Effect of rare earth Nd3+ doping contents on physical, structural, and magnetic properties of Co–Ni spinel ferrite nanoparticles

Abstract

Rare earth (RE) low doping has a significant influence on the structural, morphological, and magnetic properties of spinel ferrite nanoparticles. Therefore, rare earth neodymium (Nd) oxide was fully doped into spinel ferrite with a composition of Co0.80Ni0.20NdxFe2–xO4 (x = 0.0, 0.05, 0.10, and 0.15) using the sol-gel auto combustion method. Structural analysis of the synthesized samples with low doping of Nd using X-ray diffraction (XRD) and Rietveld refinements reveals a pure single-phase cubic structure, while the second phase appears with increasing content of Nd3+ at x = 0.10 and 0.15. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) show well-shaped spherical grains within the nanometer range of the pure Co0.80Ni0.20Fe2O4 sample, while larger grains with the presence of agglomeration are observed with doping of Nd3+ into the spinel ferrite nanoparticles. The magnetic parameters, i.e., saturation magnetization Ms, remanence and magnetic moments exhibit decreasing trend with Nd3+ doping and Ms values are in 65.69 to 53.34 emu/g range. The coercivity of the Nd-doped Co–Ni spinel ferrite sample was calculated to be 1037.76 to ∼827.24 Oe. This work demonstrates remarkable improvements in the structural and magnetic characteristics of Nd-doped Co–Ni spinel ferrite nanoparticles for multiple versatile applications.