Solvothermal reduction synthesis and characterization of superparamagnetic magnetite nanoparticles

Magnetite nanoparticles were prepared through a solvothermal reduction approach in the presence of ethylene glycol, oleic acid and trioctylphosphine oxide or hexadecylamine. The size of the magnetite nanoparticles can be controlled easily through tailoring surfactants in the system. Transmission electron microscopy images indicate that the average sizes of magnetite nanoparticles are 8 and 11 nm, depending on the surfactant. The far IR spectra further demonstrate that the products are magnetite instead of hematite. Superparamagnetism and the effect of sigma-donor and pi-acceptor type surfactants on the magnetic properties of the nanoscale materials have been investigated.