Using diamond as a metastable phase carbon source to facilitate the synthesis of graphite encapsulated metal (GEM) nanoparticles by an arc-discharge method

Graphite encapsulated metal (GEM) nanocrystals have many potentially important applications, such as use in sensor devices, or as hydrogen storage materials. To improve the synthesis efficiency of ferromagnetic GEM (Fe, Co, and Ni), synthetic diamond was used as carbon source, replacing thermodynami...

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Bibliographic Details
Published in:Journal of alloys and compounds 2007-05, Vol.434, p.678-681
Main Authors: Teng, Mao-Hua, Tsai, Shao-Wei, Hsiao, Chung-I, Chen, Yung-Der
Format: Article
Language:English
Subjects:
Metals
Nanostructures
Scanning and transmission electron microscopy
Vapor deposition
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Summary:Graphite encapsulated metal (GEM) nanocrystals have many potentially important applications, such as use in sensor devices, or as hydrogen storage materials. To improve the synthesis efficiency of ferromagnetic GEM (Fe, Co, and Ni), synthetic diamond was used as carbon source, replacing thermodynamically stable graphite, on a custom-designed tungsten arc-discharge device. The results show that diamond is a much better raw material than graphite; the new process not only raises the production rate (except for Co) of the as-made powder, but also increases the recovery percentage of GEM nanocrystals from the original 7–10% to 23–33%. The exact mechanism is still unclear, but some evidence indicates that diamond as a metastable phase of carbon probably dissolves in liquid metal pools during arcing much more easily than does the stable graphite. The experiments also provide valuable information on the phase transformation of diamond into graphite.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2006.08.275