Magnetism of Fe-doped TiO2 milled in different milling atmospheres

The Fe-doped TiO2 powders were prepared by mechanical alloying in argon, air and oxygen atmospheres and characterized using X-ray diffraction, vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. The Fe concentration was found to be 4.468, 4.227 and 4.473 at% for the powders milled in argon, air and oxygen, respectively. The Fe-doped TiO2 powders presented pure rutile structure. The Fe ions in the powders were found to take Fe2+/Fe3+ ionic valences. VSM measurements revealed that all the samples were ferromagnetic at room temperature, and the magnetic moment per Fe atom enhanced with decreasing of the oxygen partial pressures of the milling atmosphere. The enhanced magnetism is related with the increasing concentration of oxygen vacancies.