. Further, in some cases of M=rare earth elements, the coexistences of magnetism and superconductivity are observed. For these substances, the growth of large single crystals with good quality and the knowledge of the exact chemical composition are essential to the understanding of physical properties. Recently a series of compounds with more complicated structures, i. e. M_xMo₁₅X₁₉, MxMo₉X₁₁ and M₂Mo₆ X₆ (X=S, Se and Te) have also been prepared. Then the problems of these compounds in chemical side became more important. The present article reviews these substances from the viewpoint of crystal structure, crystal growth, nonstoichiometry and bonding character.