Structure and photoluminescence of TiO2 nanocrystals doped and co-doped with N and rare earths (Y3+, Pr3+)

Abstract The structural and optical properties of sol–gel synthesized TiO 2 nanoparticles doped and co-doped with N and rare earth ions (Y 3+ and Pr 3+ ) are presented. Crystal structures, phase composition, and crystallite sizes are analyzed by powder X-ray diffraction and Raman spectroscopy. The analysis of intragap excited photoluminescence indicates the formation of radiative recombinations related to different defect centers in the TiO 2 structure, generated by the presence of doping elements. In particular we assign the formation of bulk and surface defects to the presence of nitrogen in the TiO 2 matrix, whereas we observe different effects on the defective TiO 2 structure related to the two rare earths: the presence of Y 3+ ion acts as a stabilizer of the TiO 2 surface whereas the presence of Pr 3+ generates surface recombination centers.