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Controllable Synthesis of One-dimensional MoO3/MoS2 Hybrid Composites with their Enhanced Efficient Electromagnetic Wave Absorption Properties
摘要： One-dimensional MoO3/MoS2 hybrid composites were synthesized via hydrothermal synthesis; and the flexible MoO3/MoS2/PVDF nanocomposites were also controllable prepared by combining the composites with polyvinylidene fluoride (PVDF) matrix. The MoO3/MoS2/PVDF hybrids with low filler content (20 wt%) exhibited distinct microwave absorption properties in the range of 2 - 18 GHz. The minimum reflection loss can reach -38.5 dB at 8.7 GHz, and the reflection loss was less than -10 dB in the frequency range from 3.03 to 11.02 GHz with an absorber thickness of 2.0 - 5.0 mm. The MoO3/MoS2/PVDF nanocomposites exhibited better absorption properties than pure MoO3 and MoS2. The possible microwave absorbing mechanism was also discussed in detail.
关键词： microwave absorption,one-dimension,nanocomposites,Molybdenum disulfide,Molybdenum oxide
更新于2025-09-23 15:23:52
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Ultra-broadband metamaterial absorber with graphene composites fabricated by 3D printing
摘要： An ultra-broadband electromagnetic (EM) absorber composed of composite metamaterials was designed, fabricated and characterized. Polylactic-acid/reduced graphene oxide (PLA/RGO) composites with different amounts of RGO were prepared as a primary material collection. To provide good impedance matching and efficient wave attenuation, the multilayer absorbers were designed with a gradient index (GRIN) of characteristic impedance by manipulating the RGO content and the geometric parameters of the unit cell. The absorbers with different numbers of layers were fabricated by a material extrusion process, and then the reflection loss (RL) of the prepared samples was measured. Results showed that the methodology for designing a metamaterial absorber with gradient impedance and fabricating through a 3D printing process was effective in producing ultra-broadband absorbers. The seven-layer absorber achieved an absorption above 90% in a broad bandwidth of 4.5–40 GHz. This work could provide inspiration for upgrading the performance of some conventional absorbing composites through a rational design of the composite proportion and structure.
关键词： Microwave absorption,Multilayer structure,3D printing,Composite materials,Metamaterials
更新于2025-09-23 15:23:52
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Axiolitic ZnO rods wrapped with reduced graphene oxide: Fabrication, microstructure and highly efficient microwave absorption
摘要： Axiolitic Zinc oxide/reduced graphene oxide (ZnO/r-GO) hybrid was achieved by a facile one-step hydrothermal route in this work. The axiolitic ZnO rods with uniform size were equally implanted in r-GO nanosheets. The composites exhibit prominent microwave absorption performance with the Min. RL of -55.7 dB for a thickness of merely 2.0 mm and effective absorption bandwidth covering the whole Ku band, which benefits by the introducing of axiolitic ZnO rods and constructing distinct structures. The synergistic effect of dipole polarization, interface polarization and conductivity manifestly boost the microwave attenuation capacity. The results indicated that the axiolitic ZnO/r-GO hybrid is a promising candidate for application in the field of microwave absorption, electromagnetic interference shielding, communication and safety information, etc.
关键词： polarization,microwave absorption,reduced graphene oxide,axiolitic ZnO rods
更新于2025-09-23 15:22:29
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Ultrathin Flexible Carbon Fiber Reinforced Hierarchical Metastructure for Broadband Microwave Absorption with Nano Lossy Composite and Multi-scale Optimization
摘要： The implementation of thin structure for broadband microwave absorption is challenging due to requirement of impedance match across several frequency bands and poor mechanical properties. Herein, we demonstrate a carbon fiber (CF) reinforced flexible thin hierarchical metastructure (HM) composed of lossy materials including carbonyl iron (CI), multiwall carbon nanotube (MWCNT) and silicone rubber (SR) with thickness of 5mm and optimal concentration selected from twelve formulae. Optimization for the periodical unit size is applied and impacts of structural sizes on absorption performance is also investigated. An effective process combining the vacuum bag method and the hand lay-up technique is used to fabricate the HM. Experimental reflectivity of the absorber achieves broadband absorption below -10dB in 2-4GHz and 8-40GHz. Full band in 2-40GHz is covered below -8dB. Yielding stress of the HM is increased to 24MPa with attachment of CF while the fracture strain of the composite reaches 550%. The soft HM is suitable to adhere to curved surface of objects needed to be protected from microwave radiation detection and electromagnetic interference. Enhanced mechanical properties make it possible for further practical applications under harsh service environment such as ocean and machines with constant vibration.
关键词： broadband microwave absorption,hierarchical metastructure,dielectric-magnetic lossy material,flexible,mechanical properties
更新于2025-09-23 15:21:21
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Controlled hydrothermal synthesis of different sizes of BaTiO<sub>3</sub> nano-particles for microwave absorption
摘要： Different sizes of barium titanate (BaTiO3) nano-particles were synthesized from precursor H2Ti3O7 nanotubes through facile hydrothermal synthesis by using EtOH/H2O as mixing solvent. Field-emission scanning electron microscopy (FESEM) was mainly used to investigate the effects of solution alkalinity, polarity, and hydrothermal temperature on the size and morphology evolution of BaTiO3 nanoparticles. The results indicate that the presence of strong alkalinity improved the size evenness of BaTiO3 nanoparticles possibly because of the re-dissolution and re-precipitation of TiO3 2- ions. As for the reason, the addition of EtOH could lower the polarity of hydrothermal medium and make the medium reach the supersaturation more easily, thus limiting the size growth of BaTiO3 particles. In addition, the presence of EtOH led to easier formation of BaTiO3 nanoparticles even at mild hydrothermal temperature, but the particle size was limited even though the temperature was much increased. This is possibly due to lowered interfacial activity in the presence of EtOH. By adjusting solution alkalinity, EtOH/H2O volume ratios, and hydrothermal temperature, BaTiO3 nanoparticles with the average sizes of approximately 21, 53, 104, 284, and 512 nm, were obtained, and more different and controlled nano-sizes can be expected by further hydrothermal adjustment. In the end, microwave absorption evaluation indicated that the decreased size of the BaTiO3 particles enhanced the reflection loss. One possible reason is that the decreased nano-size led to the increased specific surface area of the BaTiO3 nanoparticles.
关键词： Hydrothermal synthesis,Barium titanate,Polarity,Temperature,Microwave absorption,Adjustable nano-size
更新于2025-09-16 10:30:52
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Electrostatic self-assembly synthesis of ZnFe2O4 quantum dots (ZnFe2O4@C) and electromagnetic microwave absorption
摘要： Making effective usage of quantum size effect is a foregrounded strategy to design and fabricate excellent electromagnetic microwave absorption materials. In this research, ZnFe2O4 quantum dots were coated by hybrid amorphous carbon to form a sea islands structure by a facile electrostatic self-assembly synthetic technology. Simultaneously, the rejection of heterogeneous charges leads to the formation of quantum dots, by which the quantum size effects on dielectric and magnetic characteristic were investigated. Consequently, multiple hetero-interface and interfacial polarization was originated from polycrystalline feature of ZnFe2O4 with spinel and inverse spinel structures. In particular, the electromagnetic microwave absorption properties of ZnFe2O4 were greatly optimized, as the minimized reflection loss reached -40.68 dB at the frequency 11.44 GHz and thickness 2.5 mm, while the effective bandwidth corresponding was 3.66 GHz (from 9.87 to 13.52 GHz). The largest effective bandwidth was 4.16 GHz (from 8.08 to 12.24GHz) with a thickness of 3 mm. It is suggested that high performance of microwave absorption of ZnFe2O4 quantum dots was well guided by the optimized impedance matching and attenuation constants.
关键词： Electromagnetic microwave absorption,interfacial polarization,ZnFe2O4 quantum dots,polycrystalline,Electrostatic self-assembly
更新于2025-09-16 10:30:52
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FeSiAl/ZnO-filled resin composite coatings with enhanced dielectric and microwave absorption properties
摘要： Composite coatings with resin matrix and hybrid fillers of FeSiAl and ZnO powders have been developed for their potential application as microwave absorbing coatings. The effects of FeSiAl and ZnO content on the complex permittivity, complex permeability and reflection loss (RL) of such composite coatings were studied in the frequency range of 8.2–12.4 GHz (X-band). Compared with the complex permeability, the complex permittivity showed more dependence on the absorbent content and the permittivity values increase notably with increasing FeSiAl or ZnO content. Owing to the best impedance matching and appropriate electromagnetic attenuation, the composite coating filled with 35 wt% FeSiAl and 20 wt% ZnO powders exhibits the most desirable microwave absorption properties with the effective absorption bandwidth (< ?10 dB, > 90% absorption) 3.5 GHz in 8.6–12.1 GHz and the strong absorption peak ?40.5 dB at 10.4 GHz, when the thickness is 2.2 mm. The results suggest that FeSiAl/ZnO-filled resin composite coatings could be qualified as good candidates for highly efficient and strong microwave absorbing coatings.
关键词： FeSiAl,dielectric properties,resin composite coatings,microwave absorption,ZnO
更新于2025-09-10 09:29:36
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A novel approach to prepare one-pot Fe/PPy nanocomposite and evaluation of its microwave, magnetic, and optical performance
摘要： The aim of this study was preparation of Fe/Fe2O3/Fe3O4 (Fe)/polypyrrole (PPy) nanocomposite using reductive method and investigation of its microwave absorbing properties using polymethylmethacrylate (PMMA) medium. Firstly, PPy was prepared by an oxidative polymerization method with Fe3+ as a doping agent. Next, the Fe/PPy nanocomposite was formed by insitu reduction of Fe2+ and remained Fe3+ with sodium borohydride solution under an inert nitrogen atmosphere. Finally, PPy and Fe/PPy nanostructures were separately suspended within the PMMA matrix to examine their microwave absorbing characteristics. The prepared PPy and Fe/PPy nanostructures were studied using the Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The diffuse reflection spectroscopy (DRS) analysis presented a 1.79 eV band gap for the Fe/PPy nanocomposite based on the Kubelka–Munk theory. The vibrating sample magnetometer (VSM) revealed that magnetic properties were reinforced in the Fe/PPy nanocomposite. According to the results obtained by vector network analyzer (VNA), the maximum reflection loss of Fe/PPy/PMMA nanocomposite was -76.02 dB at 8.96 GHz with a thickness of 3.2 mm, absorbing all of the x-band frequency more than 12.72 dB with a thickness of 2.8 mm. Interestingly, the Fe/PPy/PMMA nanocomposite demonstrated a bandwidth > 3.4 GHz more than 10 dB from 2.2 to 3.2 mm at the x-band frequency.
关键词： Optical performance,Magnetic properties,Fe/PPy/PMMA,Microwave absorption
更新于2025-09-09 09:28:46