| Project/Area Number |
17K19172
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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 |
Inorganic materials chemistry, Energy-related chemistry, and related fields
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| Research Institution | Kyushu University |
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Principal Investigator |
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| Research Collaborator |
Gopalan Venkatraman
Mochizuki Yasuhide
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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 | ポーラーメタル / 層状ペロブスカイト / 第一原理計算 / セラミックス / 強誘電体 / 金属 |
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| Outline of Final Research Achievements |
Our first-principles calculations revealed that total energy difference between non-polar and polar phases of a layered perovskite Ca3Ti2O7 is increased when the amount of excess electron is increased. Ca3Ti2O7 powder samples were prepared via a solid-state reaction method, and the resultant powder was mixed with a CaH2 powder and heated in a vacuumed glass tube to dope H- ions into Ca3Ti2O7. X-ray diffraction showed that the crystal structure belongs to a polar space group Cmc2_1. The semiconducting nature was revealed by the temperature dependence of electric conductivity measurements.
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| Academic Significance and Societal Importance of the Research Achievements |
電気的極性を示す(ポーラーな)点群に属する原子構造と金属的な電子構造を併せもつポーラーメタルは必然的に希少になる。このポーラーな構造と金属的電気伝導性を併せ持つ物質内部 および表面の静電的状態は、極めて想像しがたいものであり非常に興味深い。 本研究では、ペロブスカイト型酸化物の90%以上で見られる構造歪みである酸素配位八面体回転が、物質内の伝導キャリアにより阻害されない、強固な構造歪みであることを示した。ポーラーメタルの設計指針に関する大きな知見を得ることに成功したと言える。
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