Surface properties of inorganic coated Fe(2)O(3) nanoparticles characterized by XPS

Coating the surface of goethite nanoparticles by Si, Co oxides layer is one of the most important methods to improve the magnetic properties of metal magnetic recording particles. The surface electronic properties of the coated nanoparticles were studied by using XPS. Results show that there is a close, uniform, firm and ultra thin SiO(2) layer formed on the surface of hematite nanoparticles. Silica coating treatment changes the properties of the hematite cores significantly since the binding energy of Fe 2p electrons shows significant shift related to the spectrum of the untreated hematite particles. The chemical shift of the binding energy is more than 2.7eV. A possible interpretation for the shift of such spectral features is that the contact interface surface of silica layer and the hematite particle surface is similar to P-N heterojunction. The cobalt oxides are adsorbed on part of the crystal face of Fe(2)O(3) particles, and the binding energy of whole XPS spectrum mainly shows physical shift about 4.4eV due to the surface charge.