Effect of Chelation on PL Properties of Er~(3+)-doped TiO_2 Powders Prepared by Sol-gel Method

0.1-3.0mol% Er3+-doped TiO2 powders were prepared by the sol-gel method using the modified titanium (Ⅳ) n-butoxide [Ti(O-Bu)4-x(AcAc)x] as the precursor which is prepared by chelating reaction between Ti(O-Bu)4 and acetylacetone (AcAc) at room temperature and 70℃, respectively. The preparation was performed by using iso-propyl(i-PrOH) as solvent with the addition of hydrated erbium nitrated [Er(NO3)3·5H2O]. When the temperature of the chelating reaction increased from room temperature to 70℃, both phase transformation temperatures of lmol% Er3+-doped TiO2 xerogels from amorphous to anatase and anatase to rutile were decreased about 40℃. XRD analysis showed that, sintered at 700℃the phase structure for the TiO2 powders prepared by using Ti(O-Bu)4-x(AcAc)x chelated at room temperature is anatase, while that for the TiO2 powders chelated at 70℃is the mixture of anatase and rutile in small amount. The photoluminescence (PL) spectra centered at about 1.53μm with the form of multi-peak were obtained for the powders by chelating at the two temperature sintered in the temperature range of 400-800℃. For 1mol% Er3+-doped TiO2 powders sintered at 700℃, the PL peak intensity at 1.5μm increased by a factor of 3 with increasing the chelating reaction temperature to 70℃.