Superparamagnetic Fe3O4 clusters with a wide-range size tunability†

Superparamagnetic Fe₃O₄ clusters with a tunable size over a wide range were synthesized by a polyol process. The average size of the Fe₃O₄ clusters was controlled from 571 nm to 1210 nm only by aging Fe³⁺ solutions before hydrolysis of Fe³⁺ without changing the other conditions. The Fe₃O₄ clusters had both superparamagnetic properties and high saturation magnetization per particle.