A combined micro-Raman, X-ray absorption and magnetic study to follow the glycerol-assisted growth of epsilon-iron oxide sol-gel coatings

Abstract

Epsilon iron oxide (epsilon-Fe_2O_3) coatings on Si(100) substrates are obtained by an easy one-pot sol-gel recipe assisted by glycerol in an acid medium. Glycerol, given its small dimensions, enables the formation of epsilon-Fe_2O_3 nanoparticles with a size of a few nanometers and the highest purity is reached in coatings after a densification treatment at 960 degrees C. The structural and compositional evolution up to 1200 degrees C is studied by confocal Raman microscopy and X-ray absorption spectroscopy techniques, correlating the existing magnetic properties. We report a novel characterization method, which allows monitoring the evolution of the precursor micelles as well as the intermediate and final phases formed. Furthermore, the inherent industrial technology transfer of the sol-gel process is also demonstrated with the epsilon-Fe_2O_3 polymorph, impelling its application in the coatings form.