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<p>Co-precipitation method has been employed to synthesize the samarium (Sm)-substituted zinc spinel ferrite (ZnSm<sub>0.5</sub>Fe<sub>1.5</sub>O<sub>4</sub>) nanoparticles (NPs). The ferrite samples have been annealed at temperatures 400&#xa0;ºC, 500&#xa0;ºC, 600&#xa0;ºC, and 700&#xa0;ºC. Scanning electron microscopy (SEM) analysis shows the agglomerated morphology of the specimen in the form of bigger grains. Cubic spinel unit cell has been found through X-ray diffraction (XRD) analysis with average crystallite sizes in the range from 11 to 21&#xa0;nm. Magnetic properties of ZnSm<sub>0.5</sub>Fe<sub>1.5</sub>O<sub>4</sub> have been investigated through vibrating sample magnetometer (VSM) up to 5&#xa0;K. At lower temperatures, the trends of magnetic parameters, including coercivity (H<sub>c</sub>), squareness (M<sub>r</sub>/M<sub>s</sub>), magnetic moment (n<sub>B</sub>), anisotropic field (H<sub>k</sub>), exchange bias field (H<sub>ex</sub>), magneto-crystalline anisotropy (K<sub>1</sub>), and microwave frequency (ω<sub>m</sub>), are found to be increasing with decrease in temperature up to 5&#xa0;K. Remarkably high specific surface area (57–119 m<sup>2</sup>/g) and elevated dielectric constants, coupled with low dielectric tangent loss in the annealed samples, suggest promising applications in energy conservation, particularly for supercapacitors. Nyquist plots unveil the distinctive roles of grains and grain boundaries in non-Debye type conduction. The Cole–Cole plot showcases discernible semicircles, reflecting the conductive behavior of grains at lower frequencies and the significant contribution of grain boundaries at higher frequencies in both as-prepared and annealed samples. This study pioneers the exploration and reporting of solid-state parameters, including valence electron energy, Penn energy, Fermi energy, and electric polarizability for the current system, a novel contribution to the existing knowledge in the field.</p>

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Sm-substituted Zn−spinel ferrites, structural, low-temperature superparamagnetism, exchange bias and dielectric features

  • 期刊论文

  • 发表日期：

    2026年7月17日

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  • Syed Shahbaz Ali,
  • M. W. Yasin,
  • M. Zulqarnain,
  • U. Hira,
  • Muhammad Asif Hussain,
  • M. K. Zaki

摘要

Co-precipitation method has been employed to synthesize the samarium (Sm)-substituted zinc spinel ferrite (ZnSm0.5Fe1.5O4) nanoparticles (NPs). The ferrite samples have been annealed at temperatures 400 ºC, 500 ºC, 600 ºC, and 700 ºC. Scanning electron microscopy (SEM) analysis shows the agglomerated morphology of the specimen in the form of bigger grains. Cubic spinel unit cell has been found through X-ray diffraction (XRD) analysis with average crystallite sizes in the range from 11 to 21 nm. Magnetic properties of ZnSm0.5Fe1.5O4 have been investigated through vibrating sample magnetometer (VSM) up to 5 K. At lower temperatures, the trends of magnetic parameters, including coercivity (Hc), squareness (Mr/Ms), magnetic moment (nB), anisotropic field (Hk), exchange bias field (Hex), magneto-crystalline anisotropy (K1), and microwave frequency (ωm), are found to be increasing with decrease in temperature up to 5 K. Remarkably high specific surface area (57–119 m2/g) and elevated dielectric constants, coupled with low dielectric tangent loss in the annealed samples, suggest promising applications in energy conservation, particularly for supercapacitors. Nyquist plots unveil the distinctive roles of grains and grain boundaries in non-Debye type conduction. The Cole–Cole plot showcases discernible semicircles, reflecting the conductive behavior of grains at lower frequencies and the significant contribution of grain boundaries at higher frequencies in both as-prepared and annealed samples. This study pioneers the exploration and reporting of solid-state parameters, including valence electron energy, Penn energy, Fermi energy, and electric polarizability for the current system, a novel contribution to the existing knowledge in the field.