Sub 5 nm Fe3O4 nanocrystals via coprecipitation method

Magnetite nanocrystals of 2–4 nm were synthesized by a chemical coprecipitation method, by which the particle size was controlled by the reaction temperature. The nanocrystals were investigated by XRD, TEM/HRTEM, VSM and SQUID. It is found that the nanocrystals reveal well-defined superparamagnetic behavior before and after annealing, while the observation of the distinct lattices manifest the high crystallinity of the ultrasmall particles.