Negative imaginary parts of complex permeability and microwave absorption performance of core double-shelled FeCo/C/Fe2.5Cr0.5Se4 nanocomposites
Negative imaginary parts of complex permeability and microwave absorption performance of core double-shelled FeCo/C/Fe2.5Cr0.5Se4 nanocomposites
复制标题
核双壳FeCo/C/Fe2.5Cr0.5Se4纳米复合材料复磁导率负虚部及微波吸收性能
DOI：
10.1039/c6ra12772j
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发表时间：
2016-01-01
期刊：
影响因子：
3.9
通讯作者：
Zhang, Z. D.
中科院分区：
文献类型：
--
作者：
Li, D.;Feng, Y.;Zhang, Z. D.
采用电弧放电法和高温溶液化学法相结合的方法，制备了以FeCo纳米颗粒为壳层，碳和铁磁Fe 2. 5Cr 0. 5Se 4（FCS）分别为内壳层和外壳层的仙人掌形核双壳FeCo/C/Fe 2. 5Cr 0. 5Se 4纳米结构。通过改变FeCo/C与FCS的质量比x，研究了（x）FeCo/C/FCS纳米复合材料在1-18 GHz频率范围内的磁性能、电磁响应和微波吸收性能。（0 ≤ x ≤ 0. 15）FeCo/C/FCS纳米复合材料的复磁导率虚部μ′′和复介电常数虚部e′′的频率依赖性在高频范围内呈现明显的反向变化趋势。由于相位滞后，发现μ“”的负最小值与e“”的正最大值相耦合。裸FCS-石蜡复合物的最小μ′′约为-0.07，当质量比x增加到0.1和0.15时，μ ′ ′分别变为-0.44和-0.05。当x增加到0.2时，所有纳米复合材料的μ′′值变为正值。结果表明，（x = 0.1）FeCo/C/FCS-石蜡复合材料在10 GHz处的反射损耗（RL）峰值为−54.5 dB，在3-18 GHz频率范围内，通过选择合适的层厚（1.4 ~ 6 mm），RL可超过−20 dB。
Cactus-shaped core double-shelled FeCo/C/Fe2.5Cr0.5Se4 nanostructures with a spiky surface were prepared by combining an arc-discharge process with a high-temperature solution chemical method, in which FeCo nanoparticles serve as the, while carbon and ferrimagnetic Fe2.5Cr0.5Se4 (FCS) are the inside and the outside shells, respectively. The magnetic properties, electromagnetic response, and microwave absorption properties of the (x)FeCo/C/FCS nanocomposites in the 1–18 GHz frequency range were investigated by changing the mass ratio x between FeCo/C and FCS. The frequency dependences of μ′′ (imaginary parts of complex permeability) and e′′ (imaginary parts of complex permittivity) of the (0 ≤ x ≤ 0.15)FeCo/C/FCS nanocomposites show distinct inverse trends of change in the high frequency ranges. Negative minimum values of μ′′ are found to be coupled with positive maxima of e′′ due to a phase lag. The bare FCS–paraffin composite starts with a minimum μ′′ of about −0.07, which shifts to −0.44 and −0.05 when the mass ratio x is increased to 0.1 and 0.15, respectively. As x increases to 0.2, all the μ′′ values of the nanocomposites become positive. The best absorption property with a reflection loss (RL) peak of −54.5 dB at 10 GHz is obtained in the (x = 0.1)FeCo/C/FCS–paraffin composite and RL exceeding −20 dB can be achieved within the 3–18 GHz frequency range by choosing an appropriate layer thickness between 1.4 and 6 mm. The contribution of the negative μ′′ response to the microwave absorption is discussed.