| Project/Area Number |
26400381
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Mathematical physics/Fundamental condensed matter physics
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
兼下 英司 仙台高等専門学校, 総合科学系, 准教授 (60548212)
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| Co-Investigator(Renkei-kenkyūsha) |
TAKABATAKE TOSHIRO 広島大学, 大学院・先端物質科学研究科, 名誉教授 (40171540)
SUEKUNI KOUICHIIRO 九州大学, 大学院・総合理工学研究員エネルギー物質科学部門, 准教授 (10582926)
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| Project Period (FY) |
2014-04-01 – 2017-03-31
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| Project Status |
Completed (Fiscal Year 2016)
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| Budget Amount *help |
¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
Fiscal Year 2016: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2014: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | 熱電変換物質 / ガラス / 熱伝導 / クラスレート / 局在現象 / 中性子非弾性散乱 / THz振動数 / クラスレート化合物 / 構造ガラス / フォノン熱伝導 / ボソン・ピーク / 中性子散乱 / 非調和性 |
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| Outline of Final Research Achievements |
Type-I clathrate compounds exhibit glasslike thermal/dynamic properties depending on on-center or off-center due to symmetry breaking of guest-atom positions in tetrakaidecahedron cages. All of these features are associated with the phonon dynamics in the THz region, for which we have performed large-scale numerical simulations by highlighting the difference between type-I clathrates Ba8Ga16Ge30 (BGG) with on-center guest atoms and Ba8Ga16$Sn30(BGS) with off-center guest atoms. The results of the phonon densities of states D(\omega), the dynamic structure factors S(Q,E), the specific heats C(T), and the participation ratios of eigenmodes have clearly realized a drastic change from the conventional phonon dynamics of BGG to the phonon-glass dynamics of BGS. On the basis of these results, we have given the microscopic mechanism emerging glasslike thermal/dynamics behaviors in type-I clathrate compounds with off-center guest atoms.
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