Size and shape of graphene layers in commercial carbon blacks established by Debye refinement

The size and the shape of graphene layers in commercial conductive carbon blacks, Super P® and Super S®, have been determined from powder X-ray diffraction data. Using a refinement procedure based on the fundamental diffraction equation of Debye, it is shown that the ordered regions within the layers of both materials are of elliptical shape, curved in a cylindrical fashion along the longer axis of the ellipse. The regions are greater in Super P®, ellipse axes: 5.4 and 2.2 nm, than in Super S®, 4.6 and 2.1 nm, and less curved, curvature radii: 12.7 and 11.7 nm respectively. There is no crystallographic registry between layers that are equidistantly stacked into concentric groups of 6 or 7, on average.