| Abstrakt: |
Abstract: The influence of boron on the synthesis and structural features of graphites obtained under conditions of high pressures from hydrocarbon-containing initial mixtures is studied. It is shown that boron promotes processes leading to the formation of graphite by lowering the temperature required for synthesis. At the same time, it incorporates into the graphite lattice according to the principle of substitution, and leads to an increase in lattice parameter aand a decrease in lattice parameter c. This causes a shift in the X-ray diffraction peaks, but does not give rise to their additional broadening, which indicates that boron does not simultaneously cause inhomogeneous local distortions of the structure. The performed ab initio calculations make it possible to explain this by the fact that an effective charge is formed around the implanted boron atoms, which causes their mutual repulsion. The presence of fluorine in the initial system leads to inhibition of graphite formation. Thus, the method of high pressures and high temperatures can be effectively used for the synthesis of graphites, the structure and particle size of which can be controlled at the nanoscopic and microscopic scales, including the introduction of impurities that accelerate or inhibit graphite formation. |
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