Formation of magnetic nanoparticles studied during the initial synthesis stage

The formation of iron oxide nanoparticles in course of a sol-gel preparation process was traced by UV/Vis and Fe-57 Mossbauer absorption spectroscopy. Samples were extracted at different stages of the reaction. While spectra measured on samples extracted at low reactor temperatures showed the starting materials Fe(acac)(3) diluted in benzyl alcohol undergoing slow paramagnetic relaxation, a sample extracted at a reactor temperature of 180 A degrees C gave clear evidence for emerging iron oxide nanoparticles. A prolonged stay at 200 A degrees C results in a complete transformation from Fe(acac)(3) to maghemite nanoparticles.