A new phase of carbon Original Research Article

An unknown structure with close to six-fold symmetry in diffraction patterns has been found by TEM-studies of C60- and C70-samples after different stages of thermobaric treatment. The new phase may be considered as intermediate between graphite and diamond. The value 0.51 nm of parameter a0 of this phase was found to be closed to twice the value for graphite and to twice the value of parameter d110 in diamond. The atoms situated in the nodes of (0001)-graphite planes with doubled a0-parameter take part in the connection of (0001)-planes by sp-3 bonds. The connection of (0001)-graphite planes results in splitting of these planes between the layers. Four layers form the unit cell of the new phase. The unit cell contains 24 atoms. This crystal lattice can be represented as a triclinic one with parameters: a=b=0.51 nm, c=0.745 nm, α≡β=82°, γ=120°. The density of the new phase lies in the range of carbyne densities.