Balancing Dielectric Loss and Magnetic Loss in Fe–NiS2/NiS/PVDF Composites toward Strong Microwave Reflection Loss

2020 ◽  
Vol 12 (12) ◽  
pp. 14416-14424 ◽  
Author(s):  
Na Gao ◽  
Wen-Ping Li ◽  
Wen-Shou Wang ◽  
Da-Peng Liu ◽  
Yi-Min Cui ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Reflection Loss ◽  
Magnetic Loss ◽  
Microwave Reflection

scholarly journals Fabrication and electromagnetic performance of talc/NiTiO 3 composite

2018 ◽  
Vol 5 (2) ◽  
pp. 171083 ◽  
Author(s):  
Wen-Li Qin ◽  
Tian Xia ◽  
Ying Ye ◽  
Ping-Ping Zhang
Keyword(s):  
Dielectric Loss ◽  
Surface Area ◽  
Reflection Loss ◽  
Thermal Destruction ◽  
Magnetic Loss ◽  
Optimum Thickness ◽  
New Approach ◽  
Lamella Structure ◽  
Electromagnetic Performance ◽  
Maximum Reflection Loss

In this study, the electromagnetic (EM) performance of talc/NiTiO 3 composite was evaluated. The morphology of talc displayed a lamella structure; there were many nanoparticles of NiTiO 3 coated on the talc lamella . Thermal destruction occurred, which increased the surface area from 2.51 m 2  g −1 to 79.09 m 2  g −1 at the calcined stage at 650°C. The presence of NiTiO 3 increased dielectric loss and magnetic loss of talc. The calculation of EM wave absorption of talc/NiTiO 3 obtained a maximum reflection loss of −11.94 dB at the thickness of 6.85 mm; the optimum thickness for microwave absorption is 6.3–7.3 mm. This study revealed a new approach for fabricating an EM absorber and broadening applications of both talc and NiTiO 3 in EM absorption.

Α-Fe /Nd2Fe14B Nanocomposites for Electromagnetic-Wave-Absorber in GHz Microwave Frequencies

2011 ◽  
Vol 399-401 ◽  
pp. 1102-1106
Author(s):  
Li Xian Lian ◽  
Ying Liu ◽  
Long Jiang Deng
Keyword(s):  
Electromagnetic Wave ◽  
Dielectric Loss ◽  
Reflection Loss ◽  
Melt Spinning ◽  
Magnetic Loss ◽  
Annealing Treatment ◽  
Microwave Range ◽  
Absorption Property ◽  
Frequency Range ◽  
Microwave Frequencies

Nd5Fe92B3alloy was induction-melted. The α-Fe compounded low content of Nd2Fe14B nanocomposites were prepared using a melt-spinning method, subsequent annealing treatment, and ball milling. The complex permittivity, permeability of composites was measured in the 0.5-18 GHz frequency range. The permeability spectra exhibits relaxation type characteristic. The α-Fe/Nd2Fe14B composites shows an excellent microwave absorption property (reflection loss: RL<-20dB) in 9-17GHz with thin matching thickness 1.6-2.5 mm, due to the cooperate effect of magnetic loss and dielectric loss. α-Fe/Nd2Fe14B nanocomposites are thought to be a good microwave absorbers in GHz microwave range.

Magnetodielectric Ni ferrite ceramics with Bi2O3 additive for potential antenna miniaturizations

2009 ◽  
Vol 24 (2) ◽  
pp. 324-332 ◽  
Author(s):  
X.T. Liew ◽  
K.C. Chan ◽  
L.B. Kong
Keyword(s):  
Magnetic Properties ◽  
Dielectric Loss ◽  
Grain Growth ◽  
Sintering Temperature ◽  
Magnetic Loss ◽  
Liquid Phase Sintering ◽  
X Ray Diffraction ◽  
Low Dielectric ◽  
High Concentrations

This paper reports on the preparation and characterization of nickel ferrite (NiFe1.98O4) ceramics doped with Bi2O3 as sintering aid. Focus has been on the effects of concentration of Bi2O3 and sintering temperature on the densification, grain growth, dielectric, and magnetic properties of the NiFe1.98O4 ceramics, with an aim at developing magnetodielectric properties, with almost equal real permeability and permittivity, as well as sufficiently low magnetic and dielectric loss tangents, over 3 to 30 MHz (high frequency or HF band). X-ray diffraction results indicated that there is no obvious reaction between NiFe1.98O4 and Bi2O3, at Bi2O3 levels of up to 7 wt% and temperatures up to 1150 °C. The addition of Bi2O3 facilitated a liquid phase sintering mechanism for the densification of NiFe1.98O4 ceramics. The addition of Bi2O3 not only improved the densification but also promoted the grain growth of NiFe1.98O4 ceramics. To achieve sufficiently low dielectric loss tangent, the concentration of Bi2O3 should not be less than 5 wt%. The low dielectric loss tangents of the samples doped with high concentrations of Bi2O3 can be attributed to the full densification of the ceramics. Magnetic properties of the NiFe1.98O4 ceramics, as a function of sintering temperature and Bi2O3 concentration, can be qualitatively explained by the Globus model. Promising magnetodielectric properties have been obtained in the sample doped with 5% Bi2O3 and sintered at 1050 °C for 2 h. The sample has almost equal values of permeability and permittivity of ∼12, together with low dielectric and magnetic loss tangents, over 3 to 30 MHz. This material might be useful for the miniaturization of HF (3 to 30 MHz) antennas.

Synergetic dielectric loss and magnetic loss towards superior microwave absorption through hybridization of few-layer WS2 nanosheets with NiO nanoparticles

2020 ◽  
Vol 65 (2) ◽  
pp. 138-146 ◽  
Author(s):  
Deqing Zhang ◽  
Yingfei Xiong ◽  
Junye Cheng ◽  
Jixing Chai ◽  
Tingting Liu ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Microwave Absorption ◽  
Magnetic Loss ◽  
Nio Nanoparticles ◽  
Ws2 Nanosheets

scholarly journals Microwave Absorption of Crystalline Fe/MnO@C Nanocapsules Embedded in Amorphous Carbon

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Gaihua He ◽  
Yuping Duan ◽  
Huifang Pang
Keyword(s):  
Dielectric Loss ◽  
Amorphous Carbon ◽  
High Performance ◽  
Magnetic Loss ◽  
Synthesis Method ◽  
Domain Size ◽  
Carbon Matrix ◽  
Effective Bandwidth ◽  
General Duty ◽  
Enhanced Absorption

AbstractCrystalline Fe/MnO@C core–shell nanocapsules inlaid in porous amorphous carbon matrix (FMCA) was synthesized successfully with a novel confinement strategy. The heterogeneous Fe/MnO nanocrystals are with approximate single-domain size which gives rise to natural resonance in 2–18 GHz. The addition of MnO2 confines degree of graphitization catalyzed by iron and contributes to the formation of amorphous carbon. The heterogeneous materials composed of crystalline–amorphous structures disperse evenly and its density is significantly reduced on account of porous properties. Meanwhile, adjustable dielectric loss is achieved by interrupting Fe core aggregation and stacking graphene conductive network. The dielectric loss synergistically with magnetic loss endows the FMCA enhanced absorption. The optimal reflection loss (RL) is up to − 45 dB, and the effective bandwidth (RL < − 10 dB) is 5.0 GHz with 2.0 mm thickness. The proposed confinement strategy not only lays the foundation for designing high-performance microwave absorber, but also offers a general duty synthesis method for heterogeneous crystalline–amorphous composites with tunable composition in other fields.

scholarly journals Improvement of Microwave Absorbance of Polymer Composites of W-Type Hexaferrite Powders by Attachment of Frequency Selective Surface

2017 ◽  
Vol 62 (2) ◽  
pp. 1325-1328
Author(s):  
H.-S. Cho ◽  
S.-S. Kim
Keyword(s):  
Reflection Loss ◽  
Electromagnetic Waves ◽  
Polymer Matrix Composites ◽  
Magnetic Loss ◽  
Frequency Selective Surface ◽  
Substrate Material ◽  
Matrix Composites ◽  
Frequency Selective ◽  
Ferrite Composites ◽  
Minimum Reflection Loss

AbstractThis work investigates the effect of a frequency selective surface (FSS) composed of a regular array of square loop elements on the absorption properties of grounded ferrite composites. Polymer matrix composites of CoZnW hexaferrite powders having small magnetic loss were used as the substrate material. Computational tools were used to model the interaction between electromagnetic waves and materials and determine the reflection coefficient. Reflection loss and bandwidth were greatly improved by attaching an FSS with controlled electrical resistance (R) onto the grounded ferrite composites. For the FSS withR= 800 Ω, the minimum reflection loss decreased to −25 dB at 10 GHz and the bandwidth was broadened to 7.5-12.5 GHz with respect to −10 dB reflection loss.

Microwave Absorbing Properties of Fe-Filled Carbon Nanotubes/Epoxy Composite in 2-18GHz

2008 ◽  
Author(s):  
Xuchun Gui ◽  
Kunlin Wang ◽  
Jinquan Wei ◽  
Ruitao Lv ◽  
Dehai Wu
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Loss ◽  
Microwave Absorption ◽  
Electromagnetic Interference ◽  
Magnetic Loss ◽  
Magnetic Contribution ◽  
High Permittivity ◽  
Ferromagnetic Metals ◽  
Potential Applications ◽  
Iron Nanowires

Carbon nanotubes (CNTs) filled with ferromagnetic metals have potential applications of microwave absorption and electromagnetic interference shielding due to their high aspect-ratio of nanostructures that promises low percolation threshold and their inner cavities which could incorporate magnetic materials to improve the permeability and magnetic loss of composites. It has been reported that CNTs have high permittivity [1, 2]. And it could be used as dielectric microwave absorbers due to their high permittivity [3, 4]. Excellent microwave absorption should have better electromagnetic match of magnetic loss and dielectric loss. The microwave absorption could be significantly improved by matching the dielectric and magnetic contribution from respective components (e.g. CNTs and Fe) [5]. For CNTs, only dielectric loss contributes to the energy loss of microwave, while for ferromagnetic nanowires, the effect of magnetic loss becomes dominant over the dielectric loss. Either only the dielectric loss or magnetic loss may induce weak microwave absorption due to the imbalance of the electromagnetic match. Here we directly fabricated the microwave absorber by as-grown Fe-filled CNTs, which have the dielectric properties of CNTs and magnetic properties of the filled iron nanowires.

Preparation and Electromagnetic Properties of CIP/SiO2/PANI Composites

2013 ◽  
Vol 834-836 ◽  
pp. 187-190
Author(s):  
Ming Ming Wang ◽  
Zhong Lun Zhang ◽  
Wan Jun Hao ◽  
Guo Yan Hou ◽  
Zhi Jun Xin ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
In Situ Polymerization ◽  
Magnetic Loss ◽  
Electromagnetic Properties ◽  
Complex Permeability ◽  
Core Shell ◽  
Network Analyzer ◽  
Frequency Range ◽  
Xrd Patterns

CIP particles first were coated with SiO2 shell by the Stober process , then grafted the polyaniline by in-situ polymerization to prepare CIP/SiO2/PANI core-shell composites. The CIP/SiO2/PANI composites are composed the dielectric loss properties with the the magnetic loss properties, the morphologystructure and electromagnetic properties are characterized by SEMXRD and vector network analyzer, respectively. It is observed that SiO2 and PANI are on the surface of CIP particles, XRD patterns further confirm that the CIP/SiO2/PANI composites are synthesized successfully, and that interaction between components exist in the polymerization. In comparison with CIP, the complex permittivity of CIP/SiO2/PANI composites have certain enhancement in 2-18GHz frequency range, but it has a very small impact on the complex permeability.

Sign in / Sign up

Export Citation Format

Share Document