【公開日：2025.06.10】【最終更新日：2025.05.16】
課題データ / Project Data
課題番号 / Project Issue Number
24UT0112
利用課題名 / Title
金属酸化物ナノ粒子の合成と物性に関する研究
利用した実施機関 / Support Institute
東京大学 / Tokyo Univ.
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）次世代ナノスケールマテリアル/Next-generation nanoscale materials（副 / Sub）高度なデバイス機能の発現を可能とするマテリアル/Materials allowing high-level device functions to be performed
キーワード / Keywords
ナノ粒子/ Nanoparticles,電子顕微鏡/ Electronic microscope,フォトニクスデバイス/ Nanophotonics device,電子分光/ Electron spectroscopy
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
MacDougall Jessica
所属名 / Affiliation
東京大学大学院理学系研究科化学専攻
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
生井 飛鳥、吉清 まりえ、大竹 登夢
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
押川 浩之, 福川 昌宏, 森田 真理, 沖津 康平
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）,技術補助/Technical Assistance
利用した主な設備 / Equipment Used in This Project
UT-007：高分解能分析電子顕微鏡
UT-308：多機能走査型X線光電子分光分析装置(XPS)with AES
UT-005：原子分解能元素マッピング構造解析装置
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
This study investigates the effect of Mn substitution on the magnetic and electromagnetic properties of ε-Fe2O3 nanoparticles. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) were used to confirm the successful incorporation of Mn and analyze its distribution within the samples. The results demonstrate that Mn substitution leads to a decrease in saturation magnetization and an increase in coercivity and zero-field ferromagnetic resonance frequency. The goal was to develop materials suitable for electromagnetic wave absorption applications, such as high-frequency telecommunications.
実験 / Experimental
Three samples were synthesized using precursors of beta iron oxyhydroxide and manganese nitrate with varied feed ratios(=[Mn]/[Mn + Fe]): 0 (Mn0), 0.05 (Mn1), and 0.10 (Mn2). These precursors were coated with silica matrices, sintered in air at 1100 °C for 4 hours and etched with sodium hydroxide to provide red-brown powders. The structural and compositional analyses were carried out using X-ray photoelectron spectroscopy (Versa ProbeⅢ), transmission electron microscopy (JEM-2010F), scanning transmission electron microscopy with energy dispersive spectroscopy (JEM-ARM200F ThermalFE(STEM SDD)), powder X-ray diffraction (PXRD) with Rietveld refinement, and X-ray fluorescence spectroscopy (XRF). Magnetic measurements were performed using superconducting quantum interference device (SQUID) magnetometry, and the millimetre-wave absorption properties were measured with terahertz time-domain spectroscopy (THz-TDS).
結果と考察 / Results and Discussion
XRF confirmed the [Mn]/[Mn + Fe] ratio in the samples matched with the feed ratio. The XPS analysis shown in figure 1 confirmed that manganese was present as Mn2+, replacing Fe3+, and that oxygen vacancies were generated to maintain charge neutrality, which in turn influenced the lattice structure of the material. XRD analysis confirmed the main phase present in the samples was the epsilon phase, with Mn ions substituting exclusively in the distorted octahedral B site of the unit cell, and the lattice parameters varied anisotropically as the ratio of Mn ions increased. TEM images showed that the nanoparticles exhibited an average size of approximately 19 nm, with a slight increase in particle size observed as the manganese content increased (figure 2). Additionally, STEM-EDS was used to examine the spatial distribution of manganese within the nanoparticles, as shown in figure 3. The results confirmed that manganese was homogeneously distributed across all samples, indicating uniform substitution into the iron oxide structure. These structural changes correlated with variations in the magnetic properties of the material. The coercive field increased with higher manganese substitution, while the saturation magnetization decreased. The results also demonstrated that the ferromagnetic resonance frequency shifted to higher values with increasing manganese content, a trend that aligns with previous findings on other substituted iron oxides. These observations suggest that manganese substitution enhances the magnetic anisotropy of ε-Fe2O3, making it a strong candidate for millimeter-wave absorption applications.
図・表・数式 / Figures, Tables and Equations
Fig. 1 XPS spectra of Mn0, Mn1 and Mn2
Fig. 2 TEM images of Mn0, Mn1 and Mn2.
Fig. 3 STEM images of Mn1 with quantitative analysis from EDS.
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
参考文献
Jessica MacDougall, Asuka Namai, Onno Strolka and Shin-ichi Ohkoshi, "Mn-substitution effects on the magnetic and zero-field ferromagnetic resonance properties of ε-Fe2O3 nanoparticles", Mater. Adv., 2025,6, 969-976, 10.1039/d4ma00927d
謝辞本研究では、総合研究機構ナノ工学研究センターの押川様、森田様、 沖津様、福川様にご協力を頂きました。厚く御礼を申し上げます。
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
-
Jessica MacDougall, Phase Separation of ϵ‐Fe2O3 and BaFe12O19 in a Synthesis Combining Reverse‐Micelle and Sol‐Gel Techniques, European Journal of Inorganic Chemistry, 27, (2024).
DOI: 10.1002/ejic.202400148
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Jessica MacDougall, Mn-substitution effects on the magnetic and zero-field ferromagnetic resonance properties of ε-Fe2O3 nanoparticles, Materials Advances, 6, 969-976(2025).
DOI: 10.1039/D4MA00927D
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
- J. MacDougall, H. Tokoro, M. Yoshikiyo, A. Namai, and S. Ohkoshi, The 105th CSJ Annual Meeting, 2025/03/27, Osaka, Japan, Oral (To be presented)
- 生井飛鳥、大越 慎一, "ユニークなナノサイズ磁性体とその生成メカニズム", CSJカレントレビュー「固体材料開発のフロンティア」, 化学同人, 94–102 (2024.3).
- A. Namai, S. Ohkoshi, “Study of metal-substituted ε-iron oxide ferrite nanomagnets exhibiting large magnetic anisotropy”, 8th Bordeaux Olivier Kahn Discussions: Magnetism & Light (BOOK-D), Bordeaux, May 15th, 2024, Oral (invited).
- 生井飛鳥，吉清まりえ，Y. Gu，N. J. O. Silva，A. Millán，大越慎一, “イプシロン酸化鉄ハード磁性体の開発と医療応用への可能性検討”, 第40回 日本DDS学会学術集会, the University of Tokyo, 10th February, 2023, Oral.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件