1995 Fiscal Year Final Research Report Summary
Pressure-Induced Electron Transitions and Physical Anomalies in Pd-Ce Alloys of the f-Electron Systems
| Project/Area Number |
06650731
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
OKI Kensuke KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Professor, 大学院・総合理工学研究科, 教授 (70037860)
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| Co-Investigator(Kenkyū-buntansha) |
HATA Satoshi KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Res, 大学院総合理工学研究科, 助手 (60264107)
ITAKURA Masaru KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Res, 大学院総合理工学研究科, 助手 (20203078)
KUWANO Noriyuki KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Ass, 大学院総合理工学研究科, 助教授 (50038022)
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| Project Period (FY) |
1994 – 1995
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| Keywords | dense Kondo effect / high pressure / f-electron system / XANES / diamond anvil cell / Ce valence / PdCe / GaCe |
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| Research Abstract |
In this study, we have developed the fluorescence XANES measurement method using a conventional diamond anvil pressure cell (DAC) and a focused synchrotron beam at BL-7C of the Photon Factory in KEK.By this method, Ce-L_<III> XANES spectra were measured for PdCe and GaCe alloys under various high pressures up to-10 GPa. We confirmed the pressure-induced-transition of 4f electrons (the pressurechanges of Ce valence) in these alloy phases. We also carrid out high pressure electrical resistivity measurements and high pressure X-ray diffraction experiments in order to examine the relationship between the Ce valence and the anomalous resistivity (the dense Kondo effect) , and the following results were obtained.
1.The Ce valence estimated from the fluorescence L_<III> XANES spectra varies from 3.02 (at ambient pressure) to 3.14 (at 9 GPa) in GaCe alloy phases. Since the Ce valence in PdCe has the similar pressure dependence, the electron transition of 4f^1*4f^0 in alloy-phases is promoted by the external pressure.
2.In the GaCe alloy phase, the dense Kondo effect is strongly enhanced by external pressure up to about 6 GPa as in the PdCe phase. The effect becomes weaker gradually with pressure above 6 GPa.
3.The rate of decrease in volume with pressure, or the compressibility, of GaCe is remarkably larger than that of PdCe.
4.There is a most suitable Ce-Ce atomic distance, or Ce valence, for the distinct appearance of dense Kondo effect.
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