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Room Temperature Superparamagnetism observed in Foam-like Carbon Nanomaterials

Published online by Cambridge University Press:  23 March 2011

Shunji Bandow
Affiliation:
Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan
Hirohito Asano
Affiliation:
Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan
Susumu Muraki
Affiliation:
Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan
Takahiro Mizuno
Affiliation:
Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan
Makoto Jinno
Affiliation:
Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan
Sumio Iijima
Affiliation:
Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan
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Abstract

Magnet-attractive carbon nanopowder can be produced by a pulsed Nd:YAG laser (10 Hz) vaporization of pure carbon in a few % of H2 containing Ar gas at 1000°C. On the other hand, magnet-attractive nanopowder cannot be formed when vaporizing in pure Ar. As-grown carbon nanopowder includes a few to ten % of micron sized graphite flakes as the impurity. Removal of such flakes can be achieved by a centrifugal separation and the supernatant is checked by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Magnetization curve at 400 K is easy to saturate at low magnetic field of 10 kG, and no hysteresis is observed. This feature is explained by a superparamagnetism of finely dispersed ferro- or ferri-magnetic nanoparticles. Elementary analyses using electron energy loss spectroscopy (EELS) and atomic absorption spectroscopy (AAS) suggest that the observed strong magnetism should be an intrinsic carbon magnetism.

Type
Research Article
Copyright
Copyright © Materials Research Society 2011

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References

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