A new insight on the understanding of carbonisation and graphitisation mechanisms

Abstract

During carbonisation (primary and secondary) and then graphitisation processes, any organic precursor is subjected todeep structural changes which make it evolve from an isotropic to an anisotropic material, with the extent of the anisotropybeing related to the starting elemental composition, and ultimately to the graphitisability. For decades, analysing X-raydiffraction patterns has been used to evidence the related structural evolution of the material, aiming at extracting theaverage crystallite dimension La and Lc as they closely relate to the material physical properties. In particular because of thetwo-dimensional nature of the graphene-based crystallites which develop in the material and, upon heat-treatment, eitherremain so for non-graphitisable carbons or gradually convert partially or fully into three-dimensional crystals forgraphitizable carbons, accurately understanding and analysing XRD patterns has always been an issue. A new approach foranalysing XRD data is described, designated as "bottom-up", meanwhile introducing the concept of Basic StructuralComponent. A better knowledge of the overall thermally-driven structure changes which occur in the material from the cokestage to the ultimate temperature of 2800 °C is achieved, which is expected to apply to any kind of carbons, whatever their graphitisability.