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<p>This study reports the synthesis of Ni<sub>0.5</sub>Cu<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub> ferrite nanoparticles via the sol-gel technique. Structural characterization by x-ray diffraction (XRD) confirmed a cubic spinel phase (space group <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(Fd\overline{3}m\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>F</mi> <mi>d</mi> <mover> <mn>3</mn> <mo>¯</mo> </mover> <mi>m</mi> </mrow> </math></EquationSource> </InlineEquation>), while Rietveld refinement and x-ray photoelectron spectroscopy (XPS) elucidated cation oxidation states and site occupancies. The lattice parameters and crystallite size (<i>a</i> = 8.3589&#xa0;Å and <i>D</i><sub>WH</sub><i> = </i>35&#xa0;nm) of the Cu-substituted sample were larger than those of undoped NiFe<sub>2</sub>O<sub>4</sub>, attributed to Cu substitution. Fourier-transform infrared (FTIR) spectrum revealed characteristic vibrations associated with tetrahedral and octahedral sites. Optical analyses demonstrated broad UV-Vis-NIR absorption bands, a reduced direct bandgap of 2.05 eV, low Urbach energy (2.10 eV), minimal extinction coefficient (~10<sup>-4</sup>), a favorable refractive index (2.27), enhanced optical conductivity, and promising dielectric properties. Magnetic measurements indicated a ferrimagnetic-to-paramagnetic transition at a high Curie temperature (<i>T</i><sub>C</sub> = 795 K), low coercivity values (42 Oe at 5 K and 25 Oe at 300 K), and moderate saturation magnetization (58.44 emu/g at 5 K and 49.30 emu/g at 300 K), confirming soft magnetic behavior suitable for high-frequency transformers and microwave absorbers. Comparative analysis revealed a decrease in magnetic properties upon Cu substitution relative to undoped NiFe<sub>2</sub>O<sub>2</sub>. Importantly, Cu<sup>2+</sup> substitution significantly enhanced optoelectronic efficiency by promoting significant visible-light absorption, transparency, and energy conversion capabilities. These results position Ni<sub>0.5</sub>Cu<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub> as a promising multifunctional material for photocatalysis, solar energy, and optoelectronic applications.</p> Graphical Abstract <p></p>

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Structural, Cation Distribution, Optical, and Magnetic Properties of Sol-Gel Synthesized Ni0.5Cu0.5Fe2O4 Ferrite Nanoparticles for Optoelectronic and Microwave Devices

  • 期刊论文

  • 发表日期：

    2025年12月10日

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  • Souhir Heni,
  • F. I. H. Rhouma,
  • Sobhi Hcini,
  • Salah Knani,
  • Abdessalem Dhahri,
  • E. K. Hlil,
  • Malek Gassoumi,
  • Kamel Khirouni

摘要

This study reports the synthesis of Ni0.5Cu0.5Fe2O4 ferrite nanoparticles via the sol-gel technique. Structural characterization by x-ray diffraction (XRD) confirmed a cubic spinel phase (space group \(Fd\overline{3}m\) F d 3 ¯ m ), while Rietveld refinement and x-ray photoelectron spectroscopy (XPS) elucidated cation oxidation states and site occupancies. The lattice parameters and crystallite size (a = 8.3589 Å and DWH = 35 nm) of the Cu-substituted sample were larger than those of undoped NiFe2O4, attributed to Cu substitution. Fourier-transform infrared (FTIR) spectrum revealed characteristic vibrations associated with tetrahedral and octahedral sites. Optical analyses demonstrated broad UV-Vis-NIR absorption bands, a reduced direct bandgap of 2.05 eV, low Urbach energy (2.10 eV), minimal extinction coefficient (~10-4), a favorable refractive index (2.27), enhanced optical conductivity, and promising dielectric properties. Magnetic measurements indicated a ferrimagnetic-to-paramagnetic transition at a high Curie temperature (TC = 795 K), low coercivity values (42 Oe at 5 K and 25 Oe at 300 K), and moderate saturation magnetization (58.44 emu/g at 5 K and 49.30 emu/g at 300 K), confirming soft magnetic behavior suitable for high-frequency transformers and microwave absorbers. Comparative analysis revealed a decrease in magnetic properties upon Cu substitution relative to undoped NiFe2O2. Importantly, Cu2+ substitution significantly enhanced optoelectronic efficiency by promoting significant visible-light absorption, transparency, and energy conversion capabilities. These results position Ni0.5Cu0.5Fe2O4 as a promising multifunctional material for photocatalysis, solar energy, and optoelectronic applications.

Graphical Abstract