Characterization of Sm3+ doped Tio2 and Ni2+ doped Tio2 nanocrystals

We report on a new approach toward synthesis of Sm3+ doped TiO2 and Ni2+ doped TiO2 nanocrystals by shape transformation of hydrothermally treated titania nanotubes in the presence of Sm3+ or Ni2+ ions. The percentage ratio of Sm3+ (or Ni2+) to Ti4+ ions in doped nanocrystals was determined using ICP atomic emission spectroscopy. The XRD patterns revealed the homogeneous anatase crystal phase of both 0.4 at% Sm3+ doped TiO2 and 0.12 at% Ni2+ doped TiO2 nanoparticles. An average size of polyhedral Sm3+ doped TiO2 nanocrystals was between 12 and 14 nm. In the orange-red spectral region, room temperature photoluminescence signals associated with 4 G5/2 →6 HJ (J = 5/2, 7/2 and 9/2) transitions of Sm3+ was observed in Sm3+ doped TiO2 nanocrystals. Optically transparent film made of 0.12 at% Ni2+ doped TiO2 nanoparticles showed room temperature ferromagnetic ordering. The coercive field was found to be HC ~ 80 Oe.