Synthesis of multiferroic composite materials by undercooling solidification using contanireless process

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K14426
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Structural/Functional materials
• Research Institution: Chiba Institute of Technology
• Principal Investigator: OZAWA Shumpei 千葉工業大学, 工学部, 准教授 (80404937)
• Research Collaborator: Kuribayashi Kazuhiko
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 無容器凝固 / マルチフェロイック材料 / ガスジェット浮遊 / 過冷却

Outline of Final Research Achievements

It is known that the hexagonal structure with a space group of P63cm is stable in the LnFeO3 system (Ln: Lanthanide) having rare earth elements with smaller ionic radii than that of Gd3+. The hexagonal LnFeO3 (h-LnFeO3) shows multiferroic properties such as ferroelectricity and ferromagnetism in one phase so that it has attracted great interest in the field of electronic industry. However, the materials for practical applications have been still undeveloped, because the h-LnFeO3 phase shows anti-ferromagnetism as well as low magnetic transition temperature below 100 K. As one of the solutions for this issue, it is expected a nano-sized composite material consisted of h-LnFeO3 and a ferromagnetic phase. Based on this idea, it was tried a synthesize multiferroic composites consisting of h-LuFeO3 and Fe3O4 by containerless undercooling solidification in this study. As a result, a fine composite structure composed of LuMn1/3Fe2/3 O3 and MnFe2O4 was obtained when substituting of Fe by Mn.

Free Research Field

材料科学，結晶成長，高温融体物性

Academic Significance and Societal Importance of the Research Achievements

単相でありながら強誘電性や強磁性を同時に示すマルチフェロイック材料については，実用に至る物質が未だ報告されていない．この理由は，強誘電性を担保するには絶縁体でなければならないが，絶縁体で磁性を示す物質の殆どが反強磁性体だからである．本研究では，この相克を解決すべく，LnFeO3-Fe3O4系の一部をMnで置換し，かつ過冷急冷凝固させることで，マルチフェロイック材料の候補となりうる組織を得ることに成功した．また，この研究を通して得た準安定状態図や，それに基づいた過冷却メルトからの微細共晶組織成長に関する知見は，準安定相生成の科学の発展に資するものである．