2022 Fiscal Year Final Research Report
Investigation on aliovalent doping effect in nickelates with infinite structures using epitaxial thin films
| Project/Area Number |
20H02435
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 26020:Inorganic materials and properties-related
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
Matsuda Akifumi 東京工業大学, 物質理工学院, 准教授 (80621698)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | ニッケル酸塩 / エピタキシャル薄膜 / 異原子価置換 / 層状ペロブスカイト構造 / Ruddlesden-Popper構造 / トポタキシャル相変態 / 水素還元 |
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| Outline of Final Research Achievements |
Ruddlesden-Popper phase crystals (RP type, An+1BnO3n+1) have layered perovskite structures with, in which conductivity control by the layer number “n” and superconductivity in related materials have been found. However, the correlation between structures and conduction properties in multilayer crystals with n=2 or more and the effect of aliovalent substitution are expected to be elucidated regarding the mechanism different from that of its cuprate system. In this research, epitaxial thin films of La3Ni2O7(001)[110]//LaAlO3(100)[001] (n=2, Ni2.5+) and La4Ni3O10(001)[110]//NdGaO3(110)[001] (n=3, Ni2.67+) was developed, and control of their semiconducting conductivity by (Sn, Hf)-doping and reduction was found. LaNiO3(100)[001]//LaAlO3(100)[010] (n=∞, Ni3+) epitaxial thin films were also developed. Increase in metallic conductivity via electron doping and thickness reduction as well as further topochemical reduction to LaNiO2(100) crystals (Ni+) were obtained.
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| Free Research Field |
機能性セラミックス 無機材料化学 エピタキシャル薄膜
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| Academic Significance and Societal Importance of the Research Achievements |
層状ペロブスカイトRuddlesden-Popper型(RP型、An+1BnO3n+1)はab面内に無限の広がりをもち、層数nによる導電性制御、関連材料の超伝導発現も見出された。しかし、n=2以上の多層結晶における構造と伝導特性の相関や、異原子価置換による効果は、その銅酸化物系と異なる機構に関する起源の解明が期待されている。本研究は、層状型ニッケル酸塩においてn選択的にエピタキシャル薄膜を創製し、新たに4価原子置換による構造・導電性変化、また二次元構造をもつ結晶へのトポケミカル還元を見出すことにより、Ruddlesden-Popper型結晶の異原子価置換による物性制御と材料設計に迫った。
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