2018 Fiscal Year Final Research Report
Experimental verification of a criterion for forming a metastable phase from undecooled melt
| Project/Area Number |
16K06807
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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 |
Material processing/Microstructural control engineering
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| Research Institution | Chiba Institute of Technology |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
小澤 俊平 千葉工業大学, 工学部, 准教授 (80404937)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | multiferroic material / 無容器溶融凝固 / 過冷却 / LnFeO3（ln:希土類元素） |
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| Outline of Final Research Achievements |
In order to verify the hypothesis that the lower limit value of the tolerance factor TF at which metastable hexagonal LnFeO3 (h-LnFeO3) is generated in the undercooled melt of LnFeO3 (Ln: rare earth elements) is about 0.82, we performed containerless solidification experiments using samples in which a part of Ln3+ was substituted by Sc3+. Assuming the substitution rate as x, the h-LnFeO3 phase is frozen only at 0 <x <0.5 at Lu3+, 0.2 <x <0.5 at Yb3+, 0.3 <x <0.5 at Tm3+, and 0.45 at Er3+. When TF is calculated from the average radius of Ln site assuming the ionic radius of Sc3+ as 91 pm, the lower limit values of TF are 0.82, 0.82, 0.82, 0.83 for Lu3+, Yb3+, Tm3+ and Er3+, respectively. This result agrees well with the hypothesis．
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| Free Research Field |
材料プロセシング
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| Academic Significance and Societal Importance of the Research Achievements |
multiferroic materialは強磁性とと強誘電性を併せ持つ物質であり，高密度の記憶媒体として注目されている物質である．特に本研究で扱った六方晶のLnFeO3(h-LnFeO3)はその有力な候補と目されている物質であるが，その組成および製法は未だ十分には明らかにされていなかった．この点，代表者らが見いだした無容器溶融凝固法によるh-LnFeO3の創製は問題を一気に解決する画期的な研究であり，電子技術の発展に対する寄与はもとより，過冷却誘掖からの準安定相の創製についての熱力学的を明らかにするなど，学術的意義も極めて大きいと言える．
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