Effects of synthetical conditions on octahedral magnetite nanoparticles

By controlling the growth kinetics of nanoparticles, octahedral magnetite nanoparticles were successfully synthesized employing an oxidation–precipitation method with FeSO4·7H2O, NaNO3 and NaOH as starting materials. Magnetite nanoparticles with 40 nm or less can be synthesized under the following conditions: pH 9.5, F = 10–90 ml/min, T = 60–90 °C, C = 0.2–1 mol/l, t = 4 h, R = 200–500 rpm. The saturation magnetizations of octahedral magnetite nanoparticles are in the range from 80 emu/g to 90 emu/g. The remanence magnetizations of the as-prepared samples are lower than that of the bulk magnetite and the coercive forces of the as-prepared sample are around 140 Oe.