Synthesis and characterization of two crystallographic forms of Ag0.79VS2

• Two crystallographic forms of Ag0.79VS2, designated α and β, are reported.
• They are found to crystallize in the 1s-InTaS2 structure type.
• β-Ag0.79VS2 has partial ordering of the Ag sublattice and vanadium trimers.
• Ag0.79VS2 shows Pauli Paramagnetic behavior, a Seebeck coefficient of 42 µV/K at 300 K.
• Ag0.79VS2 shows metallic resistivity with an unusual hysteresis between 210 K and 130 K.

A previously unreported compound, Ag0.79VS2, has been synthesized; its structure and elementary properties are reported. Ag0.79VS2 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.

Red=Vanadium, Gray=Silver, Yellow=Sulfur. Top left is α-Ag0.79VS2 in the 1s-InTaS2 structure type. Top right: 2a×2b projection down the c-axis with displacement ellipsoids (50% probability) of atoms drawn to illustrate the split silver model. Bottom left is β-Ag0.79VS2 having the ao(3) supercell. Bottom right: projection along the c-axis, displacement ellipsoids of atoms drawn. Figure optionsDownload as PowerPoint slide