Mössbauer spectroscopy study of iron oxide nanoparticles obtained by spray pyrolysis

Abstract

Mössbauer spectroscopy was used in this study to investigate magnetite nanoparticles, obtained by spray pyrolysis and thermal treatment under H 2 reduction atmosphere. Room temperature XRD data indicate the formation of magnetite phase and a second phase (metallic iron) which amount increases as the time of reduction under H 2 is increased. While room temperature Mössbauer data confirm the formation of the cubic phase of magnetite and the occurrence of metallic iron phase, the more complex features of 77 K-Mössbauer spectra suggest the occurrence of electronic localization favored by the different crystalline phase of magnetite at low temperatures which transition to the lower symmetry structure should occur at T ∼120 K (Verwey transition).

Superparamagnetic Iron Oxide Nanoparticles (SPIONs): Synthesis and Surface Modification Techniques for use with MRI and Other Biomedical Applications

“…The 2nm coating was found to reduce the crystals' size from 15 nm (without SiO 2 shell) to 8 nm and simultaneously improve their magnetic properties by inhibiting the formation of hematite. Marques et al developed a method for the synthesis of magnetite by the thermal oxidation of an iron nitrate spray into sub-micron sized hematite spheres and subsequent reduction in H 2 [59]. The precursor was carried by air into the reaction furnace heated to 400°C-700°C and collected by an electrostatic chamber where it was then reduced at 390°C under H 2 .…”

High Surface Area Iron Oxide Microspheres via Ultrasonic Spray Pyrolysis of Ferritin Core Analogues

“…Spray pyrolysis and similar aerosol techniques are well-known as scalable synthetic methodologies for the preparation of metal oxide materials from relatively inexpensive precursors. − Porous particles with relatively high surface areas have been obtained with spray pyrolysis for carbon, − silica, , titania, alumina, Bi 2 WO 6 , Mn 3 O 4 , ZnS, and MoS 2 . Iron oxides, however, have not been previously prepared in high surface area form through spray pyrolysis; only films , and solid particles ,− have been reported.…”