Nd3+ Ion-Substituted Co1−2xNixMnxFe2−yNdyO4 Nanoparticles: Structural, Morphological, and Magnetic Investigations

Co1−2xNixMnxFe2−yNdyO4 (0.0 ≤ x = y ≤ 0.3) nanoparticles (NPs) were synthesized by the citrate sol–gel route. All the products were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and a vibrating-sample magnetometer (VSM). The cubic structure of all the samples was confirmed by phase identification of XRD patterns, using Rietveld refinement. VSM analysis confirmed the soft ferromagnetic behavior of the synthesized products. The saturation (Ms) and remanent (Mr) magnetizations decreased with an increase in the amount of substitution elements. Compared with that of pure CoFe2O4 NPs, the coercive field (Hc) increased up to 890 Oe at x = y = 0.03. The squareness ratio was found to be in the 0.55–0.46 interval, indicating that the various synthesized NPs exhibit a single domain and uniaxial anisotropy. The effective magnetocrystalline anisotropy constant (Keff), magneton number (nB)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$({n_B})$$\end{document}, and anisotropy field (Ha) were also determined, and are discussed.