An effective way to increase the high-frequency permeability of Fe3O4 nanorods
An effective way to increase the high-frequency permeability of Fe3O4 nanorods
复制标题
提高Fe3O4纳米棒高频磁导率的有效途径
DOI：
10.1039/c6nr03305a
复制
发表时间：
2016
期刊：
影响因子：
6.7
通讯作者：
Cheng Zhaohua
中科院分区：
文献类型：
--
作者：
Ren Xiao;Yang Haitao;Tang Jin;Li Zi An;Su Yi Kun;Geng Sai;Zhou Jun;Zhang Xiangqun;Cheng Zhaohua
在旋转磁场作用下，成功合成了均匀的Fe3O4磁性纳米棒，并在环氧树脂中定向。利用离轴电子全息技术，获得了处于剩余态的Fe3O4纳米棒内部和周围的磁感应场。高各向异性的Fe3O4纳米棒由于具有较强的磁形状各向异性，其感应磁场表现为单畴态。对所获得的相位图像进行定量磁矩分析，得出单个Fe3O4纳米棒的平均磁化强度为0.53 T。此外，在GHz范围内，磁取向Fe3O4 nr的磁导率实部（μ’）明显高于随机Fe3O4 nr。在1 ~ 10 GHz的μ频率依赖范围内，取向Fe3O4 NRs在4.75 GHz处的共振峰高于体相（1.2 GHz）。此外，利用OOMMF软件，随着偶极相互作用强度的增加，取向Fe3O4核磁共振的μ值提高到4.22。这些结果对开发提高磁性纳米材料在GHz工作频率下磁导率的有效方法具有指导意义。
Uniform Fe3O4 magnetic nanorods (NRs) were successfully synthesized and oriented in epoxy resin under a rotating magnetic field. Magnetic induction fields within and around a single Fe3O4 nanorod in the remanence state were obtained by off-axis electron holography. The induction fields indicated a single domain state of the highly anisotropic Fe3O4 nanorod due to its strong magnetic shape anisotropy. Quantitative magnetic moment analysis of the obtained phase image yielded an average magnetization of 0.53 T of a single Fe3O4 nanorod. Moreover, the real part of the permeability (μ′) of magnetic-oriented Fe3O4 NRs is obviously higher than that of random Fe3O4 NRs in the GHz range. The oriented Fe3O4 NRs exhibit a higher resonance peak at 4.75 GHz compared to the bulk counterpart (1.2 GHz) in the frequency dependence of μ in the range of 1–10 GHz. Moreover, the calculated μ value of the oriented Fe3O4 NRs could be improved to 4.22 with the increased dipolar interaction strength using the OOMMF software. These results could play a guiding significance in the development of an effective method to improve the permeability of magnetic nanomaterials at GHz working frequency.