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Annealing effects on the microwave permittivity and permeability properties of Fe79Si16B5 microwires and their micowave absorption performances 下载免费PDF全文
This paper reports that amorphous magnetic microwires(Fe79Si16B5) have been fabricated by a melt-extraction technique and have been annealed at 600°C and 750°C respectively.Differential scanning calorimeter measurements show that nanocrystalline magnetic phase(α-Fe) has been formed in the amorphous matrix when it was annealed at 600°C.Hard magnetic phase(Fe2B) was formed in the microwires annealed at 750°C,which increases the magnetic coercivity.Microwave permittivity and permeability are found to be dependent on the microstructures.The permittivity fitting results show that multi Lorentzian dispersion processes exist.For microwires annealed at 750°C,their resonance peaks due to the domain wall movements and natural resonance are found higher than those of microwires annealed at 600°C.The microwave absorption performance of microwires annealed at 600°C is found better than microwires annealed at 750°C. 相似文献
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Electromagnetic absorption properties of flowerlike cobalt composites at microwave frequencies 下载免费PDF全文
In this work,we report the electromagnetic absorption(EMA) properties of composites consisting of micrometersized cobalt with flowerlike architecture synthesized by a facile hydrothermal reduction method.Compared with the conventional spherical Co-paraffin composites,the flowerlike Co-paraffin composites are favorable with respect to EMA performance in the low frequency region,ascribing interfacial polarization loss and Ohmic loss to the improvement in the impedance match. 相似文献
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采用有限元微磁学模拟方法研究了Co纳米线在不同外加恒磁场下磁矩的翻转过程.研究结果表明在直径为10 nm的Co纳米线内,经过一定的形核时间将在其一端形成一个反向磁畴.磁畴壁的类型为横向畴壁,该畴壁将在一外加恒定磁场的驱动下匀速地从一端运动到另一端.畴壁的运动速度与外加磁场大小呈线性关系.在H为1000 kA/m时,发现在纳米线的两端均会形成一个“头对头”的反向磁畴.计算结果表明,畴壁内磁矩的方向旋转一个周期所导致的畴壁运动的距离相同,与外加磁场强度无关.
关键词:
磁性纳米线
微磁学模拟
磁畴
横向畴壁 相似文献
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由于等效电阻谐振条件限制, 传统的单层电路模拟吸波体(CA)结构在低频段不能形成多个谐振点. 为了突破这个限制, 本文提出了一种金属线阵列嵌入的单层CA结构. 该结构在低频段形成了双谐振峰吸收, 拓展了吸波频带. 采用准静态模型, 分析金属线阵列嵌入的单层CA结构内的电磁波的散射. 分析结果表明, 金属线阵列的嵌入使结构的介质层在低频激发等离子体谐振. 在该谐振频率点, 结构形成额外吸收峰, 该吸收峰和单层CA结构原有的吸收峰一起实现了双峰吸收. 实验和FDTD数值计算结果相符合, 结果表明该结构在不增加厚度的前提下, 扩展了低频段的吸波频段.
关键词:
金属线阵列
宽带吸波
电路模拟吸波体
电阻型频率选择表面 相似文献
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Effect of annealing treatments on the microwave electromagnetic properties of amorphous FeCuNbSiB microwires 下载免费PDF全文
The amorphous FeCuNbSiB microwires are fabricated by using the
melt extraction method and annealed separately at temperatures
T = 573, 673, 723 and 773K for 1h. The effect of annealing
treatment on the microwave electromagnetic properties of
FeCuNbSiB wires/wax composites has been investigated for the
first time. It is found that in a frequency range of
0.5--4.0GHz, the complex permittivity, permeability, magnetic
and electric loss tangents of FeCuNbSiB wires/wax composites are
strongly dependent on the annealing temperature and frequency.
For T = 573, 723 and 773K, two resonance peaks are found at
frequency f = 1.2 and 3.3GHz. However, for T = 673K,
only one resonance peak occurs at f = 3.3GHz. The resonance
peak at f = 1.2GHz is believed to be due to the
stress-induced anisotropy, while the resonance peak at f =
3.3GHz is attributed to the random anisotropy. 相似文献
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采用固相反应法制备了La0.67Sr0.33Mn1-yFeyO3(y=0,0.01,0.02,0.03)氧化物多晶样品,XRD测试表明形成了钙钛矿单相结构,铁掺人后材料的晶体结构没有明显变化。SEM测试表明样品晶粒大小为1~3μm,随着铁含量增加饱和磁化强度下降。样品室温磁导率(10kHz~1.8GHz)测试表明,复磁导率频谱曲线是典型的弛豫型谱线,且随铁离子含量增加其起始磁导率下降。同时通过最小二乘曲线拟合的方法分析了频谱曲线,分别给出了畴壁位移和磁畴转动对磁导率的贡献,结果表明,y=0,0.01的样品畴壁位移对磁导率的贡献大于畴转对磁导率的贡献,y=0.02,0.03的样品,畴转对磁导率的贡献大于畴壁位移的贡献。 相似文献
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The increasing demands for electronic devices to achieve high miniaturization, functional integration, and wide bandwidth will exacerbate the heat generation and electromagnetic interference, which hinders the further development of electronic devices. Therefore, both the issues of microwave absorption and heat dissipation of materials need to be addressed simultaneously. Herein, a multifunctional composite material is proposed by periodic arrangement of copper pillars in a matrix, based on the ... 相似文献
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