Lattice Properties

The lattice dynamics of a material are intimately connected with the elastic coefficients, which control the mechanical properties. The lattice dynamics in turn determine the phonon dispersion relations, which control the specific heat and thermal expansion, and strongly affect the transport properties through carrier scattering processes. Since the lattice dynamics for carbon fibers have not been considered explicitly, the results for crystalline graphite have conventionally been used with some modifications to take into account the small crystallite size, the high concentration of defects and the general disorder which are all prevalent in carbon fibers [Lespade et al. 1982]. To explain certain aspects of transport phenomena in carbon fibers (Chap. 8), the dispersion relations for crystalline graphite in the long wavelength approximation are used to treat electron-phonon scattering.