1995 Fiscal Year Final Research Report Summary
SYNTHESIS AND MAGNETIC PROPERTIES OF COBALT SINGLE CRYSTALLINE PARTICLES ENCAPSULATED IN CARBON CAGES
| Project/Area Number |
06650018
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | MIE UNIVERSITY |
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Principal Investigator |
MASUDA Morio MIE UNIVERSITY,FACULTY OF ENGINEERING,PROFESSOR, 工学部, 教授 (20023137)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Yahachi MIE UNIVERSITY,FACULTY OF ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (90144203)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Cobalt / Carbon / Particles / Arc discharge / Nanocapsule / Magnetism / Magnetization / Coerciveforce |
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| Research Abstract |
Carbon nanocapsules encaging Co particles were produced by arc evaporation of graphite/cobalt composite in helium gas. Crystal structures, morphology and magnetic properties of Co nanocapsules, which were prepared from various composite rods with varying Co/C ratio as well as under different He pressures, were studied.
1.Crystal Structure and Paticle Size of Co Particles
Co particles in nanocapsules were predominantly in a fcc phase. Heat treatment of the fcc-Co particles did not bring about structural transformation to hcp. Diameter of Co particles increased with the increase of He gas pressure (ca.18 nm at 50 Torr to ca.25nm at 500Torr).
2.Coercive Force as a Function of Particle Size
Coercive Force Hc decreased steeply from 640 Oe to 300 Oe when the particle size d increased from 18 nm to 21 nm, but it did not show any large changes from d=21 nm to 25 nm, suggesting that the Co particles with diameters less than ca.20 nm had single-magnetic domains.
3.Saturation magnetization
When the area of a Co-packed hole occupied more than 16% of the total cross-section of the composite rod, the saturation magnetization Ms of the prepared sample was more than 88% of the Ms for bulk Co. The reduction in Ms is due to the presence of non-magnetic graphite coating, which protect the core Co particles from oxidation and coalescence. The Ms of carbon-coated Co particles showed a temperature dependence similar to that of bulk Co.
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Research Products
(2 results)
