Single crystal growth and anisotropic magnetic properties of ferrite materials aiming to develop iron-based oxide magnets for future generations

2015 Fiscal Year Final Research Report

• Project/Area Number: 25420710
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Inorganic materials/Physical properties
• Research Institution: Kyoto University
• Principal Investigator: Nakamura Hiroyuki 京都大学, 工学(系)研究科(研究院), 教授 (00202218)
• Co-Investigator(Kenkyū-buntansha): TABATA Yoshikazu 京都大学, 大学院工学研究科, 准教授 (00343244) ; WAKI Takeshi 京都大学, 大学院工学研究科, 助教 (50463906)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: フェライト磁石 / マグネトプランバイト型 / 単結晶 / フラックス法 / メスバウア分光 / 核磁気共鳴 / 磁気異方性 / メタ磁性

Outline of Final Research Achievements

Structural and magnetic properties of magnetoplumbite-type ferrites, base materials of permanent magnets, were characterized with use of single crystals grown by flux methods. For Ca-La ferrite as the base material of the Ca-La-Co high-performance magnet, phase stability study revealed that the amount of Fe is always less the M-type regular value, suggesting a certain anomaly in the structure. This is supported by 57Fe Mossbauer spectroscopy. A jump in the hard-axis magnetization was found at low temperature. 57Fe NMR study for the single crystal under external field revealed that this phenomenon is related the the switching of the easy axis of the Fe moment at the 12k sit. Site-dependent Co valence and spin state in the La-Co co-substituted Sr ferrite were also discussed on the basis of 59Co NMR.

Free Research Field

磁性物理・磁性材料