Study on Formation Mechanism by Monitoring the Morphology and Structure Evolution of Nearly Monodispersed Fe₃O₄ Submicroparticles with Controlled Particle Sizes

We present a facile surfactant-free solvothermal method for the fabrication of nearly monodispersed Fe 3 O 4 submicroparticles with tunable particle sizes ranging from 130 to 420 nm by varying the concentration of single iron source FeCl 3 ·6H 2 O in initial solutions. The morphology and crystal structure of the as-prepared Fe 3 O 4 submicroparticles have been well characterized by using SEM/TEM/HRTEM, XRD, FT-IR, Raman spectroscopy, and XPS methods. It is found that the Fe 3 O 4 particles present single-crystal nature and strong ferromagnetic property with magnetization saturation values ranged in 54.3–88.7 emu·g –1 . A complexation–aggregation–phase transformation formation mechanism was first proposed for the nearly monodispersed single-crystal Fe 3 O 4 submicroparticles based upon the quasi-in situ monitoring of the morphology and structure evolution of the samples during the synthesis process. These size-tunable nearly monodispersed Fe 3 O 4 submicroparticles are expected to have promising applications in wide research fields such as bioseparation, targeted drug delivery, and catalysis.