10-31-07 - 10/31/07 New Carbon Forms Fullerenes CNT has...

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10/31/07 New Carbon Forms Fullerenes CNT has incredible properties Fullerenes Difference between crystalline and amorphous material. Within crystalline, can use a unit cell as a building block. In an amorphous material, there isn’t a unit cell, therefore you can’t do that. Graphite(sp 2) and Diamond (sp 3 )(diagram on slide) o Before 1985, nearly 22 years ago, we say that there are two forms of carbon, graphite and diamond. Carbon actually comes in more crystalline forms, such as CNT and fullerene (C 60 ) o Diamond-three dimensional arrangement-isotropic o Graphite: layers of carbons which forms rings—but now this is anisotropic—bonding that exists within each layer is different from between each layer. Bond length within layer is shorter than between layers. This is a 2-D arrangement. Properties in plane are different from out of plane. Thus mechanical properties are different. Bonding in graphite: o Covalent bonds between carbon atoms—to make rings (1.4 in bond length) o Van der Waals bonds between layers—distance where attraction=repulsion—lowest energy Hybridization diagrams on the diagram. Sp 2 Hybridization in Bezene( on diagram) o resonance structure because the two structures are equivalent New Forms of Carbon o Utilize benzene to become the building block for C 60 , etc. –benzenes fused together. o
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This note was uploaded on 10/24/2008 for the course ENGRI 1110 taught by Professor Giannelis during the Fall '07 term at Cornell University (Engineering School).

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10-31-07 - 10/31/07 New Carbon Forms Fullerenes CNT has...

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