Magnetic Loss Research Articles

Exploring the Microstructural Effect of FeCo Alloy on Carbon Microsphere Deposition and Enhanced Electromagnetic Wave Absorption.

The rational design of magnetic carbon composites, encompassing both their composition and microstructure, holds significant potential for achieving exceptional electromagnetic wave-absorbing materials (EAMs). In this study, FeCo@CM composites were efficiently fabricated through an advanced microwave plasma-assisted reduction chemical vapor deposition (MPARCVD) technique, offering high efficiency, low cost, and energy-saving benefits. By depositing graphitized carbon microspheres, the dielectric properties were significantly enhanced, resulting in improved electromagnetic wave absorption performances through optimized impedance matching and a synergistic effect with magnetic loss. A systematic investigation revealed that the laminar-stacked structure of FeCo exhibited superior properties compared to its spherical counterpart, supplying a higher number of exposed edges and enhanced catalytic activity, which facilitated the deposition of uniform and low-defect graphitized carbon microspheres. Consequently, the dielectric loss performance of the FeCo@CM composites was dramatically improved due to increased electrical conductivity and the formation of abundant heterogeneous interfaces. At a 40 wt% filling amount and a frequency of 7.84 GHz, the FeCo@CM composites achieved a minimum reflection loss value of -58.2 dB with an effective absorption bandwidth (fE) of 5.13 GHz. This study presents an effective strategy for developing high-performance EAMs.

Fe3O4 Nanoparticles Embedded into Pyridinic-N-Rich Carbon Nanohoneycomb with Strong dx2-Pz Orbital Hybridization for High-Performance Electromagnetic Wave Absorption.

Carbon-based magnetic nanocomposites as promising lightweight electromagnetic wave (EMW) absorbents are expected to address critical issues caused by electromagnetic pollution. Herein, Fe3O4 nanoparticles embedded into a 3D N-rich porous carbon nanohoneycomb (Fe3O4@NC) were developed via the pyrolysis of an in-situ-polymerized compound of m-phenylenediamine initiated by FeCl2 in the presence of NaCl crystals as templates. Results demonstrate that Fe3O4@NC features highly dispersed Fe3O4 nanoparticles into an ultrahigh specific pyridinic-N doping carbon matrix, resulting in excellent impedance matching characteristics and electromagnetic wave absorbing capability with the biggest effective absorption bandwidth (EAB) of up to 7.1 GHz and the minimum reflective loss (RLmin) of up to -65.5 dB in the thin thickness of 2.5 and 2.3 mm, respectively, which also outperforms the majority of carbon-based absorbers reported. Meanwhile, its high absorption performance is further demonstrated by an ethylene propylene diene monomer wave absorbing patch filled with 8.0 wt % Fe3O4@NC, which can completely shield a 5G signal in a mobile phone. In addition, theory calculation reveals that there is a strongest dx2-Pz orbital hybridization interaction between Fe3O4 clusters and pyridinic-N dopants in the carbon network, compared with other kinds of N dopants, which can not only generate more dipoles of carbon networks but also increase net magnetic moments of Fe3O4, thereby leading to a coupling effect of efficient dielectric and magnetic losses. This work provides new insights into the precise design and synthesis of carbon-based magnetic composites with specific interface interactions and morphological effects for high-efficiency EMW absorption materials.

N-doped CNTs/CoNi nanochains-carbon hollow microspheres multi-level multi-scale heterogeneous interface structures and microwave absorption properties

Constructing multi-level multi-scale heterogeneous interfaces in magnetic carbon-based composites remains a formidable challenge, requiring rational material combinations to effectively balance dielectric and magnetic losses for achieving high strength and wide frequency wave absorption. Electromagnetic wave (EMW) absorbing materials consisted of cobalt-nickel (CoNi) magnetic nanochain, nitrogen-doped carbon nanotubes (NCNTs) and hollow carbon microspheres were prepared by hydrothermal method without external magnetic field. These composites possessed a unique multi-level multi-scale heterogeneous interface structure that is highly advantageous for efficient absorption of EMWs. The CoNi nanoparticles were self-assembled into uniformly distributed and randomly oriented magnetic nanochains, which were further reassembled with NCNTs and hollow carbon microspheres to form heterogeneous interface structures resembling a rose, chrysanthemum, hedgehog ball, and bauhinia tree. Due to the high-density interface enhancing the loss ability of interface polarization, as well as the higher saturation magnetization, coercivity, and wave absorption ability of the magnetic nanochains compared to the magnetic nanoparticles themselves, the minimum reflection loss achieved is −66.86 dB, and the effective absorption bandwidth achieved is 5.01 GHz, at a content as low as 11 wt%. This study provides a new idea for generating nanochains without magnetic fields and constructing multi-level and multi-scale heterogeneous interface structures to achieve strong absorption and wide effective absorption bandwidth (EAB).

MXene-derived titanate heterojunctions with lightweight and heat-resistant properties for electromagnetic wave absorption

The development of high-efficiency titanate-based electromagnetic wave (EMW) absorbers presents a significant challenge, primarily due to the limited number of loss mechanisms available in such materials. Herein, an innovative approach has been employed, utilizing g-C3N4 as a connecting bridge linking KTi8O16.5 nanorods with Fe2O3 nanoparticles, thereby crafting a KTO/Fe2O3–CN absorber with a dual heterojunction architecture. This sophisticated structure is realized through a detailed freeze-drying process followed by heat treatment. In this structure, g-C3N4 and KTi8O16.5 originate from melamine and MXene precursors, respectively, while Fe2O3 component is derived from the thermal decomposition of FeSO4. The integrated KTO/Fe2O3–CN system fosters enhanced interfacial and dipole polarization, as well as conduction and magnetic loss, all collaboratively aiding in the attenuation of EM waves. In addition, the specially designed EMW absorber is notable for its lightweight nature, along with impressive heat dissipation and resistant performance. It demonstrates exceptional thermal stability, capable of withstanding temperatures as high as 500 °C and sustaining repeated thermal cycles at 400 °C. This strategy not only elevates the efficacy of titanate-based EMW absorbers but also paves the way for the conceptualization of high-performance, multifunctional EMW absorption materials. Such advancements hold the promise of transforming a wide range of applications that necessitate effective EM wave attenuation, marking a significant leap forward in the field.

Microstructure‐Tuned Amorphous Co2FeGe Nanoflakes for Enhanced Microwave Absorption Via Mechanical Alloying

Herein, a simple strategy for fabricating amorphous Co2FeGe nanoflakes by tuning the milling time with mechanical alloying method to enhance the microwave absorption capabilities is presented. These alloys exhibit soft magnetic properties characterized by high saturation magnetization and low coercivity. The enhancement of polarization and resonance effects, leading to improved magnetic and dielectric loss, is attributed to the refinement of crystalline size and the substantial aspect ratio of flaky particles. The minimum reflection loss reaches −48.6 dB at 4.92 GHz with an effective absorption bandwidth of 2.88 GHz in the C‐band. Due to its high Curie temperature, Co2FeGe exhibits considerable potential for maintaining highly efficient microwave absorption capabilities under high‐temperature conditions, thereby providing a novel perspective and technical means for the development of new high‐temperature‐resistant, high‐performance microwave‐absorbing materials. This is expected to play a significant role in future high‐temperature electronic countermeasure systems.

Substitution modification mechanism of YIG ferrite with a high spin-wave linewidth via fast relaxation Dy3+ ion doping and sintering modulation

YIG ferrites are often used as nonreciprocal materials in microwave ferrite devices because of their low microwave magnetic and dielectric losses. To comply with the trend of planarization and integration of microwave systems, YIG ferrites are required to withstand higher powers. In this study, we investigated the variation in material microwave properties with material composition and microstructure. The experimental results show that doping the material with high-relaxation ions Dy3+ combined with modulating the sintering holding time can effectively improve the material’s high-power microwave signal withstanding capability, and YIG ferrite with a spin-wave line width of 18.7 Oe is obtained. In addition, when the average grain size of the material is controlled within 5 μm, the effect of the average grain size on the spin-wave linewidth is more noticeable than that of Dy3+ substitution.

Fe3O4@CNTs/PANI/PI fabric with magnetic–dielectric nanonetwork as a highly efficient microwave absorber

Since the matching between the complex permittivity and permeability plays a dominant role in the performance of microwave absorbing, magnetic-dielectric materials have been increasingly used for microwave absorption. In this paper, Fe3O4 nanoparticles anchored on carbon nanotubes (Fe3O4@CNTs) were fabricated via a self-assembled technique. The efficient microwave-absorbing fabric was synthesized by building polyaniline nanofibers (PANI NFs) and Fe3O4@CNTs magnetic–dielectric network on the surface of polyimide (PI) fabric. The results of SEM, FTIR, and XRD demonstrated the presence of Fe3O4@CNTs on the fabric surface. The decomposition temperature (Td) of the fabric was beyond 580.0 °C and the fabric exhibited strong hydrophobicity (water contact angle 125.0°). The Fe3O4@CNTs/PANI/PI fabric possessed a minimum reflection loss (RL) value of −62.61 dB (>99.9 % absorption) with a matching thickness of 1.58 mm. The excellent microwave absorption capacity is attributed to the well impendence match, dielectric and magnetic loss, and the scattering loss of the special cell structure.

Construction of multi-interface magnetic FeMnC modified carbon/graphene aerogels for broadband microwave absorption

Magnetic carbon-based aerogels with low-density and strong attenuation, have attracted significant attention as microwave absorbing materials, but still face huge challenges. Herein, magnetic FeMnC modified carbon/Graphene aerogels (NCMF) were synthesized utilizing freeze casting following a carbothermal reduction process. The conductivity, defects density, material component and electromagnetic properties can be regulated by the temperature. The NCMF aerogels exhibit remarkable microwave absorption properties, with an effective absorption bandwidth of 5.76 GHz at a thickness of 2.1 mm and a minimum reflection loss as low as −50.8 dB at 7.52 GHz with a fill ratio of only 5 wt%. The exceptional microwave absorption capabilities of NCMF aerogels are attributed to the synergistic effects of dielectric loss, magnetic loss, three-dimensional (3D) carbon conductive network, and the optimal impedance matching. Consequently, this research paves a way for the development of microwave absorbing materials with lightweight, broadband and strong microwave absorption at low loading.

Electromagnetic porous lignocellulosic matrix composites: A green electromagnetic shielding material with high absorption efficient electromagnetic interference

Electromagnetic interference (EMI) shielding materials play a vital role in human society, especially in light of the rapid development of electronic communication equipment. Therefore, it is urgent to develop green, high-efficiency EMI shielding materials. Wood, as a renewable raw material, possesses significant structural advantages in studying EMI materials due to its unique 3D pore structure. Herein, we report magnetoelectric lignocellulosic matrix composites derived from the delignified wood for efficient EMI shielding. The composite was fabricated by in-situ polymerization of PEDOT conductive coating and magnetic Fe3O4 in delignified wood. The conductive 3D pore structure of Fe3O4/PEDOT@wood could effectively cause dielectric loss and multiple internal reflections. Combined with the magnetic loss of Fe3O4, the material exhibited excellent EMI shielding effectiveness (SE), which could be attributed to the synergistic effect of dielectric and magnetic losses. The Fe3O4/PEDOT@wood showed excellent conductivity (103 S/m), good magnetism (26.7 emu/g), the EMI SE up to 59.8 dB, and high SEA/SET ratios of∼84.2 % to 95.7 % at 2 mm in X -band. Moreover, the material exhibited a high compressive strength and tensile strength of 100.8 MPa and 18.1 MPa, respectively. Therefore, this work provided a reference for the preparation of high-efficiency EMI shielding materials.

Strong microwave absorption of Fe-deficient SrFe9.4Cu0.8Sn0.5O19-d with enhanced permittivity and ferromagnetic resonance by high annealing temperature

The oxygen environments of Fe+3-δ ions determine the magnetic anisotropy of M-type ferrites. The high annealing temperature increases the oxygen content and decreases the lattice strain in M-type SrFe9.4Cu0.8Sn0.5O19-d ferrites. The anisotropic field and the coercive field decrease with the increasing annealing temperature. Annealed at 1400 °C, a ferromagnetic resonance is observed at the frequency above 9.5 GHz, with the real part having a peak and the imaginary part of the permeability having a high plateau over a wide frequency range. It enables the microwave energy' dissipation by the magnetic loss. Furthermore, the extra oxygen ions ease up the dipole polarizations' rotation and significantly increase the dielectric permittivity. At thin thickness of 1.3 mm, the effective absorption bandwidth (RL≤−10 dB) of SrFe9.4Cu0.8Sn0.5O19-d annealed at 1400 °C is 7.1+ GHz from 10.9 to 18+ GHz. SrFe9.4Cu0.6Sn0.6O19-d annealed at 1400 °C has the microwave absorption bandwidth of 8.8 GHz from 9.2 to 18+ GHz at 1.6 mm. Both are very promising microwave absorbing materials.

Lanthanum Substituted Mg-Zn Ferrite Nanostructures: A Comprehensive Study of Cation Distribution, Structural, Morphological, Optical, Magnetic, Dielectric, and Electromagnetic Traits

The sol-gel auto-combustion (SC) procedure was utilised to fabricate lanthanum-doped Mg-Zn nanostructures with the chemical composition, Mg0.6Zn0.4LaxFe2-xO4, (x = 0, 0.05, 0.10). X-ray diffraction showed nanocrystalline and single-phase of Mg-Zn nanostructures. The morphological traits showed formation of irregular and aggregated grains. Fourier transform infrared spectroscopy detected the formation of two characteristic band positions that fall within the range of 400 to 600 cm−1 and may occur because of stretching vibration within metal-oxygen (M-O) cations located at interstitial positions. From the M-H loops, the excellent values of magnetic factors, such as the saturation magnetization (Ms), rentivity (Mr), and coercivity (Hc) ranging from 35.30 to 44.79 emu g−1, 1.40 to 3.75 emu g−1, and 11.56 to 41.42 Oe were obtained. The loss tangent (tan δ) was observed to be miniscule for all of the samples due to which they can be useful for electronic applications. However, the initial values of the real permeability ( μ′ ) was high and it decreases until 4 GHz, after which it acquires a constant value for rest of frequency range. However, observed low values of the magnetic loss tangent (tan δ μ ) were due to the large grain size and the high densification of the samples.

Polypyrrole modified MIL-101-Fe-derived Fe/Fe3O4@C composites for high-performance microwave absorber

Carbon-based microwave absorbing composites with magnetic-dielectric properties and multiple loss mechanism are considered to be an effective choice for solving electromagnetic pollution. In this paper, the PPy/Fe/Fe3O4@C composite was synthesized from MIL-101-Fe derivatives and subsequently coated polypyrrole (PPy) by combining hydrothermal, high-temperature pyrolysis and oxidative polymerization. The effects of pyrolysis temperature and PPy loading on components, microstructures and electromagnetic parameters were investigated. The results showed that the PPy/Fe/Fe3O4@C composite consisted of two-dimensional carbon flakes modified by magnetic particles and laminated conductive polymers. When the PPy loading is moderate, the composite reaches a minimum reflection loss (RLmin) of −61.38 dB at a 3.1 mm thickness and effective absorption bandwidth (EAB) of 5.81 GHz at the thickness of 2.2 mm. After pyrolysis, the unique three-dimensional structure of carbon sheet stacking, as well as the heterogeneous interface and conductive networks generated by the modification of magnetic particles Fe and Fe3O4 and conductive PPy, are beneficial to improve the dielectric and magnetic losses to optimize the impedance matching. These conductive polymer-modified magnetic-dielectric composites have potential for development and application in microwave absorption.

Agarics-derived porous Fe/C material activated by ZnCl2 and its enhanced microwave absorption performance

Biomass-derived carbon materials retain the unique porous structure of biological raw materials and have environmental advantages, making them a popular choice for electromagnetic microwave absorption research. The microwave absorption performance of biomass-derived carbon materials is largely influenced by their pore structure, which can be controlled by chemical activators. In this study, ZnCl2 was chosen as the activator and de-impregnated agarics with Fe(NO3)3·9 H2O for pretreatment. The Fe(NO3)3·9 H2O can provide magnetic Fe particles for the material to enhance the magnetic loss ability. And the weakly acidic ZnCl2 can avoid the pollution of the environment, and its dehydration and dehydroxylation properties can release the hydrogen and oxygen in the biomass char material in the form of water vapor, and release the hydrogen and oxygen in the biomass carbon material in the form of water vapor, and form a porous structure. porous structure. In addition, ZnCl2 will be converted to ZnO during the activation process, and the removal of ZnO by acid washing will increase the internal pore volume, form a conductive network, and form a rich three-dimensional interconnected pore structure. The pretreated samples were vacuum carbonized at high temperature to obtain agarics-derived porous Fe/C material, which is an excellent lightweight and high-performance microwave absorbing material. The resulting material has a wider absorption bandwidth and improved microwave absorption performance. At a thickness of 2.55 mm and a frequency of 8.31 GHz, the RLmin of Fe/C material is −51.14 dB. Furthermore, at a thickness of 2.13 mm, it has an effective absorption bandwidth of 3.63 GHz, covering most of the X-band.

Coupling dielectric and magnetic components on a ternary composite for enhancing impedance matching and microwave absorption

Here in, a novel ternary manganese monoxide@nitrogen-doped carbon nanotube@cobalt composite was obtained via a scalable multistep reaction pathway. Mnganese monoxide (MnO) is adopted as the microwave transparent substrate to couple dielectric and magnetic components. The abundant internal voids of MnO and numerous interfaces between MnO and carbon can increase the dielectric loss to improve the microwave absorption (MA) performance, metal cobalt is employed as the magnetic component to enhance the magnetic loss. Benefiting from the synergistic effect of heterostructures, the ternary absorber exhibits the minimum reflection loss (RLmin) of −48.65 dB@8.1 GHz@2.8 mm and the effective absorption band (EAB) of 5.8 GHz with the thickness of 1.7 mm. Furthermore, the crystal structure, material components, surface element distribution and magnetic properties of the absorbers are characterized, the structure-performance correlation between “Physical properties” and “Electromagnetic performance” is established. Finally, the reliable MA mechanism based on “hierarchical component modulation” is summarized to guide the design of MnO-based absorbers.

Microwave absorbing alkaline catalyst for biodiesel production via MIL-100(Fe): Catalytic optimization, characterizations, kinetics, and distillation simulation

Microwave heating (MW) is known for its efficacy in promoting transesterification for biodiesel production. However, the microwave-induced catalysis, linked to catalyst absorbing capability, remains poorly understood. Herein, a class of alkaline catalysts with strong microwave absorption were synthesized, validating their positive impact on transesterification. Various methods were used to reveal the relationship between microwave absorbing capacity and physicochemical properties of the synthesized catalyst (KF/Mg-MIL). Results indicated the previously recognized basicity’s role for KF/Mg-MIL was surpassed by microwave absorbing capability (permittivity and permeability) in MW (2.45 GHz). KF/Mg-MIL, with εr = 4.94′-j1.09″ and μr = 1.03′-j0.024″, efficiently transformed microwave into thermal energy via the dielectric loss and magnetic loss, saving 50 % energy consumption and reducing 1051.61 kg CO2 for per ton biodiesel compared to water bath heating (WB). Notably, “non-thermal” effect was observed with KF/Mg-MIL in MW, which reduced activation energy by 2.49 kJ/mol and increased the frequency factor by 793.32 min−1 in comparison to WB.

Porous carbon composite nanosheets loaded with magnetic FeNi/NiFe2O4 and dielectric SiO2 nanoparticles for adjustable microwave absorption

According to the escalating concern regarding the health hazards associated with electromagnetic radiation, the significance of absorbing materials underscores which could mitigate the healthy risks. While magnetic materials offer excellent absorption performance, their high density poses challenges to achieving optimal absorption efficiency. Conversely, carbon-based materials are known for their lightweight and versatile but face impedance matching issues. To address these obstacles, carbon/magnetic composite materials have been explored. However, their absorption performance has not fully met requirements due to weaker magnetic properties and increased density. Herein, we synthesized a porous carbon material embedded with magnetic FeNi/NiFe2O4 and dielectric SiO2 nanoparticles (FeNi-NiFe2O4-SiO2@PC) using carbonthermal method. By adjusting the ratio of polyvinylpyrrolidone to nitrates, the electromagnetic wave (EMW) absorption performance is adjusted. The FeNi-NiFe2O4-SiO2@PC composites display remarkable EMW absorption properties, achieving a minimum reflection loss of −69.9 dB at a thin thickness of 1.495 mm and a maximum effective absorption bandwidth of 5.68 GHz, covering the range from 12.32 to 18.0 GHz at a thickness of 1.92 mm. This outstanding performance can be attributed to the favorable impedance matching and the three-dimensional porous structure, which facilitates a 3D transmission network for multiple reflections. Additionally, the presence of FeNi, NiFe2O4, and SiO2 nanoparticles enhances magnetic loss, conductive loss, interface polarization, and dipolar polarization, leading to excellent ab. Hence, this work offers insights into the composition design of high-performance absorbing materials.

Synchronous enhancement and broadening of dielectric loss and magnetic loss induced by substituted Gd in GdFeO3-encapsulated Fe (Gd) nanoparticles

Synchronous enhancement and broadening of dielectric loss and magnetic loss is a key factor for achieving excellent microwave absorption behavior. However, one term’s reinforcement always comes at the expense of the other one. In this work, a new kind of core-shell structured nanoparticle has been designed and prepared by arc-discharge method, in which GdFeO3 is shell and Fe (Gd) solid solution works as core, respectively. Except for the typical interfacial polarization and natural resonance, the new dipole induced by asymmetric electric charge arising from substituted Gd in Fe lattice results in enhanced and broadened dielectric loss, and the strong local magnetic anisotropy induced by intensive magnetic Fe-Gd coupling between 3d-4 f electrons leads to enhanced and broadened magnetic loss. Synchronously widened and enhanced dielectric and magnetic loss ensure that GdFeO3-encapsulated Fe(Gd) nanoparticles have effective absorption bandwidth of 4.16 GHz (10.48–14.64 GHz) at 2.3 mm, compared with that (2.32 GHz at 4.9 mm) of Fe nanoparticles. This study develops an approach for synchronously enhancing dielectric loss and magnetic loss, which has potential for achieving excellent EM absorption behaviors.

Synthesis, characterization and microwave absorption properties of BaFe12O19/Ni0.5Mn0.5Fe2O4@ polyaniline nanocomposites with different ferrite percentages

AbstractIn this paper, BaFe12O19/Ni0.5Mn0.5Fe2O4@PANI core‐shell nanocomposites were synthesized with different ferrite/PANI ratios. The Ferrite nanoparticles were prepared by the auto‐combustion sol–gel method. Chemical oxidative polymerization of aniline in acidic solution along with adding ferrite nanoparticles to the composition was used for the synthesis of nanocomposites. The product then was studied by X‐ray diffractometer)XRD(, field emission scanning electron microscope (FE‐SEM), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FTIR) analyses. The magnetic properties of samples were investigated with vibrating sample magnetometer (VSM). Also, nanocomposite samples were examined in terms of the ability to absorb microwaves. Using Vector Network Analyzer (VNA). the reflection loss (RL) of nanocomposites was measured at frequencies between 2 and 18 GHz. The minimum reflection loss (RLmin) was obtained at −36.98 dB at the frequency of 13.8 GHz with an effective absorption bandwidth of 4.87 GHz for the sample with the equal ratio of ferrite/PANI. Synthesized nanocomposite as an effective compound has very high reflection loss in a wide frequency range.Highlights Thermal stability is improved by adding ferrite nanoparticles to polyaniline. The polymer shell reduces the magnetic properties of ferrite nanoparticles. There is a strong exchange coupling between hard and soft ferrite. Ferrite/polymer ratio of 1:1 has the lowest amount of reflection loss. In the X and Ku band, magnetic loss is mainly caused by eddy currents.

Preparation and properties of electromagnetic shielding leather based on magnetic MgFeCr-LDHs

Leather, as a kind of renewable biomass, is naturally rich in dipoles as well as excellent 3D fiber structure, which provides the possibility for its application in electromagnetic shielding field. This study combined the utilization of chromium-containing wastewater with the intelligent development of leather. Nano zero-valent iron (NZVI) was innovatively used to prepare magnetic Mg/Fe/Cr layered double hydroxide (MgFeCr-LDHs) by co-precipitation method while treating chromium wastewater. And magnetic MgFeCr-LDHs was used for tanning leather, which prepared electromagnetic shield leather (MgFeCr-LDHs/L). Fe3+ and Cr3+ in MgFeCr-LDHs were closely bonded with the active groups on collagen fibers by chemical bonding, which give leather hygrothermal stability. The shrinkage temperature of MgFeCr-LDHs/L reached 89.1°C. Electromagnetic shielding efficiency of magnetic MgFeCr-LDHs/L reached 25 dB due to MgFeCr-LDHs had better dielectric and magnetic losses to electromagnetic waves. Magnetic MgFeCr-LDHs/L also had good softness and mechanical properties. In summary, we expect magnetic MgFeCr-LDHs/L to be used as a wearable material in the field of electromagnetic shielding.

Enhanced electromagnetic wave absorption of La0.8Ca0.2Fe1-xMnxO3 boosted by lattice distortion and double-exchange

Perovskite LaFeO3 with ABO3 structure is regarded as a potential candidate in electromagnetic wave absorption, considering its unique dielectric-magnetic coupling loss mechanism. However, the limited attenuation ability of pristine LaFeO3 restricts its further application. In this work, the dual doping strategy is carried out to improve the dielectric and magnetic loss capacity. Ca and Mn dual doped La0.8Ca0.2Fe1-xMnxO3 are prepared by spray pyrolysis method. The minimum reflection loss (RLmin) of La0.8Ca0.2Fe0.2Mn0.8O3 reaches −52.3 dB with an effective absorption bandwidth (EAB) of 3.92 GHz at the fitting thickness of 2.08 mm. The enhancement of the dielectric loss mainly originates from strengthened dipole polarization induced by the Jahn-Teller distortion which is caused by Ca and Mn double doping. The magnetic loss can be attributed to the improvement of double-exchange between Fe3+ –O2- -Mn3+ and Mn3+ –O2- -Mn4+ owing to the introduction of Mn. This work provides new insights into regulating the electromagnetic wave absorption performance of perovskite.