Electromagnetic Wave Absorption Applications Research Articles

Carbon nanolayer-mounted single metal sites enable dipole polarization loss under electromagnetic field.

Surface modulation strategies have spurred great interest with regard to regulating the morphology, dispersion and flexible processability of materials. Unsurprisingly, customized modulation of surfaces is primed to offer a route to control their electronic functions. To regulate electromagnetic wave (EMW) absorption applications by surface engineering is an unmet challenge. Thanks to pyrolyzing surface-anchored metal-porphyrin, here we report on the surface modulation of four-nitrogen atoms-confined single metal site on a nitrogen-doped carbon layer (sM(N4)@NC, M = Ni, Co, Cu, Ni/Cu) (sM=single metal; NC= nitrogen-doped carbon layer) that registers electromagnetic wave absorption. Surface-anchored metal-porphyrins are afforded by attaching them onto the polypyrrole surface via a prototypical click reaction. Further, sM(N4)@NC is experimentally found to elicit an identical dipole polarization loss mechanism, overcoming the handicaps of conductivity loss, defects, and interfacial polarization loss among the current EMW absorber models. Importantly, sM(N4)@NC is found toexhibit an effective absorption bandwidth of 6.44 and reflection loss of -51.7 dB, preceding state-of-the-art carbon-based EMW absorbers. This study introduces a surface modulation strategy to design EMW absorbers based on single metal sites that enable fine-tunable and controlled absorption mechanism with atomistic precision.

Ultrasound-assisted freeze-drying graphitization process for the fabrication of two-dimensional carbon/Fe3O4 composite aerogels for microwave absorption

Magnetic Fe3O4 materials have received attention from researchers due to their significant wave absorption potential, but there are limitations to their efficient electromagnetic wave absorption and lightweight applications. Combining materials with dielectric properties to optimize the performance of Fe3O4 has become one of the research directions. In particular, carbon nanomaterials, such as graphene, show great application prospects in the field of microwave absorption due to their physical properties. To improve the impedance mismatch issue of graphene, researchers consider combining it with magnetic nanoparticles. Commercial applications require materials that are cost-effective, easy to produce, and environmentally sustainable, driving research on novel 2D carbon materials. In this study, 2D carbon materials were prepared by ultrasound-assisted freeze-drying/graphitization process using polymers as precursors, which simplifies the preparation process and avoids the use of expensive sacrificial templates and catalysts. The 2D carbon materials prepared by this method were used as the dielectric component in the wave-absorbing composites, and the nano effect was utilized to significantly improve the microwave absorption properties of the materials. The maximum reflection loss of the prepared graphite nano-aerogel reaches −84.16 dB and the EAB reaches 3.74 GHz. In addition, by adding Fe3O4 nanoparticles and applying an ultrasonic field for dispersion in the freeze-drying process, the nanoparticle agglomeration is effectively prevented, which provides a simple and efficient pathway for the preparation of nanocomposites.

Significantly Enhanced Electromagnetic Wave Absorption Performances and Corresponding Mechanism of LaMn1-xFexO3 Perovskites

Improving the performance of LaMnO3 perovskite is essential to make it an efficient and ultra-light electromagnetic wave (EMW) absorbing material. In this work, LaMn1-xFexO3 powders (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized by controlling the doping of Fe3+ ions at the B-site using the citric acid-assisted sol-gel method. The effects of Fe3+ ions doping content on crystal structures, magnetic properties and EMW absorption performances were investigated. The obtained LMFO-4 sample exhibited a minimal reflection loss of -54.99 dB at 13.68 GHz, with an adequate absorption bandwidth (RL < -10 dB) spanning 4.56 GHz (11.6∼16.16 GHz) at a matching layer thickness of 2.0 mm. The exceptional EMW absorption performances could be attributed to the Jahn-Teller effect, the double-exchange interactions and the magnetic interactions of Mn and Fe ions. Furthermore, the Computer Simulation Technology (CST) simulations demonstrated that the Radar Cross Section (RCS) value of LMFO-4 was lower than -25.10 dBm2 across angles ranging from -90° to 90° with a thickness of 2.0 mm, indicating the remarkable radar wave attenuation ability. These insights provided valuable guidance for advancing perovskite-based materials tailored for efficient and ultra-light electromagnetic wave absorption applications.

Defect-rich carbon nanosheets derived from p(C3O2)x for electromagnetic wave absorption applications

Defect modulation strategies have been shown to be an effective way to design efficient EMW absorbing materials, but the coexistence of multiple loss mechanisms due to the complexity of the existing models makes it difficult to elucidate the mechanism by which defect-induced dielectric losses dominate. In this work, p(C3O2)x is applied for the first time in the field of EMW absorption and the concentration of defects in the sample is controlled by changing the pyrolysis temperature. In addition, the unique molecular structure of p(C3O2)x enables the prepared samples to completely eliminate the interference of interfacial polarization and magnetic loss on EMW dissipation. The results show that the dielectric loss induced by defects significantly enhances the EMW absorption performance as the concentration of defects increases, but excessive defects lead to a sudden drop in the conductivity of the sample and reduce the EMW absorption performance. In which, the RLmin of OC-800 can reach −51.0 dB, and the EAB of OC-900 can go up to 5.6 GHz at only 1.6 mm. Finally, CST simulation verified the potential application of the prepared absorber in real scenarios. This work has improved the theoretical basis of the effect of defect-induced dielectric loss on EMW absorbing properties, and the simple synthetic raw materials and routes have made the industrialized production of highly efficient EMW absorbing materials possible.

MoSe2 nanosheets implanting on 3D hollow carbon sphere for high-efficiency electromagnetic wave absorption

Carbon-based electromagnetic wave absorption (EMA) materials are extensively studied due to their unique advantages. Nevertheless, impedance matching issues was still constraining their further research. Consequently, we successfully synthesized MoSe2 nanosheets implanting on 3D hollow carbon sphere (HCS@MoSe2) composites with core–shell structure. The complex core–shell structure high-entropy composites provided multiple dissipation mechanisms for efficient dissipation of incident electromagnetic wave energy. The implanting MoSe2 nanosheets optimized the dielectric constant of the composites, thus ensuring optimal impedance matching. The HCS@MoSe2-1 composites exhibit excellent EMA properties and a significant minimum reflection loss (RLmin) of −56.19 dB. And HCS@MoSe2-1 had an ultra-wide effective absorption bandwidth (EAB) of 7.43 GHz. The significant EMA capability attributed to the synergistic effects of conductive loss, polarization loss, and optimized impedance matching. This work paved a new path for synthesizing transition metal selenide-modified carbon-based composite materials, offering great potential as high-performance materials for EMA applications.

Preparation and microwave absorption properties of FeS2/Co-BTC composite nanomaterials

Nanocomposite materials are multiphase materials with rich interfacial nanoscale features and adjustable microstructures, which are widely used in various fields. This paper describes the synthesis of FeS2 nanospheres, Co-BTC microcrystals, and FeS2/Co-BTC nanocomposite using a solvothermal method, with SEM, XRD, and other techniques characterizing their microstructure, and tests on their magnetic, ultraviolet, and wave-absorbing properties. The results show that FeS2 is composed of nanosheets of 10 to 20 nm that form spherical particles with a diameter of 1 µm,and FeS2/Co-BTC has a well-mixed composite structure. XRD results indicate that the samples are relatively pure. The magnetic experiments indicate that among the three samples, FeS2 exhibits the highest magnetic field intensity, followed by FeS2/Co-BTC. The magnetic permeability of Co-BTC can be approximated as close to zero. The absorption results indicate that FeS2 possesses strong energy storage and dissipation capabilities. FeS2/Co-BTC exhibits strong magnetic energy storage and dissipation capabilities, as well as a larger optimal absorption bandwidth. These materials demonstrate excellent electromagnetic properties suitable for electromagnetic wave absorption applications.

Flower-Branch-Like carbon Microtube/Vanadium Selenide: A highly efficient electromagnetic wave absorbing composite

The unique layered structure and adjustable band gap of transition metal dichalcogenides (TMDs) have prompted extensive investigations into their potential for electromagnetic wave absorption (EWA). Vanadium selenide (VSe2), a notable representative of TMDs, has a larger interlayer spacing (6.1 Å) and higher conductivity (1 × 10-3 S/m), which has high advantageous in EWA applications. However, the existing research on the use of VSe2 for EWA remains relatively limited. Herein, a flower-branch-like carbon microtube/vanadium selenide (CMT/VSe2) composite was successfully synthesized via a facile solvothermal method. This composite material is composed of flower-like VSe2 nanostructures integrated with carbon microtubes. Importantly, the EWA properties of this composite can be effectively tailored by adjusting the concentration of the VSe2 precursor. The CMT/VSe2 composite exhibited a remarkable minimum reflection loss (RL) of −60.54 dB in the Ku-band, with a matching thickness of 2.27 mm. Moreover, the effective absorption bandwidth reached 6.38 GHz. These results demonstrate the great potential of this CMT/VSe2 composite material as a highly efficient EWA material. Furthermore, this work broadens the application of two-dimensional TMDs in the area of EWA.

Laser‐induced self‐propagating synthesis and electromagnetic wave absorption properties of MoAlB powders

AbstractMoAlB powders with a purity of 96 wt.% were successfully fabricated by a laser‐induced self‐propagating method using molybdenum boride (MoB) and aluminum powders as starting materials under the conditions of an n(MoB): n(Al) ratio of 1.0:1.4 and the laser linear energy density (El) of 0.9 J/mm, and the effect of raw material composition and El on the phase composition and microstructure of the resultant MoAlB powders were investigated. The minimum reflection loss (RLmin) value and effective absorption bandwidth (EAB) of the as‐prepared MoAlB absorber with a thickness of 5.0 mm were only determined as −12.5 dB (at 16.9 GHz) and 0.9 GHz (16.4–17.3 GHz) in the frequency of 1–18 GHz, respectively. Nevertheless, the RLmin and EAB of as‐prepared MoAlB powders oxidized after 3 h at 773 K increased to −18.59 dB (at 15.82 GHz) and 2.13 GHz (15.22–17.35 GHz), respectively, demonstrating that the as‐prepared MoAlB powders are potential candidates for high‐temperature microwave absorption applications. This study proposes a new efficient strategy for the preparation of boron‐based ternary compounds for high‐temperature electromagnetic wave absorption application.

Emerging fabrication of ceramic nanofiber aerogel with the application in high-temperature thermal insulation, environment, and electromagnetic wave absorption

Emerging fabrication of ceramic nanofiber aerogel with the application in high-temperature thermal insulation, environment, and electromagnetic wave absorption

Facile design and permittivity regulation of porous carbon and magnetic particles based composite nanofibers towards highly efficient electromagnetic wave absorption

Two kinds of porous carbon and magnetic particles-based composite nanofibers (PCNTF-CoFe and PCNTF-NiFe) were synthesized for electromagnetic wave (EMW) absorption. Magnetic particles were used as the catalyst to increase the crystallinity of carbon and the corresponding dielectric loss ability, while porous structure was designed to improve the impedance matching. According to the results, the dielectric loss abilities of PCNTF-CoFe and PCNTF-NiFe are enhanced without significant degradation in their impedance matching condition. Therefore, through the polarization and conduction-induced dielectric loss together with the natural and exchange resonance-induced magnetic loss, the incident EMW can be attenuated rapidly inside PCNTF-CoFe and PCNTF-NiFe. PCNTF-CoFe shows a minimum reflection loss (RLmin) of −54.6 dB and effective band width (RL≤-10 dB, EABW) of 6.0 GHz at 2.0 mm, while PCNTF-NiFe shows RLmin of −33.4 dB and EABW of 5.7 GHz at 1.7 mm. Consequently, PCNTF-CoFe and PCNTF-NiFe can be promising candidates for application in EMW absorption.

Enhanced electromagnetic wave absorption in YAG-modified SiC foam

Electromagnetic technology applications are escalating, leading to increased human exposure to electromagnetic radiation. In addressing the challenges posed by this radiation, electromagnetic wave absorbing materials stand out due to their distinguished properties. This study focused on developing porous fibrous SiC three-dimensional (3D) foams. These were synthesized by freeze-drying SiC nanofiber dispersions followed by high-temperature sintering. Measurements demonstrated that the resulting SiC foams possess a relatively low density, approximating 0.1 g cm−3. Upon microscopic analysis, it became evident that the foam's porous structure is predominantly made up of SiC fibers intermixed with yttrium aluminum garnet granules. These tailored SiC foams delivered outstanding electromagnetic wave absorption characteristics, recording a minimum reflection loss value of −63 dB. Furthermore, an expansive effective absorption bandwidth of 6.9 GHz (spanning from 9.3 to 16.2 GHz) was noted for a sample thickness of 3.15 mm. Several factors contribute to this high absorption efficacy, including multiple reflections and both interface and dipole polarizations. It is also worth noting that the SiC foam displayed commendable oxidation resistance when exposed to elevated temperatures. Cumulatively, these findings underscore the promising potential of porous fibrous SiC 3D foams in electromagnetic wave absorption applications, especially in extreme conditions.

A Liquid‐Metal‐Assisted Competitive Galvanic Reaction Strategy Toward Indium/Oxide Core−Shell Nanoparticles with Enhanced Microwave Absorption

AbstractThe preparation of core–shell structured nanoparticles using the galvanic replacement reaction of liquid metals is a simple and efficient method. However, precise modulation of the core and shell components to regulate the microwave absorption performance still needs to be further explored. In this study, various types of indium/oxide core–shell nanoparticles are prepared based on a competitive galvanic reaction of gallium‐indium liquid metals. The prepared indium/oxide core–shell structured nanoparticles exhibit superior electromagnetic (EM) wave absorption properties with a minimum reflection loss (RL) of −40.25 dB at 1.7 mm and the widest effective absorption band of 6.12 GHz at 2.1 mm. The superior wave‐absorbing properties originate from the dielectric losses of the interfacial and dipole polarizations. In addition, an externally applied magnetic field improves the polarization loss and microwave dissipation to achieve a minimum RL of −45.65 dB at 2.4 mm. The liquid‐metal‐assisted competitive galvanic reaction strategies extend the variety of core–shell structured nanoparticles for electromagnetic wave absorption applications.

Fabrication of Multiwalled Carbon Nanotubes (MWCNT) and Reduced Graphene Oxide (rGO)‐based thermoplastic polyurethane and polypyrrole nanocomposites for electromagnetic wave absorption application with a low reflection

AbstractElectromagnetic radiation (EMR) pollution is a serious concern in today's environment, causing problems not just for electronic gadgets but also for living society. The goal of this research is to fabricate thermoplastic polyurethane (TPU) and polypyrrole (PPy)‐based 95:5 blend nanocomposites using a simple solvent casting method at such a low concentration of rGO and MWCNT (0.3, 0.4, 0.5 php) (parts per hundred polymers), for electromagnetic wave (EMW) absorption applications. The chemical interaction between the different phases and morphology of the nanocomposites is characterized by Raman spectroscopy, X‐ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) techniques. The material properties, such as dielectric and magnetic properties, are analyzed in X‐band frequency (8.2–12.4 GHz). The total shielding effectiveness of (SETot) 0.5 rGO system is found to be 27 dB, whereas, for corresponding MWCNT nanocomposites, it is 26 dB. Interestingly, in 0.5 rGO nanocomposites, absorption shielding effectiveness (SEAbs) is approximately 25 dB, and reflection shielding effectiveness (SERef) is less than 2 dB, which indicates the absorption of 70% of the electromagnetic wave, and the rest gets reflected. Apart from that, the rGO‐based nanocomposites possess a greater extent of thermal stability than the corresponding MWCNT‐based nanocomposites.Highlights Fabrication of TPU‐PPy‐rGO and TPU‐PPy‐MWCNT nanocomposites by solvent casting. Low reflection of TPU‐PPy‐rGO nanocomposites with a 70% absorption rate. FESEM confirms the multilayer interface structures. Tunable Dielectric and magnetic properties of nanocomposites in X‐band. Excellent absorption dominant properties of the fabricated nanocomposites.

Enhanced electromagnetic wave absorption via optical fiber-like PMMA@Ti3C2Tx@SiO2 composites with improved impedance matching

Ti3C2Tx nanosheets have attracted significant attention for their potential in electromagnetic wave absorption (EWA). However, their inherent self-stacking and exorbitant electrical conductivity inevitably lead to serious impedance mismatch, restricting their EWA application. Therefore, the optimization of impedance matching becomes crucial. In this work, we developed polymethyl methacrylate (PMMA)@Ti3C2Tx@SiO2 composites with a sandwich-like core-shell structure by coating SiO2 on PMMA@Ti3C2Tx. The results demonstrate that the superiority of the SiO2 layer in combination with PMMA@Ti3C2Tx, outperforming other relative graded distribution structures and meeting the requirements of EWA equipment. The resulting PMMA@Ti3C2Tx@SiO2 composites achieved a minimum reflection loss of −58.08 dB with a thickness of 1.9 mm, and an effective absorption bandwidth of 2.88 GHz. Mechanism analysis revealed that the structural design of SiO2 layer not only optimized impedance matching, but also synergistically enhanced multiple loss mechanisms such as interfacial polarization and dipolar polarization. Therefore, this work provides valuable insights for the future preparation of high-performance electromagnetic wave absorbing Ti3C2Tx-based composites.

Carbonization of Ni@SiC@C nanoparticles reinforced PAN nanofibers for adjustable impedance matching

Achieving a broad bandwidth and efficient absorption of electromagnetic wave absorption materials remains a significant challenge, especially when considering electromagnetic pollution protection. One-dimensional carbon nanofibers with a three-dimensional network structure have been extensively studied to address this need. However, the high permittivity of carbon nanofibers results in a strong impedance mismatch with free space. In this work, we successfully dispersed double-shell Ni@SiC@C nanoparticles into one-dimensional carbon nanofibers (Ni@SiC@C CNFs) using electrospinning and heat treatment. We extensively explored the effect of carbonization temperature on the impedance matching and magnetic-dielectric loss for electromagnetic wave. The presence of rich interfaces from the double-shell nanoparticles and defects from N-doping optimizes the impedance matching of the composites. The exceptional electromagnetic wave absorption properties of the Ni@SiC@C CNFs are attributed to the synergistic effect between the three-dimensional conductive network, the interface electronic engineering induced by the sensibly loaded double-shell nanoparticles, and the multiple reflections, especially at a carbonization temperature of 600 ℃. The achieved minimum reflection loss value has been measured at an outstanding −53.27 dB, coupled with a remarkable absorption bandwidth that spans from 2.53 GHz to 18.00 GHz (15.47 GHz) across various thicknesses. These findings underscore the potential of the meticulously engineered Ni@SiC@C CNFs as highly promising candidates for efficient and broadband electromagnetic wave absorption applications.

SYNTHESIS OF Fe3O4 NANOPARTICLES GROWN ON RICE HUSK WASTE-DERIVED POROUS CARBON FOR HIGH-EFFICIENCY MICROWAVE ABSORPTION

In this study, a straightforward process was employed to synthesize Fe3O4 nanoparticles-decorated porous carbon derived from rice husk waste (Fe3O4/C). The composite material was made by using pyrolysis and then coprecipitation. Fe3O4 nanoparticles were dispersed evenly across the surface of a porous carbon structure made from rice husks (PC) in three dimensions (3D). The highly graphitized porous carbon framework makes the tracks for electromagnetic waves that propagate longer and increases the loss of conductivity. With its unique structure and the effects of great attenuation and good impedance matching, Fe3O4/C is much better at absorbing microwaves than pure porous carbon. Most samples have a minimum reflection loss (RL) of less than -10 dB (90% reduction) over a wide range of electromagnetic frequencies (3.6 - 18.0 GHz) when the thickness of the absorber varies from 1.5 - 4.0 mm. With a thickness of 3.0 mm, the best RL is -70.8 dB, and with a thin thickness of 1.5 mm, the effective absorption bandwidth (EAB) is 14.4 GHz. According to the findings of this study, the use of Fe3O4/C material for electromagnetic wave absorption applications holds great promise due to the low cost and extensive benefits of the preparation process, as well as its excellent electromagnetic absorption performance.

Natural green raw-based Biochar@Co/C composites: Simple water bath synthesis and excellent electromagnetic wave absorption properties

Over the last few years, wave absorbing materials synthesized based on green and eco-friendly natural materials were less studied. Carbon materials derived from natural materials, for example, have a limited absorption performance due to impedance mismatch in electromagnetic wave absorption applications. In this work, composites of MOF derivatives and biochar with strong wave absorbing capability were prepared by biochar and MOF. Biochar was green raw material originated from kapok trees in the school. Then it was compounded with MOF derivatives by pretreatment and water bath to form Biochar@Co/C composites. The effect of annealing temperature on the absorption properties was investigated by varying the annealing temperature. According to the results of the transmission line theory analysis, Biochar@Co/C-700 have RLmin value of −55.22 dB at 5.43 GHz and 3.69 mm. Also, the effective absorption bandwidth EAB can reach 6.37 GHz at 1.94 mm. And the above absorption properties were measured when the filling ratio was only 15 %. Electromagnetic parameter analyses showed that the combination between biochar and MOF derivatives greatly improves the impedance matching of the carbon-based materials, which is a vital factor that enables Biochar@Co/C-700 to have excellent wave-absorbing properties. In addition, the loss mechanism of the complexes to electromagnetic waves was also analyzed and summarized. These results provide a reference path for the preparation of high-performance electromagnetic wave absorption composites from green materials.

Microwave-absorbing performance of FeCoNi magnetic nanopowders synthesized by electrical explosion of wires

This study demonstrates fabrication of FeCoNi magnetic nanoparticles by joint electrical explosion of wires for electromagnetic wave absorption applications. An increase in the energy storage capacity of the capacitors can increase the maximum reflection loss of the nanoparticles and shift the corresponding frequency in the low-frequency direction, but has no significant effects on the maximum bandwidth. The minimum reflection loss of the magnetic nanoparticles reaches − 50.2 dB at 6.8 GHz when the thickness is 2.5 mm, while the maximum effective absorption bandwidth reaches 8.1 GHz at a thickness of 1.5 mm. The wire explosion method, as an instantaneous synthesis method with a low cost, environmental friendliness, and high-output characteristics, provides a new approach to industrial batch preparation of microwave-absorbing materials.

Enhancing electromagnetic absorption performance of Molybdate@Carbon by metal ion substitution

Transition metal molybdate (RMoO4) has been extensively studied in optics, electricity and catalysis due to its low cost and multivalent Mo atoms, while its poor electrical conductivity limits its application in electromagnetic wave absorption (EMA). Compounding molybdate with conductive materials is an effective way to improve its electrical conductivity. In this work, a homogeneous coating on the molybdate surface was achieved by utilizing a pyrrole oxidation polymerization mechanism, and then stabilized composites of Molybdate@Carbon (RMoO4@C) were obtained by high-temperature pyrolysis. The EMA properties of the nanocomposites were tuned by substituting the species of transition metal elements (RMoO4@C, R=Fe, Co, Cu). Among them, Fe2(MoO4)3@C has a minimum reflection loss of −60.62 dB at an ultra-low thickness of 1.7 mm, and the effective absorption bandwidth (EAB) can reach 4.75 GHz at 3.00 mm. This work expands the range of applications for molybdate and provides a new material basis for building high-performance EMA materials.

Lightweight cementite/Fe anchored in nitrogen-doped carbon with tunable dielectric/magnetic loss and low filler loading achieving high-efficiency microwave absorption

Magnetoelectric composites have promising application in electromagnetic wave absorption for their regulatory structures and interfacial interactions. In this research, a facile one-step pyrolyzing procedure was applied to achieve cementite/Fe nanoparticles anchored on nitrogen-doped carbon nanotubes (Fe3C/Fe/N-CNTs) composites. Fe3C/Fe encapsulated in nitrogen-doped carbon was generated through in-situ Fe-catalyzed carbothermal reactions.The obtained magnetoelectric composites displayed excellent microwave absorption properties with a minimum reflection loss of −54.4 dB at 10.4 GHz, a matching thickness of 2.3 mm, and low filler loading (15%). Moreover, even at a low matching thickness of 1.55 mm, the reflection loss was less than −10 dB in the range of 13.7–18.0 GHz, and an effective absorption bandwidth of 4.3 GHz was achieved. The outstanding microwave absorption performance can be summarized as follows. 1) The CNT network enriches the transmission path, enhancing the dielectric loss capability. 2) The hollow one-diameter CNT structure helps strengthen interfacial polarization, optimizing the impedance matching while promoting multiple reflections and scattering. 3) Magnetic Fe3C/Fe provides a strong magnetic dissipation ability and eddy current losses. 4) The heterogeneous magnetoelectric Fe3C/Fe/N-CNTs possess multiple interfaces, increasing the interfacial polarization and electromagnetic synergistic losses. This study provides a potential strategy for the large-scale synthesis of low filler loading magnetic–dielectric microwave absorbers.