1. Characteristics of split materials

Divided materials are characterized above all by the extent of their surface area in contact with the surrounding fluid (gas or liquid). For the sake of clarity, the divided materials of interest in this article have a surface area of between 0.1 m ² per gram of sample (already more than 150 times greater than that of a compact cube with a 1 cm edge) and 2,600 m ² · g ^–1 (which would be the specific area of a totally exfoliated graphite sample, i.e. one from which all the sheets have been completely separated; some activated carbons come close). Much higher values are sometimes found in recent literature, notably for porous organometallic materials (MOF's) (§