Shandong Non metallic Materials Research Institute

Jinan, China

Shandong Non metallic Materials Research Institute

Jinan, China
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Pan S.,Shandong University | Pan S.,Shandong Non Metallic Materials Research Institute | Xie P.,Shandong University | Zhang Z.,Shandong University | And 3 more authors.
ECS Journal of Solid State Science and Technology | Year: 2017

In this paper, Fe78Si9B13/polyaniline composites with different Fe78Si9B13 content are prepared through cryomilling and pressure molding. The dielectric and magnetic properties are investigated experimentally in the frequency range from 10 MHz to 1 GHz. Both dielectric and magnetic Debye-like relaxation behavior are observed in this frequency range. With the increase of the FeSiB content, the loss peaks in the permittivity spectrum show a redshift, but a blueshift in the permeability spectrum. The results indicate that the loss peak shift has a close relationship with the conductivity and domain wall displacement. As affected by the interface of polyaniline and Fe78Si9B13 particles, the conductivity of composites decrease with the increase of FeSiB content until the formation of 3D network of FeSiB particles, leading to the redshift of the loss peak in the permittivity spectrum. Meanwhile, the blueshift in the permeability spectrum is mainly caused by the domain wall displacement with high damping factor. © 2017 The Electrochemical Society.

Pan S.,Shandong University | Pan S.,Shandong Non metallic Materials Research Institute | Wang Z.,Shandong University | Chen M.,Shandong University | And 2 more authors.
Materials Letters | Year: 2017

Acrylic-polyurethane (APu) as one of self-adhesive materials has been widely used in various coating industries, however it has seldom caused the researchers concern on its dielectric property. In this paper, acrylic polyurethane and carbon fibers (CFs) composites with good dispersibility have been successfully prepared. The dielectric properties and ac conductivity of the CFs/APu composites as a function of frequency and volume fraction of CFs were studied. High dielectric constant about 700 (10 kHz) was observed in APu-14.7% CFs composites. The outstanding dielectric properties make CFs/APu composites as promising candidates for thin-film capacitors, electromagnetic shielding and attenuation coatings. © 2017

Chen M.,Shandong University | Gao M.,Shandong University | Dang F.,Shandong University | Wang N.,University of Electronic Science and Technology of China | And 3 more authors.
Ceramics International | Year: 2016

FeNiMo/Al2O3 composites with different FeNiMo content were prepared by hot-pressing sintering. Interestingly, simultaneous negative permittivity and permeability were realized in FeNiMo/Al2O3 composites with 30% FeNiMo content in the frequency range of 860MHz to 1GHz and in the frequency range of 890MHz to 1GHz for composites with 40% FeNiMo content. Experimental results and theoretical simulations indicate that the negative permeability is caused by the domain wall resonance and gyromagnetic spin resonance, while the negative permittivity is attributed to the plasma oscillation of conduction electrons and LC resonance. The negative permittivity of the FeNiMo/Al2O3 composite induced by the plasma oscillation of conduction electrons was analyzed using the Drude model. The fitting results indicated that the plasma frequency of the composites was 8.99GHz. © 2016 Elsevier Ltd and Techna Group S.r.l.

Hou Q.,Shandong University | Yan K.,Shandong University | Fan R.,Shandong University | Zhang K.,Grirem Advanced Materials Co. | And 3 more authors.
Materials Chemistry and Physics | Year: 2016

The radio frequency permittivity and permeability spectra of Fe-Si-Ni/epoxy magnetic composite materials were investigated in detail. A relaxation frequency dispersion of permittivity has been observed for the composites below percolation threshold, and tunable negative permittivity due to the plasma oscillation of delocalized electrons in interconnected Fe-Si-Ni has been obtained in the composites above but still near percolation threshold. The realization of negative permittivity in Fe-Si-Ni/epoxy composites can be applied for the electromagnetic shielding materials. © 2015 Elsevier B.V.

Chen M.,Shandong University | Fan R.-H.,Shandong University | Gao M.,Shandong University | Gao M.,Happiness | And 4 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2015

The physical properties of conductor-insulator composites often take dramatic changes near the percolation threshold (fc), leading to interesting applications, such as double negative material. This phenomenon also will be enlarged by increasing the differences between the properties of the constitutive phases. In this paper, the Fe50Ni50/Al2O3 magnetic cermets with different Fe50Ni50 volume contents (10%, 20%, 30%, 40%) were prepared via hot-pressing sintering. The permittivity of Fe50Ni50/Al2O3 composites has been studied in the radio frequency range. The results indicate that when the Fe50Ni50 content is below fc, the reactance of the composites takes a negative value, which indicates a capacitive character. The metallic Fe50Ni50 grains are isolated in the insulating ceramic matrix, leading to an in-sulator-like dielectric property. When the volume fraction of Fe50Ni50 reaches 40% which is above fc, the composites manifest an inductive character. In this case, the negative permittivity has been obtained over the whole test frequency range due to the percolation phenomenon, which makes Fe50Ni50/Al2O3 composites as promising candidates for double negative materials. © 2014 Elsevier B.V. All rights reserved.

Yan K.-L.,Shandong University | Fan R.-H.,Shandong University | Chen M.,Shandong University | Sun K.,Shandong University | And 5 more authors.
Rare Metals | Year: 2015

The nano-graphite sheet/alumina composites were prepared in situ by a facile impregnation-reduction process. The microstructure of the composites was analyzed by X-ray diffraction (XRD), and the final phase composition after reduction is Al2O3, metal Fe and graphite crystal. Scanning electron microscopy (SEM) images show that the particle size of Fe is about 20 nm, and the lamellae thickness of the graphite is about 30 nm. Then, the dielectric properties and conductive mechanism of the composites were investigated experimentally in the frequency range of 0.01–1.00 GHz by impedance analyzer. The results show that the real part of permittivity of composites increases with Fe3+ concentration, which is due to the increase in interfacial polarization between Fe and Al2O3 and the three-dimensional network of lamellar graphite formation. Therefore, tunable microtopography and electrical parameters of nano-graphite sheet/alumina composites can be realized by changing Fe3+ concentration. © 2015 The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg

Sun K.,Shandong University | Fan R.H.,Shandong University | Zhang Z.D.,Shandong University | Yan K.L.,Shandong University | And 5 more authors.
Applied Physics Letters | Year: 2015

The electromagnetic properties including ac conductivity, permittivity, and permeability of percolative Fe/Al2O3 composites, which were prepared by in-situ synthesis process, are investigated in the radio frequency range. There is an obvious percolation transition with the increase of iron contents. When iron content is beyond but near the percolation threshold, the negative permittivity and permeability are simultaneously obtained from 631 MHz to 1 GHz in sample FA30. Further increasing iron content, the Fano-like resonances are observed, and the resonance frequency where the permittivity changes from negative to positive shifts to lower frequency. In addition, the frequency region of negative permittivity and negative permeability are not overlapped any more. Hopefully, the percolative Fe/Al2O3 composites with tunable negative permittivity and negative permeability can be used as electromagnetic wave absorber. © 2015 AIP Publishing LLC.

Wang X.-A.,Shandong University | Shi Z.-C.,Shandong University | Chen M.,Shandong University | Fan R.-H.,Shandong University | And 4 more authors.
Journal of the American Ceramic Society | Year: 2014

Cobalt/alumina composites with three-dimensional cobalt networks hosted in porous alumina matrix were prepared by a facile impregnation process under low temperature. The effects of composition and microstructure on their electromagnetic properties were investigated. A percolation phenomenon appeared with cobalt content increasing, and an interesting feature of negative permittivity was obtained in the percolative composites due to the appearance of equivalent inductances, while the composites were equivalent to circuit models composed of capacitance and resistance with Co content below the percolation threshold. Meanwhile, negative permeability was obtained in the frequency range of 500 MHz-1 GHz. Further investigations showed that the electromagnetic properties of the composites could be changed significantly when the cobalt particles networks turned into sheet structure. That was to say, the electromagnetic properties of metal-ceramic composites could be tailored by their compositions and microstructures, which make it available for microwave-absorbing materials, attenuation ceramics and microwave dielectrics, etc. © 2014 The American Ceramic Society.

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