Synthesis and characterization of magnetite-maghemite nanoparticles in presence of polyethylene glycol obtained by mechanical milling

Abstract We present the synthesis and characterization of magnetite-maghemite nanoparticles obtained by mechanical milling of sub micrometric hematite in presence of polyethylene glycol (PEG) as stabilizing medium. Nanoparticles were obtained in a milling time of 24 h, being their aggregation and particle size distribution less than those obtained by us in a previous work employing a mixture of hematite and deionized water as precursor material. X-ray and room temperature Mossbauer measurements confirmed that milling products are composed only by the phases magnetite-maghemite. TEM micrographs showed quasi-spherical particles with low aggregation and mean diameter around 14 nm. Room temperature magnetization loops are consistent with ferrimagnetic multi domain nanoparticles, with saturation magnetization around 62 A m2 kg−1 and coercive field around 10.2 kA m−1. The results suggest that mechanical milling in presence of polyethylene glycol is a simple and efficient route to produce magnetite-maghemite nanoparticles with good magnetization, which can be useful for applications in nanotechnology.