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<p>In the present work, novel Fe<sub>3</sub>O<sub>4</sub>-expanded graphite-white cement composites of different wt.% ratios (5%, 10%, 20%, 30% and 40%) were prepared as viable microwave absorbers in the frequency range (8.2–12.4) GHz. Initially, the synthesized Fe<sub>3</sub>O<sub>4</sub> and expanded graphite (EG) were characterized by XRD and SEM studies confirming mean particle size of Fe<sub>3</sub>O<sub>4</sub> ~ 26.41&#xa0;nm and loose and spongy structure of EG flakes providing elevated surface area. Microwave absorption’s constitutive parameters viz. complex permittivity (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10854_2025_14757_Article_IEq1.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\({\varepsilon }_{r}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>ε</mi> <mi>r</mi> </msub> </math></EquationSource> </InlineEquation>) and permeability (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10854_2025_14757_Article_IEq2.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mu }_{r}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>μ</mi> <mi>r</mi> </msub> </math></EquationSource> </InlineEquation>) measured using Nicolson Ross method showed increasing trend with higher Fe<sub>3</sub>O<sub>4</sub> -EG wt.%. Based on transmission line theory, optimized single-layer absorber designs were fabricated for microwave absorption evaluation. The reflection loss (<i>RL</i><sub>m</sub>) was measured to be approximately −&#xa0;25&#xa0;dB at 10.8&#xa0;GHz and −&#xa0;36&#xa0;dB at 11.8&#xa0;GHz for composites with 5 wt.% and 20 wt.% loading, respectively. Further, geometrically modified perforated structure of triangular lattice pattern in the composites was proposed for broad absorption bandwidth.</p>

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Synthesis and development of Fe3O4-expanded graphite embedded cement nanocomposites as excellent X-band microwave absorber

  • 期刊论文

  • 发表日期：

    2025年4月26日

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  • Bidyut B. Saikia,
  • Nabajyoti Saikia,
  • Jyoti Prasad Gogoi,
  • P. K. Mochahari

摘要

In the present work, novel Fe3O4-expanded graphite-white cement composites of different wt.% ratios (5%, 10%, 20%, 30% and 40%) were prepared as viable microwave absorbers in the frequency range (8.2–12.4) GHz. Initially, the synthesized Fe3O4 and expanded graphite (EG) were characterized by XRD and SEM studies confirming mean particle size of Fe3O4 ~ 26.41 nm and loose and spongy structure of EG flakes providing elevated surface area. Microwave absorption’s constitutive parameters viz. complex permittivity ( \({\varepsilon }_{r}\) ε r ) and permeability ( \({\mu }_{r}\) μ r ) measured using Nicolson Ross method showed increasing trend with higher Fe3O4 -EG wt.%. Based on transmission line theory, optimized single-layer absorber designs were fabricated for microwave absorption evaluation. The reflection loss (RLm) was measured to be approximately − 25 dB at 10.8 GHz and − 36 dB at 11.8 GHz for composites with 5 wt.% and 20 wt.% loading, respectively. Further, geometrically modified perforated structure of triangular lattice pattern in the composites was proposed for broad absorption bandwidth.