Temperature evolution of microstructure of turbostratic high melting coal-tar synthetic pitch studied using wide-angle X-ray scattering method

The generalized Warren-Bodenstein's approach of scattering on turbostratic carbon was used to fit the measured X-ray scattering patterns of high melting coal-tar synthetic pitch. A computer program adopting this approach allowing fitting of whole measured scattering powder patterns was written. The program enables refinement of essential physical parameters of turbostratic carbon materials, i.e. the mean lattice parameters a0, c0, the mean cluster sizes parallel and perpendicular to the graphitic planes La and Lc, their distributions as well as the mean square atomic displacements 〈ua2〉 and 〈uc2〉. A series of high melting coal-tar synthetic pitch specimens, annealed at different temperatures, was prepared and investigated. In studied samples we observed the increase of the clusters sizes, changes in the mean lattice parameters a0, c0, and decay of disorder with increasing annealing temperature.