Synchrotron X-ray absorption of iron oxide (Fe2O3) nanoparticles: Effects of reagent concentration and sonication in co-precipitation synthesis

Synchrotron X-ray absorption spectroscopy was used to complement X-ray diffraction in the characterization of iron oxide nanoparticles synthesized by ultrasonic-assisted co-precipitation. We studied the effects of ultrasonication on the nanoparticle synthesis and used X-ray diffraction to show that impurity phases were present in samples synthesized without ultrasonication. The hematite phase was shown to be absent from our X-ray diffraction results, and X-ray absorption spectroscopy revealed a preference for the maghemite phase over magnetite. Our results showed that maghemite nanoparticles formed with larger crystallite sizes and lower structural distortion when higher reagent concentrations and longer sonication/reaction times were used. Moreover, the synthesis at low reagent concentration gave rise to materials with an amorphous maghemite phase. (C) 2017 The Physical Society of the Republic of China(Taiwan). Published by Elsevier B.V. All rights reserved.