Morphology and Structure of the Mesophase in Coal Tar Pitch

By scanning electron microscopy, X-ray phase analysis, and X-ray structural analysis, the morphology and structure of the mesophase is studied in the series: coal tar ? coal tar pitch ? a fraction ? coke residue obtained on heating the [alpha] fraction at 1200?. The X-ray structural parameters are determined: the longitudinal and transverse dimensions of the stacks of polyarene layers (L-a and L-c); the distance between layers (d(002)); and the number of layers in each stack (N). In carbonization, the two-dimensional carbon mesophase structures are converted to three-dimensional stacks. The mesophase consists of a turbostratic carbon structure and graphite-like phases. The transverse dimension of the stack formed on structuring is L-c = 1-2 nm; its longitudinal dimension is L-a = 2-6 nm. The mean distance between the layers in the samples is d(002) = 0.346-0.355 nm. The pitch has an isotropic structure since the mesophase consists of spheroids.