Valence Fluctuation in Amorphous Alloys, and Magnetic and Electrical Properties
| Project/Area Number |
61550474
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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 |
Physical properties of metals
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
FUKAMICHI Kazuaki Institute for Materials Research, Tohoku University, 金属材料研究所, 助教授 (00005969)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Valence fluctuation / Fe-Ce / Curie temperature / Magnetic moment / Random axial anisotropy / Hydrogen absorption / Density / 保磁力 / アモスファス合金 / ランダム異方性 |
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| Research Abstract |
The Curie temperature of Fe_2Ce amorphous alloys is lower than the value expected from the deGennes factor and its magnetic moment is smaller than that of Fe_2Zr amorphous alloy. These results suggest that Ce atoms become the tetravalent state in Fe due to the valence fluctuation. The X-ray diffraction analysis revealed that the coordination number and the atomic distance of Fe_2Ce amorphous alloy are very different from those of other Fe_22R(R:rare earth metal) amorphous alloys. By hydrogen absorption, the drastic changes of these structure and magnetic properties were observed. The linear relationship between the room temperature density of Fe_2R amorphous alloys and it of rare earth metals was confirmed, except for the value of Fe_2Ce. The concentration dependence of room temperature density is strange. That is, the density slightly increases with increasing the Ce content from 10% to 35% though the density of Ce is smaller than that of Fe. The means that this system does not obeys
… More
Vegard's law. These results are also explained by considering the valence fluctuation of Ce.
Rare metals have a extremely large spin-orbital angular momentum and a large random axial anisotropy is observed in the amorphous state. The huge coercive force at low temperatures for Fe-R amorphous alloys is caused by the random axial anisotropy. However, such a large coercive force is not observed in Fe_2Ce amorphous alloys. This fact is explained by the change of valence of Ce, because Ce in the tetravalent state has no magnetic moment accompanying the no random axial anisotropy.
From these results mentioned above, it is concluded that Fe-Ce amorphous allys are typical materials in fluctuating valence state. The mean free path of electrons in amorphous alloys is very short due to the randomness and the electrical resistivity is higher than the value of crystals by one or two orders of magnitude. Therefore, it is considered that the effect of the valence fluctuation on the electrical resistivity is apparently not so remarkable. Less
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Report
(2 results)
Research Products
(11 results)
