Cu2NiSnS4 Nanoparticles Supported on rGO for Dual Frequency Range Electromagnetic Shielding

Generally, a silicone rubber and a chlorinated polyethylene(CPE) have been used as a binder for the development of high-performance composite EM(Electro Magnetic) wave absorbers. In this paper, the EM wave absorption performance of natural lacquer, which is newly proposed as a binder was investigated. The prepared MnZn ferrite EM wave absorbers are mixed with natural lacquer showed excellent EM wave absorption characteristics compared with MnZn ferrite EM wave absorbers which are mixed with the conventional binders. MnZn ferrite EM wave absorbers mixed with natural lacquer were prepared and their absorption ability was also investigated The EM wave absorbers are fabricated in different proportions of MnZn, or NiZn ferrite and natural lacquer, and their reflection coefficients are measured. The permittivity and permeability are calculated by using the measured reflection coefficients. The EM wave absorption abilities are calculated according to different thicknesses of the EM wave absorbers.

Electromagnetic wave absorption properties of Ni0.5Zn0.5Fe2O4–BaTiO3–epoxy composites

Heteroatom nitrogen doping is considered an effective strategy to enhance the electromagnetic wave (EMW) absorption capacity of reduced graphene oxide (RGO). Herein, nitrogen‐doped RGO aerogels (NGAs) are synthesized via hydrothermal self‐assembly followed by lyophilization processes. Results of micromorphology analysis show that the as‐prepared NGAs display unique 3D porous and netlike structure. Moreover, the effects of nitrogen doping and filler contents on EMW absorption properties of NGAs are studied. The as‐synthesized NGA with nitrogen content of 9.41 at% and a bulk density of 8.7 mg cm–3 presents the integrated optimal EMW absorption performance. Specifically, the minimum reflection loss of –56.4 dB is achieved and maximum absorption bandwidth of 6.8 GHz is reached, covering the whole Ku band. In addition, the possible EMW absorption mechanisms of obtained NGAs are proposed. Therefore, the as‐synthesized NGAs can be exploited as promising high‐efficiency and lightweight EMW absorbers.

Electromagnetic (EM) waves are used in the oil and gas industry to identify the geology of the formation and the type of the fluid saturating the medium. There is also an interest to use the electromagnetic waves as an enhanced oil recovery (EOR) method. However, interpretation of logging data generated through electromagnetic waves or determination of the electromagnetic wave propagation in a medium as an EOR method are not easy tasks. This study aims to identify the role of different geological settings with different types of fluid saturations in the response of electromagnetic wave propagation and absorption. To reach this objective multitude-systematic laboratory scale experiments were conducted on different reservoirs fluid and rock pairs. As reservoir mineralogy, different grain size of quartz, clay, or limestone is used to prepare the reservoir rocks at different porosity. Water is known as a good absorber for EM waves, thus, pore space were saturated at different water saturations and a bitumen sample (10,000 cP, 12° API) from Canada. Prepared samples were packed into in-house-built-Plexiglas core holder which allows measurements with EM waves. The response of EM waves propagation and absorption was measured by using a vector network analyzer at varying frequencies (500 MHz to 4 GHz) through dielectric properties (dielectric constant, loss tangent, and penetration depth). The results were used to obtain correlations between dielectric properties and physical properties (reservoir rock mineralogy, porosity, water saturation, and oil saturation) of the reservoir rock-fluid blends. Water saturation gives a perfect correlation with dielectric constant and loss tangent values of the saturated medium. Because dielectric constant and loss tangent parameters provide an idea on the absorption characteristics of EM wave in the medium, and because water is a strong EM wave absorber, as it was expected, with the increase in water saturation, the dielectric constant and loss tangent parameters of the medium are also increased; on the other hand, penetration depth was decreased. With the increase in quartz content in the medium, it has been observed that EM wave penetration is enhanced. As a result, several correlations were created in this study and they can be used to better interpret the reservoir mineralogy and fluid saturation as a response to EM wave logging. Moreover, these results can be used to estimate the effective area (penetration depth) of EM wave as an EOR method in different mediums.

Electromagnetic wave (EMW) pollution adversely affects information, facilities safety, and human health, leading to the development of EMW absorbing materials, especially absorbing concrete. Here, the influence of arrangement ways of concrete iron on microwave reflectivity was analyzed, and a split ring resonator (SRR) was designed and introduced to steel-reinforced concrete to improve the EMW absorbing performance of the concrete. The simulation results show that by tuning the diameter and arrangement ways of concrete iron and introducing SRR structure, an EMW absorption concrete which can display 0.3% reflection loss ([Formula: see text]% absorption) at 2.34[Formula: see text]GHz was designed and realized. The reflectivity of concrete iron and EMW absorption capacity of concrete were investigated by a vector network analyzer, and the experimental results almost agree with the simulation results. The reflection and absorption of EMW are caused by magnetic resonance and conductive loss, magnetic loss, respectively.

For wider‐band and stronger electromagnetic (EM) wave absorption, macroporous short carbon fibers/mullite matrix (C f /Mu) composites were prepared via introducing short carbon fibers (0, 0.7, and 1.3 vol%) with length of 2‐3 mm into macroporous mullite ceramic by gel‐casting. The density of as‐prepared C f /Mu composites decreases from 2.93 g/cm 3 to 2.74 g/cm 3 , while the porosity increases from 3.32% to 10.76% with the rise in carbon fibers content. The diameter of macropores in C f /Mu composites is ranging from several microns to tens of microns. Complex permittivity and dielectric loss of the prepared composites in X‐band (8.2‐12.4 GHz) are significantly enhanced with increased carbon fibers content. The best EM wave absorption performance is obtained in the macroporous C f /Mu composites containing only 0.7 vol% carbon fibers (C f /Mu‐0.7). The maximum absorption loss of C f /Mu‐0.7 is −38.3 dB at 12.08 GHz at the thickness of 2.1 mm, and effective absorption bandwidth below −10 dB (over 90% of EM wave absorption) covers the whole X band with the thickness of 2.35 mm. The results suggest that the C f /Mu composites can be promising high‐performance EM wave absorbing materials.

Novel magnetic silicate composite for lightweight and efficient electromagnetic wave absorption

EM waves absorption properties of nitrogenous porous carbon derived from PANI fiber clusters carbonization

Enhanced microwave absorption performance of graphene/doped Li ferrite nanocomposites

Customized dielectric-magnetic balance enhanced electromagnetic wave absorption performance in CuxS/CoFe2O4 composites

Both morphological structure and chemical composition are the important factors that determine the electromagnetic wave (EMW) absorption properties of EMW absorbers. Herein, hierarchical porous carbon (HPPC) was synthesized by using polyetheretherketone (PEEK) as the starting material via the salt template method combined with KOH activation. Then, taking advantage of the hierarchical porous characteristics of the carbon, a novel EMW absorber (HPPC/CoNi) was synthesized by in situ growth of CoNi bimetallic alloys inside the above porous carbon. The as-synthesized HPPC/CoNi exhibits excellent EMW absorption performance with a minimum reflection loss (RLmin) value of -65.56 dB at 2.00 mm and a maximum effective absorption bandwidth (EAB) of 5.92 GHz at 1.80 mm. The superior EMW absorption property is ascribable to the multiple reflection/scattering induced by the hierarchical porous structure of HPPC, dielectric loss, magnetic loss, and good impedance matching. The results show that HPPC/CoNi is a potential EMW absorber with characteristics of ultra-light weight, ultrathin thickness, broad bandwidth, and strong absorption.

MXene/PEO aerogels with two-hierarchically porous architecture for electromagnetic wave absorption

A quantitative permittivity model for designing electromagnetic wave absorption materials with conduction loss: A case study with microwave-reduced graphene oxide

Synthesis of ZnS quantum dots and CoFe2O4 nanoparticles co-loaded with graphene nanosheets as an efficient broad band EM wave absorber

Synthesis of Co@N-doped carbon with yolk–shell heterostructures for efficient electromagnetic wave absorption