1990 Fiscal Year Final Research Report Summary
Systematic Research on High-Field Magnetization Process in Nd_2Fe_<14>B-type Mixed Compounds
| Project/Area Number |
01540262
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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 |
固体物性
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| Research Institution | Tohoku University |
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Principal Investigator |
KATO Hiroaki Tohoku Univ. I. M. R., Research Associate, 金属材料研究所, 助手 (40177465)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAGAWA Yasuaki Tohoku Univ. I. M. R., Professor, 金属材料研究所, 教授 (10005944)
YAMADA Motohiko Tohoku Univ. I. M. R., Associate Professor, 金属材料研究所, 助教授 (40005848)
KIDO Giyuu Tohoku Univ. I. M. R., Associate Professor, 金属材料冶究所, 助教授 (10013541)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Nd_2Fe_<14>B / Permanent Magnet / Nd-Fe-B Magnet / High Magnetic Field / Magnetization Curve / Crystalline Electric Field / Magnetic Anisotropy |
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| Research Abstract |
(1) High-field magnetization process in R_2Fe_<14>B single crystals (R : rare earth element) has been investigated experimentally and theoretically. A wide variety of magnetizations including the first-order magnetization process (FOMP) and the spin reorientation phenomena is reproduced by the following calculation : the ferromagnetism of the Fe sublattice is treated phenomenologically, and the crystalline electric field (CEF) theory is strictly applied to the R ions which are subject to the molecular field due to the Fe sublattice.
(2) The magnetic behavior of single crystal Nd_2(Fe_<1-x>Al_x)_<14>B has been studied in steady high magnetic fields up to 300 kOe. The field H_j where the FOMP occurs increases rapidly with x. The experimental data are interpreted in terms of molecular field H_m which decreases with increasing x and the CEF parameters.
(3) High-field magnetization measurements on single crystals of (Nd-Y)_2Fe_<14>B and (Nd-La)_2Fe_<14>B have been performed in steady high magnetic fields. The observed data including FOMP are successfully described by a simple dilution model based on CEF and molecular field parameters obtained for Nd_2Fe_<14>B.
(4) In the quasi-binary system (Nd_<1-x>Dy_x)_2Fe_<14>B, the field H_j increases rapidly with x, reaching 320 kOe for the sample with x=0.33. The spin reorientation temperature, on the other hand, decreases with increasing x. These data are well explained by a simple a simple mixture model, in which the total free energy is the simple superposition of those of the two end members, neglecting the Nd-Dy interaction.
(5) The high reproducibility of the present calculations enables us that the magnetic properties of the quasi-binary system (R_<1-x>R'_x)_2Fe_<14>B can be predicted for any combination of rare earth elements R and R'.
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