A unified structural approach to linear carbon polytypes

Future Directions in Carbon Science

“…Application of pressure converts the α phase into the β phase. The numbers of atoms per unit cell and the densities are, respectively, 144 and 2.68 g/cm 3 for the α phase, and 72 and 3.13 g/cm 3 for the β phase (29). Carbynes have been identified in some meteorites, but relatively little is known about them.…”

Carbon Nanotube Synthesis

“…Theoretical calculations suggest that polycumulenes are less stable than polyynes (Heimann et al, 1983). Both species are characterized by an extremely high reactivity with oxygen, hydrogen and a strong tendency to interchain cross linking (Heimann et al, 1999), thus rendering the direct observation of a pure carbyne-assembled solid is still a major challenge.…”

Response : Carbyne Forms of Carbon: Evidence for Their Existence

“…Heimann et al (11) reported that we found only small amounts of silicon, aluminum, and iron, implying that this was the case for all samples studied. However, such low concentrations apply only to the nontronite-graphite intergrowth, where the nontronite is a minor component; for the other three samples that we described, the EDS signals were very strong and could not have arisen from minor surface contaminants.…”

“…Finally, Whittaker mentions the recent work of Heimann et al (11,12). The approximately linear relation found by these investigators between the crystallographic c parameter and the chain length for seven carbynes is to be expected, since the chain length is inferred from the c parameter in the first place.…”