Microwave magnetic properties of Co50/(SiO2)50 nanoparticles

Wu, Mingzhong; Zhang, Y. D.; Hui, S.; Xiao, T. D.; Ge, Shenguang; Hines, W. A.; Budnick, J. I.; Taylor, G.W.

doi:10.1063/1.1484248

Cited by 447 publications

(189 citation statements)

References 13 publications

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“…7,11,12 The permeability (µ') (not shown) remained ~ 1 for all nanoparticle loadings over the frequency range investigated here, which was expected due to the reported resonance frequency of Fe 3 O 4 at ~ 1.5 GHz. At lower frequencies (1MHz -1GHz), the permeability also increased with nanoparticle volume loading, however a comparison with Bruggeman EMT has not yet been completed.…”

Section: Resultsmentioning

confidence: 68%

Collaborative Research and Development Delivery Order 0024: Synthesis, Processing, and Evaluation of Polymers for RF Applications

Vestal¹

2006

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information , 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YY)2 Research Objectives: The goal of this task is to develop methods to produce materials with tailored electromagnetic properties over a broad frequency range. The research effort focuses on two primary objectives: (1) Create the fundamental understanding necessary to establish relationships for nanoparticle loading and nanoparticle size on the electromagnetic properties in polymer-based nanostructured materials and (2) develop novel materials with enhanced and improved performance properties to address unique military needs for RF/microwave systems. Background:RF polymer nanocomposites are unique materials that combine novel electric and magnetic attributes with the inherent structural and processing properties of commodity polymers such as polyurethanes and PTFE. The desired electromagnetic properties for RF applications such as microelectronics and microwave communication systems are high permeability (µ), high permittivity (ε) and low loss (tan δ), where µ = ε ~ 3-5 and tan δ < 0.001. By producing materials meeting these requirements, we enable the development of higher gain antennas or conversely the miniaturization of RF devices.The understanding of the structure-property relationship of magnetic nanoparticles for RF applications is still in its infancy. Not only is there a need to develop materials with dielectric permeability and permittivity values that range from 3 to 5, with an essentially flat response over a broad frequency range, but another important objective is to develop an understanding of the properties of the fine particles inclusions and a correlation with their frequency response properties. Previous research findings published in the literature have focused on bulk materials or micron-sized particles (which behave similar to bulk materials) -very little information has been realized concerning structure-property relationship of magnetic nanoparticles for RF applications. This effort has focused upon developing an understanding of the effects of nanoparticle size, nanoparticle volume loading, and core/shell structure with the frequency dependent response from 10MHz-1GH...

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Section: Resultsmentioning

confidence: 68%

Collaborative Research and Development Delivery Order 0024: Synthesis, Processing, and Evaluation of Polymers for RF Applications

Vestal¹

2006

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“…The hysteresis loss normally can be neglected in a weak applied field. The domain-wall resonance occurs only in multi-domain materials and in the 1-100 MHz range [38]. The eddy current loss in the nanoparticles can be effectively suppressed by the outer insulator and reduced particle sizes.…”

Section: Resultsmentioning

confidence: 90%

Enhanced Polarization in Tadpole-Shaped (Ni, Al)/Aln Nanoparticles and Microwave Absorption at High Frequencies

Huang¹,

Xue²,

Lü³

et al. 2011

PIER B

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Abstract-Tadpole-shaped (Ni, Al)/AlN nanoparticles were synthesized via evaporating Ni-Al alloy in a mixed atmosphere of N 2 and H 2 . As a counterpart, the spherical-shaped (Ni, Al)/Al 2 O 3 nanoparticles were also prepared from the same target alloy while in a mixture of Ar and H 2 . The electromagnetic parameters of as-made nanoparticles/paraffin composites were then investigated in the frequency range of 2-18 GHz. Excellent microwave absorption can be obtained for the tadpole-shaped (Ni, Al)/AlN-paraffin composite at high frequencies and in a thin layer, which is thought to be the result of the enhanced polarization in the anisotropic tadpole-shaped nanoparticles. With the increasing of the composite thickness, the frequency of effective reflection loss shifts towards lower frequencies due to an improved impedance match and absorption.

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“…Eddy current loss is another factor that can influence the magnetic loss and can be calculated by Eq. (7) [46]:…”

Section: Em Absorption Performancesmentioning

confidence: 99%

Strengthened electromagnetic absorption performance derived from synergistic effect of carbon nanotube hybrid with Co@C beads

Qiao

Liu

et al. 2017

Adv Compos Hybrid Mater

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The composite structure of Co beads (200-300 nm) threaded by carbon nanotubes has been synthesized through a facile solvothermal method followed by a carbon reduction process. A carbon layer of ca. 5 nm was coated on the surface of Co beads to form a coreshell structure (CNTs/Co@C), in favor of the antioxidation of Co nanoparticles. The CNTs/Co@C hybrid showed a saturation magnetization (M s ) of 82.5 emu g −1 and a larger H c value of 258.8 Oe than bulk Co (ca. 10 Oe). Served as an EM wave absorption material, the epoxy resin composites consisting of 60 wt% and 40 wt% CNTs/Co@C hybrid exhibited effective EM absorption (RL < − 10 dB) over the frequency ranges of 1.5-15 and 1.6-20 GHz with the matching thicknesses of 1.0-7.5 and 1.0-10.0 mm, respectively. The superior EM absorption performances of CNTs/Co@C hybrid containing strong absorption, wide frequency range, thin thickness, and light weight are mainly attributed to the synergy of magnetic loss from Co beads and dielectric loss from carbon nanotubes, as well as remarkable impedance matching.

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Microwave magnetic properties of Co50/(SiO2)50 nanoparticles

Cited by 447 publications

References 13 publications

Collaborative Research and Development Delivery Order 0024: Synthesis, Processing, and Evaluation of Polymers for RF Applications

Collaborative Research and Development Delivery Order 0024: Synthesis, Processing, and Evaluation of Polymers for RF Applications

Enhanced Polarization in Tadpole-Shaped (Ni, Al)/Aln Nanoparticles and Microwave Absorption at High Frequencies

Strengthened electromagnetic absorption performance derived from synergistic effect of carbon nanotube hybrid with Co@C beads

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