Large-scale synthesis, annealing, purification, and magnetic properties of crystalline helical carbon nanotubes with symmetrical structures

Nujiang Tang*, Wei Zhong, Chak Tong AU, Aharon Gedanken, Yi Yang, Yonwei Du

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

Crystalline helical carbon nanotubes (HCNTs) are synthesized as the main products in the pyrolysis of acetylene at 450°C over Fe nanoparticles generated by means of a combined sol-gel/reduction method. Transmission electron microscopy (TEM) images reveal that there are two HCNTs attached to each Fe3C nanoparticle, and that the two HCNTs are mirror images of each other. Annealing in Ar at 750°C and purification by immersion in hot (90°C) HCl solution do not significantly change the structure of the HCNTs, despite the partial removal of Fe nanoparticles by the latter treatment. The magnetic properties of the as-prepared, annealed, and purified HCNTs have been systematically examined. The annealed sample shows relatively high magnetization due to the ferromagnetic α-Fe nanoparticles encapsulated in the HCNT nodes. In the case of HCl treatment, relatively pure HCNTs are obtained by the removal of ferromagnetic nanoparticles from the double-HCNT nodes. The effects of the amount of catalyst used in the synthesis process on the morphology and yield of the carbon products have also been investigated.

Original languageEnglish
Pages (from-to)1542-1550
Number of pages9
JournalAdvanced Functional Materials
Volume17
Issue number9
DOIs
Publication statusPublished - 18 Jun 2007

Scopus Subject Areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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