Scholarlink

<p>This study investigates the effect of nickel doping on the structural, morphological, cation distribution, and magnetic properties of Ni<sub>x</sub>Co<sub>1−x</sub>Fe<sub>2</sub>O<sub>4</sub> nanoparticles (where x = 0, 0.25, 0.5, 0.75, and 1).&#xa0;The samples were synthesized via the sol–gel auto-combustion method using citric acid as a fuel. The Ni<sub>x</sub>Co<sub>1−x</sub>Fe<sub>2</sub>O<sub>4</sub> nanostructures were characterized by X-ray diffraction (XRD), and Rietveld refinement using the MAUD software confirmed a pure single-phase cubic spinel structure with the Fd3m space group.&#xa0;Field-emission scanning electron microscopy (FE-SEM) images revealed the formation of uniform spherical structures, whose size increased gradually with Ni<sup>2</sup>⁺ incorporation. The lattice parameter decreased, while the X-ray density increased with higher nickel concentrations. This is attributed to the substitution of larger Co<sup>2</sup>⁺ ions (ionic radius: 0.74&#xa0;Å) with smaller Ni<sup>2</sup>⁺ ions (0.72&#xa0;Å). Energy-dispersive X-ray spectroscopy (EDX) verified the compositional purity of the samples. Fourier-transform infrared spectroscopy (FTIR) spectra exhibited two major absorption bands: a high-frequency band at approximately 600&#xa0;cm⁻<sup>1</sup>, assigned to tetrahedral sites, and a low-frequency band at around 400&#xa0;cm⁻<sup>1</sup>, assigned to octahedral sites.&#xa0;The optical bandgap of the nanoferrites was found to range between 1.22 and 1.61&#xa0;eV. The cation distribution was deduced from XRD intensity analysis and magnetic properties. Room-temperature vibrating sample magnetometry (VSM) measurements were used to determine key magnetic parameters, including saturation magnetization (M<sub>s</sub>), remnant magnetization (M<sub>r</sub>), coercivity (H<sub>c</sub>), rotational permeability (µ<sub>rk</sub>), anisotropy field (H<sub>a</sub>), and anisotropy constant (K<sub>1</sub>).&#xa0;The samples exhibited ferrimagnetic behavior. The values of M<sub>s</sub>, M<sub>r</sub>, H<sub>c</sub>, H<sub>a</sub>, and K₁ decreased gradually as the Ni content increased. Theoretical and experimental magnetic moments also declined with higher Ni doping. These trends are explained by cation redistribution and crystallite size effects.&#xa0;The lower magnetocrystalline anisotropy of Ni<sup>2</sup>⁺ ions reduces H<sub>c</sub>, thereby enhancing µ<sub>rk</sub> (from 1.32 to 2.96) by lowering the energy barrier for spin rotation. The lower magnetocrystalline anisotropy of Ni<sup>2</sup>⁺ ions reduces H<sub>c</sub>, thereby enhancing µ<sub>rk</sub> (from 1.32 to 2.96) by lowering the energy barrier for spin rotation. These findings highlight the potential of Ni substitution for tailoring the properties of Co-ferrite nanoparticles, making them promising candidates for microwave applications.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Study on Rietveld refinement, cation distribution, structural, and magnetic properties of NixCo1−xFe2O4 ferrite

  • 期刊论文

  • 发表日期：

    2025年10月27日

查看全文
  • Marjaneh Jafari Fesharaki

摘要

This study investigates the effect of nickel doping on the structural, morphological, cation distribution, and magnetic properties of NixCo1−xFe2O4 nanoparticles (where x = 0, 0.25, 0.5, 0.75, and 1). The samples were synthesized via the sol–gel auto-combustion method using citric acid as a fuel. The NixCo1−xFe2O4 nanostructures were characterized by X-ray diffraction (XRD), and Rietveld refinement using the MAUD software confirmed a pure single-phase cubic spinel structure with the Fd3m space group. Field-emission scanning electron microscopy (FE-SEM) images revealed the formation of uniform spherical structures, whose size increased gradually with Ni2⁺ incorporation. The lattice parameter decreased, while the X-ray density increased with higher nickel concentrations. This is attributed to the substitution of larger Co2⁺ ions (ionic radius: 0.74 Å) with smaller Ni2⁺ ions (0.72 Å). Energy-dispersive X-ray spectroscopy (EDX) verified the compositional purity of the samples. Fourier-transform infrared spectroscopy (FTIR) spectra exhibited two major absorption bands: a high-frequency band at approximately 600 cm⁻1, assigned to tetrahedral sites, and a low-frequency band at around 400 cm⁻1, assigned to octahedral sites. The optical bandgap of the nanoferrites was found to range between 1.22 and 1.61 eV. The cation distribution was deduced from XRD intensity analysis and magnetic properties. Room-temperature vibrating sample magnetometry (VSM) measurements were used to determine key magnetic parameters, including saturation magnetization (Ms), remnant magnetization (Mr), coercivity (Hc), rotational permeability (µrk), anisotropy field (Ha), and anisotropy constant (K1). The samples exhibited ferrimagnetic behavior. The values of Ms, Mr, Hc, Ha, and K₁ decreased gradually as the Ni content increased. Theoretical and experimental magnetic moments also declined with higher Ni doping. These trends are explained by cation redistribution and crystallite size effects. The lower magnetocrystalline anisotropy of Ni2⁺ ions reduces Hc, thereby enhancing µrk (from 1.32 to 2.96) by lowering the energy barrier for spin rotation. The lower magnetocrystalline anisotropy of Ni2⁺ ions reduces Hc, thereby enhancing µrk (from 1.32 to 2.96) by lowering the energy barrier for spin rotation. These findings highlight the potential of Ni substitution for tailoring the properties of Co-ferrite nanoparticles, making them promising candidates for microwave applications.