Crystal Structure of Tungsten Disulfide

Tungsten disulfide has a hexagonal layered crystal structure -- the weak bonding between atoms in a single crystal layer and the weak van der Waal’s force between the crystal layers, which makes it both lubricated and conductive and accordingly has a wide range of applications in the field of solid lubrication and electronics.

Tungsten disulfide has a hexagonal structure, with each crystal layer consisting of two layers of sulfur atoms and an intermediate layer of tungsten atoms. The strong bonding between the sulfur and tungsten atoms in the layer leads to its excellent compression resistance. At the meantime, there is a weak combination of sulfur and sulfur atoms between the adjacent crystal layers. The weak van der waal’s force which also called molecular force, is from electrostatic interactions between molecules or atoms and is divided into the main three types: the induction force, the dispersion force and the orientation force. Owing to the existing of it between layers, tungsten disulfide is prone to have a tangential displacement when stressed, and the friction coefficient decreases greatly in the process of it. This property makes a significant contribution to the applications of tungsten disulfide in the field of solid lubrication.

Have a specific look at single layer tungsten disulfide. Single layer tungsten disulfide is a kind of sandwich structure. Under this structure, upper and lower two layers are distribution areas of sulfur atoms while tungsten atoms distributing in the area of the middle layer. One tungsten atom and six sulfur atoms are bonded to each other by covalent bonds, and each sulfur atom is bonded to three tungsten atoms by covalent bonds to form a triangular pyramid. Due to the existence of band gap, tungsten disulfide presents a property of semiconductor, which makes it have a broad application perspective in the field of electronics.

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