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Uniform diamond nucleation was achieved on a Si substrate over a large area using low pressure Electron Cyclotron Resonance microwave plasma chemical vapour deposition (CVD). Diamond nucleation density as high as 10 9 cm −2 was obtained using a CH4 He gas mixture when the substrate was positively biased with respect to the grounded chamber wall. Radical densities higher than those...
Several TEM techniques are used to characterise the local structure of low dimensional forms of carbon. HREM is particularly useful to describe the defect structure of thin films of diamond or fullerenes and C 60 –C 70 nanoclusters. A columnar form of graphite is analysed, mainly by electron diffraction which allowed us to propose a growth mechanism. Diffraction contrast dark field...
The irradiation-induced self-compression of carbon onions and their transformation to diamond crystals are studied in situ by electron energy loss spectroscopy at high specimen temperature in a high-voltage electron microscope. Plasmon peaks in the low-loss region and the carbon K edge with the near-edge fine structure exhibit characteristic changes during irradiation. The spectra show the increasing...
Carbon is the most versatile element in the periodic table. Due to its ability to form both sp 3 , sp 2 , and sp hybrids and stable multiple p π &z.sbnd;p π bonds, carbon can build up 3-, 2-, 1-, and 0-dimensionally structured substances with a broad variety of physical and chemical properties. In the last decade diamond films, active carbons, carbon fibres, and...
Diamond films and particles that were synthesized by deposition from oxyacetylene flame on the molybdenum substrates under atmospheric conditions. The study deals with morphological evolution of diamond films in combustion synthesis at different temperatures of the substrate as a basis for understanding the nucleation and growth mechanisms of the diamond phase. The films and particles were studied...
A specific Raman spectrum of carbon spherical shells (onions) synthesized by annealinginduced (T = 1800 K) chipping off the outer carbon layers from 5-nm size diamond particles has been observed. It shows a clearly seen band at 1572 cm −1 . Its downshift from the position 1582 cm −1 (known for a pure graphite) is interpreted as an influence of shell curvature. The summary contribution...
The features of hydrogen free tetrahedral amorphous carbon films (ta-C) prepared by radio frequency (RF) magnetron sputtering at room temperature, with a high portion of sp 3 bonds, were examined by transmission electron microscopy. As grown specimens, presenting characteristic amorphous rings, were easily transformed to microcrystalline by low energy Ar ion beam bombardment. Characteristic...
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