title: Double-walled carbon nanotubes in composite powders.
abstract: Double-walled carbon nanotubes (DWNTs) may be interesting in many applications since the outer wall would provide an interface with the rest of the system, without modifying the inner wall. CNT-Fe/Fe3C-Al2O3 composite powders containing carbon nanotubes (CNTs) (65% of which are DWNTs) are prepared by reduction of an oxide solid solution in a H2-CH4 gas mixture. The powders and CNTs are studied by both local and macroscopical techniques. The influence of the reducing atmosphere composition and of the dwell time at 1050 degrees C is studied. There is a 6-fold increase in CNT content upon the increase in the CH4 content from 3 to 30 mol.%, but the formation of undesirable carbon nanofibers can also be promoted. A CH4 content of 12-18 mol.% is adapted for the particular iron content in these powders. Increasing the dwell time at 1050 degrees C results in the formation of CNTs with more walls.
authors.affiliation: CIRIMAT UMR CNRS 5085/LCMIE, Centre Interuniversitaire de Recherche et d'Ingénierie des Matériaux, Université Paul-Sabatier, 31062 Toulouse, France.
authors.forename: E
authors.initials: E
authors.lastname: Flahaut
authors.forename: A
authors.initials: A
authors.lastname: Peigney
authors.forename: Ch
authors.initials: Ch
authors.lastname: Laurent
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D003460:Crystallization / Q000379:methods*; D003461:Crystallography / Q000379:methods; D006358:Hot Temperature; D006859:Hydrogen / Q000737:chemistry*; D007501:Iron; D008420:Manufactured Materials; D008697:Methane / Q000737:chemistry*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000145:classification / Q000302:isolation & purification; D011208:Powders; D011786:Quality Control; D013499:Surface Properties; D013818:Thermogravimetry
chemical_list: D037742:Nanotubes, Carbon; D011208:Powders; D006859:Hydrogen; D007501:Iron; D000537:Aluminum Oxide; D008697:Methane