Enhanced Microwave Absorption Research Articles

Enhanced microwave absorption of sandwich panels with magnetized carbon fiber corrugated array reinforced PMI foam core

AbstractIntegrating periodic array structures made of metal wires or conductive inks into the foam core of electromagnetic (EM) wave absorbing sandwich panels can significantly improve broadband absorption performance. However, the complex fabrication process and poor corrosion resistance of these materials limit their practical applications. This work innovatively introduces magnetized carbon fiber (CF) into PMI foam, simultaneously achieving broadband absorption and lightweight characteristics of the sandwich structure through the design of array structure and fiber bundle geometry. Simulation analysis compared the EM absorption performance of sandwich panels with carbonyl iron powder (CIP)/CF tape and helical twisted CIP/CF rope corrugated arrays, determining the optimal array structure parameters, which were then experimentally validated. The experimental results align with the simulations, showing that CIP/CF rope corrugated arrays with an amplitude of 10 mm, a cycle length of 15 mm, and an array spacing of 15 mm provide optimal absorption performance, with a reflection loss below −10 dB across the 9–18 GHz frequency range and a maximum absorption of −33.9 dB at 17 GHz. Finally, the absorption mechanism of these sandwich structures is discussed, highlighting how the synergistic effects between the electromagnetic properties and structural morphology of CIP/CF enhance the absorption performance of the EM absorbing sandwich panel.

Defect Engineering of Anchored on F-Doped BNNR Surface to Enhance Low-Frequency Microwave Absorption and Achieve Exceptional Thermal Conductivity Properties

The growing demand for AI and smart computing drives the development of compact, lightweight electronic products to mitigate electromagnetic wave (EMW) pollution and thermal management issues. This necessitates materials with enhanced microwave absorption (MA) and optimal thermal conductivity (TC). Herein, we designed and synthesized fluorinated boron nitride nanorods (F-BNNRs) in a single step via plasma ball milling. Ammonium fluoride (NH₄F) served as the fluorinating agent for hexagonal boron nitride nanorods (h-BNNRs). F-BNNR3, with a NH₄F to h-BNNR ratio of 10:1 and 5.84% fluorine (F) content, exhibits excellent MA, achieving a minimum reflection loss (RLmin) of -68.56 dB at 5.14 GHz with a thickness of 4.32 mm. It also displays a broad MA frequency range (4.6–6.1 GHz, 15.4–17.2 GHz) with significant RL < -10 dB. Additionally, a 0.09 wt% F-BNNR3 solution achieves a thermal conductivity (TC) of 0.95 W·m⁻1K⁻1, 134% higher than that of a 0.09 wt% h-BNNR dispersion fluid. Following a post-static treatment, F-BNNR3 attains a TC of 0.86 W·m⁻1K⁻1, 118% higher than that of h-BNNR. The incorporation of F into h-BNNRs significantly enhances MA and TC performance, addressing EMW pollution and thermal management challenges in advanced communication technologies utilizing nanofluids.

Enhanced microwave absorption using multiple heterostructures derived from in-situ grown Sn-metal-organic framework on La-doped Fe3O4

As a representative magnetic oxide absorber, Fe3O4 has attracted considerable research attention owing to its remarkable magnetic saturation strength as well as semiconducting properties. Doping Fe3O4 with La3+ leads to 3d-4f magnetic coupling and ion distribution changes due to the unique electron configuration and large ionic radius of La3+, thereby greatly enhancing the magnetic performance. However, high density, low dielectric loss, and low permeability at high frequencies inhibit the electromagnetic wave absorption (EMWA) performance of ferrites. In this study, stick-shaped Sn metal-organic framework (MOF) is in-situ grown on La3+-doped Fe3O4 using a surfactant. After high-temperature annealing, the SnO2/porous carbon composites derived from Sn-MOF wrap the ferrite, forming a core-shell heterostructure, which not only prevents oxidation but also enhances the EMWA performance. Among the prepared LaxFe3-xO4/SnO2/C (LFSC) samples, LFSC-2 (with LaxFe3-xO4 to Sn-MOF ratio of 1:2) exhibits strong absorption performance with a minimum reflection loss (RLmin) of −44.1 dB. Furthermore, the gradient metamaterial based on LFSC-3 shows ultra-broadband EMWA with an effective absorption bandwidth (RLmin ≤ −10 dB) of 13.17 GHz. In addition, the LFSC-2 sample demonstrates excellent radar stealth capability in the radar cross section (RCS) far-field response, achieving an RCS reduction value of 20.4 dB·m2.

Enhanced Microwave Absorption in Organogels:The Synergy of Polar Molecules and Magnetic Particles

Herein, wideband microwave absorbing materials with high flexibility are developed by creating a novel layered organogel composite consisting of carbonyl iron particles (CIP) and polyacrylamide (PAM), employing ethylene glycol (EG) as the solvent. The microwave absorbing properties of layered absorbers with different CIP contents are investigated over the 1–18GHz range. An integrated stratified architecture was obtained using polar EG molecules and magnetic CIP particles, which were the main contributors to magnetic and dielectric losses in the PAM matrix. The results indicated that the minimum reflection loss reaches a value of −48.0dB at a thickness of 2mm and a frequency of 15.5GHz; meanwhile, an effective absorption bandwidth of 3.2GHz in the C-band can also be obtained. An analysis of the absorption mechanism shows that the combination of an impedance-matching layer composed of CIP magnetic particles and an absorption layer composed of EG polar molecules in the PAM matrix provides strong broadband absorption in the C-band. Overall, the CIP/EG@PAM organogel composites have simple preparation, high flexibility, and it has adhesion. This study provides a new strategy for designing wideband microwave absorbing materials.

Lightweight, thermally insulating SiBCN/Al2O3 ceramic aerogel with enhanced high-temperature resistance and electromagnetic wave absorption performance

Owing to tunable dielectric properties, light weight and high porosity, polymer-derived SiBCN ceramic aerogels possess significant application prospects in electromagnetic wave (EMW) absorption and thermal insulation. However, due to inadequate oxidation resistance, the structural collapse and performance deterioration of SiBCN aerogels will easily occur in high-temperature aerobic environments, limiting their application. Herein, to address this issue, a novel and straightforward strategy based on typical polymer-derived-ceramic (PDC) aerogel method and impregnation with boehmite sol was proposed for synthesizing SiBCN/Al2O3 composite ceramic aerogels. The microstructure, phase composition, thermal insulation, oxidation resistance and EMW absorption properties of SiBCN/Al2O3 ceramic aerogels were investigated. The resulting SiBCN/Al2O3 composite aerogel demonstrates superior high-temperature structural stability, exhibiting an ultra-low linear shrinkage of only 6.5 % following heat treatment at 1200 °C for 2 h in air. Additionally, the composite aerogel shows a low thermal conductivity of 0.039 W/mK and a low density of 0.112 g/cm3. The SiBCN/Al2O3 composite aerogel, composed of dielectric SiBCN, conductive free carbon, and insulating alumina, demonstrates outstanding EMW absorption properties with a minimum reflection loss of −48.6 dB and an effective bandwidth of 5.8 GHz. The enhanced microwave absorption performance is mainly attributed to the improved impedance matching, multiple reflection, and enhanced interfacial polarization resulting from the introduction of Al2O3. Given prominent oxidation resistance, thermal insulation and EMW absorption properties, the SiBCN/Al2O3 composite aerogel paves the way for developing microwave absorption and thermal insulation integrated material in high-speed vehicles.

Enhanced microwave absorption properties of Ti3AlC2 particles modified by a facile preoxidation strategy

MAX phases are considered to be promising microwave absorbing materials in fifth-generation (5G) communications, but their high electrical conductivity causes impedance mismatching, weakening their ability to absorb microwaves. Here, we present a universal preoxidation strategy to improve the impedance matching and the microwave absorption performance of a Ti3AlC2 MAX phase absorbing material. The microwave absorption properties of Ti3AlC2 particles were enhanced after preoxidation at temperatures of 500-700 °C for only 30 min in air, as compared with unoxidized Ti3AlC2 particles. More interestingly, the 600 °C-preoxidized Ti3AlC2 material reached a minimum reflection loss (RLmin) value of -50.56 dB at 8.87 GHz, superior to -12.36 dB at 12.82 GHz for the original Ti3AlC2 material. The preoxidized Ti3AlC2 particles were covered by a thin oxidation layer comprising both amorphous TiO2 (a-TiO2) and rutile TiO2 (R-TiO2). The oxidation layer endows the preoxidized Ti3AlC2 particles with good impedance matching, and a large number of nano-interfaces of a-TiO2/R-TiO2 and micro-interfaces of a-TiO2/Ti3AlC2 also contribute to the dielectric loss mechanism, thus improving its microwave absorption ability. This work provides a practical strategy for the fundamental study and the optimal design of MAX microwave absorbing materials.

MoS2 Decorated on 1D MoS2@Co/NC@CF Hierarchical Fibrous Membranes for Enhanced Microwave Absorption.

The design and development of high-quality electromagnetic waves (EMW) absorbing materials play a vital role in combating the escalating negative effects of microwave radiation and interference. Herein, MoS2@Co/NC@CF fibrous membranes are successfully fabricated by electrospinning technology and carbonization, and a molybdenum disulfide (MoS2) layer is synthesized on the surface of these fibers via hydrothermal method. The seed-assisted growth method not only effectively avoids the accumulation and improves the loading of ZIF-67 particles, so as to ensure that the magnetic components in the fibers are evenly distributed in a wider range, rather than only intermittently present in some sites. Meanwhile, the introduction of semiconductor MoS2 as the shell further optimizes the impedance matching and improves the EMW absorption performance of the carbon fibrous membranes: the minimum reflection loss (RLmin) is -67.56dB, and the maximum effective absorption bandwidth (EABmax) is further expanded to 6.56GHz (2.1mm, 11.44-18GHz). This work provides a feasible method for developing high-efficient EMW-absorbing materials.

Rapid synthesis and enhanced microwave absorption of carbon-supported high-entropy metal oxide

Complex preparation process and long annealing time of high-entropy metal oxide (HEO) limit its extensive application as microwave absorber at civil and military fields. Herein, a rapid synthesis method of mesocarbon microbeads (MCMB)-loaded spinel structure (FeCoCrNiMnCu)O is studied via plasma flow. In the presence of extreme plasma heating rate, a nanoscale high-entropy phase can be formed while modifying the surface activity of carbon. Simultaneously, due to the short synthesis time, gaseous conversion of carbon under high temperature aerobic conditions is avoided. By appending of carbon, the dual-media absorber exhibits better absorption performance with a maximum peak (-44.7 dB), which achieves over 90 % absorption in 11.2–15.5 GHz with a thickness of only 1.9 mm. Interestingly, the real and imaginary parts of complex permittivity increase remarkably. The former change is attributed to the expansion of heterogeneous hole carrier region and the latter dues to the interfacial polarization of the strongly coupled interface. The increase of dielectric loss and conductance loss leads to great improvement of microwave absorption. Our study injects new vitality into the preparation of HEO for advanced applications and the as-prepared HEOM is promised to be high-efficient microwave absorber based on robust stability and excellent absorbing performance.

Defect introduction and interfacial strategies for enhancing microwave absorption in carbon-based materials

Poor impedance matching and a single loss mechanism are typical challenges for carbon-based materials to become efficient microwave absorbers. To address these issues, defect introduction and interfacial strategies are effective methods for enhancing microwave absorption through the micro-mechanism of material interaction with microwaves. Additionally, forming a homogeneous composite material is crucial for achieving good impedance matching. In this study, we used a controlled solvent-thermal method to achieve self-assembled interfacial intercalation, yielding amorphous VOPO4/rGO nanohybrids, which show significantly enhanced microwave absorption properties. The abundant defects introduced by VOPO4 within the amorphous layered composites disrupt the charge distribution, contributing to polarization loss. The graphene nanosheets expose more VOPO4 structural units, facilitating increased conductivity and enriching the microwave absorption mechanism. As a result, the prepared VOPO4/rGO nanohybrids demonstrate outstanding microwave absorption, with the effective absorption bandwidth covering the entire Ku-band (11.6–18.0 GHz) at a thickness of 2.3 mm. This research provides an important reference for understanding the mechanisms that enhance the electromagnetic wave absorption of carbon-based materials.

Tailoring SrFe12O19 – MoS2 composites for enhanced microwave absorption performance in X-band

The electromagnetic wave-absorbing composites, incorporating strontium hexaferrite and molybdenum disulfide (SrFe12O19-MoS2), are synthesized by mixing in different weight ratios. In the present work, strontium hexaferrite (SrFe12O19) is developed through a low-temperature auto-combustion method while two-dimensional molybdenum disulfide (MoS2) is synthesized by a facile hydrothermal process. The materials and their composites undergo analysis using characterization techniques such as X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and vibrating sample magnetometer (VSM) to assess their structural, morphological, and magnetic properties, respectively. The minimal reflection loss (RLmin) of – 47.35 dB is observed at 8.66 GHz for the SrFe12O19-MoS2 (50 %-50 %) composite cast into pellets for microwave absorption analysis in the X-band frequency range. This RLmin is obtained with a sample thickness of 1.7 mm. An adequate bandwidth of 3.1 GHz, representing 77.5 % of the entire X band, is observed for a loss below −10 dB. The synergistic interaction between magnetism and dielectricity makes it an efficient electromagnetic absorber for modern technologies.

Self-assembly Ti3C2Tx MXene/ZnCo2O4@ZnO heterostructure with Schottky junction for regulating BIEF to enhance microwave absorption

Currently, heterogenous interface engineering on absorbers is shown to boost the electromagnetic wave absorption (EMA) performance effectively. However, challenges remain in investigating the mechanisms by studying heterojunctions between heterogeneous interfaces. Herein, a self-assembly Ti3C2Tx MXene/ZnCo2O4@ZnO (MZCZ) heterostructure with abundant Schottky heterogenous interfaces generating a controllable built-interface electric field (BIEF) effect is fabricated to achieve exceptional EMA ability. The formative BIEF between the unbalanced distribution charges promotes charge separation and migration, increasing polarization loss. Fortunately, the obtained MZCZ1 exhibits the reflection loss (RL) value of −69.78 dB under the ultralow thickness of 1.501 mm and the optimal minimum RL (RLmin) value of −74.41 dB, respectively. The excellent performance can be ascribed to the multiple polarization loss, conduction loss, natural resonance, and exchange resonance characteristics. Moreover, by the Computer Simulation Technology (CST) software, the designed circular cone and circular truncated cone periodicity structure with the MZCZ1 absorber both exhibit a super-wide effective absorption bandwidth (EAB) covering the whole C, X, and Ku band. This study can pioneer a novel approach to developing functional EMA materials and provide a valuable direction for further study of EMA mechanisms at heterogeneous interfaces.

Relaxation behaviour, conductive grains and resistive boundaries of bismuth-based double perovskite Bi2-xLaₓFeGaO₆

The successful synthesis of the ceramic Bi2-xLaxFeGaO6 powder ceramic sample with varying La content (x = 0.01, 0.03, 0.07, 0.10) were synthesized via the solid-state method. Analysis using X-ray diffraction at room temperature was carried out to examine its structure, revealing a crystallite size of approximately 22.07–50.84 nm. This size indicates the potential applications in microwave technology due to its small grain size, which has the capability to enhance microwave absorption properties. The dielectric constant of the material shows an increase with the frequency applied, in accordance with the behaviour anticipated by the dielectric HN model and Debye model. This model proposes that the material's dielectric response can be manipulated by modifying the applied frequency, making it a valuable tool in the material design for specific purposes. The full width at half maximum (FWHM) curve of the electrical modulus displayed variability, suggesting the existence of a non-Debye relaxation mechanism in the material. This indicates that the material could possess distinct electrical properties that might be beneficial for certain applications. The outcomes demonstrated a negative temperature coefficient resistance (NTCR), indicating a decrease in the material's resistance with increasing temperature. Such behaviour can be advantageous in situations where temperature variations require monitoring or regulation. The Cole-Cole plot illustrated that the grains exhibit conductive behaviour at lower frequencies, a crucial insight for comprehending the material's electrical properties. In conclusion, these results indicate that the ceramic Bi2-xLaxFeGaO6 for x = 0.01, 0.03, 0.07, 0.1) showcases promising attributes for various applications, particularly in microwave technology and electrical conductivity.

Synthesis of hierarchical carbon Nanofibers-CoNi/C composites for enhanced microwave absorption efficiency

Developing lightweight, highly absorption and broadband microwave absorbents to combat severe electromagnetic radiation pollution poses a significant challenge. In this study, we designed a novel chain-like CNFs-CoNi/C nanocomposite by in-situ growth of bimetallic MOFs on the CNFs followed by calcination. The resulting CoNi/C composite with hollow structure was uniformly distributed along the 1D CNFs. The unique porous structure and heterogeneous interface derived from MOFs facilitated efficient scattering and multiple reflections of microwaves. By harnessing interfacial polarization loss, dipole polarization loss, and conduction loss mechanisms synergistically, the chain-shaped porous multi-stage CNFs-CoNi/C composite exhibited exceptional microwave absorption performance at a filling ratio of 10 %. It achieves a maximum reflection loss of −70 dB and an absorption bandwidth (EAB) for RL ≤ -10 exceeding 4.82 GHz with a corresponding thickness as low as 1.25 mm. This study introduced a lightweight and highly absorptive material that offers valuable insights into developing high-performance electromagnetic wave absorbing materials through organic composite comprising MOF and carbon materials.

Heterogeneous interface engineering of spindle shaped Fe/C through optimizing impedance response for enhanced microwave absorption and thermal conductivity

Heterogeneous interface design is pivotal in creating lightweight, broadband, and high-efficiency electromagnetic wave (EMW) absorption materials. These materials enhance wave absorption by adaptively matching impedance. In this study, spindle-shaped Fe/C nanocomposites with heterogeneous interfaces and diverse surface microtopographies were synthesized by calcining iron-supported metal-organic frameworks (MOFs). During controlled pyrolysis, Fe3+ was reduced by carbon and conversely induced the graphitization of carbon, which is essential for the distribution and appearance of Fe and graphitized carbon as well as for modulating impedance matching. The porous structure of the Fe/C composites and the polarization loss and ferromagnetic resonance from the defective carbon and Fe magnetic particles synergistically enhance the wave absorption performance. The Fe/C-700 nanocomposite achieves a reflection loss (RL) of −55.9 dB at 12.48 GHz with an effective absorption bandwidth (EAB, RL ≤ −10 dB) of 3.9 GHz at 1.8 mm. The Fe/C-900 nanocomposite demonstrates a significant RL of −63.5 dB at 15.8 GHz with an EAB of 4.4 GHz between 13.6 GHz and 18 GHz at 1.5 mm, and an EAB of 5.5 GHz at 1.63 mm. These improvements are attributed to the impedance matching facilitated by the introduction of Fe magnetic particles and graphitized carbon. Additionally, the thermal conduction pathway formed among the Fe/C nanocomposites significantly enhances the thermal conductivity to 0.502 W m−1 K−1. Thus, this work offers a novel approach to the design of advanced wave-absorbing and thermal conductive materials by optimizing impedance through heterogeneous interfaces.

Graphene-Wrapped Magnetic Multichamber Ti3C2Tx Spheres for Stable Broadband Microwave Absorption.

Two-dimensional transition metal carbides/nitrides (MXenes) have aroused widespread interest in the field of microwave absorption because of their unique layered structures. However, the inherent aggregation, poor impedance matching, and low chemical stability of MXenes inevitably obstruct their practical applications. Herein, a multichamber Fe3O4/Ti3C2Tx@reduced graphene oxide (FT@RGO) hierarchical structure was constructed through self-assembly and sacrificial template strategies where the Ti3C2Tx nanosheets were assembled into hollow microspheres that were decorated with Fe3O4 nanospheres and wrapped by RGO nanosheets. The massive heterointerfaces and interior cavities favor enhanced microwave absorption performance via interfacial polarization, multiple scattering/reflections, and dielectric-magnetic synergistic effects. Consequently, the synthesized ultralight FT@RGO foam (0.009 g/cm3) presents superior microwave absorption ability with the minimum reflection loss of -50.5 dB at the matching thickness of 2.5 mm and effective absorption bandwidth of 8.0 GHz covering the frequency range of 10.0-18.0 GHz at the thickness of 2 mm. Furthermore, the encapsulation of hollow Ti3C2Tx spheres by RGO nanosheets avoids direct contact with external air, which considerably improves the stability of Ti3C2Tx and ensures the long-term application of FT@RGO foam in a conventional environment. This work provides a reference for the structural design of MXene-based materials as broadband and durable microwave absorbers.

Synergistic effects of nitrogen/oxygen co-doping in 3D mesoporous carbon nanospheres for enhanced microwave absorption

Mesoporous carbon nanospheres have attracted significant attention in the microwave absorption (MA) field due to the broad benefits provided by their mesoporous structure. This study presents a facile hard template strategy to construct distinctive 3D N/O co-doped mesoporous carbon nanospheres (NOCS). The high surface area, abundant mesopores, and high nitrogen (N) doping levels, with proper defects on the surface provide multiple sites to absorb electromagnetic waves (EMW). Mesoporous carbon nanospheres achieve significant reflection loss (RL) of −48.19 dB and extensive effective absorption bandwidth (EAB) up to 5.52 GHz. Moreover, computer simulation technology (CST) demonstrated that all simulated Radar cross-section (RCS) values were below 20 dB m2. Thus, this work holds significant promise for effective microwave absorbers using mesoporous carbon nanospheres.

Polypyrrole nanoclips-coated Co/C nanostructures with enhanced microwave absorption

There is a challenge to boost the electromagnetic wave absorption performance of magnetic carbon-based materials by rationally adjusting the structure of MOF. In this paper, nanoclip-shaped polypyrrole (PPy) was wrapped on the surface of the Co/C nanoparticle derived from Co-MOF via in-situ polymerization of pyrrole with the help of cetylammonium bromide. The electromagnetic parameters of prepared Co/C@PPy can be easily tuned by adjusting the feed ratio of PPy to Co/C. The optimum value of reflection loss (RL) for Co/C@PPy is −45.49 dB at 2.4 mm and 15.12 GHz when the feed ratio of pyrrole to Co/C is 200 μL to 80 mg, and the effective absorption bandwidth (EAB, RL ≤ −10 dB) reaches 5.97 GHz (11.76–17.73 GHz) at the matching thickness of 2.5 mm. This study paves the way for further design and preparation of the nanocomposites based on MOF-derived nanostructures with excellent EMW absorption performance.

Enhancement of Microwave Absorption Properties of Crystal‐Engineered Perovskite Oxide Using Cobalt Ferrite

A multiferroic composite that comprises of a non‐ferromagnetic ferroelectric material with a high dielectric constant and a non‐ferroelectric ferromagnetic material with a high magnetostriction is of tremendous interest as microwave absorption material due to its applicability in tunable microwave phase shifters, resonators, filters, absorbers, etc. In the previous work, the solid solution of strontium titanate and sodium bismuth titanate (Sr0.5(Na0.5Bi0.5)0.5TiO3, SNBT50), which is observed to possess a very high dielectric constant at room temperature (Ferroelectrics, Vol 583, 252–263 [2021]), is successfully reported. Thus, in this work, a core–shell magnetoelectric composite is prepared by coating highly ferromagnetic and magnetostrictive cobalt ferrite onto a diamagnetic but strongly ferroelectric SNBT50 to enhance its magnetic properties and to investigate the modification in microwave absorption. Detailed characterization of electric and magnetic parameters in microwave frequency range (1–20 GHz) reports substantial enhancement in the magnetic permeabilities as well as the magnetic loss of the composite system, as opposed to bare SNBT50. This results in improved impedance matching in the system and enhanced microwave absorption, with a minimum reflection loss (RL) of −20.19 dB and an increased effective absorption bandwidth of 4.56 GHz at a mere 2.7 mm absorber length. Consequently, in this investigation, a promising pathway is established for the development of multiferroic composites with favorable magnetoelectric coupling at room temperature that possesses wide absorption bandwidth and suitable RL, making them highly suitable for use in multiferroic‐based microwave components.

Enhanced microwave absorption in Fe3O4@PS/MWCNT multicomponent composites: Fabrication, characterization, and performance analysis

Multiple-component materials with advanced microstructure are increasingly utilized in the development of microwave absorption materials. In this paper, a magnetic hollow sphere composed of Fe3O4@PS was fabricated by simply depositing Fe3O4 nanoparticles onto the surface-modified PS hollow spheres through electrostatic interactions. The microwave absorption properties of Fe3O4 @PS hollow spheres were studied by varying the loading capacity of Fe3O4. The results show that when the Fe3O4 content is 28.59 wt%, the optimal minimum reflection loss is −26.9 dB with effective absorption bandwidths (RL ≤ −10 dB) exceeding 0.3 GHz. Furthermore, the straightforward combination of the Fe3O4@PS with MWCNTs enables the enhancement of the microwave absorption up to −41.4 dB at 14.5 GHz, with an effective absorption bandwidth exceeding 5.9 GHz (12.1–18 GHz) at a thickness of 2 mm. This study is expected to provide valuable insights into the design of nanocomposites for microwave absorption applications.

Enhanced microwave absorption in GaFeO3 coated CoFe2O4 nano-hollowsphere

As a multiferroic material with substantial magnetoelectric coupling, gallium ferrite (GaFeO3, GFO) has been intensively studied in recent years. Cobalt ferrite (CoFe2O4, CFO) nano-hollowsphere (NHS), on the other hand, is found to be an efficient material for electromagnetic (EM) wave absorption. In this work, a composite consisting of magnetostrictive CFO NHS coated with GFO nanoparticles [(1−x)CoFe2O4 – xGaFeO3, for x = 0.0, 0.9, 0.7, 0.5, 0.3, and 1.0] is prepared as an effective strategy to develop highly efficient microwave material. The EM wave absorption properties of the samples are thoroughly investigated across a widely used frequency range of 1–20 GHz. Remarkable performance of the x = 0.7 composite is evident by its effective bandwidth of approximately 3 GHz and a minimum reflection loss of approximately −63.26 dB. Moreover, the excellent impedance matching, with |Zin/Z0| ≅ 1.00, observed in the aforementioned composite, satisfies well with the required characteristics for a superior microwave absorber. Therefore, a core–shell nanostructure consisting of CFO NHS as core and GFO with optimized shell thickness can be used successfully in microwave devices.