Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Nat Commun. 2012;3:1035. doi: 10.1038/ncomms2038.
Magnetic ferrites such as Fe(3)O(4) and Fe(2)O(3) are extensively used in a range of applications because they are inexpensive and chemically stable. Here we show that rhodium-substituted ε-Fe(2)O(3), ε-Rh(x)Fe(2-x)O(3) nanomagnets prepared by a nanoscale chemical synthesis using mesoporous silica as a template, exhibit a huge coercive field (H(c)) of 27 kOe at room temperature. Furthermore, a crystallographically oriented sample recorded an H(c) value of 31 kOe, which is the largest value among metal-oxide-based magnets and is comparable to those of rare-earth magnets. In addition, ε-Rh(x)Fe(2-x)O(3) shows high frequency millimetre wave absorption up to 209 GHz. ε-Rh(0.14)Fe(1.86)O(3) exhibits a rotation of the polarization plane of the propagated millimetre wave at 220 GHz, which is one of the promising carrier frequencies (the window of air) for millimetre wave wireless communications.
磁性铁氧体，如 Fe(3)O(4) 和 Fe(2)O(3)，由于其价格低廉且化学性质稳定，被广泛应用于各种领域。在这里，我们展示了通过纳米尺度化学合成方法，使用介孔硅作为模板制备的铑取代的 ε-Fe(2)O(3)，即 ε-Rh(x)Fe(2-x)O(3)纳米磁铁，在室温下表现出 27 kOe 的巨大矫顽力（H(c)）。此外，在具有结晶取向的样品中记录到 31 kOe 的 H(c)值，这是金属氧化物基磁铁中最大的值，与稀土磁铁相当。此外，ε-Rh(x)Fe(2-x)O(3)在高达 209 GHz 的频率下表现出高的毫米波吸收。ε-Rh(0.14)Fe(1.86)O(3)在 220 GHz 时表现出传播毫米波的偏振面旋转，这是毫米波无线通信的有前途的载波频率（空气窗口）之一。
