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14 results on '"Ma, Jianna"'

12. Application of unit polarization strategy to achieve high-performance electromagnetic absorption by designing ternary SiO2@TiO2-C composite.

Author

Ma, Jianna, Quan, Bin, Liu, Wei, Liang, Xiaohui, Zhang, Yanan, Li, Daoran, Cheng, Yan, and Ji, Guangbin

Subjects
*POLARIZATION (Electrochemistry), *SILICA, *X-ray diffraction, *SURFACE morphology, *TRANSMISSION electron microscopy
Abstract

Unit polarization has been regarded as an important role on the attenuation of dielectric loss as well as the microwave absorption. To solve the serious electromagnetic interference issue (EMI), the unit polarization strategy has been put forward in this research by development of ternary SiO 2 @TiO 2 -C composites. The detailed phase composite, unit size, morphologies have been characterized by the XRD, XPS and TEM. Owing to the enhanced dielectric loss and improved impedance matching, SiO 2 @TiO 2 -C composites show excellent electromagnetic absorbing properties. In detail, the minimum reflection loss value at 1.9 mm is up to - 60.09 dB for the SiO 2 @TiO 2 -C composite and the qualified absorption frequency bandwidth of 4.36 GHz (10.92–15.28 GHz) can be obtained. Furthermore, the absorption mechanism has been proposed in depth by analyzing the unit polarization intensity. [ABSTRACT FROM AUTHOR]

Published
2017
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13. Strong Electromagnetic Wave Response Derived from the Construction of Dielectric/Magnetic Media Heterostructure and Multiple Interfaces

Author

Quan, Bin, Liang, Xiaohui, Ji, Guangbin, Ma, Jianna, Ouyang, Peiyi, Gong, He, Xu, Guoyue, and Du, Youwei

Abstract

A novel yolk–shell structure of cobalt nanoparticle embedded nanoporous carbon@carbonyl iron (Co/NPC@Void@CI) was synthesized via metal organic chemical vapor deposition (MOCVD) and subsequent calcination treatment. The in situgeneration of void layer, which originated from the shrink of a Co-based zeolitic imidazolate framework (ZIF-67) during carbonization, embodies distinct advantage compared to the conventional template method. Thanks to the introduction of custom-designed dielectric/magnetic media heterostructure and multiple interfaces, the composites filled with 40 wt % of Co/NPC@Void@CI samples in paraffin exhibit a maximum reflection loss of −49.2 dB at 2.2 mm; importantly, a broad absorption bandwidth (RL < −10 dB) of 6.72 GHz can be obtained, which covers more than one-third of the whole frequency region from 10.56 to 17.28 GHz. This study not only develops the application of carbonyl iron as a high-efficiency light absorber but also initiates a fire-new avenue for artificially designed heterostructures with target functionalities.

Published
2013
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14. Achieving the interfacial polarization on C/Fe 3 C heterojunction structures for highly efficient lightweight microwave absorption.

Author

Zhang Y, Liu W, Quan B, Ji G, Ma J, Li D, and Meng W

Abstract

Design of dielectric/magnetic heterostructure and multiple interfaces is a challenge for the microwave absorption. Thus, in this study, a novel C/Fe 3 C nanocomposites have been fabricated by annealing the precursors obtained by the facile chemical blowing of polyvinyl pyrrolidone (PVP) and Fe(NO 3 ) 3 ·9H 2 O. By changing the content of Fe(NO 3 ) 3 ·9H 2 O, the honeycomb-like structure with scads of pores and electromagnetic parameters could be successfully tailored. When the addition of Fe(NO 3 ) 3 ·9H 2 O is ranging from 1 to 2g, honeycomb-structured nanocomposites possess high performance microwave absorption when mixed with 90wt% paraffin. The minimal reflection loss is -37.4dB at 13.6GHz and effective bandwidth can reach to 5.6GHz when the thickness is 2.0mm, indicating its great potential in microwave absorbing field. Its outstanding microwave performance is tightly related to the porous structure and substantial interface such as carbon/air and carbon/Fe 3 C, which are in favor of the impedance matching and interfacial polarization. Thus, our study may provide a good reference for the facile synthesis of light-weight carbon-based nanocomposites with effective interfacial polarization., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Published
2017
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