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阐述了在离子辐照下生成各种碳纳米结构体研究的发展现状,探讨了相应的生长机制和一些相变机理 ,提出了一些有待解决的问题 ,并对其发展方向作了展望. The synthesis of carbon nanostructures, such as fullerenes, nanotubes, onions and diamond, by using ion irradiation, has been reviewed and the growth mechanisms of these carbon nanostructures as well as their phase transitions are simply discussed. It shows that high density plasma engendered by ion irradiation plays an important role in the growing of carbon nanostructures. In addition, it indicates that ion irradiation, due to its great flexibility of experimental parameters, is enormously convenient in... 相似文献
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《Current Applied Physics》2015,15(3):265-273
An in-situ approach to synthesize lithium–graphite nanotubes (LGN) is demonstrated using chemical vapour deposition (CVD). Lithium acetate was used as precursor and as a self-intercalating agent in the presence of copper. Methane was selected as the secondary carbon source. To synthesize lithium–graphite nanotubes (LGN), CVD reactor was set to 500 °C in the presence of argon (200 sccm), hydrogen (40 sccm) and methane (75 sccm) gas under atmospheric conditions. X-ray diffraction shows that the samples are highly crystalline with the c-axis oriented toward the (002) and (111) planes of the graphitic carbon. High resolution transmission and scanning electron microscopic analyses of the samples shows that lithium has been doped into the layers of graphitic carbon matrix. They also show the formation of an alloy phase with distinctive lattice boundaries and stacked graphitic carbon with a small number of nanorods (lithium carbide). HR-Raman analysis shows the characteristic D and G bands of SP2 carbon with a narrow G band and broad D band indicating defects produced through doping. X-ray photoelectron spectroscopy results show the presence of predominant lithium and carbon peaks. Thermal analysis shows that the sample is stable up to 300 °C in air. 相似文献
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Olga Shenderova Suzanne Hens Igor Vlasov Stuart Turner Ying‐Gang Lu Gustaaf Van Tendeloo Amanda Schrand Sergey A. Burikov Tatiana A. Dolenko 《Particle & Particle Systems Characterization》2014,31(5):580-590
The synthesis of a new class of fluorescent carbon nanomaterials, carbon‐dot‐decorated nanodiamonds (CDD‐ND), is reported. These CDD‐NDs are produced by specific acid treatment of detonation soot, forming tiny rounded sp2 carbon species (carbon dots), 1–2 atomic layers thick and 1–2 nm in size, covalently attached to the surface of the detonation diamond nanoparticles. A combination of nanodiamonds bonded with a graphitic phase as a starting material and the application of graphite intercalated acids for oxidation of the graphitic carbon is necessary for the successful production of CDD‐ND. The CDD‐ND photoluminescence (PL) is stable, 20 times more intense than the intrinsic PL of well‐purified NDs and can be tailored by changing the oxidation process parameters. Carbon‐dot‐decorated DNDs are shown to be excellent probes for bioimaging applications and inexpensive additives for PL nanocomposites. 相似文献
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Amin Azizi Tushar Khosla Brian S. Mitchell Nasim Alem Noshir S. Pesika 《Particle & Particle Systems Characterization》2014,31(4):474-480
Large‐scale and tunable synthesis of FeCo/graphitic carbon (FeCo/GC) core–shell nanoparticles as a promising material for multipurpose biomedical applications is reported. The high‐quality graphitic structure of the carbon shells is demonstrated through high‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction (XRD), and Raman spectroscopy. A saturation magnetization of 80.2 emu g?1 is reached for the pure FeCo/GC core–shell nanoparticles. A decrease in the saturation magnetization of the samples is observed with an increase in their carbon content with different carbon morphologies evolved in the process. It is also shown how hybrid nanostructures, including mixtures of the FeCo/GC nanoparticles and multi‐walled carbon nanotubes (MWNTs) or carbon nanorods (CNRs), can be obtained only by manipulation of the carbon‐bearing gas flow rate. 相似文献
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A. N. Obraztsov A. P. Volkov I. Yu. Pavlovskii A. L. Chuvilin N. A. Rudina V. L. Kuznetsov 《JETP Letters》1999,69(5):411-417
Layers of oriented carbon nanotubes and nanometer-size plate-shaped graphite crystallites are obtained by chemical vapor deposition
in a glow-discharge plasma. A structural-morphological investigation of a carbon material consisting of nanotubes and nanocrystallites
is performed, and the field-emission properties of the material are also investigated. It is shown that electron field emission
is observed in an electric field with average intensity equal to or greater than 1.5 V/μm. The low fields giving rise to electron
emission can be explained by a decrease in the electronic work function as a result of the curvature of the atomic layers
of graphitic carbon.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 5, 381–386 (10 March 1999) 相似文献
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Peter J.F. Harris 《哲学杂志》2013,93(18):2355-2363
The formation of novel structures by the passage of an electric current through graphite is described. These structures apparently consist of hollow three-dimensional graphitic shells bounded by curved and faceted planes, typically made up of two graphene layers. The curved structures were frequently decorated with nano-scale carbon particles, or short nanotubes. In some cases, nanotubes were found to be seamlessly connected to the thin shells, indicating that the formation of the shells and the nanotubes is intimately connected. Small nanotubes or nanoparticles were also sometimes found encapsulated inside the hollow structures, while fullerene-like particles were often seen attached to the outside surfaces. With their high surface areas and structural perfection, the new carbon structures may have applications as anodes of lithium ion batteries or as components of composite materials. 相似文献
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The synthesis of diamond at high pressure and high temperature and the discovery of fullerenes and carbon nanotubes are among the most important achievements in carbon science. In the present work, we report the synthesis of diamond from carbon nanotubes at 4.5 GPa and 1300°C. Under these conditions, no diamond crystals were obtained when graphite was used as the starting material. The detailed investigation shows that at high pressure and high temperature carbon nanotubes first transform into quasi-spherical onion-like structures and then into diamond crystals. Our work suggests that carbon nanotubes can be used for the synthesis of high-quality diamond crystals at lower pressure and temperature. 相似文献
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The atomic processes associated with energy storage and release in irradiated graphite have long been subject to untested speculation. We examine structures and recombination routes for interstitial-vacancy (I-V) pairs in graphite. Interaction results in the formation of a new metastable defect (an intimate I-V pair) or a Stone-Wales defect. The intimate I-V pair, although 2.9 eV more stable than its isolated constituents, still has a formation energy of 10.8 eV. The barrier to recombination to perfect graphite is calculated to be 1.3 eV, consistent with the experimental first Wigner energy release peak at 1.38 eV. We expect similar defects to form in carbon nanostructures such as nanotubes, nested fullerenes, and onions under irradiation. 相似文献
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The tubulization process of amorphous carbon nanopillars was observed in situ by transmis-sion electron microscopy. Amorphous carbon nanopillars were transformed into graphitic tubules by annealing at 650-900 degrees C in the presence of iron nanoparticles. A molten catalyst nanoparticle penetrated an amorphous carbon nanopillar, dissolving it, and leaving a graphite track behind. An iron nanoparticle moved with its shape changing like an earthworm. We concluded that the tubulization mechanism is a solid-(quasiliquid)-solid mechanism where the carbon phase transformation is a kind of liquid phase graphitization of amorphous carbon catalyzed by liquefied metal-carbon alloy nanoparticles. 相似文献
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A. S. Manukyan A. A. Mirzakhanyan G. R. Badalyan G. H. Shirinyan E. G. Sharoyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2010,45(3):132-136
Using the solid-phase pyrolysis and chemical vapor deposition of nickel-phthalocyanine, we have fabricated ferromagnetic Ni
nanoparticles in carbon matrices. The composition, structure, morphology, and magnetic properties of samples were investigated
by means of scanning electron microscopy, energy dispersive X-ray microanalysis, X-ray diffraction technique, and ferromagnetic
resonance. It is shown that the sizes of nanoparticles can be varied from ∼10 nm to ∼500 nm depending on the temperature and
time of pyrolysis. The used method allows us to synthesize metal nanoparticles in different carbon matrices: in amorphous
carbon plates, in graphitic capsules, and in carbon nanotubes. 相似文献
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G. Kovach A. Karacs H. Csorbai M. Veres L. Papadimitriou G. Pet? 《Applied Surface Science》2008,254(9):2790-2796
CVD polycrystalline diamond film, pulse laser-deposited (PLD) carbon film and highly oriented pirolitical graphite (HOPG) as reference, were modified by means of Ar+ ion bombardment and characterized by means of Raman scattering, transmission electron microscopy, electron-diffraction (TEM), reflected electron energy loss specroscopy (REELS) and X-ray photoelectron spectroscopy (XPS) techniques. It was found that the diamond was transferred to a carbon with halo-like morphology and disordered stack of graphene segments. Instead of the well-known electron energy loss peak of graphite at 6.5 eV, a new REELS peak appeared at 4-5 eV energies. The observed effect was explained by the modification of π-system in carbon films as a consequence of the formation of non-planar, nanometer-sized graphitic planes. 相似文献
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M.A. Pimenta A.P. Gomes C. Fantini L.G. Canado P.T. Araujo I.O. Maciel A.P. Santos C.A. Furtado V.S.T. Peressinotto F. Plentz A. Jorio 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):88
Resonance Raman and photoluminescence excitation (PLE) spectroscopies are used to study the optical properties of different types of carbon nanostructures such as carbon nanotube, nanoribbons, nanographites and graphite edges. In the resonance Raman experiments of carbon nanotubes, the (n,m) assignment is obtained by comparing the experimental and theoretical diameter and chirality dependence of the optical transitions. The influence of the environment on the optical transitions of the nanotubes is also obtained in the Raman experiments. The PLE measurements in different samples of carbon nanotubes show both direct and phonon-assisted optical transitions, and the results give new evidences that the optical transitions in nanotubes have an excitonic character, which is very strong for the low energy transitions. We also analyze the Raman spectra of nanoribbons and nanographites, showing that this technique is an important tool for defect characterization in graphitic materials, and can be used to distinguish the atomic structure of the graphite edges. 相似文献
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We have grown carbon nanotubes (CNT) by pulsed laser deposition (PLD) at 1000 °C in Ar atmosphere. A Nd/YAG laser was used for irradiation of a graphite target containing Ni and Co rods. High-resolution scanning electron microscopy (HRSEM) and transmission electron microscopy (TEM) images showed that “closed” carbon nanotubes were grown between clusters of metallic particles, so that the individual nanotubes were arranged in parallel to each other forming a shape of “Rope-Bridge”. The nanotubes structure was analyzed by high-resolution transmission electron microscopy (HRTEM) and their type was found to be of MWNT, containing about five SWNT. Total diameter was 5-20 nm and their length was about 1 μm. High homogeneous distribution carbon nanotubes were grown and different structures were observed such as well-aligned carbon nanotubes, bamboo-like and Y-junction carbon nanotubes. 相似文献
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《Current Applied Physics》2009,9(3):629-632
An idea of using pure iron and graphite electrodes was employed for synthesizing carbon nanoparticles by arc discharge in liquid nitrogen. The synthesized products consist of multiwalled carbon nanotubes (MW–CNT), carbon nanohorns (CNH), and carbon nanocapsules (CNC) with core–shell structure. Effect of metallic cathode and discharge current on product structure and yield had been experimentally investigated. Typical evidence of transmission electron microscopic images revealed that under some certain conditions of discharge in liquid nitrogen the synthesized products mainly consisted of CNCs with mean diameter of 50–400 nm. When conventional graphitic electrodes were employed, CNHs with some MW–CNTs were mainly synthesized. Meanwhile, MW–CNTs with diameter of 8–25 nm and length 150–250 nm became less selectively synthesized as cathode deposit under the condition of discharge in liquid nitrogen with higher arc current. The production yield of carbon nanoparticles synthesized by either carbon–carbon or carbon–iron electrodes became also lower with an increase in the arc current. 相似文献
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用射频等离子体辅助化学气相沉积方法生长碳纳米洋葱.电子显微镜观察表明,产物中无碳纳米管等伴随生成,因而制得了较高产率、较高纯度的纳米洋葱.尤其是Co-SiO2催化剂生长的碳纳米洋葱,实心、光滑,且内无催化剂颗粒,其外层由未闭合的、呈波浪状的石墨片构成,显示出与众不同的微观结构和性能.提出了该方法中碳纳米洋葱的生长机理为碳笼由里向外嵌套形成球形粒子.对波浪状、非闭合结构的形成过程进行了讨论.
关键词:
射频等离子体
化学气相沉积
碳纳米洋葱 相似文献