Influence of thermal treatments on phase formation and magnetic behaviour in metal transition doped TiO2

Transition metal doped TiO2 samples, with nominal composition TM5(TiO2)95 (TM=Mn, Fe, Co and Ni), were obtained by thermal treatment at 673, 773 and 973 K in air to study the role of impurities in the origin of magnetism. X-ray diffraction (XRD) experiments only detect the rutile phase in the 673 K thermally treated samples but evidence of other phases was detected by Mössbauer spectroscopy and ac-susceptibility measurements. All samples presented magnetic behaviour. The estimated magnetic moments were lower than those obtained by ab initio calculations.