Manipulating the permittivities and permeabilities of epoxy/silver nanocomposites over a wide bandwidth

Su, Shih-Chieh; Chang, Tsun-Hsu

doi:10.1063/5.0006835

Cited by 14 publications

(7 citation statements)

References 31 publications

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“…The transmission/reflection methods can characterize materials' electromagnetic (EM) properties over a broad frequency range. The measured transmission/reflection coefficients using a network analyzer uniquely determine the complex permittivity ε and the complex permeability µ , when the sample thickness d is smaller than half of the guide wavelength ( g ) 25 . Here, we adapt the relative permittivity ε/ε 0 (= ε ′ + iε ′′ ) and permeability µ/µ 0 (= µ ′ + iµ ′′ ).…”

Section: Resultsmentioning

confidence: 99%

Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

Chang

et al. 2021

Sci Rep

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The epoxy/magnetite nanocomposites express superparamagnetism under a static or low-frequency electromagnetic field. At the microwave frequency, said the X-band, the nanocomposites reveal an unexpected diamagnetism. To explain the intriguing phenomenon, we revisit the Debye relaxation law with the memory effect. The magnetization vector of the magnetite is unable to synchronize with the rapidly changing magnetic field, and it contributes to diamagnetism, a negative magnetic susceptibility for nanoparticles. The model just developed and the fitting result can not only be used to explain the experimental data in the X-band but also can be used to estimate the transition frequency between paramagnetism and diamagnetism.

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Section: Resultsmentioning

confidence: 99%

Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

Chang

et al. 2021

Sci Rep

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“…Many different types of composites have been reported. Polymers doped with conductive fillers, such as graphene [ 11 ], silver [ 12 ] or other metals [ 13 ], are able to increase the dielectric constant drastically, but at the expense of low compatibility with printed circuit boards (owing to large leakage current) and high signal attenuation (due to severe Ohmic loss). On the other hand, ferromagnetic dopants, e.g., Fe 3 O 4 [ 14 ], and ferroelectric dopants such as PZT [ 15 ], TiO 2 [ 16 , 17 , 18 ], SrTiO 3 [ 19 ], BaTiO 3 [ 3 , 4 , 5 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ] or other oxides [ 17 , 18 ], are also good candidates.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of BaTiO3–Epoxy Nanocomposites in the Microwave Regime

2021

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We synthesized BaTiO3–epoxy nanocomposites (particle size < 100 nm) with volume fractions up to 25 vol. %, whose high-frequency complex permittivity was characterized from 8.2 to 12.5 GHz. The maximum dielectric constant approaches 9.499 with an acceptable loss tangent of 0.113. The dielectric loss gradually saturates when the particle concentration is higher than 15 vol. %. This special feature is an important key to realizing high-k and low-loss nanocomposites. By comparing the theoretical predictions and the experimental data, four applicable effective-medium models are suggested. The retrieved dielectric constant (loss tangent) of 100-nm BaTiO3 nanopowder is in the range of 50–90 (0.1–0.15) at 8.2–12.5 GHz, exhibiting weak frequency dispersion. Two multilayer microwave devices—total reflection and antireflection coatings—are designed based on the fabricated nanocomposites. Both devices show good performance and allow broadband operation.

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“…Figure 2a shows a schematic diagram of the tool, including the permanent and reactive parts, as well as a coating around the permanent part. The coating is a protective layer made of materials such as epoxy resins [20], which are identified as materials with a magnetic permeability in the range of 1 [21], and are used to prevent any aggressive agents from attacking the permanent part. The coating with non-magnetic properties in Figure 2b illustrates the cubic profile of the FMM tool.…”

Section: Numerical Fmm Modelmentioning

confidence: 99%

Parametric Study to Evaluate the Geometry and Coupling Effect on the Efficiency of a Novel FMM Tool Embedded in Cover Concrete for Corrosion Monitoring

Kadkhodazadeh

Ihamouten

Souriou³

et al. 2022

Remote Sensing

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Rebar corrosion represents a major threat to the durability of reinforced concrete structures, primarily in marine environments. Various Non-Destructive Evaluations (NDE) have been developed to detect rebar corrosion; although most of these have delivered successful results, a lack of reliable techniques for proper corrosion prognosis still remains. Under the French Research Agency (ANR) project’s “LabCom OHMIGOD” framework, we introduce here a novel embedded tool to evaluate the level of cover concrete contamination from aggressive agents responsible for causing corrosion. This tool is divided into two parts: a reactive part exposed to corrosion, and a permanent part protected against corrosion. Using magnetic materials in both parts entails “Functional Magnetic Materials” (FMM) and generates a Magnetic Observable (MO). Through the evolution of corrosion on the reactive part, its magnetic properties become affected, which in turn modifies the MO. By means of regular monitoring of MO variations, it is possible to evaluate the aggressive agent ingress. Consequently, by using a variety of FMM tools placed at different concrete depths, it is possible to indirectly evaluate the rebar corrosion risk. This paper presents a numerical model of the tool employing Ansys software. The underlying objective is to investigate tool accuracy through its key parameters, namely, geometry, relative distance to the receiver, coupling effect, and border effect from the rebar. Simulation results demonstrate that by choosing an efficient geometry for the reactive part (25 mm × 25 mm × 1 mm) and position for the tool (between 1 and 3 mm), both a sufficient MO variation range and a negligible coupling effect can be obtained when the FMM is more than 5 cm from any ferromagnetic material.

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Manipulating the permittivities and permeabilities of epoxy/silver nanocomposites over a wide bandwidth

Cited by 14 publications

References 31 publications

Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

Dielectric Properties of BaTiO3–Epoxy Nanocomposites in the Microwave Regime

Parametric Study to Evaluate the Geometry and Coupling Effect on the Efficiency of a Novel FMM Tool Embedded in Cover Concrete for Corrosion Monitoring

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