Structures and properties of new ordered defect phases in the vanadium chromium sulfide system

The system V(x)CrS₂ (0 < x =1) has been investigated by X-ray and neutron powder diffraction. Five single-phase regions have been identified. All single-phase materials adopt pseudolayered structures, in which octahedral sites between alternate pairs of close packed sulfide layers are fully and partially occupied by cations. With increasing vanadium content, rhombohedral M₂S₃, trigonal M₂S₃, monoclinic M₃S₄, trigonal 3C-M₇S₈, and hexagonal M(1-x)S structures are successively observed. All single-phase materials exhibit semiconducting behavior, consistent with a variable range hopping conduction mechanism. Magnetic properties show considerably greater variation. The phase with the lowest vanadium content (rhombohedral M₂S₃) exhibits ferrimagnetic ordering at 100(10) K. Phases with higher vanadium content also exhibit long-range magnetic ordering, with the exception of the monoclinic M₃S₄, which is a spin glass (T(g) = 40(5) K).