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МАТЕРИАЛЫ 2-Й МЕЖДУНАРОДНОЙ ИНТЕРНЕТ КОНФЕРЕНЦИИ ПО СИНТЕЗУ, ИССЛЕДОВАНИЮ И
ПОЛ У Ч ЕН И Ю М ЕТАЛЛ У ГЛ ЕРОДСОДЕРЖАЩИХ ТУЬУЛЕНОВ, ПРЕДСТАВЛЕННЫЕ УЧАСТНИКАМИ ПРОЕКТА ИНТАС-97-30810
MATERIALS OF 2-d INTERNATIONAL INTERNET CONFERENCE ON SYNTHESIS, INVESTIGATION AND
APPLICATION OF METAL CARBON CONTAINING TUBULENES SUBMITTED BY MEMBERS OF PROJECT
INTAS-97-30810
FORMATION OF CARBON NANOTUBES AND NANOPARTICLES IN THE PROCESS OF STIMULATED CARBONIZATION OF AROMATIC HYDROCARBONS
V.I KODOLOV*, A.P. KUZNETSOV, A.A. DIDIK. L.G. MAKARQVA. I.N. SHABANOVA, A.YU. VOLKOV*, E.G. VOLKOVA*
Basic Research-educational center of chemical physics and mesoscopx. Udmurt research center UrD RAS, Ural Division of Russian academy of sciences. ""Institute of metal physics UrD RAS.
ABSTRACT. Products of stimulated carbonization of aromatic hydrocarbons were investigated by methods of X-ray photoelectron spectroscopy, electron microscopy and electron microdiffraction. Using transmission electron microscopy methods it was found out that multi-wall carbon nanotubes and fibers with diameters 20 - 100 nm are formed during carbonization process. XPE spectra and electron diffraction data prove the amorphous nature of carbon formation.
Key words: multi-wall carbon nanotubes. carbon nanoparticles. X-ray photoelectron spectroscopy, transmission electron microscopy.
' Corresponding author. For correspondence: Vladimir I. Kodolov, DRHE Center of Chemical Physics and Mesoscopy, Udmurt Scientific Center, Russian Academy of Sciences, 7 Studencheskaya str., Izhevsk, 426069. Russia, Fax: (83412)431713, e-mail: kodol@istu.udm.ru..
ХИМИЧЕСКАЯ ФИЗИКА И МЕЗОСКОПИЯ. Том 3, № 1
V.l KODOLOV, A.P. KUZNETSOV, A.A D1DIK. L.G. MAKAROVA. I.N. SHABANOVA. A.YU VOLKOV. E.G. VOLKOVA
1. INTRODUCTION
Since their discovery by Iijima in 1991 [1] carbon nanotubes and other carbon nanostructures attract the enonnous attention of researchers. The most widespread methods of carbon nanostructures obtaining comprise high-energetic influence on graphite: electric-arc |2| or laser graphite spraying [3]. Another method consists in the process of chemical carbon precipitation from gaseous phase (CVD-process) [4]. At the same time the data available [5] indicate the possibility of nano-sized carbon particles obtaining in processes when all reagents are in condensed state. Similar processes are successfully used in the processes of carbon fibers obtaining with the participation of transition metals as catalysts of carbonization and fibers growth [6].
2. EXPERIMENTAL
Carbonized product is obtained with the help of the following procedure: 1.78 g of anthracene (0.01 mol) is introduced during stirring in the melt of 2.66 - 26.67 g. aluminium chloride, clarified by sublimation, (0.02 - 0.2 mol), equimolar quantity of sodium chloride (1.17-11.7g) and 1.3 - 3.9 g anhydrous nickel chloride (0.01 - 0.03 mol). The melt temperature is 300°C. After the evolution of hydrochloride is over, the molten mixture of the components is hold at the above temperature for 3 hours. After the mixture is cooled down to the room temperature, it is washed by 5 liters of double distilled water, concentrated hydrochloric acid, water to pH=7 and o-xyiene to remove organic products. The products obtained are powders of black color. The products yield is 80-90% on the calculation of pure carbon.
The products obtained are investigated using the methods of X-ray photoelectron spectroscopy, transmission electron microscopy and electron microdiffraction. The samples for the investigation of XPE-spectra are applied on indium base. The spectra are taken on X-ray photoelectron spectrometer (radiation A1K<,) and X-ray electron spectrometer ES-2401 (radiation MgiCo) in vacuum 10"5 Pa. Samples microphotographs are obtained on transmission electron microscope JEM-200CX with accelerating voltage 160 kV.
3. RESULTS AND DISCUSSION 3.1. C|S core level spcctra
According to the review spectra, carbon and oxygen are present in the samples investigated. As the total content of oxidized groups in the samples in the majority of cases does not exceed 5% and Ois peaks of oxygen are of low contrast, only the state of carbon is analyzed. Cis spectra are factored into components, corresponding to different carbon bond types. The peaks with binding energy 284,1 - 284,3 eV sort with sp2 bound carbon in graphite, 285 eV sort with amorphous carbon or C-H groups and peaks with binding energy 287 eV sort with CO2 groups [7]. According to the intensity of corresponding peaks the content of various
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XMMHHECKAfl OH3HKA H ME30CK0nMR Tom 3, № 1
I ORMA I ION OE CARBON NANOTUBES AND NANOPARTICLES IN I l lb PROCESS Ol S I [Ml I A I El) C ARBON'IXA I ION 01 AROMATIC HYDROCARBONS
carbon types in the samples investigated is calculated. I he results of spectral investigation of the samples are shown in Table 1. Typical spectrum is shown in Fig. 1.
The peak with binding energy 282 eV is found in sample No. 1 which we ascribe to carbon bound into nickel carbide, the content of carbide carbon :s 5%. Due to the given data the increase of both aluminium chloride and nickel chloride content increases the content of graphite-like products in the samples obtained. The quantity of nickel chloride introduced into the reaction has a great influence on the yield of graphite-like products. It is known [6] that nickel is a good graphitization catalyst. In all sample^. except sample No. 4. low-intensive peak of "shake-up" satellite shifted relative to the basic carbon line by 6-7 eV is found in C|S spectra. Low intensity of this peak proves low regulation degree of graphite layers and/or great quantity of defects in their structure.
3.2 Electron-microscopic investigation of carbonized samples
During electron-microscopic investigation it is found out that bo:h amorphous and crystalline formations are present in the samples.
Mainly the samples microstructure represents perforated films twisted into a roll joining each other by side surfaces (Fig. 2). The perforation sizes on the films are 0.5 - 0.25 pm. Also the presence of nanoparticles (Fig. 3a), which can have both spherical and polyhedral shape, is found in the samples. Electron microdiffraction of these particles is characteristic for amorphous state and has only diffusive rings (Fig. 3b). thus allowing to suggest that there is no hollow in the center [8]. Besides, microcrvstaliine state is observed for all the samples; a large amount of point reflections are clearly seen in microdiffraction patterns (Fig. 4) and their phase analysis shows that they belong to graphite, diamond and nickel.- The number of particles having microcrystalline composition increases, as the amount of nickel chloride introduced into the reaction becomes greater.
Table 1. Content of carbon various types in samples investigated
Sampl c No. Initial composition of carbonization stimulator (per lmol of anthracene) Cgraphilf (%) contcnt Camorph ( So) content CO; groups content (%)
1 AlCl3:NiCl2 = 2:l 45.8 44.7 4.5
2 AlCl3:NiCl2= 10:1 50 47 3
3 AlCl3:NiCl2 = 20:1 69.7 23.4 6.9
4 AlCl3:NiCl2= 10:2 80.9 14.7 4.4
XMMMMECKAfl OH3MKA M ME30CK0nUfl. Tom 3, № 1
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V.l KODOLOV, A.P. KUZNETSOV, A.A. D1D1K. L.G. MAKAROVA, I.N. SHABANOVA, A.YU. VOLKOV, E.G. VOLKOVA
279 280 281 282 283 284 285 286 287 288 289 290 291
Binding energy (eV)
Fig. 1. XPE spectrum C\s of sample No. 2
In the samples obtained under the ratio anthracene : nickel chloride =1:1 (samples 1 and 2) the formations in the shape of nanotubes with diameters 20 - 50 nm are observed, in sample No. 2 the tubes are partially filled with liquid (Fig. 5). The total nanotubes content among all nanostructures observed does not exceed several percent.
4. CONCLUSIONS
It is found out that nanoparticles consisting of amorphous and graphite-like crystalline carbon are formed in the process of low-temperature stimulated carbonization of aromatic hydrocarbons. In accordance with XPE spectroscopy and electron diffraction the quantity of graphite-like carbon increases together with the increase of nickel chloride content in the initial mixture.
Electron-microscopic investigation reveals the presence of carbon nanoparticles of spherical and polyhedral shape having mainly amorphous structure in the products obtained.
The formation of carbon nanoparticles and multi-wall nanotubes consisting of carbonized material, obtained by rolling the planes into a roll or spiral is determined.
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XHMHHECKAfl OM3MKA M ME30CK0riWfl. Tom 3, № 1
FORMATION OF CARBON NANOTUBES AND NANOPAR TICLES IN THE PROCESS OF STIMULATED CARBONIZATION OF AROMATIC HYDROCARBONS
Fig. 2. Perforated film of carbonized material (rolling points are indicated by arrows)
b
Fig. 3. Carbon nanoparticles (sample No. 2)
(a) Microstructure
(b) Corresponding microdiffraction
xmmumeckah cdh3mka m me30ck0rihfl. tom 3, № 1
ll
v.l KODOLOV, A.P. KUZNETSOV, A.A. DIDIK, L.G. MAKAROVA, I.N. SHABANOVA, A.YU. VOLKOV, E.G. VOLKOVA
Fig. 4. Microdiffraction pattern of microcrystalline particles (sample No. 4)
Fig. 5. Carbon multi-wall nanotube filled with liquid (sample No. 2) REFERENCES
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4. P. Nikolaev, M.J. Bronikowski, R.K. Bradley, F. Rohmund, D.T. Colbert, K.A. Smith, R.E. Smalley Chem. Phys. Lett. 313 (1999) 91.
5. W.K. Hsu, J.Li, H. Terrones, M. Terrones, N. Grobert, Y.Q. Zhu, S. Trasobares, J.P. Hare, C.J. Pickett, H.W. Kroto, D.R.M. Walton Chem. Phys. Lett. 301 (1999) 159.
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