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Issue 5, 2019
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Symmetrical polyhedron-bowl Co/CoO with hexagonal plate to forward electromagnetic wave absorption ability

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Abstract

Symmetrical polyhedron-bowl (twin-hexagonal frustum-pyramid) structured Co/CoO products were prepared via a simple polyol reduction approach. The effects of reaction conditions (solvent constituents and reaction times) on the morphologies of Co/CoO products were investigated in detail. The microwave absorption performances of Co/CoO polyhedron paraffin composites with various Co/CoO contents were also studied. The results showed that the Co/CoO polyhedron paraffin composites exhibit enhanced microwave absorption properties with an increased Co/CoO content in the certain amount range. This phenomenon is observed because the conductive networks are gradually formed to cause leakage current loss with increasing Co/CoO content. However, the large leakage current induces impedance mismatch to prohibit microwaves from entering absorbers with a relatively high Co/CoO content. Thus, the Co/CoO polyhedrons paraffin composite with 50 wt% Co/CoO displays excellent microwave absorption properties. The optimal reflection loss (RL) is −45.3 dB at 12.5 GHz with a thickness of 1.7 mm. The effective absorption (below −10 dB) bandwidth can be tuned to the frequency of 4.5–18.0 GHz with thickness of 1.0–4.0 mm. The abundant reflection and scattering were caused by the symmetrical polyhedron-bowl structure. The micro-capacitors formed between Co/CoO as electrodes, paraffin as a dielectric, and the interfacial polarization collectively contribute to microwave absorption abilities.

Graphical abstract: Symmetrical polyhedron-bowl Co/CoO with hexagonal plate to forward electromagnetic wave absorption ability

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Publication details

The article was received on 01 Oct 2018, accepted on 30 Nov 2018 and first published on 30 Nov 2018


Article type: Paper
DOI: 10.1039/C8CE01677A
Citation: CrystEngComm, 2019,21, 816-826

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    Symmetrical polyhedron-bowl Co/CoO with hexagonal plate to forward electromagnetic wave absorption ability

    B. Zhao, Y. Li, J. Liu, L. Fan, K. Gao, Z. Bai, L. Liang, X. Guo and R. Zhang, CrystEngComm, 2019, 21, 816
    DOI: 10.1039/C8CE01677A

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