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Graphite intercalation compound
Graphite intercalation compounds are intercalation compounds with a graphite host  . In this type of compound the graphite layers remain largely intact and the guest molecules or atoms are located in between. When the host and the guest interact by charge transfer the in-plane electrical conductivity generally increases. When the guest forms covalent bonds with the graphite layers as in fluorides or oxides the conductivity decreases as the conjugated sp² system collapses. In a graphite intercalation compound not every layer is necessarily occupied by guests. In so-called stage 1 compounds graphite layers and intercalated layers alternate and in stage 2 compounds two graphite layers with no guest material in between alternate with an intercalated layer. The actual composition may vary and therefore these compounds are an example of non-stoichiometric compounds. It is customary to specify the composition together with the stage.
Additional recommended knowledge
Potassium graphite is denoted as KC8 and is one of the strongest reducing agents known. It is prepared under inert atmosphere by melting potassium over graphite powder. The potassium is absorbed into the graphite and a color change from black to bronze is observed. The resulting solid is also quite pyrophoric. Structurally, composition can be explained by assuming that the potassium to potassium distance is twice the distance between hexagons in the carbon framework. The bond between graphite and potassium atoms is ionic and the compound is electrically conductive. .
Potassium graphite has also been used as a catalyst in polymerizations and as a coupling reagent for aryl halides to biphenyls .
In one study  freshly prepared KC8 is treated with 1-iodododecane delivering a modification (micrometre scale carbon platelets with long alkyl chains sticking out providing solubility) that is soluble in chloroform. Another potassium graphite compound, KC24, has been used as a neutron monochromator.
Tetracarbon monofluoride is denoted as C4F. It is prepared by reacting gaseous fluorine mixed with hydrogen fluoride with graphite at room temperature. The compound has blackish-blue color.
Other examples are graphite bisulphate and graphite oxide.
Examples of complex graphite intercalation compounds are those with barium and ammonia guests (Ba(NH3)2.5C10.9(st.1)) or those with caesium, hydrogen and potassium (CsC8.K2H4/3C8(st.1)).
Categories: Inorganic compounds | Carbon forms
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Graphite_intercalation_compound". A list of authors is available in Wikipedia.|