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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., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The effect of Er 3+ and Y 3+ ion-co-substituted Mn 0.5 Zn 0.5 Er x Y x Fe 2-2 x 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., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

TiO 2 (0-10 wt %)-doped nanocrystalline Ni 0.4 Cu 0.3 Zn 0.3 Fe 2 O 4 (Ni-Cu-Zn) ferrites were synthesized using the sol-gel route of synthesis. The cubic spinel structure of the ferrites having the Fd 3 m space group was revealed from the analysis of Rietveld refined X-ray diffraction (XRD) data. The secondary phase of TiO 2 with a space group of I 41/ amd was observed within the ferrites with doping, x > 3 wt %. The values of lattice parameter were enhanced with the addition of TiO 2 up to 5 wt % and reduced further for the highest experimental doping of 10 wt %. Field emission scanning electron microscopy (FESEM) images exhibit the spherical shape of the synthesized particles with some agglomeration, while the compositional purity of prepared ferrite samples was confirmed by energy-dispersive X-ray spectroscopy (EDX) and elemental mapping. The cubic spinel structure of the prepared ferrite sample was confirmed by the Raman and Fourier transform infrared (FTIR) spectra. UV-visible diffuse reflectance spectroscopy was utilized to study the optical properties of the ferrites. The value of band gap energy for the pristine sample was less than those of the doped samples, and there was a decrement in band gap energy values with an increase in TiO 2 doping, which specifies the semiconducting nature of prepared ferrite samples. A magnetic study performed by means of a vibrating sample magnetometer (VSM) demonstrates that the values of saturation magnetization of the ferrites decrease with the addition of TiO 2 content, and all investigated ferrites show the characteristics of soft magnetic materials at room temperature. The Mössbauer study confirms the decrease in the magnetic behavior of the doped ferrites due to the nonmagnetic secondary phase of TiO 2 ., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)