Magnetic Properties, Electron Paramagnetic Resonance, and Photoelectron Spectroscopy Studies of Nanocrystalline TiO2 Co-Doped with Al and Fe

Abstract

Electron paramagnetic resonance, X-ray photoelectron spectroscopy, field dependence of magnetization, X-ray diffraction, and transmission electron microscopy are applied for the characterization of Al-doped TiO2 nanopowders with Fe impurities synthesized by the autoclave-assisted hydrothermal method and annealed in vacuum or in hydrogen. The sizes of the TiO2:(Al, Fe) nanoparticles are estimated to be about 10-20 nm. It is proposed that Al ions are presumably placed in the TiO2 lattice in interstitial positions. Moreover, Fe3+ ions can occupy tetrahedral positions of Ti4+ ions as a result of Al-doping. The results suggest that Al-doped TiO2 nanopowders with Fe impurities annealed in vacuum or hydrogen display both intrinsic and extrinsic ferromagnetic properties.