Development of new nanocomposite-type ferrite magnets yielding strong magnetic force

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K04900
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Nanomaterials engineering
• Research Institution: Ehime University
• Principal Investigator: YAMAMURO SAEKI 愛媛大学, 理工学研究科(工学系), 准教授 (10402653)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: ナノコンポジット / スピネルフェライト / 共析反応 / 固相プロセス / 液相プロセス / 磁性材料 / 粉末 / ナノ粒子

Outline of Final Research Achievements

By employing the eutectoid decomposition of FeO, we have fabricated ferrite-based magnetic nanocomposites consisting of a lamellar nanostructure of a ferromagnetic metal (Fe) and a ferrimagnetic spinel ferrite (Fe3O4). It was found that the room-temperature magnetization measurements for nanocomposite powders prepared by a solid-phase process gave rise to a high saturation magnetization above 100 emu/g, which is larger than that of single-phase Fe3O4. Such high magnetization is ascribed to the presence of the Fe phase, which has a large saturation magnetization. A smooth magnetization curve with single-phase-like behavior was observed for nanocomposite specimens despite the coexistence of two magnetic phases, suggesting that the two phases could be magnetically exchange-coupled. The addition of cobalt resulted in an enhanced coercivity, indicating the formation of cobalt ferrite with a high magnetocrystalline anisotropy.

Free Research Field

ナノ材料

Academic Significance and Societal Importance of the Research Achievements

FeOの共析分解により得られたFeとスピネルフェライトからなるラメラ複合組織が、ナノコンポジット磁石として機能する可能性について示した。特にCo添加の結果からは、構成酸化物相であるスピネルフェライト相を自在に置き換えることができる可能性を示すことができた。スピネルフェライトは構成金属イオンを別種の金属イオンで置換することにより磁気特性を多彩に制御できることから、各種スピネルフェライトとFeからなるナノコンポジット作製の新たな手法を提示することができた。