The rapid proliferation of electromagnetic technology has led to severe electromagnetic pollution, driving an urgent need for efficient microwave-absorbing materials. Nickel-zinc ferrites are widely studied for this purpose; however, their inherent impedance mismatch, resulting from the large disparity between complex permeability and permittivity, leads to strong surface reflection and severely limits absorption efficiency. This study systematically investigates the regulatory effect of indium ion (In3+) doping on the microwave absorption performance of spinel-type nickel‑zinc ferrites. First, Ni0.48 Zn0.32 Cu0.2 Cr0.1 Inx Fe1.9-x O4 (x = 0, 0.1, 0.2, 0.3) ferrite powders were synthesized via a solid‑state reaction method, with the optimal doping level identified as x = 0.1. Subsequently, using this optimal composition, a series of composite materials with ferrite to β-SiC mass ratios of 9:1, 8:2, and 7:3 was prepared via high-energy ball milling. The introduction of non‑magnetic SiC aimed to achieve magnetic dilution, thereby optimizing the impedance matching and loss characteristics of the composites. Phase and morphological characterizations confirmed that all samples exhibited a pure spinel structure, with both phases uniformly distributed in the composites. Scanning electron microscopy revealed that the ferrite particles displayed regular morphology, with sizes ranging from 3 to 3.5 µm, and were well‑dispersed and mechanically integrated with the SiC particles. Electromagnetic measurements indicated that appropriate In3+ doping (x = 0.1) improved the minimum reflection loss from -18.76 dB to -19.84 dB. Further composite formation with SiC led to a remarkable enhancement in absorption performance: at the optimal ratio (9:1), the composite achieved a significantly lower minimum reflection loss of ‑35.49 dB at 7.52 GHz, along with a broadening of the effective absorption bandwidth (RL ≤ -10 dB) from 4.0 GHz to 4.4 GHz. This work demonstrates that the absorption enhancement in the In-doped ferrite/SiC composite originates solely from the increased attenuation constant driven by boosted dielectric loss, providing a practical design paradigm for high-performance ferrite‑based microwave absorbers. These findings provide clear experimental evidence and mechanistic insights for the design of high‑performance ferrite‑based composite microwave absorbers.

Structural and microwave absorption properties of silicon carbide composited indium-doped nickel-zinc ferrites

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发表日期：

2026年6月17日

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

摘要

The rapid proliferation of electromagnetic technology has led to severe electromagnetic pollution, driving an urgent need for efficient microwave-absorbing materials. Nickel-zinc ferrites are widely studied for this purpose; however, their inherent impedance mismatch, resulting from the large disparity between complex permeability and permittivity, leads to strong surface reflection and severely limits absorption efficiency. This study systematically investigates the regulatory effect of indium ion (In³⁺) doping on the microwave absorption performance of spinel-type nickel‑zinc ferrites. First, Ni_0.48 Zn_0.32 Cu_0.2 Cr_0.1 In_x Fe_1.9-x O₄ (x = 0, 0.1, 0.2, 0.3) ferrite powders were synthesized via a solid‑state reaction method, with the optimal doping level identified as x = 0.1. Subsequently, using this optimal composition, a series of composite materials with ferrite to β-SiC mass ratios of 9:1, 8:2, and 7:3 was prepared via high-energy ball milling. The introduction of non‑magnetic SiC aimed to achieve magnetic dilution, thereby optimizing the impedance matching and loss characteristics of the composites. Phase and morphological characterizations confirmed that all samples exhibited a pure spinel structure, with both phases uniformly distributed in the composites. Scanning electron microscopy revealed that the ferrite particles displayed regular morphology, with sizes ranging from 3 to 3.5 µm, and were well‑dispersed and mechanically integrated with the SiC particles. Electromagnetic measurements indicated that appropriate In³⁺ doping (x = 0.1) improved the minimum reflection loss from -18.76 dB to -19.84 dB. Further composite formation with SiC led to a remarkable enhancement in absorption performance: at the optimal ratio (9:1), the composite achieved a significantly lower minimum reflection loss of ‑35.49 dB at 7.52 GHz, along with a broadening of the effective absorption bandwidth (RL ≤ -10 dB) from 4.0 GHz to 4.4 GHz. This work demonstrates that the absorption enhancement in the In-doped ferrite/SiC composite originates solely from the increased attenuation constant driven by boosted dielectric loss, providing a practical design paradigm for high-performance ferrite‑based microwave absorbers. These findings provide clear experimental evidence and mechanistic insights for the design of high‑performance ferrite‑based composite microwave absorbers.