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<p>The narrow effective absorption bandwidth of conventional single-component ferrite absorbers severely limits their practical applicability. Herein, a high-entropy spinel ferrite with a nominal composition of (Fe<sub>0.2</sub>Co<sub>0.2</sub>Ni<sub>0.2</sub>Cu<sub>0.2</sub>Mg<sub>0.2</sub>)Fe<sub>2</sub>O<sub>4</sub> was successfully synthesized via a quenching strategy, in which Fe, Co, Ni, Cu, and Mg divalent cations were designed in equimolar proportions. The effects of sintering temperature on the phase structure, magnetic properties, and microwave absorption performance were systematically investigated. A single-phase spinel structure with abundant oxygen vacancies was obtained at a sintering temperature of 1100 °C, crystallizing in the Fd-3m space group. Over the sintering temperature range of 800–1200 °C, all samples exhibited ferrimagnetic behavior. With increasing sintering temperature, the continuous incorporation of multiple cations into the spinel lattice induced pronounced lattice distortion, leading to a gradual increase in saturation magnetization (<i>M</i><sub>s</sub>) and a non-monotonic evolution of coercivity (<i>H</i><sub>c</sub>), which first decreased and then increased. At 1100 °C, the sample delivered an <i>M</i><sub>s</sub> of 56.03 emu/g and an <i>H</i><sub>c</sub> of 207.46 Oe. Within the 2–18 GHz frequency range, the HEO-1100 sample achieved a minimum reflection loss of -29.94 dB at a matching thickness of 5.0 mm. Moreover, a maximum effective absorption bandwidth of 6 GHz, covering 11.04–17.04 GHz, was obtained at a reduced matching thickness of 2.22 mm. These findings provide a theoretical basis for the development of high-entropy spinel ferrite microwave absorbers prepared via quenching.</p>

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Formation mechanism and microwave absorption properties of high-entropy spinel ferrite (Fe0.2Co0.2Ni0.2Cu0.2Mg0.2)Fe2O4

  • 期刊论文

  • 发表日期：

    2026年7月31日

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  • Yingying Shen,
  • Jiayi Qin,
  • Ting Zhang,
  • Yong Wang,
  • Jinlin Li,
  • Bingang Lu,
  • Jianghua Zheng

摘要

The narrow effective absorption bandwidth of conventional single-component ferrite absorbers severely limits their practical applicability. Herein, a high-entropy spinel ferrite with a nominal composition of (Fe0.2Co0.2Ni0.2Cu0.2Mg0.2)Fe2O4 was successfully synthesized via a quenching strategy, in which Fe, Co, Ni, Cu, and Mg divalent cations were designed in equimolar proportions. The effects of sintering temperature on the phase structure, magnetic properties, and microwave absorption performance were systematically investigated. A single-phase spinel structure with abundant oxygen vacancies was obtained at a sintering temperature of 1100 °C, crystallizing in the Fd-3m space group. Over the sintering temperature range of 800–1200 °C, all samples exhibited ferrimagnetic behavior. With increasing sintering temperature, the continuous incorporation of multiple cations into the spinel lattice induced pronounced lattice distortion, leading to a gradual increase in saturation magnetization (Ms) and a non-monotonic evolution of coercivity (Hc), which first decreased and then increased. At 1100 °C, the sample delivered an Ms of 56.03 emu/g and an Hc of 207.46 Oe. Within the 2–18 GHz frequency range, the HEO-1100 sample achieved a minimum reflection loss of -29.94 dB at a matching thickness of 5.0 mm. Moreover, a maximum effective absorption bandwidth of 6 GHz, covering 11.04–17.04 GHz, was obtained at a reduced matching thickness of 2.22 mm. These findings provide a theoretical basis for the development of high-entropy spinel ferrite microwave absorbers prepared via quenching.