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.