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<p>This study investigates the effect of magnetic dilution with nonmagnetic oxides—aluminum oxide, mullite, and titanium dioxide—on the microwave absorption behavior of spinel nickel zinc ferrite (Ni<sub>0.5</sub>Zn<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub>). Ni<sub>0.5</sub>Zn<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub> (NZF) is synthesized via sol–gel auto-combustion, and three 1:1 mechanically mixed composites [Ni<sub>0.5</sub>Zn<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub>-α-Al<sub>2</sub>O<sub>3</sub> (NZF-A), Ni<sub>0.5</sub>Zn<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub>-mullite (NZF-M), and Ni<sub>0.5</sub>Zn<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub>-TiO<sub>2</sub> (NZF-T)] are prepared, embedded at 50% loading in an epoxy matrix, and subsequently cured at room temperature. Powder x-ray diffraction (XRD) investigations demonstrate a uniform distribution of phases in the NZF-A, NZF-M, and NZF-T composites, wherein both NZF and nonmagnetic α-Al<sub>2</sub>O<sub>3</sub> or mullite or anatase phases coexist consistently without any discernible segregation of other secondary phases within the matrix. Scanning electron microscopy reveals a homogeneous distribution of NZF-M and NZF-T, while NZF-A displays dispersed Al<sub>2</sub>O<sub>3</sub> nanoparticles within the NZF matrix. Magnetic hysteresis measurements show S-shaped loops for NZF, NZF-A, and NZF-M, while NZF-T exhibits no hysteresis. The electromagnetic characterization derived from experimental permittivity and permeability indicates absorption around 75% (reflection loss, <i>R</i><sub><i>L</i></sub> ~ −5&#xa0;dB) for bandwidth of 2&#xa0;GHz at a thickness of 4&#xa0;mm for the NZF-A composites. NZF-T composites with a thickness of 3.5&#xa0;mm exhibit absorption of over 80% (<i>R</i><sub><i>L</i></sub> ~ −7&#xa0;dB) within the 9.5–11&#xa0;GHz range. Optimal performance is achieved for NZF-M composites with thickness greater than 3&#xa0;mm, which exhibit consistent absorption above 80% (<i>R</i><sub><i>L</i></sub> ~ −7&#xa0;dB) across the whole frequency range of 8–12&#xa0;GHz. Ni<sub>0.5</sub>Zn<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub> alone shows absorption greater than 80% only for bandwidth of 1&#xa0;GHz with material thickness greater than 3&#xa0;mm. Overall, magnetic dilution broadens absorption bandwidth, with mullite dilution (NZF-M) yielding the best performance, expanding the effective bandwidth from 2&#xa0;GHz (NZF-A) to 4&#xa0;GHz.</p>

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Effects of Magnetic Dilution on the Microwave Absorption Properties of Nickel Zinc Ferrite Composite

  • 期刊论文

  • 发表日期：

    2025年12月8日

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  • Abanti Nag,
  • K. S. Venu,
  • Vineetha Joy,
  • Hema Singh

摘要

This study investigates the effect of magnetic dilution with nonmagnetic oxides—aluminum oxide, mullite, and titanium dioxide—on the microwave absorption behavior of spinel nickel zinc ferrite (Ni0.5Zn0.5Fe2O4). Ni0.5Zn0.5Fe2O4 (NZF) is synthesized via sol–gel auto-combustion, and three 1:1 mechanically mixed composites [Ni0.5Zn0.5Fe2O4-α-Al2O3 (NZF-A), Ni0.5Zn0.5Fe2O4-mullite (NZF-M), and Ni0.5Zn0.5Fe2O4-TiO2 (NZF-T)] are prepared, embedded at 50% loading in an epoxy matrix, and subsequently cured at room temperature. Powder x-ray diffraction (XRD) investigations demonstrate a uniform distribution of phases in the NZF-A, NZF-M, and NZF-T composites, wherein both NZF and nonmagnetic α-Al2O3 or mullite or anatase phases coexist consistently without any discernible segregation of other secondary phases within the matrix. Scanning electron microscopy reveals a homogeneous distribution of NZF-M and NZF-T, while NZF-A displays dispersed Al2O3 nanoparticles within the NZF matrix. Magnetic hysteresis measurements show S-shaped loops for NZF, NZF-A, and NZF-M, while NZF-T exhibits no hysteresis. The electromagnetic characterization derived from experimental permittivity and permeability indicates absorption around 75% (reflection loss, RL ~ −5 dB) for bandwidth of 2 GHz at a thickness of 4 mm for the NZF-A composites. NZF-T composites with a thickness of 3.5 mm exhibit absorption of over 80% (RL ~ −7 dB) within the 9.5–11 GHz range. Optimal performance is achieved for NZF-M composites with thickness greater than 3 mm, which exhibit consistent absorption above 80% (RL ~ −7 dB) across the whole frequency range of 8–12 GHz. Ni0.5Zn0.5Fe2O4 alone shows absorption greater than 80% only for bandwidth of 1 GHz with material thickness greater than 3 mm. Overall, magnetic dilution broadens absorption bandwidth, with mullite dilution (NZF-M) yielding the best performance, expanding the effective bandwidth from 2 GHz (NZF-A) to 4 GHz.