共查询到20条相似文献,搜索用时 372 毫秒
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采用磁控溅射工艺制备了CoFeNbZrRE非晶态薄膜,重点研究了掺杂稀土元素(RE)的种类和掺杂量对薄膜微结构、软磁性能、微波磁导率及其频谱特性的影响。结果表明,少量稀土元素的掺杂对该类薄膜的微结构和软磁性能影响较小,但可增强薄膜磁谱的弛豫性,从而影响其微波磁导率。增加稀土元素的掺杂量能显著提高薄膜的弛豫性和微波磁损耗,且重稀土元素比轻稀土元素表现出更强的弛豫性。适当选取稀土元素的种类和含量,CoFeNbZrRE类非晶态薄膜在吉赫兹微波段复磁导率实部和虚部均可高于100,有望在超薄层吸波材料中获得应用。 相似文献
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Ti~(4+)-Zn~(2+)复合取代对Co_2Z六方铁氧体电磁性能的影响 总被引:1,自引:1,他引:0
采用固相反应法制备Co2Z型六方铁氧体材料Ba3Co2TixZnxFe24–2xO41。研究了Ti4+-Zn2+复合取代对其显微结构和电磁性能的影响。结果表明:随Ti4+-Zn2+取代量的增加,材料磁导率实部μ'与介电常数实部ε'先增加后减小;矫顽力Hc先减小后增加。当取代量x=0.50时,具有最大的μ'(约17)以及最小的Hc(1700.64A/m)。Ti4+-Zn2+复合取代改变了晶粒的大小和形状,从而改变了材料的体密度和择优取向,进而提高其磁导率实部μ'。 相似文献
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传输/反射法测量微波吸收材料电磁参数的研究 总被引:1,自引:0,他引:1
通过从HP8722ET网络分析仪提取散射参数,研究了以乙丙橡胶为基体,磁性材料羰基铁粉为吸收剂的微波吸收材料同轴测试样品在同轴夹具中位置L1与样品长度L2的测量误差对其电磁参数测量结果的影响,提出了减小测量误差的方法.结果表明:在2.6~18GHz范围内,L1存在-0.08mm的绝对误差使得相对介电常数实部ε′与虚部ε″,相对磁导率实部μ′与虚部μ″的测量值与真实值的最大相对误差值分别达3.1%、168.0%、3.7%和-10.0%;L2存在-2%的相对误差使得ε′、ε″、μ′和μ″的测量值与真实值的最大相对误差值分别达3.5%、30.0%、4.0%和5.0%.采用光学显微镜的静态方法测量样品长度和使用辅助定位夹具可以减小测量误差,提高电磁参数测试结果的精确度。 相似文献
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A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 μm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG) structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied. 相似文献
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扁平化对FeSi吸波材料微波电磁性能的影响 总被引:4,自引:3,他引:1
为阐明吸收剂颗粒形状与吸波材料微波电磁性能之间的关系,采用机械球磨工艺对气雾化球形FeSi合金粉末进行扁平化处理并制成FeSi吸波材料。借助SEM和矢量网络分析仪,研究了球磨时间对FeSi颗粒形貌及1~18GHz内吸波材料电磁参数与吸波性能的影响。结果表明:随着球磨时间的增加,FeSi颗粒的扁平率增大。与未球磨样品相比,球磨32h的FeSi合金吸波材料的ε'在整个频率范围内增大了0.5倍,μ'(在1GHz时)由1.24增大到1.94,μ"(在1GHz时)由1.00增大到1.30。扁平化处理明显改善了FeSi吸波材料的低频吸波性。 相似文献
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Xinhua Zhu Jianmin Zhu Shunhua Zhou Zhiguo Liu Naiben Ming Shengguo Lu Helen Lai-Wah Chan Chung-Loong Choy 《Journal of Electronic Materials》2003,32(10):1125-1134
The (Ba1−xSrx)TiO3 (BST) ferroelectric thin films exhibit outstanding dielectric properties, even at high frequencies (>1 GHz), and large, electric-field
dielectric tunability. This feature makes them suitable for developing a new class of tunable microwave devices. The dielectric
properties and dielectric tuning property of BST thin films are closely related to the film compositions, substrate types,
and post-deposition process. The successful implementation of BST films as high-frequency dielectrics in electrically tunable
microwave devices requires a detailed understanding of both their processing and material properties. This paper will review
the recent progress of BST thin films as active dielectrics for tunable microwave devices. The technical aspects of BST thin
films, such as processing methods, post-annealing process, film compositions, film stress, oxygen defects, and interfacial
structures between film and substrate, are briefly reviewed and discussed with specific samples from the recent literature.
The major issues requiring additional investigations to improve the dielectric properties of BST thin films for tunable microwave
applications are also discussed. 相似文献
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The microwave properties of barium strontium titanate (Ba0.6Sr0.4TiO3) thin films grown on (100) LaAlO3 (LAO) and (100) MgO single-crystal substrates through the sol–gel technique were investigated. The interdigital capacitor (IDC) technique was used to measure the nonlinear dielectric properties in the frequency range from 1 GHz to 10 GHz. The results show that the Curie temperature, capacitance, and tunability of the films are strongly dependent upon the substrate. The film fabricated on the LaAlO3 substrate has a higher tunability of 16.77% than that grown on the MgO substrate (~8.38%), measured at 10 GHz with an applied voltage of 35 V. The loss tangent is a linear function of the frequency in the microwave range, and the film grown on the MgO substrate has a lower loss tangent than that grown on the LAO substrate. This work reveals the great potential of Ba0.6Sr0.4TiO3 (BST) films for application in tunable microwave devices. 相似文献
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螺旋形碳纤维结构吸波材料的制备及性能研究 总被引:1,自引:0,他引:1
用基板法以乙炔为碳源,镍板为催化剂,PCI,为助催化剂,通过化学气相沉积制备了螺旋形碳纤维手性吸收剂,并研究了其在2~18GHz的微波电磁特性:具有较高的介电损耗,电磁参数随频率的增大有减小的趋势,有利于实现宽频吸波。以螺旋形碳纤维作为吸收剂制备了Nomex蜂窝夹芯结构吸波材料,复合材料的厚度为9.5mm时,在3.76~18GHz反射率R小于-10dB,反射率小于-10dB的频宽为14.24GHz;最大吸收峰在10.4GHz,反射率R为-21.62dB。探讨了螺旋形碳纤维的吸波机理,螺旋形碳纤维是一种非常有发展前景的手性吸收剂和吸波材料。 相似文献
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A method is presented for the contactless measurement at microwave frequencies of the resistivity of thin films of semiconductors deposited on insulating substrates. The resistivity is determined through a measurement of the change in the power loss or Q of a microwave cavity upon insertion of the sample. In addition to the intended application, knowledge can be obtained about microwave power losses in supported thin films. Calculated microwave losses in the semiconductor films are presented in a normalized form as a function of the thickness and electrical properties of both the film and the supporting substrate at 9.0 GHz (X band) and 23.0 GHz (K band). These calculations were made for germanium on calcium fluoride and sapphire substrates. The power losses are normalized on a unit surface area and a unit surface field intensity basis. Limited experimental data are presented for germanium on calcium fluoride. The computed curves show that a maximum in power dissipation for a fixed substrate thickness and frequency is reached at higher and higher film resistivities as the film thickness increases. A very strong dependence of power loss on substrate thickness is demonstrated. 相似文献
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Mohammad Mousavinia Ali Ghasemi Ebrahim Paimozd 《Journal of Electronic Materials》2014,43(7):2573-2583
Ni/Co/Sn-substituted strontium ferrite [SrFe12?x (Ni0.5Co0.5Sn) x/2O19]/multiwalled carbon nanotube (MWCNT) nanocomposites were produced by assembling ferrite particles on the external surfaces of MWCNTs. Various techniques including x-ray diffraction (XRD) analysis, transmission electron microscopy, field-emission scanning electron microscopy (FE-SEM), and Fourier-transform infrared (FTIR) spectroscopy were used to demonstrate the successful attachment of ferrite particles onto the external surfaces of the MWCNTs. XRD analysis and FTIR spectroscopy confirmed the presence of strontium ferrite and carbon nanotube phases in ferrite and nanocomposite samples, respectively. FE-SEM micrographs indicated the formation of ferrite particles on the outer surfaces of MWCNTs in nanocomposite samples. Furthermore, vibrating-sample magnetometer (VSM) and reflection loss (RL) measurements were performed to assess the magnetic and microwave characteristics of the synthesized samples. VSM loops confirmed a relatively strong dependence of the saturation magnetization and coercivity on the volume percentage of MWCNTs. With the introduction of MWCNTs or an increase in the substitution, the saturation magnetization and coercivity were decreased. The RL properties of the nanocomposites were investigated in the 8 GHz to 12 GHz frequency range. The sample with 80 wt.% nanocomposite content showed a maximum RL of ?35 dB at 8.3 GHz with a 4 GHz absorption bandwidth over the extended frequency range of 8 GHz to 12 GHz for absorber thickness of 1.8 mm. The RL evaluations indicated that these nanocomposites have high potential for application as wide-band electromagnetic wave absorbers at GHz frequencies. 相似文献
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Mohammad Mousavinia Ali Ghasemi Ebrahim Paimozd 《Journal of Electronic Materials》2013,42(9):2784-2792
This study is intended to evaluate the structural, magnetic, and microwave properties of Ni-Co-Sn-doped strontium hexaferrite SrFe12?x (Ni0.5Co0.5Sn) x/2 O19 particles with x = 0 to 2.5 synthesized by a sol–gel combustion method. These particles were evaluated to characterize the structural, magnetic, and reflection loss properties of prepared samples by use of x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FTIR) spectroscopy, vibrating-sample magnetometer (VSM), and vector network analyzer. The XRD results confirmed the presence of strontium ferrite phase with magnetoplumbite structure in all synthesized samples. The results of FTIR analysis indicated the formation of functional groups such as metal-oxygen (Sr-O and Fe-O) and carboxylic groups during the sol–gel process. In addition, FE-SEM micrographs indicated that submicron particles with different morphologies such as spherical, pyramidal, irregular, and hexagonal platelet shapes appeared in the structure. According to hysteresis loops, magnetization and coercivity decreased due to occupation of Ni-Co-Sn cations at low levels of substitutions. The microwave absorption characteristics of this ferrite were investigated in the 8 GHz to 12 GHz frequency range. The sample with 80 wt.% ferrite content showed a maximum reflection loss of ?29 dB at 9.6 GHz with 4 GHz bandwidth through the entire frequency range of 8 GHz to 12 GHz for absorber thickness of 1.5 mm. Based on microwave measurements of reflectivity, this material with the expressed chemical composition could be proposed as a good choice for electromagnetic compatibility and other practical applications such as microwave absorption at high frequencies. 相似文献