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2007, Journal of Magnetism and Magnetic Materials
The complex permittivity (ε′–jε″), complex permeability (μ′–jμ″) and microwave absorption properties of ferrite–polymer composites prepared with different ferrite ratios of 50%, 60%, 70% and 80% in polyurethane (PU) matrix have been investigated in X-band (8.2–12.4 GHz) frequency range. The M-type hexaferrite composition BaCo+20.9Fe+20.05Si+40.95Fe+310.1O19 was prepared by solid-state reaction technique, whereas commercial PU was used to prepare the composites. At higher GHz frequencies, ferrite's permeabilities are drastically reduced, however, the forced conversion of Fe+3 to Fe+2 ions that involves electron hopping, could have increased the dielectric losses in the chosen composition. We have measured complex permittivity and permeability using a vector network analyzer (HP/Agilent model PNA E8364B) and software module 85071. All the parameters ε′, ε″, μ′ and μ″ are found to increase with increased ferrite contents. Measured values of these parameters were used to determine the reflection loss at various sample thicknesses, based on a model of a single-layered plane wave absorber backed by a perfect conductor. The composite with 80% ferrite content has shown a minimum reflection loss of −24.5 dB (>99% power absorption) at 12 GHz with the −20 dB bandwidth over the extended frequency range of 11–13 GHz for an absorber thickness of 1.6 mm. The prepared composites can fruitfully be utilized for suppression of electromagnetic interference (EMI) and reduction of radar signatures (stealth technology).
Materials Science and Engineering B-advanced Functional Solid-state Materials
Complex permittivity and microwave absorption properties of BaTiO 3–polyaniline composite2005 •
BaTiO3–polyaniline composites with different mixture ratios, 75/25, 50/50 and 25/75, have been prepared in polyurethane resin, keeping pigment to volume concentration (PVC) constant as ∼25 in all the samples. For this, BaTiO3 powder by oxide route and polyaniline by chemical oxidation route have been synthesized. The complex permittivity (ε′r−jε″r)(ε′r−jε″r) and reflection loss (dB) of the composites have been measured at different microwave frequencies in X-band (8.2–12.4 GHz) employing vector network analyzer model PNA E8364B and software module 85071. Reflection loss (dB) has been calculated for different thicknesses of the composites using measured values of ε′rε′r and ε″rε″r. It is found that the absorption properties of the composite improve with increasing % of polyaniline. A maximum reflection loss of −15 dB (97% power absorption) at 10 GHz with a bandwidth of 3 GHz (full frequency width at half of the peak response) has been achieved. Materials can find applications in suppression of electromagnetic interference (EMI), and reduction of radar signature.
Composites Part A-applied Science and Manufacturing
Complex permittivity and microwave absorption properties of a composite dielectric absorber2006 •
Two types of composite samples were prepared using dielectric particulates such as BaTiO3, polyaniline and conducting carbon in polyurethane matrix. One of the composite samples contains synthesized BaTiO3 and polyaniline, while the other sample using, the commercial ingredients. Structural properties of both synthesized and commercial BaTiO3 and polyaniline have been investigated. Complex permittivity (εr′-jεr″) and microwave absorption properties of the prepared composites were studied in X-band (8.2–13.5 GHz). An optimized composite sample with synthesized BaTiO3 and polyaniline has shown a maximum reflection loss of −25 dB (>99% power absorption) at 11.2 GHz with a bandwidth (full frequency width at half of the maximum response) of 2.7 GHz in a sample thickness of 2.5 mm. The measured absorption values have been validated by theoretical calculations. Materials can find applications in suppression of electromagnetic interference (EMI) and reduction of radar signature.
Applied Physics A
Electromagnetic and microwave absorption properties of carbonyl iron and carbon fiber filled epoxy/silicone resin coatingsJournal of Alloys and Compounds
Electromagnetic and microwave absorption properties of surface modified Fe–Si–Al flakes with nylon2012 •
Physica Status Solidi (a)
Influence of matching thickness on the absorption properties of doped barium ferrites at microwave frequencies2006 •
The development and characterization of hexagonal ferrite powders of BaFe9Mn1.5Ti1.5O19, BaFe9Mn1.5Co1.5O19, and BaFe9Ti1.5Co1.5O19 as the microwave absorbers have been investigated. The ferrites were fabricated by conventional ceramic technology. The developed ferrite powders 80% by weight were mixed with polyvinylchloride plasticizer and fired to form rubber-ferrite with the thickness of 1.5 mm, 2 mm and 2.5 mm. XRD was used to identify structures of the samples. The magnetoplumbite structures for all the samples have been formed. Vibrating sample magnetometer was used to determine the hysteresis loops of barium ferrite and BaFe9Mn1.5Ti1.5O19 at room temperature. The vector network analyzers in the frequency range of 12 to 20 GHz have measured the reflection loss properties of rubber-ferrite. It was concluded that BaFe9Mn1.5Ti1.5O19 with thickness of 2 mm could be designed as a wide-band microwave absorber. By SEM, the size and morphology of grains in BaFe9Mn1.5Ti1.5O19 ferrite were examined. The results showed that ferrite with grain size of 5 µm do not have any impurities. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Journal of Magnetism and Magnetic Materials
Complex permittivity, permeability and microwave absorbing properties of (Mn 2− x Zn x )U-type hexaferrite2010 •
Complex permittivity, permeability and microwave absorbing properties of a U-type hexaferrite series Ba4Mn(2−x)ZnxFe36O60 (with 0≤x≤2 in step of 0.5) have been examined in the X-band (8.2–12.4 GHz) frequency range. The series have been prepared using conventional solid state reaction route. Microstructural variations with composition have been found with X-ray diffraction (XRD) and scanning electron microgram (SEM). The complex permittivity (ε⁎=ε′−jε″) and permeability (μ⁎=μ′−jμ″) were measured using vector network analyzer (Agilient Make model PNA E8364B). These parameters were then used for calculating the reflection loss for determination of microwave absorbing properties. Addition of Zn resulted in an increase in reflection loss from −4 dB (or 60 % absorption) in sample with x= 0 to −32 dB (99.92% absorption) in sample with x=1 when the sample thickness was 1.7 mm. Multiple peaks of resonance were obtained in the dielectric and magnetic loss spectra for all samples with x>0. ...
Journal of Thermal Spray Technology
Hexaferrite/Polyester Composite Coatings for Electromagnetic-Wave Absorbers2011 •
Scientific Reports
A Study on Microwave Absorption Properties of Carbon Black and Ni0.6Zn0.4Fe2O4 Nanocomposites by Tuning the Matching-Absorbing Layer StructuresMicrowave absorption properties were systematically studied for double-layer carbon black/epoxy resin (CB) and Ni0.6Zn0.4Fe2O4/epoxy resin (F) nanocomposites in the frequency range of 8 to 18 GHz. The Ni0.6Zn0.4Fe2O4 nanoparticles were synthesized via high energy ball milling with subsequent sintering while carbon black was commercially purchased. The materials were later incorporated into epoxy resin to fabricate double-layer composite structures with total thicknesses of 2 and 3 mm. The CB1/F1, in which carbon black as matching and ferrite as absorbing layer with each thickness of 1 mm, showed the highest microwave absorption of more than 99.9%, with minimum reflection loss of −33.8 dB but with an absorption bandwidth of only 2.7 GHz. Double layer absorbers with F1/CB1(ferrite as matching and carbon black as absorbing layer with each thickness of 1 mm) structure showed the best microwave absorption performance in which more than 99% microwave energy were absorbed, with promising m...
Journal of Applied Physics
Complex permittivity, permeability, and X-band microwave absorption of CaCoTi ferrite composites2000 •
Materials Science and Engineering: B
Complex permeability and permittivity and microwave absorption studies of Ca (CoTi) xFe12-2xO19 hexaferrite composites in X-band microwave …1999 •
SN Applied Sciences
Synthesis of suitable material for microwave absorbing properties in X-bandJournal of Alloys and Compounds
Effects of divalent ions substitution on the microstructure, magnetic and electromagnetic parameters of Co2W hexagonal ferrites synthesized by sol–gel method2013 •
Journal of Magnetism and Magnetic Materials
Characterization of Sr-substituted W-type hexagonal ferrites synthesized by sol–gel autocombustion method2013 •
Journal of Materials Science
Dielectric constant, magnetic permeability and microwave absorption studies of hot-pressed Ba-CoTi hexaferrite composites in X-band2006 •
Current Applied Physics
The role of Ga substitution on magnetic and electromagnetic properties of nano-sized W-type hexagonal ferrites2013 •
Current Applied Physics
Magnetic and microwave attenuation behavior of Al-substituted Co2W hexaferrites synthesized by sol-gel autocombustion process2012 •
Scientific Reports
Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1−xZnxFe2O4/NBR Composites over 2–12.4 GHz: A Strategic Material System for Stealth Applications2017 •
Journal of Magnetism and Magnetic Materials
Microwave behavior of ferrites prepared via sol–gel method2002 •
Materials Science and Engineering B-advanced Functional Solid-state Materials
Microwave absorption studies of Ca–NiTi hexaferrite composites in X-band2000 •
Journal of Magnetism and Magnetic Materials
Complex permittivity, permeability and wide band microwave absorbing property of La3+ substituted U-type hexaferrite2010 •
Journal of Physics D: Applied Physics
Co-Al-substituted strontium hexaferrite for rare earth free permanent magnet and microwave absorber application2021 •
International Nano Letters
Exploring the feasibility of development of nanomaterial-based microwave absorbersJournal of Materials Engineering and Performance
Electric and Dielectric Properties of Cr-Ga Substituted BaM Hexaferrites for High-Frequency Applications2013 •
Materials & Design
Development of “tuned microwave absorbers” using U-type hexaferrite2010 •
2012 •
Journal of Materials Science
Polymeric nanocomposites for electromagnetic wave absorption2009 •
Journal of Materials science: Materials in Engineering
Elucidation of microwave absorption mechanisms in Co–Ga substituted Ba–Sr hexaferrites in X-band2018 •
Ceramics International
Microwave absorption study of carbon nano tubes dispersed hard/soft ferrite nanocomposite2012 •
2020 •
Defence Science Journal
Development of E Waste based Composite Microwave Absorbing Material2017 •
Journal of Magnetism and Magnetic Materials
The role of matching thickness on the wideband electromagnetic wave suppresser using single layer doped barium ferrite2011 •
Ceramics International
Development of hard/soft ferrite nanocomposite for enhanced microwave absorption2011 •