2013 Fiscal Year Final Research Report
Synthesis of layered transition-metal oxynitrides: search for novel oxynitride superconductors
| Project/Area Number |
24654094
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Condensed matter physics II
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| Research Institution | Hokkaido University |
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Principal Investigator |
MOTOHASHI Teruki 北海道大学, 工学(系)研究科(研究院), 准教授 (00323840)
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| Co-Investigator(Renkei-kenkyūsha) |
KIKKAWA Shinichi 北海道大学, 大学院工学研究院, 教授 (10127219)
MASUBUCHI Yuji 北海道大学, 大学院工学研究院, 助教 (80466440)
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| Project Period (FY) |
2012-04-01 – 2014-03-31
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| Keywords | 超伝導 / オキシナイトライド / 層状構造 |
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| Research Abstract |
The present work dealt with search for novel layered superconductors among oxynitrides, a material family with mixed anions. We focused on Li-Nb oxynitrides, containing a layered arrangement of chemically distinct two metals of Li and Nb.
A hexagonal oxynitride Li0.88Nb3.0(O0.13N0.87)4 was synthesized through ammonia nitridation of LiNb3O8. X-ray and neutron diffraction analyses revealed that this oxynitride consists of alternate stacking of octahedral and prismatic layers with different Li/Nb ratios: significant amounts of Li and Nb atoms (Li/Nb = 43/57) coexist in the octahedral layer, while the prismatic site is preferentially occupied by Nb (Li/Nb = 3/97). A metallic behavior was accompanied by an abrupt drop of electrical resistivity at about 3 K. Furthermore, large diamagnetism and specific-heat anomaly were observed below this temperature, suggesting the appearance of superconductivity in the Li-Nb oxynitride.
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