| 摘要 |
Allotropic C modifications, apart from graphite and diamond, are formed by dissolving C in melts of metals, including alkali- and alkaline earth-elements, and/or salts and subsequently reducing the solvent content. The dissolution is pref. carried out at a temp. between m.pt. and critical temp. of the solvent, pref. under a, pref. controlled, pressure at least equal to the solvent vapour pressure. The pptn. of C can also be carried out by cooling down to a temp. above or below the m.pt., pref. at a controlled rate. Solvent may also be extracted, pref. at a controlled rate, at the same time as the cooling takes place. Foreign atoms can be built into the C matrix by adding them to the melt as elements or cpds. e.g. by contacting the melt with a liquid or gaseous coolant which contains the elements or ions required. An electrical bias can be applied between the solvent and the coolant. Also claimed is the process of building foreign atoms into a C matrix by contacting the matrix with the elements or ions under the correct thermodynamic conditions. USE/ADVANTAGE - Gives alternative C-allotropic modifications in a controlled way, i.e. dependent on controlled formation conditions. The process yield is high compared with current processes involving deposition from the gas-phase. The content of graphite e.g. can be influenced by the speed of evaporation of the solvent. The use of an electrical bias can concentrate the particles formed in a required area (electrostatic particle pptn.)
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