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1.
《Ceramics International》2023,49(15):25074-25084
Functional core-shell heterostructure, which can integrate the characteristics of multiple components to achieve synergistic effects, have been widely explored in electromagnetic wave (EMW) absorption materials. In this work, core-shell ZnO@ZnO/FeNi microrods (MRs) derived from ZnO@ZnFeNi hydroxide (ZnFeNi OH) are prepared by a simple hydrothermal reaction and subsequent pyrolysis process. The introduction of FeNi alloy helps to optimize the impedance matching of ZnO, thus improving the EMW absorption performance. The different impedance matching properties of core-shell ZnO@ZnO/FeNi MRs are realized by adjusting the ZnO/FeNi shell thickness by changing the hydrothermal reaction time. When the hydrothermal time is 10 h, the core-shell ZnO@ZnO/FeNi MRs supplies the optimal EMW absorption performance with the minimum reflection loss of −53.7 dB and the widest absorption bandwidth of 5.3 GHz at a filler content of 33%. The synergistic effect of ZnO–FeNi interfacial polarization and the strong dielectric-magnetic loss are responsible for its superior EMW absorption performance. This work provides a valuable strategy for constructing core-shell dielectric@ magnetic composites to obtained high efficiency absorber. 相似文献
2.
Yurun Feng Xue Guo Junbin Lu Jie Liu Guantong Wang Hongyu Gong 《Ceramics International》2021,47(14):19582-19594
The SiCN(Fe) fibers with excellent one-dimensional microstructure and electromagnetic wave (EMW) absorption performance were synthesized by combining polymer-derived ceramics (PDCs) method and electrospinning. The in-situ generation of Fe3Si and CNTs by adding ferric acetylacetonate (FA) into the raw materials effectively improved the dielectric properties, magnetic properties and the impedance matching performance of the SiCN(Fe) fibers. The EMW absorption performance of SiCN(Fe) fibers were mainly based on dipole polarization loss, interface polarization loss and eddy current loss. The RLmin value of SiCN(Fe) fibers reached ?47.64 dB at 1.38 mm and the effective absorption band (EAB, RL ≤ ?10 dB) reached 4.28 GHz (13.72–18 GHz, 1.35 mm). 相似文献
3.
《Ceramics International》2023,49(2):2130-2139
In this research, we developed a wideband electromagnetic wave absorber suitable for the X-band frequency by using a unique hybrid nanocomposite structure made of FeWO4 embellished with Ag3PO4 nanopowders. Simple chemical hydrothermal and microwave-aided hydrothermal procedures were used to successfully produce single-phase spherical-like FeWO4 and FeWO4@Ag3PO4 nanocomposite powders. Using XRD, FTIR, VSM, FESEM, and VNA methods, the phase constituents, morphological, magnetic, and electromagnetic properties of the produced nanocomposite materials were assessed. The resin-based nanocomposite absorber sample allows to obtain a maximum reflection loss of ?21 dB with a matching thickness of 1.8 mm at the ferromagnetic resonance of 10.4 GHz with a 3.8 GHz effective absorption bandwidth, which is evaluated using the waveguide technique, when the filler loading percentage reaches 40 wt percent (S40). S40 had superior impedance matching capabilities, a wide effective absorption bandwidth, and a high absorption capacity when compared to other produced absorber samples. The best sample is prepared for free-space testing with the dimension of 200 × 200 mm and an optimum thickness of 1.8 mm, and the results demonstrate a good agreement between the waveguide and free-space technique results. This absorber sample's wideband absorption capacity was attained by adjusting the magneto-electric composition and enhancing the interfacial characteristics brought on by the core-shell construction. In this study, a design approach for efficient microwave absorbers based on a magneto-electric hybrid nanocomposite structure is presented, using waveguide and free-space experimental methods in two different ways. 相似文献
4.
《Ceramics International》2023,49(8):12240-12250
A careful approach to the optimization of magnetic and dielectric losses in nanomaterials can improve the electromagnetic wave absorption loss performance for certain microwave absorption applications. In this study we prepared dual core (Fe/TiCN) coated with nitrogen (N) doped carbon shell nanocomposite by arc-discharge method under mix atmospheres of working gases and with varying elemental compositions. Among all nanocomposites, (Fe/TiC0.7N0.3)@N–C dual-core@ N- doped shell nanocomposite exhibits enhanced microwave absorption. Owing to the novel dual-core@ N-doped shell structure and numerous defects induced by doping N in carbon shells, an improved dielectric relaxation in composite is observed and the minimum reflection loss was reached −44.36 dB at 5.3 GHz for 4.8 mm thickness. 相似文献
5.
《Ceramics International》2021,47(23):33373-33381
There are few reports on the application of Magnéli Ti4O7 in the field of electromagnetic wave absorption. Herein, we designed and prepared a Ti4O7/magnetic metal composite via an electrostatic assembly with in-situ reduction reaction. This system utilized distinct magnetic coupling deriving from the subtle designed structures and magnetic-dielectric synergy. The core-shell magnetic metallic nanoparticles/oxygen deficient Ti4O7 are useful microwave absorbers in terms of wide broadband, strong absorption and ultra-low filler amount. The optimal reflection loss of Ti4O7@CoNi composite was −43.6 dB at 2.5 mm, meanwhile the effective absorbing band could reach over 5.12 GHz at only a 2.7 mm thickness. The results confirm that the dependence of the electromagnetic characteristics of the absorber on the filler ratio, frequency, and absorber thickness. Therefore, this work may be beneficial in constructing core-shell structured magnetic metal/Magnéli Ti4O7 composites to tune electromagnetic parameters and strengthen electromagnetic absorption. 相似文献
6.
Yongfeng Wu Yunwang Zhong Yan Guan Chong Gu Guangyu Shao Benyang Shi Zhiming Su Binbin Xu Zhaoju Yu Anhua Liu 《Journal of the American Ceramic Society》2020,103(12):6764-6779
In this work, porous core-shell structured Co2Si@SiC/C/SiOC/SiO2/Co3O4 nanoparticles were fabricated by a polymer-derived ceramic approach. The in situ formation of mesopores on the shell, microstructural, and phase evolution of resulting nanoparticles were investigated in detail. The obtained nanoparticles-paraffin composites possess a very low minimum reflection coefficient (RCmin) −60.9 dB, broad effective absorption bandwidth 3.50 GHz in the X-band and 15.5 GHz in the whole frequency range (from 2.5 to 18 GHz). The results indicate outstanding electromagnetic wave (EMW) absorbing performance among all the reported cobalt-based nanomaterials, due to the reasons as follows: (a) The unique core-shell structure as well as complex phase composition of SiC/C/SiOC/SiO2/Co3O4 in the shell, result in a large number of heterogeneous interfaces in the nanoparticles; (b) Nanoparticles have both dielectric and magnetic loss; (c) Mesopores in the shell prolong the propagation path of EMW, thereby increasing the absorption/reflection ratio of EMWs. Thanks to the material structure design, the resulting core-shell structured cobalt-containing ceramic nanoparticles have great potential for thin and high-performance EMW absorbing materials applied in harsh environment. 相似文献
7.
《Ceramics International》2022,48(4):5217-5228
In order to overcome the problems caused by electromagnetic pollution, the design and development of high-performance microwave absorbers is urgently required. In this work, a hierarchical ZnFe2O4@MnO2@RGO composite was successfully fabricated via a facile and rapid hydrothermal method. Its unique core-shell structure and synergistic effect between multiple components are beneficial for electromagnetic wave absorption. The morphology, elemental composition, microstructure and microwave absorption characteristics were systematically studied. With a filler loading of 20 wt%, the composite presents a minimum reflection loss (RLmin) of ?46.7 dB and an effective absorption bandwidth (EAB) as wide as 5.2 GHz at a thickness of 2.5 mm. The superior absorption ability profits from a special microstructure, good impedance matching, multiple attenuation features, interfacial polarization, and the synergistic effect of dielectric and magnetic loss. Consequently, this work lays a foundation for the design of high-performance electromagnetic wave absorbers with multicomponent heterogeneous structures. 相似文献
8.
《Ceramics International》2022,48(17):24877-24887
Environmentally friendly microwave absorbers with superior electromagnetic wave absorption, lightweight and hydrophobic ability have received considerable attention in practical applications. However, addressing the above-mentioned characteristics is simultaneously a tremendous challenge. Along these lines, in this work, a lightweight and efficient hybrid material was fabricated by employing simple self-assembly of core-shell ZnFe2O4@C nanospheres embedded within longan shell-derived honeycomb-like porous carbon. The results display that the carbon skeleton not only improves the conduction loss, but also promotes the reflection and scattering of EM wave. In addition, the core-shell ZnFe2O4@C microspheres are conducive to enhancing the ability of interface polarization and magnetic loss, and further improving the synergistic effect between the dielectric loss and magnetic loss. Furthermore, the unique structure of the ZnFe2O4@C@BPC endows it excellent hydrophobicity and avoids water vapor contamination in practical applications. Precisely, at a thickness of 3.4 mm, the minimum reflection loss (RL) is up to ?58.6 dB at 12.9 GHz. Notably, the effective absorption bandwidth (EAB) is as wide as 9.1 GHz (8.9–18.0 GHz), covering almost the entire X and Ku bands. Consequently, this outstanding performance renders the ZnFe2O4@C@BPC composite quite attractive for a broad range of applications in lightweight, hydrophobic microwave absorption materials. 相似文献
9.
《Ceramics International》2022,48(14):19709-19719
A carbon-silica nanomaterial for electromagnetic wave (EW) absorption was synthesized using a modified one-pot method. The unique hydrolysis-polymerization process forms a SiO2@SiO2/Carbon@Carbon core-shell structure. The growth process of the material was studied by transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Nanoparticles were successfully synthesized with a core-shell structure after 6 h of reaction, and the composite material showed excellent EW absorption performance with a thickness of 3.8 mm. The minimum reflection loss (RLmin) was ?56.3 dB, and the broadest effective absorption bandwidth (EAB) (RL ≤ 10 dB, 90% absorption) covered 5.15 GHz (12.48–17.63 GHz) with 1.8 mm of thickness. There is no significant difference in the EW absorption performance with increasing reaction time. Thus, this study provides a method for synthesizing EW-absorbing materials with shorter reaction time, simpler process, and excellent absorption properties, possibly a candidate for further application. 相似文献
10.
Zhilan Du Dashuang Wang Xinfang Zhang Zhiyu Yi Jihai Tang Pingan Yang Rui Cai Shuang Yi Jinsong Rao Yuxin Zhang 《International journal of molecular sciences》2023,24(1)
In this work, a novel core-shell structure material, NiFe layered double hydroxide (NiFe LDH) loaded on SiO2 microspheres (SiO2@NiFe LDH), was synthesized by a one-step hydrothermal method, and the spontaneous electrostatic self-assembly process. The morphology, structure, and microwave absorption properties of SiO2@NiFe LDH nanocomposites with different NiFe element ratios were systematically investigated. The results show that the sample of SiO2@NiFe LDH-3 nanocomposite has excellent microwave absorption properties. It exhibits broadband effective absorption bandwidth (RL < −10 dB) of 8.24 GHz (from 9.76 GHz to 18.0 GHz) and the reflection loss is −53.78 dB at the matched thickness of 6.95 mm. It is expected that this SiO2@NiFe-LDH core-shell structural material can be used as a promising non-precious, metal-based material microwave absorber to eliminate electromagnetic wave contamination. 相似文献
11.
《Ceramics International》2017,43(2):1887-1894
Fe3O4/reduced graphene oxide (RGO) nanocomposite was synthesized by a simple hydrothermal method and then SiO2 coated onto Fe3O4 by a modified Stӧber method. The transmission electron microscopy and field emission scanning electron microscopy characterization indicate that masses of Fe3O4@SiO2 core-shell structure nanospheres attached to the RGO sheets, and that the thicknesses of SiO2 shells are about 20–40 nm. The X-ray diffractograms and Raman spectra illustrate that the synthesized samples consist of highly crystallized cubic Fe3O4, amorphous SiO2 and disorderedly stacked RGO sheets. The magnetic hysteresis loops reveal the ferromagnetic behavior of the samples at room temperature. In addition, the Fe3O4@SiO2/RGO paraffin composite exhibit excellent electromagnetic wave absorption properties at room temperature in the frequency range of 2–18 GHz, which are attributed to the effective complementarities between the dielectric loss and magnetic loss. For Fe3O4@SiO2/RGO-1 and Fe3O4@SiO2/RGO-2 nanocomposite, the minimum reflection loss can reach −26.4 dB and −16.3 dB with the thickness of 1.5 mm, respectively. The effective absorption bandwidth of the samples can reach more than 10.0 GHz with the thickness in the range of 1.5–3.0 mm. It is demonstrated that such nanocomposite could be used as a promising candidate in electromagnetic wave absorption area. 相似文献
12.
《Ceramics International》2022,48(15):21656-21662
With the fast development of E-communication technology, effective electromagnetic wave absorbing materials are highly needed to address the growing electromagnetic pollution. Herein, Indium doped tin microsphere/reduced graphene oxide (In–Sn/rGO) composites with rich impurity defects were synthesized via the sol-gel and hydrothermal method. The excellent microwave absorption of In–Sn/rGO composites can be attributed to the modifications of electronics status and Fermi energy level after In doping. This can significantly increase the carrier mobility between In–Sn microspheres and rGO sheets to strike a superior interfacial polarization loss. As a result, the maximum absorptivity can reach ?51.16 dB at 8.73 GHz (thickness: 3.5 mm) with a lower filler loading of 10 wt%. Meanwhile, the synthesized In–Sn/rGO composites also exhibit an ultra-wide absorbing frequency range of 13.84 GHz (within the X band, Ku band, and most of the C band). This research provides a new idea for the synthesis of effective microwave absorbing material by introducing impurity defects. 相似文献
13.
《Ceramics International》2022,48(20):30206-30217
The SiCN/Fe/Ni ceramics codoped with iron acetylacetonate (FA) and nickle acetylacetonate (NA) was synthesized by polymer-derived ceramics (PDCs) method in this study. The microstructure, phase composition and electromagnetic wave (EMW) absorption properties of the samples were analyzed. The polarization loss and conduction loss of materials were analyzed by the direct current (DC) multimeter and the contribution rate of polarization loss was more than 94% in the whole frequency band. The results showed that C, SiC, Fe2Si, Ni3Si, γ- (Fe, Ni) and CNTs were formed after pyrolysis which provided lots of heterogeneous interface and enhanced the interfacial polarization. Meanwhile, Ni could enter the lattice of Fe and formed a unique electronic configuration, which reinforced the conductivity and stability of Fe. In addition, the in-situ generated Fe2Si and Ni3Si provided magnetic loss and conduction loss. The RLmin value of SiCN/Fe/Ni-3 ceramic was ?52.06 dB at 1.54 mm and the effective absorption band (EAB, RL ≤ ?10 dB) reached 4.21 GHz (13.79–18 GHz, 1.43 mm). 相似文献
14.
《Ceramics International》2016,42(4):5278-5285
Activated hollow carbon fibers (ACHFs) decorated with carbon nanotubes (CNTs) and nickel nanoparticles (CNTs–Ni–ACHFs) were prepared by thermal reduction and chemical vapor deposition technique. Microwave reflection loss, permittivity and permeability of CNTs–Ni–ACHFs composites as novel electromagnetic wave absorbents were studied in the frequency range of 2–18 GHz. It was demonstrated that CNTs–Ni–ACHFs absorbents possessed the best microwave absorbing performances whose minimum reflection loss was −43.457 dB at 13.10 GHz with a thickness of 2.0 mm, which is much better than those of Ni–ACHFs and ACHFs samples. The dielectric polarizations and magnetic loss derived from the effect of the porous structures, Ni nanoparticles, and defects in the CNTs–Ni–ACHFs composites are playing an important role for the excellent microwave absorbing performances. 相似文献
15.
《Ceramics International》2022,48(17):25049-25055
Recently, composite materials with outstanding absorption properties, like extraordinary absorbing capability, light weight, and thin in size, are required to solve the challenges of electromagnetic pollution. In addition, most of the work is based on the optimization of absorber material structure, and microstructure. In the current work, we improved the reflection loss feature of Bi0.5Nd0.5FeO3 nanopowders via decoration with polyindole polymer by tuning the filler loading of the nanocomposite in the matrix. XRD, UV–Vis, XPS, and FESEM were used to determine the physicochemical features of the as-prepared nanocomposite. The minimum RL was lowered further with the increasing filler loading at 25 wt%. The lower RL of ?22 dB was noticed for 2.2 mm thickness at 11.5 GHz. The maximum value of the SER for a 25 wt% sample was 5.5, whereas 19 dB and 24.5 dB values were recorded for SEA and SET, respectively. The resonance peak above 11.5 GHz demonstrated the better outcome of the absorber at high frequency. Good impedance matching characteristics, conductive features, dielectrics, and magnetic losses were all credited with the excellent reflection loss and electromagnetic interference shielding efficiency. The as-prepared nanocomposite materials that have been proven are interesting prospects for electromagnetic reflection loss and interference shielding that is lightweight, flexible, and extremely effective. 相似文献
16.
Bin Du Junjie Qian Ping Hu Chao He Mei Cai Xuan Wang Anze Shui 《Journal of the American Ceramic Society》2020,103(3):1732-1743
Polymer-derived ceramics (PDCs), such as SiOC, SiCN, SiBCN, and SiC are considered the best candidates for designing high-performance microwave absorber due to their controllable structure, homogeneous element composition at atom level, tunable electromagnetic and electrochemical properties. Herein, Fe ions doped silicon oxycarbide (Fe ions-SiOC) ceramics have been successfully fabricated via solvothermal method. The electromagnetic absorption performances of the nanocomposites prove to be controllable via tailoring Fe ion contents. The Fe ions effectively enhance both the interfacial polarization of amorphous SiOC, and the dielectric properties of the nanocomposites but barely effect magnetic properties of the nanocomposite. As for 0.16 mol/L-SiOC ceramics annealed at 1450°C, the effective absorption bandwidth as high as 2.00 GHz and reflection loss of −59.60 dB at 5.40 GHz with the thickness of 4.55 mm are obtained. Such work opens up a novel and simple route to scale up the PDC-based materials with broadband and excellent microwave absorbing performances. 相似文献
17.
Zhi Zhang Hui Liu Wenke Zhou Fan Wu Aming Xie Ziming Xiong Shuo Wang 《Ceramics International》2021,47(13):18157-18166
In this work, a novel graphene-based ternary composite NiOx@CS/reduced graphene oxide (rGO) consisting of magnetic nanoparticles (NiOx) and porous carbon spheres (CS) were successfully synthesised through facile hydrothermal and high-temperature sintering approaches. Owing to the ternary structure, the dielectric and magnetic capacity of the composite was improved. Further, the synergistic effect of two loss mechanisms improves the absorption efficiency of electromagnetic waves. The maximum reflection loss of NiOx@CS/rGO-20 wt% was ?69.3 dB at 7.2 GHz and the absorption bandwidth with reflection loss below ?10 dB was 4.04 GHz (6.36–10.4 GHz). Hence, the NiOx@CS/rGO ternary composite with a combination of dielectric and magnetic loss-facilitated absorption provides a new design paradigm for tuneable elimination of electromagnetic signals. 相似文献
18.
《Ceramics International》2021,47(21):30448-30458
Morphological configuration plays a vital role in regulating the absorption performance of magnetic materials. Herein, a novel challenge is discussed on electromagnetic loss features of two hard and soft magnetic materials with hierarchical brain-coral like structure and rod-like structure. In this study, pure SrFe12O19 (Sr) as hard magnetic component and CoFe2O4 (Co) as soft magnetic component with two distinct morphologies were successfully synthesized by facile hydrothermal and solvothermal methods. In the first approach, electromagnetic loss features of rod and brain-coral-like particles were investigated, and in second approach -according to the obtained results-microwave absorption performance of a mixture of hard/soft magnetic components with hierarchical structure were evaluated. The minimal reflection loss (RL) for brain-coral-like particles of individual Sr and Co samples were −17.6 dB (at 18.8 GHz with 9 mm thickness) and −31.2 dB (at 8.1 GHz with 10 mm thickness), respectively, which show far better performance than rod-like structure. Remarkably, the composite of Sr and Co micro-particles with hierarchical structure exhibited strong RL value of −38 dB with 2.6 GHz effective absorption bandwidth at the thickness of 2.5 mm, with a filling ratio of 40 wt%. According to the results, it is founded that the electromagnetic loss features are crucially boosted via hierarchical configuration of magnetic materials. Increment in complex permittivity and permeability, accounting for the formation of cross-linked networks in the hierarchical structure, promoted the interfacial polarization phenomena with different relaxation times and appearance of multi resonance peaks. 相似文献
19.
Yupeng Wei Jingpeng Lin Tiantian Jiang Linqi Li Kangyou Zhong Junwei Zhang Yong Peng 《Ceramics International》2021,47(6):7937-7945
Core-shell C/NiP microfiber composites were fabricated via electroless plating in this work. Their microstructure and electromagnetic properties were adjusted by annealing treatment and different phosphorus (P) content in the NiP coating. The C/NiP microfibers composites with 6 wt % P content in the NiP coating annealed at 300 °C remarkably owns ?46.7 dB strong reflection loss at 10.0 GHz with the thickness of 2.0 mm, and the effective bandwidth (RL ≤ ?10 dB) reaches 8.1 GHz (3.1–11.2 GHz). This work shows that the annealing conditions and different P concentrations in the coating layers for C/NiP microfibers composites are the effective way to optimize the electromagnetic wave absorption performance. 相似文献
20.
《Ceramics International》2023,49(19):31364-31377
To create a spinel ferrite with excellent performance for electromagnetic (EM) wave absorption in the low frequency range of 4–6 GHz, compositions based on Co0.75Zn0.125Fe0.125Fe2O4 (CZF–1) and Co0.5Zn0.25Fe0.25Fe2O4 (CZF–2) with multiple elements substituted for A sites were synthesized by using solvothermal method. Hollow porous magnetic/magnetic heterostructure microspheres (HHMs) of CZF–A1 and CZF–A2 with multiple interfaces were prepared by hydrogen–thermal reduction of CZF–1 and CZF–2, and their unique structure and EM absorption properties were investigated in detail. The widest effective absorption bandwidth (EAB) of CZF–A1 and CZF–A2 was 4.1 GHz (13.6–17.7 GHz) and 3.7 GHz (8.0–11.7 GHz) for a corresponding thickness of 1.4 mm and 2.0 mm, respectively. In addition, the minimum reflection loss (R.Lmin) of CZF–A1 and CZF–A2 reached –49.1 dB (at fm = 13.4 GHz) and –45.0 dB (at fm = 4.2 GHz) at a thicknesses of 1.6 mm and 3.7 mm, respectively. More specifically, in the low frequency region of 4–6 GHz, CZF–A1 and CZF–A2 exhibited excellent EM wave absorption due to the effective regulation of their natural resonance frequency. The EM wave absorption frequency band of CZF–A1 and CZF–A2 samples was able to completely cover the 4–6 GHz frequency region for at coating thickness of CZF–A1 and CZF–A2 was only 3.5 mm and 3.3 mm respectively, and their R.Lmin reached –36.5 dB and –22.6 dB. Moreover, the absorption mechanisms of CZF–A1 and CZF–A2 including magnetic resonance, eddy current loss, interfacial polarization and dipole polarization were also investigated in detail. This research provides new insights and guidance for the development of spinel ferrite-based EM absorbers for high efficiency EM wave absorption in the low frequency (4–6 GHz) region. 相似文献