2001 Fiscal Year Final Research Report Summary
Clarification of Coercive Mechanism in Rare Earth Iron Nitride Sm-Fe-N magnet
| Project/Area Number |
12640351
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
FUJI Hironobu Hiroshima University, Faculty of Integrated Arts and Sciences, Professor, 総合科学部, 教授 (30034573)
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| Co-Investigator(Kenkyū-buntansha) |
ORIMO Shin-ichi Hiroshima University, Faculty of Integrated Arts and Sciences, Assistant, 総合科学部, 助手 (40284129)
EKINO Toshikazu Hiroshima University, Faculty of Integrated Arts and Sciences, Associate Professor, 総合科学部, 助教授 (40185103)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Permanent magnet / Corcivity mechanism / Sm2Fe17N3 powder / Particle size dependence / Surface cleaning effect / Nitride |
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| Research Abstract |
For clarifying the role that the interstitial N atoms played on the microscopic scale for basic magnetism in R_2Fe_<17>N_3, we determined the enhancements of Fe magnetic moments on the crystallographically different atomic sites and crystalline electric field parameter A_2^0 upon nitrogenation by neutron diffraction studies of the rhombohedral Y_2Fe^<17> and Y_2Fe_<17>N_<3.1> and high-field magnetization measurements of single crystalline Nd_2Fe_<17> and Nd_2Fe_<17>N_3, respectively. The results obtained are compared with those estimated by the band structure calculation. For clarifying the coercivity mechanism in Sm_2Fe_<17>N_3, we also examined the particle (powder) size and surface cleaning effects on the coercive field μ_0H_c for the Sm_2Fe_<17>N_3 single crystal powder. The results indicate that μ_0H_c monotonically decreases with increasing the particle size, suggesting that the coercivity mechanism is of a nucleation type. When there are many nucleation sites on the surface of Sm_2F_<17>N_3 powder before surface cleaning, the value of μ_0H_c is relatively small and reveals strong temperature dependence, while μ_0H_c is strongly enhanced by surface cleaning, leading to relatively weak temperature dependence. In this work, we obtained the resultant maximum energu product (BJH)_<max> = 330 kJ/m3, which is the highest as far as we know.
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