Interference Of Electromagnetic Waves Research Articles

Poly(styrene sulfonic acid)-Grafted Carbon Black Synthesized by Surface-Initiated Atom Transfer Radical Polymerization.

Owing to their excellent electrical conductivity and robust mechanical properties, carbon-based nanocomposites are being used in a wide range of applications and devices, such as electromagnetic wave interference shielding, electronic devices, and fuel cells. While several approaches have been developed for synthesizing carbon nanotubes and carbon-black-based polymer nanocomposites, most studies have focused on the simple blending of the carbon material with a polymer matrix. However, this results in uncontrolled interactions between the carbon filler and the polymer chains, leading to the agglomeration of the carbon filler. Herein, we report a new strategy for synthesizing sulfonated polystyrene (PSS)-grafted carbon black nanoparticles (NPs) via surface-initiated atom-transfer radical polymerization. Treatments with O2 plasma and H2O2 result in the effective attachment of the appropriate initiator to the carbon black NPs, thus allowing for the controlled formation of the PSS brushes. The high polymeric processability and desirable mechanical properties of the PSS-grafted carbon black NPs enable them suitable for use in nonfluorinated-hydrocarbon-based polymer electrolyte membranes for fuel cells, which must exhibit high proton conductivity without interrupting the network of channels consisting of ionic clusters (i.e., sulfonic acid moieties).

A review: Advancement in metamaterial based RF and microwave absorbers

Microwave absorbers (MAs) are specially designed structures which dissipate an incident electromagnetic (EM) wave by converting it into thermal energy and thereby prevents reflection and/ or transmission. The MAs are extensively in demand due to their property to reduce the electromagnetic wave interference (EMI) and to enhance electromagnetic shielding (EMS). MAs are also used in potential military applications as a stealth technology to design stealth aircrafts, warships and army clothing etc. due to the reduction of radar cross section (RCS) of the defense equipment by the absorber coating. In this review work, study of metamaterial-based MAs, their characteristics viz. left-handed material property, permittivity and permeability have been discussed in detail. Metamaterials (MMs) or artificial materials that play a significant role in reducing the size and thickness of MAs depending upon the frequency of operation. In this work, theoretical background of MM-based absorbers detailing the effect of permittivity and permeability on absorber performance has also been discussed. Different applications of absorbers are elaborately covered in this paper. Furthermore, frequency selective surface (FSS) which is a two-dimensional array has the capability to reflect or transmit EM wave completely or partially depending upon the nature of FSS. Therefore, distinct categories of FSS-based absorbers are discussed according to the frequency of operation, bandwidth and material specification where the effect of different design parameters is also critically analyzed. The objective of this review paper is to provide an exhaustive study of the unique attributes of MAs having a diverse range of applications for frequencies ranging from microwave, terahertz upto optical frequency domain. This review paper is certainly a vital tool for researchers to accurately understand, explore and work on MA design and selection as per user defined specific frequency and applications.

Microwave absorption and thermal conductivity properties in NPC@MoSe2/PDMS composites

As electronic devices develop rapidly toward miniaturization and integration, electromagnetic wave (EMW) interference and heat accumulation problems have risen sharply, thus thermal conductivity-EMW absorption integrated materials (HCMAMs) have received extensive attention. Herein, a dual-function hierarchical porous NPC@MoSe2 filler was constructed by salt-template-assisted freeze-drying, calcination and hydrothermal reaction. 3D Nitrogen-doped porous carbon (NPC), a thermal and conductive path, is the prerequisite for the integration of EMW absorption and thermal conduction. Dense MoSe2 layer reduces the discrepancy of impedance and phonon frequency between NPC and Polydimethylsiloxane (PDMS), optimizing the impedance matching and reducing the interface thermal resistance. Remarkably, under the fillings of only 15 w%, NPC@MoSe2-2/PDMS exhibits optimal EMW absorption with a minimum reflection loss (RLmin) of −51.6 dB@18 GHz and an effective bandwidth (EAB) of 7.1 GHz, and excellent thermal conductivity performance with a thermal conductivity of 0.97 W/m·K, which is 304% higher than that of pure PDMS. Overall, this dual-functional NPC@MoSe2-2/PDMS has great potential in protecting integrated electronic devices.

Hierarchical structures of carbon nanotubes anchored on core-sheath microrads toward electromagnetic wave absorption and shielding with Joule heating and superhydrophobic capacities

Hierarchical structures with synergistic dielectric-magnetic compositions are highly desired for electromagnetic wave absorption and interference shielding applications. Fabricating lightweight and high-performance electromagnetic protection composites with additional functions are demanded to suppress severe electromagnetic radiation and interference pollution. Herein, a unique three-dimensional hierarchical structure consisting of 1D multi-walled carbon nanotubes anchored on 1D MXene@CF core-sheath microrods are rationally proposed via electrostatic self-assembly and hydrothermal strategy as well as subsequent thermal-catalysis treatment. The multi-walled carbon nanotubes encapsulated with magnetic CoNi nanoparticles are immobilized onto core-sheath microrods matrix, constructing effective 1D/1D electron migration bridges and the uniformly dispersed magnetic component to facilitate magnetic coupling effect. Consequently, profiting from the optimized impedance matching, enhanced conduction loss, dielectric polarization, and magnetic loss, the as-prepared sample shows an outstanding absorption capacity with reflection loss value of −56.8 dB and X-band full absorption. When used as electromagnetic shielding materials, the composites exhibit exceptional electromagnetic interference shielding properties. In addition, the upgraded mechanical strength, remarkable voltage-driven Joule heating and superhydrophobic properties endow the absorbers with multi-scenario adaptability and long life-time applications. This work provides well-designed hierarchical structures for high-performance electromagnetic absorbing and shielding with the great prospect of multifunctional applications.

Resonators with tailored optical path by cascaded-mode conversions

Optical resonators enable the generation, manipulation, and storage of electromagnetic waves. The physics underlying their operation is determined by the interference of electromagnetic waves, giving rise to the resonance spectrum. This mechanism causes the limitations and trade-offs of resonator design, such as the fixed relationship between free spectral range, modal linewidth, and the resonator’s refractive index and size. Here, we introduce a new class of optical resonators, generating resonances by designing the optical path through transverse mode coupling in a cascaded process created by mode-converting mirrors. The generalized round-trip phase condition leads to resonator characteristics that are markedly different from Fabry-Perot resonators and can be tailored over a wide range. We confirm the existence of these modes experimentally in an integrated waveguide cavity with mode converters coupling transverse modes into one supermode. We also demonstrate a transverse mode-independent transmission and show that its engineered spectral properties agree with theoretical predictions.

Directional electromagnetic interference shielding of asymmetric structure based on dual-needle 3D printing

Some special electronic equipment not only need to avoid the interference of external electromagnetic waves (EMWs), but also need to transmit effective signals. Therefore, the development of directional electromagnetic interference (EMI) shielding materials has a great prospect. The asymmetric structure, consisting of the porous magentic rGF (reduced graphene oxide and Fe3O4) layer and the dense electrical conductivity rGM (reduced graphene oxide and MXene) layer, was constructed by dual-needle 3D printing technology. After encapsulation and curing with polydimethylsiloxane (PDMS), the rGF/rGM/PDMS composites were prepared. When the ratio of rGF and rGM layers is 6:4, the SE values of rGF-6/rGM-4/PDMS composites are 38.75 dB and 30.79 dB respectively when EMWs are incident on the rGF layer and rGM layer respectively, and the ΔSE of which is about 8 dB. The results showed that the asymmetric structure composed of porous magnetic layer and dense deeply electric conductive layer could generate a special process of "weak reflection-absorption-strong reflection-reabsorption" for incident EMW. At the same time, the simulation results of the waveguide method validated the experimental results, and further explained the directional EMI shielding mechanism of asymmetric structure. For the first time, this work designs an asymmetric structure based on the double needle 3D printing technology, which provides useful inspiration for the structural design and potential application of directional EMI shielding materials.

Simultaneous manipulation of polarization relaxation and conductivity toward self-repairing reduced graphene oxide based ternary hybrids for efficient electromagnetic wave absorption.

In consideration of the growing electromagnetic wave (EMW) pollution and interference, it is of crucial and imperative significance to develop high-efficiency EMW absorption materials. Herein, hierarchical hybrid network of MoS2@poly (3, 4-ethylenedioxythiophene) (PEDOT)/reduced graphene oxide (rGO) were successfully constructed and fabricated through the combination of oxidative polymerization and microwave-irradiated thermal reduction. The original defects in graphene oxide (GO) could be in situ repaired by introducing carbon source, and the rational regulation of polarization relaxation and conductivity of composites could be achieved. Profiting from the good impedance matching, ameliorated conductivity and enhanced dipole polarization as well as interfacial polarization by introducing GO/defect-recovered rGO and conductive PEDOT, both the MoS2@PEDOT/GO and MoS2@PEDOT/rGO composites exhibited outstanding EMW absorption performances. In details, the minimum reflection loss (RLmin) and effective absorption bandwidth (EAB) of MoS2@PEDOT/GO can reach -48.65dB at 4.5mm, and 6.48GHz (11.52-18GHz) at 2.2mm, respectively. And the EAB of MoS2@PEDOT/rGO can reach 7.04GHz (10.8-17.84GHz) with an optimized RLmin of -32.41dB at 2.1mm under 20wt% filler loading. Therefore, these composites can be regarded as competitive candidates for lightweight and high-efficient EMW absorbers.

Electromagnetic Wave Absorption Performance of Carbon Nanocoils by Using Mixed Ferrites as Catalyst

Rapid development of electronic devices and advanced technology creates more electromagnetic wave interference that is harmful to human health as well as equipment. Thus, the use of electromagnetic (EM) wave absorber becomes more focused among researchers and attracted more public attention. Carbon nanocoils (CNs) have been introduced due to its chemical, physical and mechanical properties that can produce lightweight, wide absorption range and strong absorption. This research highlights the use of mixed ferrites (Fe3O4 and CoFe2O4) as catalyst to grow carbon nanocoils. Different weight percentages of Fe3O4 and CoFe2O4 were mixed to grow carbon nanocoils and further used as fillers to be incorporated into epoxy matrix. The morphological study of synthesized carbon nanocoils and reflection loss of the prepared polymer composites were studied in the range of X-band and Ku-band at thickness 1 mm, 2 mm, and 3 mm. The reflection loss achieved shows that mixed ferrites as catalyst to grow carbon nanocoils have great potential to be used as an excellent EM wave absorbers at low thickness.

Phase-Difference-Dependent Surface Plasmon Polariton Waveguide Coupling in a Symmetrical Dual-Channel Metal-Insulator-Metal Structure

This work reports a phase difference modulated coupling of two surface plasmon polariton (SPP) sources in a symmetrical two-channel metal-insulator-metal (MIM) waveguide device. In the device, two sources with different initial phases interact indirectly through the function of a rectangular cavity. With the phase difference varying, we have achieved tunable SPP coupling followed by continuously adjustable filtering property and Fano resonance. Further results show that the tunable SPP coupling in the resonance cavity can be well described by the electromagnetic wave interference theory. Moreover, we have also demonstrated the excellent performance of this phase-difference-dependent MIM waveguide in refractive-index sensing and have achieved considerable sensitivity as high as 818.8 nm/RIU. This research has great significance for tunable filtering and signal compensation in MIM waveguide-based photonic chips and also provides a device with high potential in refractive-index sensing.

Spin‐Controlled Reconfigurable Excitations of Spoof Surface Plasmon Polaritons by a Compact Structure

AbstractThe photonic spin Hall effect (SHE) arises from the spin–orbit interaction of lights and plays an important role in light–matter interactions. The phenomenon of spin‐momentum locking validates photonic SHE with unprecedented abilities in wave manipulation. Here, the directional coupling and spin‐momentum locking in spoof surface plasmon polaritons (SSPP) are demonstrated. The transverse spin angular momentum in SSPP is calculated using effective medium theory and the study shows the spin direction is inherently locked to the propagation direction, thus manifesting the spin–orbit interaction of electromagnetic (EM) waves. The spin‐momentum locking is further verified by projecting linearly and circularly polarized waves onto a scatterer‐SSPP structure. It is observed that the helicity of the incident EM wave governs the propagation direction of excited SSPP modes and the directional coupling originates from constructive and destructive interferences of two orthogonal modes. Reconfigurable transmissions of SSPPs are further demonstrated. The proposed design can find applications in reconfigurable sensors, antennas, and power dividers. This approach demonstrates the spin‐momentum locking in SSPPs and introduces new degrees of freedom to manipulate SSPPs by engineering the helicity and interference of EM waves.

Biomass-based carbon aerogel/Fe3O4@PEG phase change composites with satisfactory electromagnetic interference shielding and multi-source driven thermal management in thermal energy storage

The development of multifunctional materials to eliminate electromagnetic wave interference (EMI) and achieve multi-source driven thermal management for electronic devices has become a consensus. In this work, biomass-based carbon aerogels (LG) were prepared and used as porous supporting material to encapsulate magnetic Fe3O4@polyethylene glycol (Fe3O4@PEG) by vacuum impregnation. Form-stable LG-based phase change composites (LGP) were obtained, which had excellent thermal storage capability and satisfactory EMI shielding effectiveness (SE). With the supporting and bridging effects of GO, LGP-3–0 % has a high latent heat enthalpy of 156.32 J/g and excellent electrical conductivity of 281.1 S/m. With addition of 7 wt% Fe3O4, LGP-3–7 % achieves satisfactory EMI SE of 53.83 dB. Furthermore, LGP-3–7 % exhibits an outstanding performance of multi-source driven thermal management, including light-to-thermal, magnetic-to-thermal, and electro-to-thermal conversion. In short, LGP show the wide application prospects for electronic device to avoid EMI and achieve thermal management.

Facile synthesis and electromagnetic wave responses of Cu2−xS hollow cube and its derivatives

With the proliferation of wireless communication technologies, electromagnetic wave interference (EMI) threatens modern industry and society, such that lightweight and easy-fabricated microwave absorbers are in great demand. In this paper, Cu2−xS hollow cubes and their derivatives were successfully synthesized by Cu2O cubic templates in a process of pre-sulphuration and hydrochloric acid etching. At the different concentrations of hydrochloric acid, Cu@Cu7S4 and CuS were attained. The Cu@Cu7S4/paraffin composite had a minimum microwave reflection loss of − 39.2 dB at the thickness of 2.4 mm and an effective absorption bandwidth covering 85 % of the entire X-band. The CuS/paraffin composite exhibited excellent EMI shielding performance of 55.4 dB at 18 GHz.

Multilayered Cu/NiFe thin films for electromagnetic interference shielding at high frequency

Cu/NiFe multilayers with different structures were fabricated by electroplating for electromagnetic wave interference shielding in the high-frequency region. The electromagnetic wave interference shielding effectiveness of the symmetric, asymmetric, and thickness-gradient multilayer films was evaluated to optimize these structures. The thickness of the NiFe layer, which acts as an interlayer between Cu layers, is an important factor. The five-layered thin film (S9), with a thickness gradient that continues to increase toward the lower layer, shows an electromagnetic interference shielding effectiveness of − 74 dB in the wideband region, even though the total thickness of the multilayer is 1 µm. Focused ion beam, scanning electron microscopy, vector network, X-ray diffraction, four-point probe, and inductively coupled plasma–optical emission spectroscopy analyses were performed to characterize the multilayered Cu/NiFe thin films. • A Cu/NiFe multilayer was fabricated via electroplating. • The electrical conductivity and shielding effectiveness were investigated. • The electromagnetic interference shielding mechanism of the multilayer was studied.

Tuning Electro-Magnetic Interference Shielding Efficiency of Customized Polyurethane Composite Foams Taking Advantage of rGO/Fe3O4 Hybrid Nanocomposites.

Electromagnetic interference (EMI) has been recognized as a new sort of pollution and can be considered as the direct interference of electromagnetic waves among electronic equipment that frequently affects their typical efficiency. As a result, shielding the electronics from this interfering radiation has been addressed as critical issue of great interest. In this study, different hybrid nanocomposites consisting of magnetite nanoparticles (Fe3O4) and reduced graphene oxide (rGO) as (conductive/magnetic) fillers, taking into account different rGO mass ratios, were synthesized and characterized by XRD, Raman spectroscopy, TEM and their magnetic properties were assessed via VSM. The acquired fillers were encapsulated in the polyurethane foam matrix with different loading percentages (wt%) to evaluate their role in EMI shielding. Moreover, their structure, morphology, and thermal stability were investigated by SEM, FTIR, and TGA, respectively. In addition, the impact of filler loading on their final mechanical properties was determined. The obtained results revealed that the Fe3O4@rGO composites displayed superparamagnetic behavior and acceptable electrical conductivity value. The performance assessment of the conducting Fe3O4@rGO/PU composite foams in EMI shielding efficiency (SE) was investigated at the X-band (8–12) GHz, and interestingly, an optimized value of SE −33 dBw was achieved with Fe3O4@rGO at a 80:20 wt% ratio and 35 wt% filler loading in the final effective PU matrix. Thus, this study sheds light on a novel optimization strategy for electromagnetic shielding, taking into account conducting new materials with variable filler loading, composition ratio, and mechanical properties in such a way as to open the door for achieving a remarkable SE.

Electromagnetic Interference Shielding Effectiveness of Natural and Chlorobutyl Rubber Blend Nanocomposite

The science and technology of electrical equipment for communication experience a rapid growth rate. However, the unwanted interference of electromagnetic waves of different electronic devices brought serious anxiety about human health as well as the lifetime and performance of the systems. To combat these consequences, we need to lessen the electromagnetic wave emission by making our devices more noise-sensitive. Herein, we incorporated carbon nanotubes (CNTs) at different ratios into natural rubber (NR) and chlorobutyl rubber (CIIR) to achieve shielding efficiency, along with carbon nanofibers (CNFs), nanoclay (NC), and carbon black (CB) to manipulate EMI shielding performance. The blend of CIIR/NR in a 70/30 (w/w) ratio also mixed with CNT, CNF, CB and NC. The effect of different fillers and their concentration/combination was analyzed by UV spectroscopy, demonstrating an absorbance peak in CIIR in 320 nm. From FTIR spectroscopy, it was evident that CIIR/CNT (5 phr), NR (30 wt.%)/CIIR (70 wt.%)/CB (5 phr), and NR (30 wt.%)/CIIR (70 wt.%)/CNT (5 phr) new bonding signatures were detected. The dielectric spectroscopic analyses were reflected in dielectric loss, dielectric permittivity and AC conductivity, where NR (30 wt.%)/CIIR (70 wt.%)/CB (5 phr) blend nanocomposite with 5 dB showed significantly higher EMI shielding performance compared to CIIR/CNT (5 phr) and CIIR/CNF (5 phr) with 29 and 15 dB, respectively. The greater the concentration of nanofiller, the lower the electromagnetic interference (EMI) shielding, i.e., CIIR/CNT (10 phr) with 15 dB (≈−48% dB), but with more agglomeration. Surprisingly, even a combination of fillers did not lead to higher EMI performance, such that CIIR/CNT (5 phr)-CB (20 phr) showed an EMI shielding value of 59 dB.

One-dimensional metallic, magnetic, and dielectric nanomaterials-based composites for electromagnetic wave interference shielding

One-dimensional metallic, magnetic, and dielectric nanomaterials-based composites for electromagnetic wave interference shielding

Thermal Spray Coatings for Electromagnetic Wave Absorption and Interference Shielding: A Review and Future Challenges

This review aims to consolidate scattered literature on thermally sprayed coatings with nonionizing electromagnetic (EM) wave absorption and shielding over specific wavelengths potentially useful in diverse applications (e.g., microwave to millimeter wave, solar selective, photocatalytic, interference shielding, thermal barrier‐heat/emissivity). Materials EM properties such as electric permittivity, magnetic permeability, electrical conductivity, and dielectric loss are critical due to which a material can respond to absorbed, reflected, transmitted, or may excite surface electromagnetic waves at frequencies typical of electromagnetic radiations. Thermal spraying is a standard industrial practice used for depositing coatings where the sprayed layer is formed by successive impact of fully or partially molten droplets/particles of a material exposed to high or moderate temperatures and velocities. However, as an emerging novel application of an existing thermal spray techniques, some special considerations are warranted for targeted development involving relevant characterization. Key potential research areas of development relating to material selection and coating fabrication strategies and their impact on existing practices in the field are identified. The study shows a research gap in the feedstock materials design and doping, and their complex selection covered by thermally sprayed coatings that can be critical to advancing applications exploiting their electromagnetic properties.

Significant enhancement of thermal conductivity in segregated(GnPs&MWCNTs)@Polybenzoxazine/(Polyether ether ketone) -based composites with excellent electromagnetic shielding

• Segregated structural composites assist in thermal conductivity enhancement. • Segregation provides more conductive reflective interfaces for shielding. • Polybenzoxazine modification increased polymer-filler interfacial interaction. • Hybrid fillers improve the interconnected filler transmission network. With the rapid development of integration and multi-functionality of electronic devices, polymer-based composites with thermal management and electromagnetic wave interference (EMI) are in urgent demand. Herein, a segregated structure multi-walled carbon nanotubes-graphite nanosheets/polyetheretherketone (PEEK) composite modified by polybenzoxazine (PBZ) have been fabricated via vacuum-assisted filtration and melting-point pressing methods. Different sizes of PEEK composite granules would yield different thermal conductivity (TC) and EMI performance of the resulting segregated composites. The TC of (GnPs&MWCNTs)@PBZ/PEEK with the grain of 200 meshes reach up to 3.38 (through plane) and 6.27 W/(m·K) (in plane) at 19.84 vol% filler loading, which is 1400% and 2600% higher than that of pure PEEK, respectively. The obtained composites also exhibit excellent EMI shielding effectiveness (54.4 dB), electrical conductivity, and thermal stability. Based on the Agari modeling, it is demonstrated that the more compact heat chain network is formed for segregated composites rather than fillers randomly distributed composites. This study provides a viable approach for enhancing the thermal conductivity of polymers-based composites with EMI capability.

High Absorption Electromagnetic Wave Properties of Composite CoFeO3 Synthesized by Simple Mechanical Alloying

Electronic equipment demand is strongly correlated to the electromagnetic wave interference (EMI), which causes severe effects on human health. Microwave absorbing materials (MAMs) are one method to protect human health from EMI. Cobalt nanoparticles show high performance as MAMs. Here, we have synthesized CoFeO3 by simple mechanical alloying for increased multiple reflections, interfacial polarization, magnetic domain loss, electron spin loss, internal resonance, hoping electron, conductive loss, and multiple scattering for improved absorption of EMI waves. We determined the electronic properties from the Quantum Espresso (QE) and corresponding results are discussed. The metallic character comes from the d-state of transition metal atoms Fe (II) and Co which are sufficiently large in magnitude in the Fermi level of band structure and density of state (DOS) distribution. Crystallite size in the range of 13.6 to 18.7 nm with surface morphology shows irregular shapes of the particles. For CoFeO3 as MAMs, we found that the reflection loss (RL) is −55 dB (lower than the previous reported −43.2 dB) at 10–11 GHz for a thickness of 8 mm, indicating that this study shows high potential of CoFeO3 as an alternative composite for MAMs applications.

Preparation and identification of a biocompatible polymer composite: Shielding against the interference of electromagnetic waves

Hybrid composites containing Cu nanostructures (NSs), reduced graphene oxide (RGO), and polystyrene (PS) were produced for electromagnetic shielding application. First, Cu NSs including nanoparticles (NPs), nanorods (NRs), and nanowires (NWs) were prepared by a green method using eucalyptus bark extract from the reaction of copper(II) chloride in ethylene glycol (EG) at 186 °C. The FE-SEM images, XRD patterns, and Raman spectroscopy were used to characterize these NSs. The RGO/PS composite was prepared by introducing RGO to the PS matrix. The tensile test revealed that by adding 10% of RGO to the PS matrix, the tensile strength of the RGO/PS composite increased by 13.8%. The thermal properties of the RGO/PS composite indicated that with the uniform incorporation of RGO on the PS matrix, the thermal stability of the polymer composite was elevated to 350 °C and the Tg to 112 °C. Conductive polymer nanocomposites (PNCs) were prepared by adding Cu NSs to the RGO/PS composite. The results showed that these PNCs had electromagnetic interference (EMI) shielding; the shielding effectiveness of PNCs containing 10% RGO and 25% Cu NWs was 36.0 dB at 8.0 GHz and 29.5 dB at 12.0 GHz. The predominant mechanism of protection in the frequency range and percentages of the filler under study was of the reflection type.