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Systematic study on synthesis and purification of double-walled carbon nanotubes synthesized via CVD

Jedrzejewska A., Kalenczuk R. J., Mijowska E.

Materials Science Poland

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2011

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Vol. 29, No. 4

292--298

EN

Carbon nanotubes have unique properties, such as thermal and electrical conductance, which could be useful in the fields of aerospace, microelectronics and biotechnology. However, these properties may vary widely depending on the dimensions, uniformity and purity of the nanotube. Nanotube samples typically contain a significant percentage of more allotropes forms of carbon as well as metal particles left over from catalysts used in manufacturing. Purity characterization of double-walled carbon nanotubes (DWCNTs) is an increasingly popular topic in the field of carbon nanotechnology. In this study, DWCNTs were synthesized in a catalytic reaction, using Fe:MgO as catalyst and methane or methane/ethanol as carbon feedstock for chemical vapor deposition (CVD). The addition of ethanol as carbon feedstock allowed to investigate the influence of oxygen on the sample quality. The purification of the as-produced material from the metallic particles and the catalyst support was performed by sonication in an acid solution. The influence of the duration of the acid treatment using ultrasound on the sample purity was investigated, and the optimal value of this parameter was found. Transmission electron microscopy (TEM) images confirmed the removal of impurities and served to elucidate the morphology of the samples. The purity of carbon nanotubes was analyzed using thermal gravimetric analysis (TGA). The Raman spectra of the samples, as a measure of the concentration of defects, were also reported.

2

Synthesis of carbon nanotubes via chemical vapor deposition by using rareearth metals as catalysts

Jędrzejewska A., Wnuk K., Kaleńczuk R. J., Borowiak-Paleń E.

Polish Journal of Chemical Technology

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2010

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Vol. 12, nr 3

29-32

EN

This work presents the results of the synthesis of carbon nanotubes using the CVD method. Fe:MgO catalyst was used, also in combination with rare earth elements (gadolinium (Gd), dysprosium (Dy)), which when used alone, are not efficient as catalysts in nanotube growth. Synthesis was performed both at reduced pressure (10-3 mbar) and atmospheric pressure, with constant parameters dependent on the process parameters.

3

Preparation and characterization of catalyst mix Fe-Co/MgO for carbon nanotubes growth

Steplewska A., Jędrzejewski R., Borowiak-Palen E.

Polish Journal of Chemical Technology

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2008

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Vol. 10, nr 3

1-3

EN

Fe-Co/MgO is one of the most common catalyst mix applied to carbon nanotubes (CNTs) growth in chemical vapor deposition process. Therefore, here we present detailed study on the preparation and characterization of Fe-Co/MgO. The precursors of Fe and Co are iron (II) acetate and cobalt acetates, correspondingly. The molar ratio of the catalyst mix is Fe:Co:MgO=1:1:100. Initially, thermogravimetric analysis (TGA) of the mixture was performed. TGA analysis of it indicated the stepwise mass losses which pointed out the crucial thermal conditions for the changes in the elemental composition, morphology, crystallographic structure and vibrational properties. In current state of the art the lowest growth temperature for singlewalled carbon nanotubes is 550°C in CVD technique and here the characterization of the catalyst mix strongly suggest that this temperature can be decreased what would enhance the compatibility of CNT growth with current complementary metal-oxide-silicon (CMOS) technology for CNTs-based nanoelectronics. The morphology, crystallographic structure, elemental composition of the samples and its spectroscopic properties were performed via high resolution transmission electron microscopy (TEM), X-ray diffraction (XRD) and Infrared spectroscopy (IR), respectively.

4

Simple model for the thermal conductivity estimation on the basis of Raman and ESR spectroscopy measurements

Masierak W., Fabisiak K., Kaczmarski M., Kozanecki M.

Optica Applicata

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2006

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Vol. 36, nr 2-3

225-234

EN

The diamond films were grown at different working gas pressure in the range of 20-80 mbar by using hot filament chemical vapor deposition (HF CVD) technique. It was observed that the film morphology was dependent on deposition pressure and changed from so called "ball-like" via (111) and (100) type to the morphology of mixed character. The diamond film quality was studied by means of Raman and ESR (electron spin resonance) spectroscopy measurements. Within the presented work a simplified model for heat conductivity was proposed which allows to estimate the value of the thermal conductivity on the basis of Raman and ESR measurements. The obtained results are in good agreement with those reported in literature.