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Intercalating metal halides reduces interplane interactions and lowers friction.
LAMELLAR COMPOUNDS CONSIST OF STRONGLY BONDED PLANAR LAYERS that have weak van der Waals forces between them. The presence of the weak interlaver interactions has been suggested to facilitate shear along directions parallel to the layers to lower the friction coefficient.
There are several well-known examples of such lubricious lamellar compounds, the best known of which are graphite and molybdenum disulfide. A product of tribochemical reactions with chlorine-containing additives, ferrous chloride (FeCI2) is also a layered compound and has low friction.
The weak interlayer forces in lamellar compounds also result in unique properties by allowing chemicals to be "intercalated" between these layers. Graphite, in particular, can intercalate a wide variety of materials, including alkali metals, and this property is exploited to store lithium in lithium-ion batteries that are commonly used in laptop computers, for example.
Since the resulting graphite intercalation compounds also have lamellar structures, they are also expected to display low friction. Because the presence of the intercalated layer separates the graphene (single graphite) sheets, the interlayer...