Size controlled and morphology tuned fabrication of Fe3O4 nanocrystals and their magnetic properties

Size controlled and morphology tuned fabrication of Fe3O4 nanocrystals were achieved by a simple hydrothermal method using (NH4)2Fe(SO4)2·6H2O, hexamethylenetetramine, and sodium sulfate as original reaction materials. Fe3O4 particles with controlled size ranging from 160 nm to 2 μm were obtained by adding an appropriate amount of NH4Ac to the reaction system. Fe3O4 quadrangular nanoplates with side length of about 500 nm were fabricated by adding optimum amount of urea. Box-like Fe3O4 nanocrystals were synthesized by adjusting the mol ratio between (NH4)2Fe(SO4)2·6H2O and hexamethylenetetramine. The as-synthesized products were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Room-temperature magnetization curves that measured by vibrating sample magnetometer show morphology and size dependent magnetism.