Influence of the composition of a H2-CH4 gas mixture on the catalytic synthesis of carbon nanotubes-Fe/Fe3C-Al2O3 nanocomposite powders

Carbon nanotubes-Fe-alumina nanocomposites. Part I: influence of the Fe content on the synthesis of powders

Oxides based on a-alumina and containing various amounts of Fe (2, 5, 10, 15 and 20 cat%) were prepared by decomposition and calcination of the corresponding mixed-oxalates. Selective reduction of the oxides in a H2±CH4 atmosphere produces nanometric Fe particles which are active for the in-situ nucleation and growth of carbon nanotubes. These form bundles smaller than 100 nm in diameter and se...

Effect of hydrogen on catalyst nanoparticles in carbon nanotube growth

The structures of carbon nanotubes grown from catalytic nanoparticles via plasma-enhanced chemical vapor deposition in CH4 /H2 mixtures show a strong dependence on the H2-to-CH4 ratio in the feed gas. A suite of characterization techniques, including optical emission, infrared, and Raman spectroscopies combined with convergent-beam and selected-area electron diffraction, and high-resolution sca...

Synthesis of carbon nanotube-Fe-Al2O3 nanocomposite powders by selective reduction of different Al1.8Fe0.2O3 solid solutions

Carbon nanotubes-Fe-Alumina nanocomposites. Part II: microstructure and mechanical properties of the hot-Pressed composites

Carbon nanotubes±Fe±Al2O3 massive composites have been prepared by hot-pressing the corresponding composite powders, in which the carbon nanotubes are arranged in bundles smaller than 100 nm in diameter and several tens of micrometers long, forming a web-like network around the Fe±Al2O3 grains. In the powders, the quantity and the quality of the carbon nanotubes both depend on the Fe content (2...

Growth of conformal single-walled carbon nanotube films from Mo/Fe/Al2O3 deposited by electron beam evaporation

We discuss growth of high-quality carbon nanotube (CNT) films on bare and microstructured silicon substrates by atmospheric pressure thermal chemical vapor deposition (CVD), from a Mo/Fe/Al2O3 catalyst film deposited by entirely electron beam evaporation. High-density films having a tangled morphology and a Raman G/D ratio of at least 20 are grown over a temperature range of 750–900 C. H2 is ne...