Graphenes bonding forces in graphite are widely known as an example of the van der Waals forces. Well-known experimental facts relative to graphite negate this. A comparison of physical properties of graphite and molecular crystals and metals is shown. A model of dominant weak metallic bonding forces between graphenes is proposed. Brief theoretical background to the model is given.

The electrical properties of nitrogen‐containing amorphous hydrogenated carbon layers are investigated. The nitrogen concentration was between 0 and 6 at%. The electrical conductivity is found to increase with the nitrogen content. The temperature dependent conductivity in the temperature range between 150 and 350 K can be well fitted by a semi‐empirically derived equation which considers the conductivity as a superposition of two hopping mechanisms with different activation energies. Together with experimental results on the optical properties and the mass density, these data allowed to propose a structural model which explains the observed effects in terms of familiar a‐C:H cluster models.

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Hydrogenated amorphous carbon (a‐C : H) films obtained by are evaporation of pure graphite rods under the pressure of hydrogen: 13, 66, 133, and 400 Pa, respectively, subsequently annealed in vacuum at different temperatures in the range 300 to 800 °C are examined by de conductivity and ESR measurements. For comparison the same measurements are performed on nonhydrogenated a‐C films obtained in the same way in pure argon atmosphere. Differences observed for both series of samples are explained by the role of hydrogen incorporated to a‐C: H films.