vanadium selenide is a versatile and useful metal used in alloys for high-speed tool steels, redox batteries, and other applications. This hard, silvery-grey metallic element occurs naturally in 65 minerals and fossil fuel deposits. It is artificially isolated from these materials and stabilized against further oxidation with the formation of an oxide layer.

Obtaining Single-Layer VSe2 on Au(111) with STM and DFT

Using the controllable structural manipulation of vanadium selenide compounds, single-layer VSe2 has been successfully synthesized on Au(111). Combining STM and DFT calculations, it is revealed that the initial honeycomb structure of VSe2 develops with a periodicity (moire periodicity) that is assigned to the material. Subsequently, with sequential annealing at elevated temperatures, defective structures develop with streaked patterns due to the selective loss of Se atoms. These defects can be reversed to the pristine VSe2 by resupplying Se, demonstrating the structural reversibility between vanadium selenide compounds.

Structural Transition to a Turbostratically Disordered Misfit Layer Compound

By using the modulated elemental reactants technique, we have synthesized a new compound of the V-Se binary system with a complex lattice constant. The compound exhibits a charge density wave (CDW) transition, which has not been observed in previous misfit layer compounds. Electrical transport measurements also suggest that the compound undergoes a CDW transition.

The structural characteristics of the compound have been characterized via X-ray diffraction and transmission electron microscopy, with a number of distinct intergrowths between bilayers of SnSe and VSe2 trilayers perpendicular to the c-axis. These intergrowths have a random rotational disorder between the layers.