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<p>To improve the inherently poor impedance matching of spinel ferrites, a synergistic strategy combining Cr<sup>3+</sup> doping, in-situ reduction to metallic Ni, and amorphous carbon modification via a ternary carbon source is proposed. A porous Cr<sup>3+</sup>-doped Ni-Zn ferrite composite co-modified with in-situ-generated metallic Ni and amorphous carbon was fabricated by pyrolysis of sucrose/citric acid/polyethylene glycol under N<sub>2</sub> atmosphere. The composites feature a hierarchical porous structure, with Ni nanoparticles and carbon uniformly decorating the ferrite surface. Saturation magnetization increases progressively with carbon content owing to the formation of ferromagnetic Ni<sup>0</sup>, while coercivity rises to 20 Oe. The complex permittivity is substantially enhanced: the real part (<i>ε</i>′) increases from 3.8 to 11.0 and the imaginary part (<i>ε</i>″) from 0.1 to 3.8 (at 10&#xa0;GHz). At a thickness of 2.6&#xa0;mm, the composite with 10 wt % carbon source achieves an effective absorption bandwidth of 5.44&#xa0;GHz, while the 20 wt % sample delivers a minimum reflection loss of −&#xa0;44.1&#xa0;dB at a thickness of only 2.4&#xa0;mm. This strategy offers an effective pathway for designing broadband, low-thickness ferrite-based microwave absorbers.</p>

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In-situ construction of porous carbon/chromium-doped nickel-zinc ferrite composites for enhanced microwave absorption

  • 期刊论文

  • 发表日期：

    2026年7月19日

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  • Zhihao Geng,
  • Yujie Yang,
  • Hongyu Ding,
  • Tan Hu,
  • Shaofan Ge,
  • Xiyan Wang,
  • Ying Tang

摘要

To improve the inherently poor impedance matching of spinel ferrites, a synergistic strategy combining Cr3+ doping, in-situ reduction to metallic Ni, and amorphous carbon modification via a ternary carbon source is proposed. A porous Cr3+-doped Ni-Zn ferrite composite co-modified with in-situ-generated metallic Ni and amorphous carbon was fabricated by pyrolysis of sucrose/citric acid/polyethylene glycol under N2 atmosphere. The composites feature a hierarchical porous structure, with Ni nanoparticles and carbon uniformly decorating the ferrite surface. Saturation magnetization increases progressively with carbon content owing to the formation of ferromagnetic Ni0, while coercivity rises to 20 Oe. The complex permittivity is substantially enhanced: the real part (ε′) increases from 3.8 to 11.0 and the imaginary part (ε″) from 0.1 to 3.8 (at 10 GHz). At a thickness of 2.6 mm, the composite with 10 wt % carbon source achieves an effective absorption bandwidth of 5.44 GHz, while the 20 wt % sample delivers a minimum reflection loss of − 44.1 dB at a thickness of only 2.4 mm. This strategy offers an effective pathway for designing broadband, low-thickness ferrite-based microwave absorbers.