A new insight on the understanding of carbonisation and graphitisation mechanisms

During carbonisation (primary and secondary) and then graphitisation processes, any organic precursor is subjected to deep structural changes which make it evolve from an isotropic to an anisotropic material, with the extent of the anisotropy being related to the starting elemental composition, and ultimately to the graphitisability. For decades, analysing X-ray diffraction patterns has been used to evidence the related structural evolution of the material, aiming at extracting the average crystallite dimension L-a and L-c as they closely relate to the material physical properties. In particular because of the two-dimensional nature of the graphene-based crystallites which develop in the material and, upon heat-treatment, either remain so for non-graphitisable carbons or gradually convert partially or fully into three-dimensional crystals for graphitizable carbons, accurately understanding and analysing XRD patterns has always been an issue. A new approach for analysing XRD data is described, designated as "bottom-up", meanwhile introducing the concept of Basic Structural Component. A better knowledge of the overall thermally-driven structure changes which occur in the material from the coke stage to the ultimate temperature of 2800 degrees C is achieved, which is expected to apply to any kind of carbons, whatever their graphitisability.