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 a0 and c0 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.