Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Materials Science Poland

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Preparation of ultra-large-scale catalysts for catalytic vapour deposition of carbon nanotubes

Bachmatiuk A., Kaleńczuk R. J., Rümmeli M. H., Gemming T., Borowiak-Palen E.

Materials Science Poland

2008

Vol. 26, No. 1

105--111

One of the most important issues in the controlled synthesis of carbon nanotubes is finding a simple way to synthesize the catalyst nanoparticles with a controlled size. The preparation of iron nanoparticles via an organic route has been presented in the paper. The nanoparticles, of the diameter ranging between 9.5 and 31 nm, supported on magnesia, were used as a catalyst in chemical vapour deposition to produce bulk scale carbon nanotubes. Two carbon feedstocks (ethanol and cyclohexane) were examined. In the optimization process, the pyrolysis temperature was varied between 650 st.C and 850 st.C. In this simple approach, no additional carrier gas was used. Multiwalled carbon nanotubes with a very low diameter distribution (19.5-2.5 nm) were fabricated. Their composition was analysed via X-ray diffraction. The samples were characterized by the resonance Raman spectroscopy and high-resolution transmission electron microscopy.

Influence of the packing effect on stability and transformation of nanoparticles embedded in random matrices

Hermann H., Elsner A., Gemming T.

Materials Science Poland

2005

Vol. 23, No. 2

541--549

The compression of random hard sphere systems does not lead to the formation of iscosahedral short - range order. Instead, icosahedral clusters embedded in a hard sphere system with a medium packing fraction are not stable against densification and they dissolve with an increasing packing fraction. Random homogeneous hard sphere models with equal spheres transform into nanometre scale composites of face-centred cubic nanocrystals embedded in a dense random packed matrix when the mean packing fraction of 0.64 is exceeded.