The Effect of Growth Temperature on Magnetic Properties of Electrocrystallized Iron Oxide Nanoparticles in the Presence of β-cyclodextrin

Electrocrystallized iron oxide nanoparticles were prepared by a chronoamperometric technique in the presence of beta-cyclodextrin. The electrocrystallization process was performed with two iron electrodes in an electrolytic bath. The effect of bath temperature on structural properties and magnetization of the nanoparticles was studied. Fourier transformation infrared (FT-IR) spectroscopy, X-ray diffraction, electron microscopy, magnetometry, and Mossbauer spectroscopy were used to characterize the samples. X-ray diffraction (XRD) patterns confirmed the formation of the spinel Fe3O4 crystal structure. FT-IR spectra confirmed the presence of organic molecules at the surface of the particles. Electron microscope images showed the mean particle size is in the range of 20-80 nm. Based on these images, we found that tuning the growth conditions has a strong effect on particle size and morphology. High resolution transmission electron microscope images showed the aggregation of very fine crystallite with different orientations. The lattice striations confirmed the well-crystallized nature of the nanoparticles. Room-temperature magnetization loops showed all samples are magnetically soft, with very little hysteresis, and that the specific magnetization, ranging from 14-65 Am-2 kg(-1), is highly dependent on particle size and experimental conditions. Room-temperature Mossbauer spectra are typical of nonstoichiometric Fe3-delta O4, with a small excess of Fe3+, 0.07 <= delta <= 0.18. Our results showed that it is possible to improve the crystal structure of the particles by tuning the growth parameters.