Abstract：Fe3O4 nanocrystals were synthesized by coprecipitationgamma radiation with polyethylene glycol or polyvinyl pyrrolidone as dispersant. Fe3O4 nanocrystals were characterized in order to elucidate the morphology, structure and magnetism by transmission electron microscopy,Xray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometer respectively. The formation mechanism of Fe3O4 nanocrystals was also studied. The results indicate that polyethylene glycol and polyvinyl pyrrolidone can produce steric effect to avoid agglomeration of particles as polymeric dispersants. Fe3O4 nanocrystals are cubic phase and highenergy radiation favours the improvement of morphology. The crystallinity and dispersity of nanoparticles are improved by gamma radiation compared with the particles obtained by traditional coprecipitation. The sizes of Fe3O4 nanoparticles are in the range of 5~20 nm. The magnetic properties change markedly under γradiation. The saturation magnetization obviously decreases and the coercive force of the nanoparticles change very little.
2010, Vol. 31 
