Structural, Magnetic, and Mossbauer Parameters’ Evaluation of Sonochemically Synthesized Rare Earth Er(3+) and Y(3+) Ions-Substituted Manganese–Zinc Nanospinel Ferrites

[Image: see text] The effect of Er(3+) and Y(3+) ion-co-substituted Mn(0.5)Zn(0.5)Er(x)Y(x)Fe(2–2x)O(4) (MZErYF) (x ≤ 0.10) spinel nanoferrites (SNFs) prepared by a sonochemical approach was investigated. Surface and phase analyses were carried out using SEM, TEM, and XRD. Hyperfine parameters were determined by fitting room-temperature (RT) Mossbauer spectra. Magnetic field-dependent magnetization data unveiled the superparamagnetic nature at RT and ferrimagnetic nature at 10 K. RT saturation magnetization (M(S)) and calculated magnetic moments (n(B)) are 34.84 emu/g and 1.47 μ(B), respectively, and have indirect proportionalities with increasing ion content. M(S) and n(B) data have a similar trend at 10 K including remanent magnetizations (M(r)). The measured coercivities (H(C)) are between 250 and 415 Oe. The calculated squareness ratios are in the range of 0.152–0.321 for NPs and assign the multidomain nature for NPs at 10 K. The extracted effective magnetocrystalline constants (K(eff)) have an order of 10(4) erg/g except for Mn(0.5)Zn(0.5)Er(0.10)Y(0.10)Fe(1.80)O(4) SNFs that has 3.37 × 10(5) erg/g. This sample exhibits the greatest magnetic hardness with the largest magnitude of H(C) = 415 Oe and an internal anisotropy field H(a) = 1288 Oe among all magnetically soft NPs.