UV-vis and Infrared Spectroscopic Investigation of Feroxyhite Nanomaterial Synthesis by AC Atmospheric Microplasma*

Feroxyhite nanomaterials were synthesized in aqueous solutions by AC atmospheric microplasma at room temperature.  The synthesized nanomaterials were characterized by X-ray powder diffraction, Raman scattering, and electron microscopy.  The chemical reaction during the plasma synthesis was in situ and ex situ investigated by UV-vis spectroscopy and infrared spectroscopy.   The initiation phase of the nanomaterial was detected from UV-vis absorption and infrared bands of hydroxyl radical.  The synthesis-time-dependent crystallographic quality was detected from the bandgap of the nanomaterials, which was calculated with the Tauc method from the UV-vis spectra.  The effects of voltage and electric strength were investigated too.  The mechanism of the plasma synthesis was discussed.