Low-cost, ecofriendly, and large-scale synthesis of nanostructured Co1−xMnxFe2O4 microgranules with enhanced magnetic performance by chemical spray drying processing

We report, for the first time, the low-cost, eco-friendly, and large-scale synthesis of spray-drying production of Mn-substituted CoFe2O4 (Co1−xMnxFe2O4; x = 0.0–0.2; CMF) microgranules and their structural, morphological, and magnetic properties and performance characteristics in detail. The comprehensive study explored the intimate relationships between cation disorder or inversion degree due to Mn substitution in CoFe2O4 (CF) microgranules and corresponding changes in the structural and magnetic properties. Crystal structure and morphology studies indicate the formation of spherical shape, single cubic mixed inverse spinel structure of all the CMFO- microgranules with a size variation in the range of ⁓6.5–7.5 µm. Small angle X-ray scattering analyses indicate that the nanostructured CMF microgranules exhibit a virtually hard-sphere-like interaction. It is concluded that distortions are related to Co ions at octahedral locations due to Mn substitution in all materials. Raman spectroscopic studies, which corroborate with other structural studies, also reveal that replacing Co with Mn increases the degree of inversion in the cubic inverse spinel structure. Divalent (Co2+, Mn2+) and trivalent (Fe3+, Mn3+) cations are distributed differently across tetrahedral and octahedral sites. In addition to large-scale chemical synthesis, our results demonstrate the enhanced magnetic saturation from 82.27 to 86.18 emu/gm and 77.05–79.87 emu/gm for Co0.9Mn0.1Fe2O4 at 10 K and 300 K, respectively. In order for the proposed architectural design to serve as a crucial building block for a wide range of technological applications and be applicable to a large class of spinel ferrites, we present our attempt to draw the necessary fundamental scientific explanation from the trends in the local structural parameters and magnetic characteristics of CMF nanomaterials.