Functionalization and characterization 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 beta-cyclodextrin concentration, applied potential and bath temperature on the structural properties and magnetization of the nanoparticles was studied. FT-IR spectroscopy, X-ray diffraction, electron microscopy, magnetometry and Mossbauer spectroscopy were used to characterize the samples. 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 microscopy images showed that the mean particle size is in the range 20-80 nm. Based on these images, we found that tuning the growth conditions has a strong effect on the particle size and morphology. High-resolution transmission electron microscopy images showed the aggregation of very fine crystallites with different orientations. The lattice striations confirmed the well-crystallized nature of the nanoparticles. The ring-like electron diffraction patterns are attributed to diffraction from the crystal planes of iron oxide nanoparticles. Room-temperature magnetization loops showed that all samples are magnetically soft with very little hysteresis, but the specific magnetization ranging from 14-80 A m(2) kg(-1) is highly dependent on the particle size and the experimental conditions. The room-temperature Mossbauer spectra are typical of non-stoichiometric 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.