Impact of Sm(3+) and Er(3+) Cations on the Structural, Optical, and Magnetic Traits of Spinel Cobalt Ferrite Nanoparticles: Comparison Investigation

[Image: see text] In this study, we investigated a comparison of the structure, morphology, optic, and magnetic (room temperature (RT)) features of Er(3+) and Sm(3+) codoped CoFe(2)O(4) (CoErSm) nanospinel ferrite (NSFs) (x ≤ 0.05) synthesized via hydrothermal (H-CoErSm NSFs) and sonochemical (S-CoErSm NSFs) approaches. The formation of all products via both synthesis methods has been validated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), along with energy-dispersive X-ray (EDX) and transmission electron microscopy (TEM) techniques. The single phase of the spinel structure (except for the Hyd sample with x = 0.03) was evidenced by XRD analysis. The D(XRD) (crystallite size) values of H-CoErSm and S-CoErSm NSFs are in the 10–14.7 and 10–16 nm ranges, respectively. TEM analysis presented the cubic morphology of all products. A UV–visible percent diffuse reflectance (DR %) study was performed on all products, and E(g) (direct optical energy band gap) values varying in the 1.32–1.48 eV range were projected from the Tauc plots. The data of RT magnetization demonstrated that all prepared samples are ferromagnetic in nature. M–H data revealed that rising the contents of cosubstituent elements (Sm(3+) and Er(3+) ions) caused an increase in M(s) (saturation magnetization) and H(c) (coercive field) in comparison to pristine samples. Although concentration dependence is significant (x > 0.02), no strict regularity (roughly fluctuating) has been ruled out in M(s) values for doped samples prepared via the hydrothermal method. However, sonochemically prepared samples demonstrated that M(s) values increase with increasing x up to x = 0.04 and then decrease with the further rise in cosubstituent Sm(3+) and Er(3+) ions. The calculated values of M(s) and H(c) were found to be greater in H-CoErSm NSFs compared to those in S-CoErSm NSFs. The present investigation established that the distribution of cations and the variation in crystallite/particle sizes are efficient to control the intrinsic properties of all samples.