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<p>The structural, morphological, and magnetic properties of silica (SiO<sub>2</sub>)-incorporated nickel ferrite (NiFe<sub>2</sub>O<sub>4</sub>) nanoparticles synthesized by a sol–gel autocombustion method are reported. NiFe<sub>2</sub>O<sub>4</sub> powder was calcined at 500°C for 3&#xa0;h and then physically mixed with commercial SiO<sub>2</sub> nanoparticles to form composites containing 0&#xa0;wt.%, 25&#xa0;wt.%, 50&#xa0;wt.%, and 75 wt.% SiO<sub>2</sub>. X-ray diffraction confirms a cubic spinel NiFe<sub>2</sub>O<sub>4</sub> phase (Fd-3&#xa0;m) on an amorphous silica background; weak Fe<sub>2</sub>O<sub>3</sub> reflections are present in some composites but were not quantified. Scherrer analysis shows gradual crystallite-size broadening with SiO<sub>2</sub> loading; field emission scanning electron microscope (FE-SEM) indicates improved dispersion and reduced average particle diameter (from ~73.4&#xa0;nm for pure NiFe<sub>2</sub>O<sub>4</sub> to ~42.5&#xa0;nm for the 75 wt % SiO<sub>2</sub> composite). Fourier transform infrared spectroscopy (FTIR) spectra display Fe–O and Si–O–Si vibrational modes consistent with physically dispersed amorphous silica. Room-temperature vibrating sample magnetometry (VSM) yields saturation magnetizations Ms (reported per gram of composite) of 37.193&#xa0;emu g<sup>–1</sup>, 25.687&#xa0;emu g<sup>–1</sup>, 23.316&#xa0;emu g<sup>–1</sup>, and 17.476 emu g<sup>–1</sup> for 0&#xa0;wt.%, 25&#xa0;wt.%, 50&#xa0;wt.%, and 75 wt.% SiO<sub>2</sub> composites, respectively a monotonic reduction attributable to magnetic dilution and size/surface effects. These results demonstrate straightforward matrix-mediated tuning of NiFe<sub>2</sub>O<sub>4</sub> magnetic properties via post-mixing with SiO<sub>2</sub>.</p>

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Silica-Induced Structural Refinement and Magnetic Dilution of NiFe2O4 Nanocomposites

  • 期刊论文

  • 发表日期：

    2025年12月15日

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  • Hanaa Shahab Ahmed,
  • Ali M. Mohammad,
  • Ibrahim Nazem Qader,
  • Karukh Ali Babakr,
  • Hero S. Ahmed Al-Jaf,
  • Bala Talib Ali,
  • Balen H. Ahmed,
  • Mohammed B. Jumaa

摘要

The structural, morphological, and magnetic properties of silica (SiO2)-incorporated nickel ferrite (NiFe2O4) nanoparticles synthesized by a sol–gel autocombustion method are reported. NiFe2O4 powder was calcined at 500°C for 3 h and then physically mixed with commercial SiO2 nanoparticles to form composites containing 0 wt.%, 25 wt.%, 50 wt.%, and 75 wt.% SiO2. X-ray diffraction confirms a cubic spinel NiFe2O4 phase (Fd-3 m) on an amorphous silica background; weak Fe2O3 reflections are present in some composites but were not quantified. Scherrer analysis shows gradual crystallite-size broadening with SiO2 loading; field emission scanning electron microscope (FE-SEM) indicates improved dispersion and reduced average particle diameter (from ~73.4 nm for pure NiFe2O4 to ~42.5 nm for the 75 wt % SiO2 composite). Fourier transform infrared spectroscopy (FTIR) spectra display Fe–O and Si–O–Si vibrational modes consistent with physically dispersed amorphous silica. Room-temperature vibrating sample magnetometry (VSM) yields saturation magnetizations Ms (reported per gram of composite) of 37.193 emu g–1, 25.687 emu g–1, 23.316 emu g–1, and 17.476 emu g–1 for 0 wt.%, 25 wt.%, 50 wt.%, and 75 wt.% SiO2 composites, respectively a monotonic reduction attributable to magnetic dilution and size/surface effects. These results demonstrate straightforward matrix-mediated tuning of NiFe2O4 magnetic properties via post-mixing with SiO2.