Nanocomposite thin films containing Pt nanoparticles dispersed in an α-Fe2O3 matrix by RF sputtering

Abstract

The preparation of nanocomposite thin films that phase-separate Pt and α-Fe2O3 was investigated. These films were prepared on water-cooled glass substrates by radio frequency sputtering in an Ar atmosphere. X-ray diffraction patterns reveal that iron oxide forms Fe3O4 in the as-deposited state and undergoes a phase transition to α-Fe2O3 after heat treatment in the air. Pt is phase-separated from iron oxides in the as-deposited state and during heat treatment in the air, with a crystallite size of less than 2 nm in the as-deposited state, which varies between 2 and 15 nm after heat treatment in the air, estimated from the x-ray diffraction peaks. High-resolution transmission electron microscopy of the sample after heat treatment in the air reveals that spherical particles with a relatively uniform size are dispersed, which are assigned to Pt from fast Fourier transform analysis, while the surrounding area is assigned to α-Fe2O3. Thus, the thin film forms a nanocomposite thin film in which Pt nanoparticles are dispersed in α-Fe2O3.