Synthesis of superparamagnetic Fe₃O₄ nanocrystals in reverse microemulsion at room temperature

Abstract

Superparamagnetic Fe3O4 nanocrystals were prepared via chemical precipitation in reverse microemulsion at room temperature. The water-in-oil reverse microemulsion system was composed of Triton X-100 as a surfactant, n-butanol as a co-surfactant, cyclohexane as a continuous oil phase, and aqueous phase. Powder X-ray diffraction and transmission electron microscopy results demonstrated that the nanoparticles were pure Fe3O4 with a polyhedral spinel structure and with an average size of 15 nm. Moreover, the sizes of Fe3O4 nanoparticles did not change as water/surfactant mole ratios (W-0) increased from 5 to 60. From the magnetometer measurements data, the products exhibited superparamagnetic property with saturation magnetisations of 64.6 emu g(-1) at room temperature. Such method was easy and mild, and could synthesise other metal oxide in such experiment situation.