Synthesis of colloidal β-Fe2O3nanostructures—influence of addition of Co2+on their morphology and magnetic behavior

β - Fe 2 O 3 nanostructures of different shapes have been synthesized by the hydrolysis of FeCl 3 in the absence and presence of Co 2+ ions. These materials have been characterized by UV–vis spectroscopy, x-ray diffraction, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and superconducting quantum interference device magnetometry (SQUID). The addition of Co 2+ transforms the shape of nanosized β - Fe 2 O 3 from rods to become spherical. These nanostructures demonstrate superparamagnetic behavior. The extent of saturation magnetization is enhanced by a factor of 3 from 0.49 to 1.56 emu g −1 upon addition of 0.12% Co 2+ .