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<p>The unique size-dependent structural and physical properties of Cr doped spinel ferrites have garnered significant attention due to their wide-ranging applications. In this work, CoCrₓFe<sub>2-x</sub>O4 (x = 0.0, 0.5, 1.0, 1.5, and 2.0) nanoparticles were synthesized using the citrate–gel auto-combustion method and sintered at 700&#xa0;°C. XRD analysis confirmed a pure cubic spinel phase for all samples, with the lattice parameter decreasing slightly from 8.3862&#xa0;Å to 8.3835&#xa0;Å as chromium content increased. HRTEM imaging revealed predominantly spherical particles with an average grain size of approximately 40&#xa0;nm. Magnetic characterization showed a significant decrease in saturation magnetization (Ms) from 41.74&#xa0;emu/g for x = 0.0 to 1.37 emu g⁻<sup>1</sup> for x = 2.0, representing a reduction of ~ 96.7%, while the magnetic moment per formula unit decreased from 1.72 to 0.21 μB. Conversely, the coercivity (Hc) exhibited an overall increase relative to the doped samples, peaking at 1303.8 Oe for the pure cobalt ferrite. Dielectric studies indicated that the dielectric constant (ε’) and loss tangent (tanδ) decreased with increasing frequency, following the Maxwell–Wagner interfacial polarization model. Specifically, ε’ values for x = 0.0 dropped from approximately 1500 to near-constant values at higher frequencies. AC conductivity (σ<sub>AC</sub>) was found to rise with frequency, consistent with the small polaron hopping (SPH) mechanism. These results demonstrate that Cr<sup>3+</sup> substitution effectively tunes the magnetic and electrical response of cobalt ferrites for multifunctional applications.</p>

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Structural, magnetic, and dielectric properties of Cr substituted Cobalt Ferrite nanoparticles synthesized by citrate-gel auto-combustion

  • 期刊论文

  • 发表日期：

    2026年2月28日

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  • Rajkumar S. Pandav,
  • Sachin S. Pujari,
  • Amit A. Bagade,
  • Vashishtha M. Gurme,
  • Umesh B. Sankpal

摘要

The unique size-dependent structural and physical properties of Cr doped spinel ferrites have garnered significant attention due to their wide-ranging applications. In this work, CoCrₓFe2-xO4 (x = 0.0, 0.5, 1.0, 1.5, and 2.0) nanoparticles were synthesized using the citrate–gel auto-combustion method and sintered at 700 °C. XRD analysis confirmed a pure cubic spinel phase for all samples, with the lattice parameter decreasing slightly from 8.3862 Å to 8.3835 Å as chromium content increased. HRTEM imaging revealed predominantly spherical particles with an average grain size of approximately 40 nm. Magnetic characterization showed a significant decrease in saturation magnetization (Ms) from 41.74 emu/g for x = 0.0 to 1.37 emu g⁻1 for x = 2.0, representing a reduction of ~ 96.7%, while the magnetic moment per formula unit decreased from 1.72 to 0.21 μB. Conversely, the coercivity (Hc) exhibited an overall increase relative to the doped samples, peaking at 1303.8 Oe for the pure cobalt ferrite. Dielectric studies indicated that the dielectric constant (ε’) and loss tangent (tanδ) decreased with increasing frequency, following the Maxwell–Wagner interfacial polarization model. Specifically, ε’ values for x = 0.0 dropped from approximately 1500 to near-constant values at higher frequencies. AC conductivity (σAC) was found to rise with frequency, consistent with the small polaron hopping (SPH) mechanism. These results demonstrate that Cr3+ substitution effectively tunes the magnetic and electrical response of cobalt ferrites for multifunctional applications.