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With the aim to obtain enhanced absorbing performance at small thickness and low filling, a robust strategy to fabricate zinc oxide (ZnO) modified carbon fiber (CF) structures have been successfully prepared by using low temperature hydrothermal method. Due to the multi-interface polarization caused by the high specific surface area of the complex heterostructures and the improvement of impedance matching, the composites show excellent electromagnetic wave absorption properties. Under the condition of low filling content (20wt%) and ultra-thin thickness (1.5mm), the excellent absorption performance of minimal reflection loss of −34.4 dB and an effective absorption bandwidth (RL ≤ −10 dB) of 4.94 GHz is achieved. In addition, the effective absorption bandwidth covers the whole 2-18 GHz band with the increase of thickness from 0.5 to 10 mm. This work provides an innovative method for designing the matching layer of carbon-based absorbing materials, and ZnO@CF heterostructure is expected to become a potential absorbing material.

The main gas layer of the Lower Paleozoic in the Yan'an gas field in the Ordos Basin is the carbonate rock of the Majiagou Formation, which is a low-porosity and low-permeability reservoir. Its storage space is mainly composed of intercrystalline pores, intercrystalline dissolved pores, dissolved caves and micro-fractures, with strong heterogeneity. The reservoir generally contains pyrite, which makes the resistivity value negatively abnormal, which interferes with the identification of low-resistivity fluids in the high-resistivity background. This leads to the failure of traditional logging interpretation methods and the low coincidence rate of reservoir interpretation. Through the statistical analysis of 240 drilling and gas testing data, the sensitive parameters of logging total hydrocarbon and logging resistivity are selected from many reservoir parameters. On this basis, after effective technical treatment, a “gas logging bright spot-resistivity dark spot technology” for carbonate reservoirs is formed. Through the field application and gas test results of 35 wells in Yan'an gas field in 2021, the interpretation coincidence rate is as high as 83%, which is much higher than the previous traditional method coincidence rate (44.3%). This study organically combines the advantages of mud logging and logging technologies, and establishes a reservoir interpretation chart and standard, which solves the long-standing problem of low coincidence rate in the identification of carbonate reservoir fluids in the geological community. An effective method for predicting favorable carbonate oil and gas areas is provided.

Metal-organic frameworks (MOFs) derivatives have been widely explored as highly efficient electromagnetic absorbing materials. Due to their diverse coordination arrangements, morphologies, and unique structures, MOFs provide promising avenues for synthesizing materials with customized properties. However, strategies for tailoring properties of low-dimensional MOFs-derived absorbers with hollow structures remain a considerable challenge. Herein, a well-defined Co@N-doped porous carbon composite (Co/N PC) with double-shell hollow structures has been successfully developed through self-templating-polymerization and subsequent pyrolysis. The proposed strategy for the synthesis of hollow architecture involves three simple steps (i) coordination, (ii) dissociation, and (iii) dopamine (DA) polymerization. The synthetic approach is realized at room temperature without a need for solvent etching. By effectively optimizing parameters including void thickness, surface structures, and graphitization levels, the as-designed Co/N PC composites feature wide absorption bandwidth of 5.93 GHz at a thickness of 2.4 mm with a filler loading of 15 wt%. The exceptional performance of microwave absorption (MA) is primarily achieved through excellent dielectric loss, and enhanced impedance matching, due to increased conductive loss through porous hollow structures and dipolar/interfacial polarization. This work provides an eco-friendly and facile route to designing hollow MOFs derivatives, offering substantial parameter space for optimized future lightweight and efficient absorbing materials.

The dodecahedral structure formed by etching ZIF-67 and introducing NICo2S4 on the surface exhibits excellent microwave absorption performance.

On-line detection of fault characteristic gases released by the insulation oil of transformers is developed as a scientific basis for estimating explosion accidents. However, the performance of most gas sensors, such as H2 and C2H2 sensors, is usually affected by temperature, and there exists large detection error when the temperature of transformer oil changes in operation. And the existing temperature compensation methods suffer from problems such as low integration, large volume, and high costs. Herein, a sensor array based on three triple-electrode sensors with carbon nanotubes was fabricated. Each of the three sensors has three vertically stacked electrodes with various interelectrode distances. The first and second sensors were used to detect H2 and C2H2, respectively, and the third sensor was used to measure temperature. All the detection mechanisms are based on the dependence of discharge current on gas concentration and temperature. The sensor array could detect H2/C2H2 mixture and temperature due to the exponential function between the output currents and electrode separations. The proposed sensor exhibited low relative and repeatability error values less than 5.1% and 4.9%, respectively, and displayed humidity compensation potential like temperature. High integration makes the sensor array superior among the other mechanism sensors.

The green and facile strategy of producing high efficiency microwave absorption materials (MAMs) has attracted wide attention, but remains a challenge. In this work, polydopamine (PDA) was used as carbon source and nitrogen source, polyvinylpyrrolidone (PVP) was used as protective layer and dispersant, and nanoparticles with concave cube morphology were prepared by self-template eco-friendly method. By adjusting the addition amount of PDA and PVP, the MOF derived materials with three morphologies of pure ZIF-67 nanoparticles, core-shell adhesion cube and concave cube can be precisely controlled. Compared with the other two kinds of absorbers, the sample with concave cube morphology shows excellent electromagnetic wave absorption (EMA) performance. Furthermore, the excellent EMA performance comes from the efficient electron transport channel with unique concave cube morphology, multi-interface polarization process and Co nanoparticles high impedance matching. The analysis demonstrates that when the filling ratio of the concave cube sample is 15%, its effective absorption bandwidth is 5.97 GHz, which can basically cover the Ku band (12.0–18.0 GHz), and the corresponding thickness is 1.88 mm. Our research provides a meritorious approach for the design and preparation of high efficiency MAMs by considering the effects of the morphology and filling ratio of the absorber comprehensively.

The engineering of core-shell nanostructures provides a great potential to induce interfacial polarization relaxation and optimize impedance matching. Herein, core-shell-structured MHCS@MoS2 nanospheres are developed using hollow carbon (MHCS) and stacked MoS2 nanosheets. Heterostructures between cores and shells significantly boost the interface polarization effect and effectively reduce the electromagnetic wave (EMW) reflection caused by highly conductive MHCS. Thereby, efficient and broadband electromagnetic microwave absorption (EMA) performance can be achieved. Through controlling the thickness of MoS2 shells and the graphitization of MHCS cores, the effective absorption bandwidth (fE) of MHCS@MoS2 can reach 6.21 GHz at the thickness of only 2.1 mm. The nanodesigned core-shell-shaped MHCS@MoS2 nanospheres are demonstrated as a promising high-performance EMA material.

Accompanied by the increasingly serious disordered electromagnetic radiation to trigger electromagnetic pollution become a new generation source which is harmful and difficult to protect, it is still a enormous challenge to develop a novel microwave absorbing materials (MAM) with low-density and wide absorption band. Here, we propose an advanced strategy to encapsulate red blood cell-like mesoporous carbon spheres with magnetic nanoparticles in terms of the problems of poor impedance matching, narrow absorption band of single dielectric loss material or high density of single magnetic loss material. A novel microwave absorber (MRBC), exhibited with the characteristics of ultra-high specific surface area (BET specific surface area: >500 m2/g), uniform mesoporous properties (Pore diameter: 7–8 nm) and special hollow structure and composed of carbon spheres with intact red blood cell morphology and magnetic nanoparticles, was obtained by the combination of double vacuum sintering processes and glycolate pyrolysis process. The unique microstructure and the synergistic effect of multiple dielectric loss and magnetic loss capability make MRBC-3 achieve an effective bandwidth of 5.77 GHz at a low filling rate (15 wt%) and an ultra-thin thickness (1.74 mm). Meanwhile, the minimum reflection loss of MRBC-4 is −64.26 dB. Furthermore, we use normalized input impedance to discuss the special properties of quarter wavelength matching layer, and verify the location of minimum reflection loss.

As a typical fascinating microstructure, the core-shell structure provides abundant possibility for material design in various fields including nano-engineering. In addition, the popular MOF derivatives have been widely explored and recognized as the most potential candidates for functional materials, especially in the field of microwave absorption (MA). Combined with the advantages of their structure and function, it is expected to maximize the synergistic effect and achieve amazing MA performance. In this paper, a series of core-shell CF@C/Co composites were assembled by using lightweight and conductive CF as the core and cubic ZIF-67-derived C/Co with controllable structure and adjustable graphitization as the shell. The intrinsic relationships between shell structure, component content, graphitization degree, electromagnetic parameters and various microwave loss behaviors are analyzed. After properly adjusting the degree of graphitization on the basis of derivation of various C/Co shells, A3-600 with obvious multi-polarization effect were obtained. A3-600 achieves an effective absorption bandwidth of 6.25 GHz at 1.71 mm and the best reflection loss of −71.95 dB at 1.78 mm. This dual strategy of shell evolution design and graphitization control has been proved to be an effective method to coordinate electromagnetic matching and construct multi-polarization effect to enhance the performance of MA.

The combination of Ag nanomaterials and special nanostructures can significantly amplify the conversion of electromagnetic energy, especially in microwave absorption applications. Herein, a kind of...

The hydrangea-like Ni/NiO/C composites have been successfully synthesized by in-situ pyrolysis stemmed from Ni-MOFs. The composition and structure can be adjusted by controlling the pyrolysis temperature, and it leads to the graphitization degree and electromagnetic parameters. A broad effective absorption bandwidth of the composite up to 5.67 GHz with the maximum reflection loss of −47.72 dB in 1.9 mm thickness. The results demonstrate hydrangea-like Ni/NiO/C composites have superior microwave absorption resulted from the synergistic effect between the unique structure, dielectric loss, and magnetic loss. Therefore, this work confirmed that hydrangea-like structure composite can be an ideal candidate for highly efficient microwave absorption materials with a facile preparation process and flexible control of electromagnetic parameters.

The micro-morphology design of nanomaterials has always been a hot issue in the field of microwave absorption. In this work, multi-shell structure is made on the basis of hollow structure and porous structure, and the effect of shell number of nanoparticles on microwave absorption properties is studied. Multi-shell hollow porous carbon nanoparticles (HPCNs-m) were prepared by simple liquid phase method combined with layer-by-layer process, and their micro-morphology, chemical structure, electromagnetic properties and microwave absorption properties were studied by a variety of characterization methods. The results show that the multi-shell structure is beneficial to improve the conductivity loss and polarization loss, so as to enhance the microwave absorption properties of the samples. In all samples, the effective absorption bandwidth (EAB) of three-shell hollow porous carbon nanoparticles (HPCNs-3) is 5.17 GHz under the thickness of 1.6 mm, and the best reflection loss (RL) is −18.13 dB at 14.66 GHz. This work expands the study of the effect of the number of shells on microwave absorption properties, and provides a useful reference for the design of microwave absorbers.

Carbon materials have the potential to be excellent absorbing materials due to their lighter weight, easy-to-control graphitization degree and good dielectric properties. However, a single carbon material is often difficult to achieve the ideal electromagnetic wave attenuation effect due to the imbalance of impedance matching and the lack of magnetic loss. In this work, a simple solgel method was used to control the hydrolysis reaction of tetraethyl orthosilicate and the synthesis reaction of phenolic resin to prepare the core–shell precursor of silica coated with phenolic resin/silica spheres. After high-temperature calcination and pickling etching, hollow carbon spheres (HPC) with porous structure were obtained. By adjusting the calcination temperature, the crystallinity and dielectric properties of HPC can be easily adjusted. With an ultra-low filling ratio of 5 wt%, HPC can obtain a wide-band effective microwave absorbing performance of 5.73 GHz (2–18 GHz band) under an ultra-thin thickness of 2.0 mm, which is an excellent absorbing agent with lightweight, thin thickness, strong absorbing ability and wide absorbing band. Considering the simple preparation scheme, HPC is expected to become one of the candidates for high-efficiency microwave absorbers. The special hollow, porous structure and suitable degree of graphitization are the main reasons for the effective wave absorption of HPC.

MOFs with high tunability are considered ideal candidates as microwave-absorbing materials. Strict experimental conditions can ensure the repeatability and maximize the potential of such materials. In this study, cubic ZIF-67 carbides synthesized at different solution temperatures showed an adjustable average size, and then by adjusting the calcination temperature we could control the degree of graphitization, so as to explore the synergistic effect of these two aspects to achieve an in-depth understanding of the electromagnetic properties and microwave absorption properties. The results showed that sample 30-600 (with the former number referring to the synthesis temperature and the latter to the calcination temperature) showed the widest effective absorption bandwidth (5.75 GHz, 1.8 mm) and the optimal reflection loss (-56.92 dB, 2.1 mm). The best matching electromagnetic parameters were obtained under the synergistic action of a smaller particle size and appropriate degree of graphitization, so as to achieve strong attenuation characteristics under low electromagnetic wave reflection. The microwave loss mechanism of the sample mainly involved dielectric losses, such as from conductance loss, dipole polarization, and interface polarization. Starting from the experimental details, this work proposes a dual control strategy for developing microwave-absorbing materials with both simplicity and practicability, which provides a useful reference for other microwave absorbents synthesized at room temperature.

In the present work, novel Ni0.5Zn0.5Nd0.04Fe1.96O4 ferrite (NZNF)/polyaniline (PANI) nanocomposites were prepared by interfacial polymerization. The crystal structure, microstructure and electromagnetic parameters of the samples were investigated in detail, indicating that PANI grew uniformly on the surface of ferrite like coral. By testing the electromagnetic parameters, it was found that PANI significantly improved the real and imaginary parts of the dielectric constant of the samples, thus affecting the impedance matching and attenuation performance. The addition of PANI adversely affected the impedance matching, but had a good effect on attenuation capacity. When the amount of aniline was 25 wt% of the ferrite, the impedance matching and attenuation capacity of the as-prepared NZNF/PANI nanocomposite reached the optimal balance. The NZNF/PANI-25 nanocomposite exhibited a maximum reflection loss of −37.4 dB at 8.4 GHz, and the effective absorption bandwidth was 4.9 GHz at a thickness of 4.0 mm. This novel absorbing material is a promising absorbent with strong and wide band absorption characteristics.

Impedance matching and enhanced microwave attenuation have been proven to be effective strategies for improving reflection loss (RL) and widening of the effective absorption (RL

Magnetoelectric coupling is a key strategy to obtain high-performance microwave absorption materials. Especially for carbon matrix composites, the absorbing capacity can be optimized via the tuning of the graphitization degree and the content ratio of the magnetic and dielectric components. Based on this theory, a simple strategy, consisting of the solvothermal method and annealing in an inert atmosphere, is adopted in this study to combine CoNi magnetic alloys with graphitized carbon into micron-scale composite spherical particles. Additionally, special attention is paid to the correlation among the graphitization degree of carbon matrix, component proportion, and dielectric response ability, so as to achieve a flexible micromorphology design and a tunable microwave absorption performance. When the pyrolysis temperature is offset to the best of 700 ℃, a broadband absorption of 6.61 GHz (reflection loss - 10 dB) is achieved at an ultrathin matching thickness of 1.9 mm. Adjusting the carbon content can further optimize the impedance matching and realize a high-intensity absorption with a reflection loss of - 72.7 dB. Our work proposes a useful strategy to realize the effective combination of the magnetic and dielectric loss mechanisms and boost the microwave absorption capacity toward achieving the desired broadband and a high-efficiency absorption performance.

In this study, a magnetic/dielectric composite precursor is obtained by in situ growing zeolitic imidazolate framework-67 nanoparticles on the surface of acidified multi-walled carbon nanotubes (MWCNTs). After pyrolyzing the precursor in an argon atmosphere, a kind of nano-heterogeneous composite wave absorber was prepared. Subsequently, a new type of magnetic/dielectric wave-absorbing composite was prepared by heating and curing Co–C–MWCNTs and epoxy resin, and the properties of the composite were adjusted by changing the content of Co–C–MWCNTs. A variety of modern characterization methods were used to systematically study the micro-morphology, element composition and electromagnetic properties of the composite. The results show that after the combination of MWCNTs and Co–C particles with regular dodecahedron structure, a special synergistic effect appears. The addition of magnetic MOF derivatives not only improves the impedance matching characteristics of the composite and increases the magnetic loss mechanism, but also provides a new path for the transmission of electromagnetic waves because of its special pore structure and the three-dimensional network structure formed by cross-linking with MWCNTs. The interface polarization and multiple scattering effects greatly improve the attenuation efficiency of electromagnetic waves. In X-band (8–12 GHz), the Co–C–MWCNTs/EP composite with a loading of 17.5 wt% can achieve an effective absorption bandwidth of 2.38 GHz when the matching thickness is 1.6 mm. The combination of novel MOF-derived materials and traditional carbon materials is expected to provide new ideas for the design of composites with microwave absorption capabilities.

Based on the surface analysis of carbon fiber, an epoxy resin matrix with good wettability to carbon fibers had been developed and studied, and the influence of winding tension on the interface and mechanical properties of the composite were studied. The surface morphology of carbon fiber and the active functional groups of sizing agent were analyzed. In order to form a good interface combination, the wettability between carbon fibers and epoxy resin matrix was characterized by dynamic contact angle. The winding tension played an important role in the mechanical properties of composites. Therefore, a kind of carbon fiber reinforced composites, Naval Ordnance Laboratory (NOL) rings were fabricated using different winding tensions. Particularly, when the winding tension was 30 N, the interfacial bonding between carbon fibers and resin matrix was the most compact and firm. The tensile strength and interlaminar shear strength (ILSS) of NOL rings reached high values, 2712 MPa and 75 MPa, respectively.

In this work, stearyltrimethylammoium bromide (STAB) was used to modify montmorillonite (MMT). Subsequently, the modified organic montmorillonite (OMMT) was added into 4,4′-Bismaleimidodiphenyl methane (BDM) and 2,2′-Diallylbisphenol A (DBA) copolymerization system to prepare BDM/OMMT wave-transparent nanocomposites with 0–5 wt% OMMT content. It is found that the addition of OMMT improves the microstructure, thermal properties, and wave-transparent properties of BDM composites. At the addition of 2 wt%, the thermal stability of the resin system is the best, and the fracture morphology changes from brittle fracture characteristics to ductile fracture characteristics. Meanwhile, in X-band (8–12 GHz), OMMT-2 wt% with the thickness less than 2 mm or within 8–10 mm has excellent transmittance (> 90%). Moreover, the effect of temperature change on the wave-transparent performance of BDM/OMMT nanocomposites is investigated. From room temperature to 200 °C, the stability of high-temperature transmittance of OMMT-2 wt% is enhanced, and it still has good transmittance (> 90%) within in a wide thickness range at 200 °C. The enhancement of these properties is closely correlated with the interaction interface formed between OMMT and BDM resin matrix. The addition of OMMT can increase the design selection of BDM resin system and expand its application as a wave-transparent material.

Double-layer absorbers have recently been extensively studied because single-layer absorbers can hardly meet the requirements of advanced absorbing materials. However, determining how to couple the matching and absorption layers remains a challenge. In the present work, we applied the hydrothermal method to prepare an ultrasmall Fe3O4 nanoparticle and a hierarchical MXene/Fe3O4 composite and then studied the microwave attenuation capabilities of single- and double-layer absorbers containing these two materials with different thicknesses. Absorbers with well-coupled layers showed improved absorption performance on account of the excellent impedance matching behavior of the Fe3O4 layer and the high microwave attenuation capability of the MXene/Fe3O4 layer. When the thickness of the matching layer filled with Fe3O4 was 0.1 mm and that of the absorption layer filled with MXene/Fe3O4 was 1.9 mm, a maximum reflection loss of −48.7 dB was achieved at 9.9 GHz. More importantly, when the thicknesses of the matching and absorption layers were 0.9 and 1.1 mm, respectively, the effective bandwidth was nearly 3.9 GHz. The double-layer absorbers with enhanced absorption properties may be regarded as a new generation of materials for electromagnetic wave absorption.

Ideal electromagnetic (EM) wave absorption materials should exhibit strong absorption peaks and broad effective absorption bandwidths, which are important for EM protection and the stealth technology. Despite considerable advancements in this field in recent years, EM absorption materials have not reached their full potential to meet all the above-mentioned requirements, especially the broad absorption bandwidth at low frequencies. Herein, we synthesized a Co-doped NiZn ferrite (CNZFO)/polyaniline (PANI) on Ti3C2TX MXene composite with a hierarchical structure via three facile steps: exfoliation, hydrothermal process, and modified interfacial polymerization. The CNZFO particles and PANI chains as well as the small number of TiO2 particles uniformly grafted between the Ti3C2TX layers formed a unique sandwich-like structure. The multiple-layer composite showed excellent EM wave absorption with a maximum reflection loss (RL) of −37.1 dB at only 2.2 mm. It showed an effective bandwidth (RL

The addition of polyamide veil (PAV) to the interlaminar area of carbon fiber (CF) fabric/epoxy composites can effectively increase their toughness with high accuracy. Vacuum-assisted resin infusion (VARI) was used to fabricate composite structures. VARI was applied to obtain a PAV, which is an interleaf between fabric piles of CFs. The thermoplastic PAV was dissolved in epoxy when the PAV was cured at high temperature. A phase-separated morphology with a PAV-rich secondary phase was formed during the curing process. Experimental results indicated that compression after impact (CAI), which is the average value of CAI, increased by threefold when two layers of PAV were added. The thermal and mechanical characteristics of the composite were analyzed and compared at room temperature and high-temperature wet conditions.

In the present work, high purity cubic silicon carbide (β-SiC) was synthesized by using resorcinol-formaldehyde aerogel coated silica as precursor at high temperature. Subsequently, β-SiC was coated with various concentrations of silver nanoparticles (Ag NPs) by tin sensitization electroless plating. Thereafter, the effect of various Ag NPs contents on the dielectric and microwave absorption properties of β-SiC was investigated in detailed. It is found that the Ag NPs can significantly increase the overall complex permittivity, reduce the thickness of the absorber and increase the absorption bandwidth to some extent. Despite, the improvement of the attenuation ability of electromagnetic wave with increasing contents of Ag NPs also has an adverse effect on impedance matching. The improvement in the microwave absorption of β-SiC coated with Ag NPs mainly comes from the enhancement of dipole polarization, interface polarization and conductivity loss. In the 2–18 GHz band, Ag@SiC (1.0 g/L) can achieve an effective bandwidth of 4.99 GHz at a thickness of 1.6 mm, and it is a kind of lightweight, high-temperature microwave absorbent with excellent performance.

Nanocrystalline Ni–Zn ferrites with different neodymium contents (Ni0.5Zn0.5NdxFe2-xO4) were synthesized by sol-gel route combined with self-propagating combustion (SPC) method. The presence of surface functional groups, crystal structure and morphology of the samples were studied by FT-IR, XRD and SEM. The results show that the prepared samples are composed of spinel phase under the condition of low neodymium content, like the pure Ni–Zn ferrite. While neodymium oxide appears after the content of Nd3+ exceeds a certain limit (x > 0.04) and there exist two phases in the ferrite. The results of vibrating sample magnetometer (VSM) and vector network analyzer (VNA) show that adjusting the content of Nd is significant in improving the dielectric properties and microwave absorption capacity of the materials, specifically at low frequencies. When x 0.04, the magnetic loss ability decreases rapidly (e.g., Ms decreases from 82.47 emu/g to 59.77 emu/g). Meanwhile, the dielectric loss increases slowly and the microwave absorption capacity decreases.

Electromagnetic (EM) wave absorber with broad and robust absorption performance over wide incident angle range is persistently desired in specific applications. In this work, we propose and demonstrate a broadband and wide-angle metamaterial absorber (MA) based on a hybrid of stereo spoof surface plasmonic polariton (SSPP) structure and planar resistive metasurface. At first, we design a broadband SSPP absorber by adjusting the dispersion and loss of the artificial plasmonic structure (PS) simultaneously. Furthermore, owing to utilize its spatial phase manipulation ability, we integrate a resistive metasurface on top of the PS to construct a modified circuit analog (CA) absorber with a dispersive metamaterial spacer. The absorption mechanism of the hybrid structure is analyzed theoretically. The results indicate that the hybrid MA is equipped with broad and robust absorption performance over a wide incident angle range due to the synergistic absorption of the PS and metasurface. Finally, a prototype of the hybrid MA is fabricated by silk-printing technic and its absorption performances are measured. The experimental results can verify the theoretic ones and indicate that proposed hybrid MA can achieve 90% absorptivity from 3.9 GHz to 10.6 GHz with thickness of 7.0 mm, which is only 106% times of the ultimate thickness corresponding to the absorption performance of MA. In general, the concept and design offer a distinct approach of utilizing SSPP to design absorbers with excellent performances from radio frequency to optic band, which are promising for extensive applications.