A.M. Calle, , L.C. Sanchez, J.D. Arboleda, J.J. Beltran, C.A. Barrero, J. Osorio, K. Nomura

Fe-doped TiO2 powders were obtained by mechanical alloying. The starting materials were anatase TiO2 and metallic iron (a-Fe) or hematite (a-Fe2O3). The influence of different milling conditions such as: ball to powder weight ratio, milling time, rotation velocity of supporting disc, and dopant concentration on the structural and magnetic properties were investigated. All experiments were performed in atmospheric conditions. The milled powders were characterized by X-ray diffraction (XRD) using Rietveld refinement and room temperature Mo¨ ssbauer spectrometry. The XRD patterns of all samples show the coexistence of both anatase and rutile phases and also the high-pressure srilankite phase. Mo¨ ssbauer spectra reveal the presence of Fe2þ and Fe3þ states in Fe-doped TiO2 as well as a-Fe or a-Fe2O3 in samples obtained from metallic iron or hematite, respectively. The Fe3þ contribution could be attributed to Fe incorporated in the TiO2 structure and the Fe2þ can be probably assigned to surface ferrous ions in the TiO2.