Phase transfonnation of β-Fe2O3 hollow nanoparticles

The phase transformation of beta-Fe2O3 with a hollow nanostructure was first investigated by in-situ X-ray diffractometry (XRD) at elevated temperatures. As a starting material, the beta-Fe2O3 hollow nanoparticles (HNP) less than 40 nm in size were prepared by chemical vapor condensation (CVC) process. The XRD analysis revealed that the initial beta-Fe2O3 phase was transformed to gamma-Fe2O3 at 500 degrees C, and no further transformation from gamma-Fe2O3 to alpha-Fe2O3 was observed up to 800 degrees C. The experimental findings indicate that the increase of surface area derived from the hollow structure is responsible for the decrease of the transformation temperature and the stability of the gamma-Fe2O3 phase at high temperatures. (c) 2007 Elsevier B.V. All rights reserved.