| Project/Area Number |
17K19048
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Applied condensed matter physics and related fields
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Research Collaborator |
Ozawa Takahiro
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| Project Period (FY) |
2017-06-30 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000)
Fiscal Year 2018: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2017: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
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| Keywords | パラジウム / 水素 / 電気抵抗 / 準安定 / 核反応 / 電気伝導特性 / 水素化物 / 伝導特性 |
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| Outline of Final Research Achievements |
We synthesized palladium thin films with a thickness of about 10 nm, and investigated the hydrogenation process and electric properties of the film by the conductivity measurement and hydrogen depth profiling with nuclear reaction analysis. The hydrogenation was performed by exposure of the sample to hydrogen gas and hydrogen ion irradiation. It was found that the thermodynamically stable hydride phase was formed with the former method, whereas a metastable hydride phase was produced by the latter method. The metastable hydride phase produced by the ion irradiation was found to relax to the stable phase with increasing time. This relaxation is caused by hydrogen diffusion and its time scale was analyzed as a function of the sample temperature. It was found that the relaxation occurs as a thermal activation and quantum tunneling processes at high and low temperatures, respectively. Furthermore, the 50 K anomaly was examined in relation to the hydride structure.
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| Academic Significance and Societal Importance of the Research Achievements |
金属水素化物は，高温超伝導の候補物質として注目されるとともに，クリーンなエネルギー源である水素の貯蔵や純化に利用されるなど，基礎的にも応用的にも重要かつ興味深い物質である．従来は熱力学的に安定な水素化物が研究され，その物性が明らかにされてきた．ところが近年，熱平衡では実現しない準安定な水素化物が特異な物性を発現する可能性が示唆され，大きな注目を集めている．本研究では，従来行われていなかった低エネルギーイオン照射という手法でこれまでにない準安定水素化物を形成し，その構造と物性を明らかにすることで，新規物性発現とそのメカニズム解明を目指して研究を行った．
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