A unified structural approach to linear carbon polytypes

Compounds obtained by high-temperature treatment of graphite are thought to be linear carbon polytypes with sp-configuration and carbon–carbon chains, either conjugated triple bonded or cumulated double bonded, parallel to the c -axis. At least 10 crystallographically documented linear carbon forms (carbynes) have been reported. To relate the contradictory and confusing information found in the literature, a simple classification is suggested here based on a linear relationship between number of atoms in a chain ( n ) and the unit cell parameters a 0 and c 0 of all carbyne forms known. It is assumed that chains are kinked, and that the distribution of kinked spacings may be a function of the temperature of formation of the carbyne forms in question.