Microwave Absorption Characteristics Research Articles

BST@Copper Nanowire/Epoxy composites with excellent microwave absorption in the X-band

In this work, hybrid epoxy nanocomposites containing varying loading of copper nanowires (CuNW), Ba0.7Sr0.3TiO3 (BST), and BST@CuNW hybrid nanoparticles were prepared and analyzed for their microwave absorption characteristics. The nanoparticles used in this study were prepared using a facile co-precipitation and hydrothermal methodology. The synthesized nanoparticles were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) for their morphology and phase determination. While the XRD results confirmed the presence of BST and CuNW, the SEM micrographs obtained on the hybrid BST@CuNW nanoparticles show BST anchored on the CuNW surfaces. A series of epoxy composites containing varying loading of synthesized nanoparticles were prepared and characterized for their microwave properties, such as complex permittivity, shielding effectiveness, and power coefficients. The results indicate that nanocomposites containing BST@CuNW hybrids exhibited enhanced dielectric loss and more significant microwave power absorption compared to samples with equivalent CuNW and/or BST loading. The best composite sample, i.e., a one-millimeter-thick epoxy containing 10:15 (wt/wt) CuNW: BST hybrid nanoparticles with an estimated density of 1.49 g/cc attenuated 99.1 % of incident microwave power and exhibited a shielding effectiveness value of 21.2 dB in the X-band (8–12 GHz) of the microwave frequency spectrum. These lightweight polymer composites with high microwave absorption in the X-band are useful for military and civilian applications.

Study on the microwave absorption properties of FeCoNiCrMn/PLA 3D printed composites

The work in this paper is dedicated to the study of wave-absorbing materials for applications in extremely harsh environmental conditions such as seawater and oil. In this paper, FeNiCrMn high-entropy alloy material with corrosion resistance and polylactic acid (PLA) material with high strength and high modulus were used to prepare more environmentally adaptable FeNiCrMn/PLA electromagnetic(EM) microwave-absorbing materials by two-step method of ball milling and melt extrusion.The physical phases, microscopic morphology, EM parameters and mechanical performance of FeCoNiCrMn/PLA composites were characterized using XRD, SEM, Vector Network Analyzer and Universal Testing Machine respectively. The microwave-absorbing properties of FeCoNiCrMn/PLA composites were investigated, and the effects of their components and micro-morphology on the microwave-absorbing and mechanical performance were discussed. The results show that when the FeCoNiCrMn content reaches 25wt% and the thickness is 4.5mm, the minimum reflection loss of FeCoNiCrMn/PLA composites reaches -24.58dB, and the effective microwave-absorbing bandwidth is 2.51 Ghz. The maximum tensile strength and elongation at break of the composites could reach 23.83MPa and 7.12%, respectively. The microwave-absorbing ability of FeCoNiCrMn composites is mainly due to their rich EM loss mechanisms, including dielectric losses such as dipole polarization, interface polarization, defect-induced polarization, etc., as well as magnetic losses such as natural resonance, exchange resonance, and eddy current losses. Finally, the wide-angle microwave-absorbing characteristics of FeCoNiCrMn/PLA 3D-printed composites were investigated, the results showed that the composites with FeCoNiCrMn content of 25wt% had Radar Cross Section (RCS) values lower than -10 dBm² within the microwave incidence angle of -90° < θ < -6° and 6° < θ < 90°, which indicated that the composites had wide-angle microwave-absorbing capability. The materials have microwave-absorbing properties along with a certain degree of mechanical strength, and at the same time have good environmental adaptability. The FeCoNiCrMn/PLA composite wire can be used in FDM technology to prepare structural microwave absorbers, realizing the integration of “material-design-manufacturing”, which has a broad application prospect in the field of EM microwave absorption and 3D printing.

Microwave Absorption Properties of Hexagonal Ba3(VO4)2 through Zn Doping: A Comprehensive Analysis of Ba3–xZnx(VO4)2

The current study explores the influence of Zinc (Zn) doping on the crystallography, optical behavior, dielectric properties, and microwave absorption characteristics of hexagonal Barium Vanadate (Ba3(VO4)2). Samples were systematically synthesized with Zn doping concentrations of x = 0, 0.05, 0.1, 0.15, and 0.2 mol%, resulting in Ba3–xZnx(VO4)2. Employing various characterization techniques, the alterations in structural, optical, and electrical responses due to incremental Zn incorporation are reported. The UV–VIS DRS absorption spectra reveal a decrease in energy bandgap with increasing concentration of Zn. The lowest optical energy band gap observed was 3.65 eV for x = 0.2 mol% Zn. Notably, at a thickness of 6.5 mm, the material achieved a high reflection loss of −82.37 dB at 12.47 GHz for x = 0.05 mol% of Zn. Similarly, the same material configuration exhibited a maximum effective absorption bandwidth (EAB) of 5.01 GHz, spanning a frequency range from 12.24 to 17.25 GHz when the thickness was set to 5.5 mm. Furthermore, as the Zn concentration increased from x = 0.05 to 0.2 mol%, a decreasing trend in reflection loss was observed, correlating well with the dielectric parameters of samples with different Zn concentrations. The work provides insightful correlations between Zn doping levels and the material’s performance in potential applications ranging from optoelectronics to electromagnetic wave absorption.

Optimizing the electromagnetic wave absorption properties of core-shell Fe/FeN/Fe3C@GN nanoparticles by low-temperature NH3 plasma

Surface modification via low-temperature plasma has an extensive application prospect in different engineering fields due to its comprehensive merits in facilitating the introduction of functional groups and creating more heterogeneous interfaces. Herein, a simple high-temperature plasma method is developed to get novel multiple-phase nanocomposites of core-shell Fe/FeN/Fe3C@GN nanoparticles with bifunctional characteristics of microwave absorption (MA) and anti-corrosion. And then, we further investigate the MA properties of Fe/FeN/Fe3C@GN nanoparticles after low-temperature NH3 plasma etching. It is found that surface modification of Fe/FeN/Fe3C@GN nanoparticles can generate remarkable changes in specific surface areas, Raman features and MA properties of these nanocomposites. The Fe/FeN/Fe3C@GN nanoparticles after NH3 plasma etching possess excellent MA properties with an optimal reflection loss (RL) of −51.0 dB at an ultra-thin thickness of 1.9 mm with a low filling content of 30 wt% and the corresponding effective absorption bandwidth (EAB < −10 dB) up to 4.7 GHz (13.3–18.0 GHz). The fascinating MA properties of etched Fe/FeN/Fe3C@GN nanoparticles may be attributed to the cooperative effect of several points: (i) The NH3 plasma etch introduces a large number of polar functional groups, which can be regarded as the polarization center to produce more polarization loss; (ii) The appropriate dielectric loss and impedance matching achieve a good balance, and the abundant heterogeneous interface significantly enhances the polarization relaxation loss; (iii) The existence of hetero-nanostructure further improves the multiple reflections and scattering of the propagating microwaves. In addition, this work provides a new strategy for the design and fabrication of core-shell MA materials.

Facile and rapid synthesis method of dielectric nanocomposite for simultaneous enhancement of electromagnetic wave absorbing/shielding characteristics

The present study involves the fabrication of poly[4-(2-thiophene)aniline] (PTA) nanocomposite for absorption-dependent shielding applications, demonstrating enhanced absorption and small reflection properties. The Microwave absorption characteristics of the fabricated polymer were studied at different loading ratios, resulting in a minimum reflection loss (RLmini) of − 44 dB for the 8 wt % loading ratio. The macromolecular architecture of the PTA material offers higher dielectric loss resulting from higher conduction and interfacial loss. Additionally, the shielding performance is also evaluated, and the sample containing 8 wt % filler demonstrates an impressive − 36.5 dB shielding efficacy. The performance of polymers is significantly impacted by their unit periodic order arrangement. Conducting polymers with linear structure and special π-orbitals angles possess unique characteristics in comparison to their branched and the random copolymer, making them highly sought after as efficient organic conductors, magnetic substances, electrochromic materials, and high dielectric agents. Monomer units contained two periodical cyclic structures and the creation of the inductive effects of heteroatoms elongates the conjugation and reduces the energy bandgap difference between the HOMO and LUMO levels, enabling smoother electron flow and enhancing absorption capacity. The findings indicate that PTA nanocomposite is a promising radar-absorbing coating material due to its superior absorption ability and outstanding shielding performance.

Achieving high-efficiency electromagnetic wave absorption performance in a 3-layer hierarchical porous magneto-dielectric nanocomposite

Hierarchical porous structures along with micro- and nanoparticles of magneto-dielectric components in sandwich structure design have superior potential applications in the field of electromagnetic wave absorption, due to high active dissipation phenomena such as multiple scatterings and reflections between components, 3D network pores and layers, coupling interactions between each layer, promotion of interfacial polarization, and so on. The Sandwich-Structure absorber composed of hierarchical porous Bi2MoO6, Cu microparticles, and FeNi nanoparticles was effectively constructed with optimization in layer thickness and low filler loading percentage. The microwave absorption characteristics of absorber samples varied in thickness but all less than 1.6 mm in total thickness were thoroughly examined. The as-prepared sandwich structure displayed a unique microwave absorbing behavior due to the multiple-layer structure, the dielectric dissipation property of both Bi2MoO6, Cu microparticles and the magnetic dissipation feature of FeNi nanoparticles, as well as the complementary effect between particles and layers. Minimum reflection loss (RLmini) of −45.5 dB at 5.5 GHz is obtained with proper optimization of layer order and thickness in a resin base 3-layer absorber sample with Bi2MoO6 placed as a top layer with 0.4 mm thickness, FeNi placed as a middle layer with 0.5 mm thickness, and finally Cu placed as a bottom layer with 0.7 mm thickness. The results show that the as-prepared 3-layer nanocomposite sample has a high potential for usage in microwave absorption in the low-frequency band.

Vat photopolymerization 3D printing SiBCN ceramic metamaterials with strong electromagnetic wave absorption

Starting from the simulation prediction, SiBCN polymer-derived-ceramic metamaterials, integrating both structure and function in a single component, were obtained using vat photopolymerization technology starting from a preceramic polymer. The low-density gyroid triply periodic minimal surface (TPMS) structures used in this study increases the multiple reflection loss of electromagnetic wave (EMW) in the macro-interpenetrating channel structure, generates surface characteristics (stair-stepping effect) structure interface polarization, and improves microwave absorption characteristics. The possible multiple reflection effects of a gyroid structure on electromagnetic waves are discussed by Computer Simulation Technology simulation. At the same time, the precipitated phases in polymer derived ceramics (PDCs) were adjusted by controlling the pyrolysis temperature. The results show that the crystal phases (such as β-SiC and C) precipitated in the gyroid structure sample pyrolyzed at 1200°C enrich the heterogeneous interface polarization in the material. In addition, C forms a (semi-)conductive network, which increases the conductivity loss. The effective absorption bandwidth (EAB, RL<-10 dB) of the samples pyrolyzed at 1200°C was 3.09 GHz (thickness of 2.21 mm) and the minimum reflection loss (RLmin) was −70.6 dB (thickness of 2.31 mm), indicating that the samples have favorable EMW absorption properties and great potential for applications, providing a foundation for the preparation of high-performance lightweight structural ceramics.

Highly electrically conductive MOF/conducting polymer nanocomposites toward tunable electromagnetic wave absorption

Metal-organic frameworks (MOFs) have attracted significant interest as self-templates and precursors for the synthesis of carbon-based composites aimed at electromagnetic wave (EMW) absorption. However, the utilization of high-temperature treatments has introduced uncertainties regarding the compositions and microstructures of resulting derivatives. Additionally, complete carbonization has led to diminished yields of the produced carbon composites, significantly limiting their practical applications. Consequently, the exploration of pristine MOF-based EMW absorbers presents an intriguing yet challenging endeavor, primarily due to inherently low electrical conductivity. In this study, we showcase the utilization of structurally robust Zr-MOFs as scaffolds to build highly conductive Zr-MOF/PPy composites via an inner-outer dual-modification approach, which involves the production of conducting polypyrrole (PPy) both within the confined nanoporous channels and the external surface of Zr-MOFs via post-synthetic modification. The interconnection of confined PPy and surface-lined PPy together leads to a consecutive and extensive conducting network to the maximum extent. This therefore entails outstanding conductivity up to ∼14.3 S cm−1 in Zr-MOF/PPy composites, which is approximately 1–2 orders of magnitude higher than that for conductive MOF nanocomposites constructed from either inner or outer modification. Benefiting from the strong and tunable conduction loss, as well as the induced dielectric polarization originated from the porous structures and MOF-polymer interfaces, Zr-MOF/PPy exhibits excellent microwave attenuation capabilities and a tunable absorption frequency range. Specifically, with only 15 wt.% loading, the minimum reflection loss (RLmin) can reach up to –67.4 dB, accompanied by an effective absorption bandwidth (EAB) extending to 6.74 GHz. Furthermore, the microwave absorption characteristics can be tailored from the C-band to the Ku-band by adjusting the loading of PPy. This work provides valuable insights into the fabrication of conductive MOF composites by presenting a straightforward pathway to enhance and regulate electrical conduction in MOF-based nanocomposites, thus paving a way to facilely fabricate pristine MOF-based microwave absorbers.

Preparation of a double-layer bionic bamboo structure absorber based on CB/PLA-TPU composites and its broadband microwave absorption characteristics

The study of the mechanical characteristics and microwave absorption capabilities of multifunctional composite materials in complex environments has attracted considerable interest in recent years. Inspired by the structure of bamboo in nature, a novel double-layer microwave absorber structure, a CB/PLA-TPU composite bionic bamboo joint’s structure, was conceived and manufactured for this investigation. This structure ingeniously integrates the load-bearing attributes of bamboo joints with the microwave absorption qualities of CB composites. At the material level, enhancing the CB particle content enhances the matrix's folds and defects, thereby improving its dielectric polarization loss capacity. An effective absorption bandwidth of 3.84 GHz was achieved, with a minimum reflection loss of −60.24 dB at a 2.58 mm thickness and a 9.2 GHz frequency. The bionic bamboo absorber's unit structure is meticulously engineered, with experimental simulations validating its performance. According to the findings, the structure attains a 10.03 GHz broadband absorption and a yield strength of 11.6 MPa. It maintains broadband absorption capabilities above 9 GHz even at oblique incidence angles for TM polar wave (0–60°) and TE polar wave (0–30°). The biomimetic design based on bamboo offers significant potential for engineering applications in stealth technology under adverse conditions.

Non-iridescent magnetite photonic crystal films and pigments with enhanced magnetic coupling effect

Non-iridescent structural color films and pigments with novel enhanced microwave absorption characteristics are successfully fabricated at room temperature for the first time. The quasi-uniform magnetite nanoparticles (CV = 0.10 ∼ 0.20) with high refractive index (n = 2.42) and broad light absorption provide evident low-angle-independent property for the structural color pigments. More importantly, a universal technical protocol is developed for preparation of photonic crystals with inorganic nanoparticles, i.e., through designing of the binding strength between nanoparticles and mediated molecules, the slurry modulus is increased to 105 Pa, which effectively drives the nanoparticles to rapidly assemble into closely packed ordered arrays by our-designed powerful assembly technique. Additionally, the structural color materials are subjected as photonic crystal pigments (∼20 wt%) embedding in a transparent polymer matrix to form color coatings. Remarkably, the photonic crystal pigments exhibit strong magnetic coupling effect and enhanced microwave absorption performance due to the regular arrangement, with superior reflection loss (RLmin) values of −14.97 dB (increase by 65.8 % compared with randomized magnetic nanoparticles), and the effective absorption bandwidth (EAB) of 2.15 GHz. This new kind of photonic crystal pigment, combining visual color and radar wave absorption, provides a novel idea for developing of multi-wave-band high-performance stealth materials.

Aspects of annealing and particle morphology on the microwave absorption characteristics of carbonyl iron powders

Aspects of annealing and particle morphology on the microwave absorption characteristics of carbonyl iron powders

Electromagnetic wave absorption mechanism and wear corrosion characteristics of Ti3SiC2 MAX phase-doped Ni/AlN composite coating with core-shell structure based on laser cladding-induced pitaya-like multi-level heterogeneous interface

To satisfy the service requirements of wave-absorbing materials in harsh environments, it is important to design and manufacture corrosion-resistant composite-absorbing materials. According to the strategy of impedance matching and the dissipation behaviour of nickel-based alloys, AlN ceramics, and MAX-phase Ti3SiC2 multicomponent composite-regulated materials were studied. As an additive manufacturing technology, multilevel heterointerface composites with core–shell structures were obtained by laser cladding. The construction of a unique core–shell structure of a metal–ceramic and ceramic (core)–ceramic (shell) multi-level heterogeneous interface increased the interfacial relaxation and multiple dissipation and improved the impedance matching. The results enabled the N20M3 cladding coating to exhibit excellent microwave absorption characteristics, with a reflection loss of −32.84 dB at the ultra-thin thickness of 1.8 mm. Additionally, the composites exhibited excellent corrosion resistance, high hardness, and relatively good resistance to erosion wear. This work promotes the durability of wave-absorbing materials under severe conditions, as well as the integration of the efficient manufacturing of wave-absorbing materials.

Design and microwave absorption characteristics of porous lamellar hard carbon materials

Porous lamellar hard carbon structures were synthesized using the direct hard template strategy with phenolic resin as the C source and ZnO as the template. The porosity of the hard carbon materials is adeptly fine-tuned by regulating the ZnO nanoparticle content. Notably, the introduction of porosity to lamellar hard carbon materials is shown to have a significant impact on their microwave absorption properties. A porous lamellar hard carbon material with impressive microwave absorption performance is synthesized, culminating in an optimal reflection loss of −45 dB and an effective absorption bandwidth of 4.08 GHz, even at a minimal absorber thickness of ∼2.0 mm, with a mere 16.7% filling rate. These findings illustrate how the control of porosity provides a new design avenue for tailoring the absorption characteristics for microwave absorbers. This design approach will support the further development of versatile microwave absorption solutions, helping to address the prevalence of electromagnetic pollution.

Microwave-absorbing characteristics of secondary copper smelting fly ash: High-temperature dielectric properties, thermal behavior, and microwave heating mechanism

Investigating the microwave-absorbing characteristics of secondary copper smelting fly ash (SCFA), which is both a hazardous waste and valuable secondary resource, can be expected to expedite the efficient application of microwave heating technology in the comprehensive treatment of fly ash. Here, we have examined SCFA and its pure components, namely PbCl2, ZnO, and ZnS phases, with regard to thermal behavior and microwave-absorbing characteristics. Our results indicate that SCFA has excellent microwave-absorbing performance in the temperature range 30–800 °C, with a dielectric loss coefficient ε″ of 5.68 × 10−2 F m−1 at ambient temperature and a maximum value of 36.29 × 10−2 F m−1 at 550 °C. As a consequence, the SCFA could be heated to 700 °C within 12.6 min. The heating process of SCFA can be divided into three main stages: removal of adsorbed water and bound water (<260 °C), oxidation reactions of Pb, PbO, ZnS, and PbS (260–437 °C), and deoxygenation reactions of PbO2, Pb3O2, and Pb3O4 (437–1000 °C). The dielectric properties and thermal characteristics of SCFA are closely related, with PbCl2 exerting a significant influence. We propose herein a microwave-heating mechanism of SCFA based on analysis of its thermogravimetric characteristics, dielectric properties, and heating behavior in a microwave field.

Manipulating the phase and morphology of MgFe2O4 nanoparticles for promoting their optical, magnetic, and microwave absorbing/shielding characteristics

Morphology and phase regulation shed light on the tuning of microwave absorbing characteristics, as well as magnetic and optical features. Not only is the development of electromagnetic wave absorbing materials the best way to equip us against harmful electromagnetic waves in the technology era, but the widespread applications of microwave absorbers in military and civilian fields have also enhanced their importance. Hence, MgFe2O4 nanoparticles were synthesized, and then (1) its main crystalline phase was divided into Mg, Fe2O3, and Fe3O4, and (2) its morphology was manipulated to evaluate the influence of morphology and phase on the microwave absorbing performance, optical characteristics, and magnetic capability. The novel precursors, along with modified sol-gel and solvothermal scenarios, were applied to regulate the structures toward strengthening the features. Interestingly, polyethylene terephthalate (PET) was chosen as the recyclable plastic to fabricate the final composites to evaluate the microwave absorbing/shielding characteristics due to its fascinating susceptibilities as building materials, minimizing environmental hazards and implementing green and sustainable manufacturing. Noticeably, Mg/Fe3O4/PET nanocomposite gained a brilliant RL of −95.50 dB at 21.80 GHz meanwhile the one-pot-synthesized Fe2O3/MgFe2O4 composited by PET attained a maximum RL of −71.32 dB at 23.06 GHz and an ultra-high efficient bandwidth (RL ≤ −20 dB) of 8.50 GHz with only thickness of 0.50 mm. Interestingly, the PET-based microwave absorbers were fabricated with a low filling ratio of 10 wt%. More significantly, the samples illustrated proper shielding efficiency, desirable for practical applications in the modern era.

Microwave-enhanced sulfate roasting for lithium extraction from lepidolite: A comprehensive study

Currently, the sulfate method used for roasting lepidolite to extract lithium presents several issues, including high energy consumption and low recovery efficiency. To address these limitations, we have employed microwave external fields to enhance lithium extraction and modified the roasting process. Microwave-enhanced roasting reduces heating time from 43 to 20 min, significantly lowering energy consumption compared to conventional roasting. Experimental results reveal that the optimal conditions are ferrous sulfate: potassium sulfate: calcium oxide: ore = 2:0.6:0.1:1, roasting temperature at 775 °C, and roasting time of 2 h, resulting in a lithium leaching efficiency of 95.9%. The study of dielectric properties shows that the addition of sulfate improves the microwave absorption characteristics of lepidolite, facilitating rapid heating in the microwave field. Additionally, uniform microwave heating reduces sample melting and adhesion, leading to looser clinker and improved lithium leaching efficiency. The microwave-enhanced sulfate roasting technology holds significant importance for the study of lithium extraction from lepidolite.

Ni1−xZnxFe2O4/coal-based carbon composites with tunable electromagnetic wave absorption properties prepared with microwave irradiation and hydrothermal reaction

A simple hydrothermal method combined with microwave irradiation was used to synthesize nickel-zinc ferrite/coal-based carbon (Ni1−xZnxFe2O4/CBC) composites. The influences of Zn2+ concentration on the magnetism and microwave absorption characteristics of Ni1−xZnxFe2O4/coal-based carbon composites were examined. The Ni1−xZnxFe2O4 particles were equally anchored on the coal-based carbon within the Ni1−xZnxFe2O4/CBC composites. The dielectric and magnetism characteristics of Ni1−xZnxFe2O4/CBC composites can be improved simultaneously by adjusting the Zn2+ concentration. The minimum reflection loss (RLmin) for the sample at x = 0.4 is −65.5 dB for a thickness of 4.0 mm. The samples also have typical soft magnetic properties. Furthermore, some possible mechanisms of microwave absorption are investigated. Our Ni1−xZnxFe2O4/CBC composites show great potential for microwave absorption applications.

The 3D Printing of Novel Honeycomb-Hollow Pyramid Sandwich Structures for Microwave and Mechanical Energy Absorption.

Honeycomb sandwich (HS) structures are important lightweight and load-bearing materials used in the aerospace industry. In this study, novel honeycomb-hollow pyramid sandwich (HPS) structures were manufactured with the help of fused deposition modeling techniques using PLA and PLA/CNT filaments. The microwave and mechanical energy absorption properties of the HPS structures with different geometry parameters were studied. Compared with the HS structure, the HPS structure enhanced both microwave absorption and mechanical properties. The HPS structures possessed both broadband and wide-angle microwave absorption characteristics. Their reflection loss at 8-18 GHz for incident angles of up to 45° was less than -10 dB. As the thickness of the hollow pyramid increased from 1.00 mm to 5.00 mm, the compressive strength of the HPS structure increased from 4.8 MPa to 12.5 MPa, while mechanical energy absorption per volume increased from 2639 KJ/m3 to 5598 KJ/m3. The microwave absorption and compressive behaviors of the HPS structures were studied.

Design and high efficient construction of bilayer NiCoO2/Poly(1-NA-co-oT) nanocomposite absorber for X-band stealth applications

In this study, we have synthesized poly(1-NA-co-oT) and sphere-like NiCoO2 nanomaterials and then samples-with-layers were prepared to examine microwave absorption properties. For mono-layer, NiCoO2 exhibits superior microwave absorption capabilities than poly(1-NA-co-oT) sample. And for the bilayer sample, different samples were prepared with different layer thicknesses having poly(1-NA-co-oT) layer on top and NiCoO2 as base layer. The optimal bilayer sample having 1-mm thickness of each layer had excellent microwave absorption characteristics; indicating achieving a significant level of absorption necessitates a careful equilibrium between dielectric and magnetic loss. Additionally, best bilayer specimen has excellent absorption characteristics, as shown by its minimum reflection loss (RLmini) of −36 dB and effective absorption bandwidth of 3.5 GHz. Simulated and experimental findings of the bilayer optimal sample were compared and they were in accordance. The aforementioned results indicate a potential shift in the future creation of microwave-absorbing materials.

Facile and mass-producible Ni-added iron nanowires with excellent microwave absorbing performance

The application of magnetic nanocrystalline powders as radar absorption materials is increasingly attracting R&D interest. Severe agglomeration and mass production, however, are critical issues for practical application of magnetic nanoparticles. In the present study, iron nanowires with varying amounts of nickel addition (0, 1, 10, 30, and 50 wt%) were synthesized via direct reduction of iron salts with the aid of strong NdFeB magnets. The yield rate of these Ni-added iron nanowires (NiFe NWs) exceeded 1 g/min, making them suitable and was feasible for mass production. The characteristics of the so-obtained NiFe NWs were confirmed using field emission scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy. Composite resins with NiFe NWs additions (3, 5, and 10 wt%) were prepared and examined using the coaxial line method to reveal their microwave absorption characteristics. Experimental results showed that composite resins with 10 wt% NiFe NWs additions possessed superior microwave absorbing properties, with the Ni1Fe99 NWs-added product exhibiting the best performance. When produced with a thickness of 1.7 mm, the reflection loss of the composites reached −39.28 dB at 12.53 GHz. Additionally, the efficient maximum absorption bandwidth was 3.33 GHz, ranging from 14.27 to 17.60 GHz.