An X-Ray Study of Carbon Black

TLDR

X‑ray studies of carbon blacks, prepared under varied conditions and heat treatments, reveal that typical carbon black differs from finely divided graphite. Patterns were recorded in evacuated cameras using Cu Kα radiation monochromated by rocksalt reflection, and the resulting clusters were quantified by microscopy, electron microscopy, and surface‑area measurements. The diffraction patterns display (00l) and (hk) reflections, indicating graphite‑like layers that are parallel and equidistant yet randomly oriented, with interlayer spacing slightly larger than graphite; heat treatment enlarges these layer groups and, upon graphitization, the material abruptly transforms into crystalline graphite, while small‑angle scattering reveals clusters a few hundred angstroms in size.

Abstract

X-ray studies have been made of a number of carbon blacks, prepared under different conditions, and subject to various heat treatments. The patterns were made in evacuated cameras, using Cu Kα radiation monochromated by reflection from rocksalt. The patterns consist of crystalline reflections (00l), and two-dimensional lattice reflections (hk). The structure is one of true graphite layers arranged roughly parallel and equidistant, but otherwise completely random. The dimensions within a layer are the same as in graphite; the layer separation is somewhat larger than in graphite. The effect of heat treatment is to increase the size of the parallel layer groups. At graphitization the material changes discontinuously to the crystalline graphite structure. The usual carbon black is not finely divided graphite. Small angle scattering studies indicate the existence of clusters a few hundred angstroms in size. It is these clusters which are measured by microscope counts, by the electron microscope, and by surface areas, rather than the much smaller parallel layer groups.