Synthesis and characterization of two crystallographic forms of Ag _0.79VS₂

A previously unreported compound, Ag_0.79VS₂, has been synthesized; its structure and elementary properties are reported. Ag _0.79VS₂ crystallizes in two forms, designated as the α and β, related to the 1s-InTaS₂ structure. Single crystal x-ray diffraction shows the α form to have a single layer hexagonal structure with a unit cell of 3.213(3) Å×7.809(6) Å, consisting of layers of edge-shared VS₆ triangular prisms separated by layers of Ag. The β form is similar but has an ^ao(3) supercell in the basal plane, yielding a unit cell of 5.573(5) Å×7.822(6) Å. Both forms have disordered and displaced silver in the basal plane, but the β form has partial ordering of its silver sublattice and in-plane vanadium trimers. Resistivity measurements show metallic temperature dependence with an unusual hysteresis between 210 K and 130 K. Magnetic susceptibility measurements show Pauli Paramagnetic behavior. The Seebeck coefficient at 300 K is 42 μV/K.