TY - JOUR
AU1 - Oberlin, A.
AU2 - Oberlin, M.
AB - Progressive graphitization is measured from X‐ray patterns by the probability P for finding a carbon layer pair reaching the graphite order in the solid. TEM studies show that all carbons (whether graphitizing or not) contain small basic structural units less than 10 Å both in thickness and in diameter which acquire, locally, a preferred parallel orientation during the carbonization process, i.e. at the end of tar release. However, tilt and twist boundaries remain between adjacent units which create wrinkled layers. All the materials are porous; from microporous if the orientation is less than 50–100 Å (non‐graphitizing carbons) to macroporous if the preferred orientation is due to coalesced mesophase spheres (graphitizing carbons). For graphitization to occur it is necessary to have small basic structural units distributed in large areas of preferred orientation. Graphitization occurs only after a sudden elimination of the defects situated at the boundaries between two adjacent structural units, i.e. after development of perfect two dimensional order by dewrinkling and stiffening of the carbon layers (turbostratic structure made of large layers). If both Lamax and Lcmax are too small (micropores) graphitization is impossible. There is a continuous range of materials extending between those with the smallest regions possessing the same molecular orientations (non‐graphitizing carbons) and the largest (graphitizing carbons). A nearly continuous increase of P (from P = 0 to P = 0.8) was found by studying a great variety of kerogens, coals and asphalts. For a given sample, the maximum possible value of P depends only on the size of the oriented areas which itself depends only on the elemental composition at the very moment of its production. There is an opposite influence of the hydrogenated functional groups and the cross‐linking functional groups such as oxygen, sulphur and nitrogen.
TI - Graphitizability of carbonaceous materials as studied by TEM and X‐ray diffraction
JF - Journal of Microscopy
DO - 10.1111/j.1365-2818.1983.tb04600.x
DA - 1983-12-01
UR - https://www.deepdyve.com/lp/wiley/graphitizability-of-carbonaceous-materials-as-studied-by-tem-and-x-ray-L1UROj8Am5
SP - 353
EP - 363
VL - 132
IS - 3
DP - DeepDyve
ER -