One-pot synthesis of size-controlled Fe3O4 microclusters: Preserving superparamagnetism at microscale

Superparamagnetic nanoparticles (NPs) have gained significant attention for their unique properties and applications, but facile and scalable synthesis combining their superparamagnetic traits with the stability of larger particles remains challenging. This study presents a novel one-pot solvothermal method for synthesizing size-tunable Fe3O4 microclusters that preserve superparamagnetic properties at the microscale. We systematically investigated the effects of reaction time and surfactant type on the formation and characteristics of these microclusters, achieving precise size control ranging from 0.37 to 1.8 mu m. Through detailed analysis of intermediate products and final structures, we elucidated the growth mechanism, revealing a clear clustering process of primary nanocrystals into larger spherical microclusters. This study introduces a versatile and novel approach to controlling the properties of Fe3O4 microclusters, bridging the gap between nanoscale and microscale superparamagnetic materials. This research not only offers a versatile approach to tailoring Fe3O4 microcluster properties for specific applications but also contributes to the broader understanding of size-controlled synthesis of magnetic materials.