Structure and Physical Properties
In MoS2, each Mo(IV) center occupies a trigonal prismatic coordination sphere, being bound to six sulfide ligands. Each sulfur centre is pyramidal, being connected to three Mo centres. In this way, the trigonal prisms are interconnected to give a layered structure, wherein molybdenum atoms are sandwiched between layers of sulfur atoms. Because of the weak van der Waals interactions between the sheets of sulfide atoms, MoS2 has a low coefficient of friction, resulting in its lubricating properties. Other layered inorganic materials exhibit lubricating properties (collectively known as solid lubricants (or dry lubricants)) including graphite, which requires volatile additives, and hexagonal boron nitride.
MoS2 is diamagnetic, indirect bandgap semiconductor similar to silicon, with a gap of 1.2 eV. As a semiconductor it has an indirect electronic bandgap of about 1.8 eV in the bulk. Because of its anisotropic structure, it exhibits anisotropic conductivity. It has been often investigated as a component of photoelectrochemical (e.g. for photocatalytic hydrogen production) applications and more recently for microelectronics applications. Single layers have proven to have properties differing from the bulk, including a direct electronic bandgap.
Nanotubes and buckyball-like molecules composed of MoS2 have been prepared and shown to exhibit unusual tribology and electronic properties.
Read more about this topic: Molybdenum Disulfide
Famous quotes containing the words structure, physical and/or properties:
“Vashtar: So it’s finished. A structure to house one man and the greatest treasure of all time.
Senta: And a structure that will last for all time.
Vashtar: Only history will tell that.
Senta: Sire, will he not be remembered?
Vashtar: Yes, he’ll be remembered. The pyramid’ll keep his memory alive. In that he built better than he knew.”
—William Faulkner (1897–1962)
“To many women marriage is only this. It is merely a physical change impinging on their ordinary nature, leaving their mentality untouched, their self-possession intact. They are not burnt by even the red fire of physical passion—far less by the white fire of love.”
—Mary Webb (1881–1927)
“The reason why men enter into society, is the preservation of their property; and the end why they choose and authorize a legislative, is, that there may be laws made, and rules set, as guards and fences to the properties of all the members of the society: to limit the power, and moderate the dominion, of every part and member of the society.”
—John Locke (1632–1704)