Bonding of diamond

Fig. 10 Schematic representation of surface dangling bonds of diamond and passivation by hydrogen. ...

Diamond being optical, high thermal conductive, semi- conductive and very hard materials, itself is widely expected to become an industrial materials of twenty first century. Metal alloys and ceramic materials containing diamond with such a useful feature will be also developed as new materials. The bonding is one approach to fabricate diamond composite materials. Instantaneous bonding of diamond... 

Diamond and graphite cannot be positively identified using electron diffraction techniques alone, but Raman spectroscopy will, however, clearly differentiate the sp bonding of graphite and the sp bonding of diamond. 

A related advantage of studying crystalline matter is that one can have synnnetry-related operations that greatly expedite the discussion of a chemical bond. For example, in an elemental crystal of diamond, all the chemical bonds are equivalent. There are no tenninating bonds and the characterization of one bond is sufficient to understand die entire system. If one were to know the binding energy or polarizability associated with one bond, then properties of the diamond crystal associated with all the bonds could be extracted. In contrast, molecular systems often contain different bonds and always have atoms at the boundary between the molecule and the vacuum. 

Thermal Expansion. The averaged value of the coefficient of linear thermal expansion of diamond over the range 20 to 100°C is 1.34 X 10 cm/cm/ C and 3.14 x 10 from 20 to 800°C. At room temperature the values for sihca glass and diamond ate 0.5 X 10 and 0.8 X 10 , respectively. The relatively low expansion combined with the low reactivity of diamonds, except for carbide formation, leads to some challenges in making strong bonds between diamond and other materials. 

Covalent bonding appears in its pure form in diamond, silicon and germanium - all materials with large moduli (that of diamond is the highest known). It is the dominant... 

If the polymer is completely cross-linked (/= 1) then the modulus (Ej) is known it is that of diamond, 10 GPa. If it has no covalent bonds at all, then the modulus (E2) is that of a simple hydrocarbon like paraffin wax, and that, too, is known it is 1 GPa. 

Diamond is an important commodity as a gemstone and as an industrial material and there are several excellent monographs on the science and technology of this material [3-5]. Diamond is most frequently found in a cubic form in which each carbon atom is linked to fom other carbon atoms by sp ct bonds in a strain-free tetrahedral array. Fig. 2A. The crystal stmcture is zinc blende type and the C-C bond length is 154 pm. Diamond also exists in an hexagonal form (Lonsdaleite) with a wurtzite crystal structure and a C-C bond length of 152 pm. The crystal density of both types of diamond is 3.52 g-cm. ... 

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