Metals or metal compounds with a high chemical affinity for the heteroatoms in the carbons. They are distributed as fine particles within the carbon materials to be graphitized.
Iron and iron compounds are most frequently used as @P04941@ inhibitors when @P04941@ is related to sulfur.
PAC, 1995, 67, 473. 'Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)' on page 502 (https://doi.org/10.1351/pac199567030473)