Preparation of Fe3O4 and γ-Fe2O3 Nanoparticles by Liquid and Gas Phase Processes

Abstract

The liquid and gas phase synthesis of γ-Fe2O3 and Fe3O4 nanoparticles and their coating with SiO2 as well as their characteristics have been studied. The liquid phase synthesis included hydrolysis of FeCl3.6H2O and FeSO4 ⋅ 7H2O solution at presence of urea and NaOH with subsequent ultrasonic treatment of FeO(OH)/Fe(OH)2 precipitations. The gas phase synthesis was based on evaporation of coarse grained FeO/Fe2O3 and Fe2O3 in radio frequency nitrogen plasma. The liquid phase synthesis provides preparation of Fe3O4 and γ-Fe2O3 nanoparticles with average particles size in the range of 16 nm – 26 nm. Coated nanoparticles were prepared by their treatment with TEOS solution in hexane in the presence of NH4OH and surface active compounds. It is shown that the one-step plasma synthesis has high production rate but the average particle size was in the range of 30 nm – 80 nm and size distribution is wider with respect to the chemical route.