Structural, Microstructure and RL curves of Double Layer Microwave Absorber Based on Fe3O4/Carbon Fiber and Fe3O4/rGO.
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•Fe3O4/carbon fiber and Fe3O4/rGO nanocomposites were ...synthesized by solvothermal process.•XRD, FESEM VSM and VNA were used to determine the properties.•rGO/F with 3mm thickness depicted minimum RL of −50.2 dB at 9.5 GHz.•Double layer absorber with 2.0 mm thickness shows minimum RL of −52.5 dB at 10.8 GHz.
Recently, preparation of lightweight absorbers with high performance capability are urgently needed for practical demanded in order to solve the severe electromagnetic pollution. In the present study, two different composites (Fe3O4/carbon fiber and Fe3O4/rGO) were uniformly incorporated into resin epoxy matrix to obtain single and double layer X-band absorber with 20 wt% filler loading. Each of the composites were prepared via solvothermal process. According to the results, the minimum reflection loss values for each single layer Fe3O4/carbon fiber and Fe3O4/rGO absorber were −15 dB (3 mm thickness and 1.5 GHz bandwidth) and −50 dB (3 mm thickness and 4 GHz bandwidth) respectively. By assembling two-layer absorber in which Fe3O4/rGO composite placed at upper layer and Fe3O4/carbon fiber composite placed at bottom layer the minimum reflection loss reached to −52 dB (total thickness 2 mm and 4 GHz bandwidth). The special design of the absorber optimizes the thickness by improving the impedance matching characteristic. The results show that Fe3O4/rGO composite with high dielectric loss as an upper layer and Fe3O4/carbon fiber composite with high magnetic loss as bottom layer can be used as matching and absorber layer, respectively.
•Tuning the impedance matching characteristics by using appropriate amount of polyaniline.•Economical and wide bandwidth RA was prepared from magnetoelectric powders.•Lightweight microwave absorber ...with just 35 wt% filler loading.•Practical microwave absorber was produced by resin epoxy matrix.•PPY shell improve the RL to −35 dB at matching frequency of 11.2 GHz.
In this research, polyaniline@Ba0.5Sr0.5Fe12O19@MWCNTs nanocomposite was prepared via co-precipitation and in-situ polymerization methods, respectively. Microstructural, magnetic and electromagnetic wave absorption analysis of the prepared nanocomposite were studied via XRD, FESEM, VSM and VNA. Compared with Ba0.5Sr0.5Fe12O19@MWCNTs, the microwave absorption bandwidth of the coated nanocompoite with polyaniline was significantly enhanced, which increased to approxiamately 4 GHz from 3 GHz. The effective microwave absorption performance of the Ba0.5Sr0.5Fe12O19@MWCNTs nanocomposite was attributed to increase in the interfacial polarization, improvement in impedance matching as well as porous geometric structure. Specially, by tuning the dielectric and magnetic properties of absorber components, the microwave absorption characteristics can be optimized for broad frequency range. As a consequence, it is concluded that the prepared ternary nanocomposite could be used as lightweight, broadband microwave absorber.
The aim of this review was to analyze/investigate the synthesis, properties, and applications of polyvinyl alcohol-halloysite nanotubes (PVA-HNT), and their nanocomposites. Different polymers with ...versatile properties are attractive because of their introduction and potential uses in many fields. Synthetic polymers, such as PVA, natural polymers like alginate, starch, chitosan, or any material with these components have prominent status as important and degradable materials with biocompatibility properties. These materials have been developed in the 1980s and are remarkable because of their recyclability and consideration of the natural continuation of their physical and chemical properties. The fabrication of PVA-HNT nanocomposites can be a potential way to address some of PVA's limitations. Such nanocomposites have excellent mechanical properties and thermal stability. PVA-HNT nanocomposites have been reported earlier, but without proper HNT individualization and PVA modifications. The properties of PVA-HNT for medicinal and biomedical use are attracting an increasing amount of attention for medical applications, such as wound dressings, drug delivery, targeted-tissue transportation systems, and soft biomaterial implants. The demand for alternative polymeric medical devices has also increased substantially around the world. This paper reviews individualized HNT addition along with crosslinking of PVA for various biomedical applications that have been previously reported in literature, thereby showing the attainability, modification of characteristics, and goals underlying the blending process with PVA.
•H/S and H/S@CF nanocomposites were prepared using one-step sol–gel method.•XRD, FESEM and VSM were used to determine the properties of nanocomposites.•FESEM analysis depicted the honey comb like ...structure of H/S@CF.•The maximum reflection loss (RL) of H/S@CF nanocomposite was −45 dB at 12.4 GHz.
BaFe12O19/Ni0.5Co0.5Fe2O4 (H/S) as magnetic composite powder and subsequently carbon foam decorated with BaFe12O19/Ni0.5Co0.5Fe2O4 (H/S@CF) nanocomposites were prepared using one-step sol–gel and dip coating methods, respectively. Phase structures, morphology, magnetic and electromagnetic properties were evaluated using X-ray diffraction (XRD), Field emission electron microscopy (FESEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) respectively. According to the results, through XRD analysis, presence of pure barium hexaferrite, spinel ferrite and carbon are revealed. Rietveld refinement was also done to evaluate the phases in the prepared nanocomposites. FESEM analysis depicted the honey comb like structure of H/S@CF sample. Based on electromagnetic measurements, smooth and continuous behavior for permittivity and permeability of H/S@CF composite revealed strong interfacial polarization and migration of charges in the direction of field. The minimum reflection loss of H/S@CF nanocomposite was − 45 dB at a matching frequency of 12.4 GHz, and the effective bandwidth under − 10 dB was 4 GHz with a thickness of 2 mm. The excellent microwave absorption performances of H/S@CF nanocomposite may be ascribed because of the less dielectric, magnetic losses and high dielectric properties. H/S@CF nanocomposite is expected to be a suitable candidate for aeronautic and aerospace fields because of low cost, lightweight and better microwave absorbing material.
•Successfully synthesize of rod like Sr2FeReO6 and polygonal SnS2 powders.•The microwave dissipation performance in bilayer absorber tuned by tuning layer arrangement.•Flexible tuning of the ...impedance matching by varying the composition and layers thickness.•The synergistic effect of magnetic and dielectric losses was revealed.
Due to their special characteristics, bi-layer absorbers have drawn more attention in the field of microwave absorbers. These characteristics include synergistic effects between layers, the ability to tune absorption by adjusting layer arrangement, composition in each layer, and an improvement in interfacial polarization, which is the most effective feature for dissipating the incident wave. In this study-two distinct magnetic and magneto-dielectric components with SrFeReO6 and SrFeReO6/SnS2 composition were synthesized through solvothermal and polyol methods. The electromagnetic characteristics of paraffin base absorbers with varying filler loading percentages of SnS2 and SrFeReO6/SnS2 contents (20 and 40 wt%) were determined. These findings were used to design a bi-layer absorber with an optimum thickness and layer arrangement for achieving the wideband absorber with high absorption capability. Compared with the single layer absorber, the bi-layer absorber in which 40 wt% of SnS2 is placed at the top layer with 1 mm optimum thickness and 40 wt% of SrFeReO6/SnS2 is placed at the bottom layer with 1 mm thickness, the best absorption reaches −18 dB by covering almost the whole X-band frequency. The synergistic impact of tailoring the particle's shape, composition, and layer arrangement is what gives bi-layer absorbers their exceptional microwave dissipation performance as compared to single layer one. The findings demonstrated the potential of the designed bi-layer absorber in X-band frequency as an absorber with excellent performance and broad bandwidth capability.
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Tunable microwave absorption characteristics are highly desirable for industrial applications such as antenna, absorber, and biomedical diagnostics. Here, we report BiNdxCrxFe1-2xO3 ...(x = 0, 0.05, 0.10, 0.15) nanoparticles (NPs) with electromagnetic matching, which exhibit tunable magneto-optical and feasible microwave absorption characteristics for microwave absorber applications. The experimental results and theoretical calculations demonstrate the original bismuth ferrite (BFO) crystal structure, while Nd and Cr injection in the BFO structure may cause to minimize dielectric losses and enhance magnetization by producing interfacial defects in the spinel structure. Nd and Cr co-doping plays a key role in ordering the BFO crystal structure, resulting in improved microwave absorption characteristics. The BiNd0.10Cr0.10Fe1.8O3 (BNCF2) sample exhibits a remarkable reflection loss (RL) of −37.7 dB with a 3-mm thickness in the 10.15 GHz-10.30 GHz frequency region. Therefore, Nd and Cr doping in BFO nanoparticles opens a new pathway to construct highly efficient BFO-based materials for tunable frequency, stealth, and microwave absorber applications.
•polyindole-PANI co-polymer@BiFeO3 composite was synthesized by hydrothermal in-situ polymerization.•XRD, UV–Vis, FESEM and VNA were used to evaluate the physicochemical and electromagnetic ...properties of the BiF/PoPa composite.•Reflection losses, matching loss capacity of the single layer BiF/PoPa absorber was also evaluated.•polyindole-PANI co-polymer@BiFeO3 nanocomposites was found to be influenced by filler loading content regulation.•Enhanced absorption bandwidth (EAB) of BiF/PoPa sample with 40 wt% shows 3.5 GHz bandwidth having minimum RL −17.8 dB.
It's still a significant difficulty to find microwave absorbers that have outstanding microwave dissipation performance in hostile environments. Herein, the core–shell structure of polyindole-PANI co-polymer@BiFeO3 nanocomposite is successfully prepared via in-situ polymerization method. The introduction of a co-polymer shell on the surface of magnetic BiFeO3 nanoparticles considerably tuned the attenuation constant and impedance matching characteristics. The electromagnetic characteristics and microwave absorption feature of the polyindole-PANI co-polymer@BiFeO3 nanocomposites may be found to be influenced by filler loading content regulation. The sample containing 40 wt% of polyindole-PANI co-polymer@BiFeO3 nanocomposite with a thickness of 1.5 mm had a minimum reflection loss of −17.8 dB and a 3.5 GHz effective absorption bandwidth at 13.6 GHz frequency. Polyindole-PANI co-polymer@BiFeO3 nanocomposite with outstanding microwave dissipation capabilities might be useful in a wide range of high-frequency wave applications.
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.
Yttrium iron garnet (YIG) and yttrium aluminum iron garnet (YAIG) nanoferrite samples were synthesized by microemulsion method. The effect of sintering was examined by heating the samples at 900, ...1000, and 1100°C. The YIG and YAIG samples were then characterized using X-ray diffraction and field-emission scanning electron microscopy. Static and dynamic magnetic properties were measured by evaluating initial permeability, Q factor, and vibrating sample magnetometry properties of YIG and YAIG samples. YIG samples sintered at 1100°C showed higher initial permeability and Q factor compared with YAIG samples. However, hysteresis loops also showed variations in the saturation magnetization, remanence, and coercivity of YIG and YAIG samples sintered at 900, 1000, and 1100°C. The observed magnetic parameter such as saturation magnetization, coercivity and initial permeability are strongly affected by increasing temperature. The saturation magnetization and coercivity of YIG and YAIG nanoferrites were found in the range 11.56–19.92emu/g and 7.30–87.70Oe respectively. Furthermore, the decreasing trends in the static and magnetic properties of YAIG samples may be due to the introduction of Al ions in the YIG crystal lattice. Thus, YIG and YAIG sintered at 1100°C can be used for wide-ranging frequency applications.
•Static and dynamic magnetic properties of YIG and YAIG nanoferrites were determined.•Saturation magnetization, Q and initial permeability increased in YIG nanoferites.•Possible use of these nanoferrites for sensing and switching applications.
Rare earths RE's (Pr, Y, Gd, Ho, Yb) substituted MnZn spinel ferrites with composition of Mn0.5Zn0.5M0.02Fe1.98O4 (M = Pr, Y, Gd, Ho, Yb) are prepared by sol gel combustion approach. Low sintering ...temperature (500 °C) is used to sinter the RE's doped MnZn samples. MnZn samples are further characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to measure the cubic crystalline structure, particle size, morphology, porosity and grain size. Cubic crystalline phase of prepared RE's doped MnZn ferrites is confirmed by x-ray diffraction (XRD). The morphology, porosity and grain size are observed using FESEM. The magnetic properties of RE's doped MnZn nanoferrites are analyzed by vibrating sample magnetometer (VSM). Coercivity (Hc), remanence (Mr) and saturation magnetization (Ms) are calculated from the magnetic loops. The saturation and remanence of the nanoferrites are increased by the substitution of RE's metal ions and varies from 14.76 to 26.36 emu/g and 9.98–22.48 emu/g respectively. Bohr magneton and anisotropy constant are calculated from the recorded magnetic data. The conductive analysis of the prepared samples is studied at 40 °C −300 °C temperature, leading to the conductivity measurements from 1.12 × 10-2 Ω-1-cm-1 to 9.52 × 10-2 Ω-1-cm-1. UV–Vis spectroscopy is used to determine the semi conducting nature of RE's doped MnZn spinel ferrite samples. The magnetic, conductive and optical study of the RE's doped MnZn nanoferrites sintered at low temperature suggests the use of these materials for microwave absorption, supercapacitor, lithium ion batteries and nanoelectronics industrial applications.
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