Controlled synthesis and defect dependent upconversion luminescence of Y2O3: Yb, Er nanoparticles

Er3+ and Yb3+ co-doped Y2O3 nanoparticles have been prepared by using a coprecipitation method followed by a post-thermal-treatment, in which a surfactant (cetyltrimethylammonium bromide, CTAB) plays an important role in the size-controlling and upconversion luminescence tuning. The green (H-2(11/2), S-4(3/2) -> I-4(15/2)) and red emission (F-4(9/2) -> I-4(15/2)) intensity can be effectively tuned by varying the surfactant concentration, which can induce the defects in the as-obtained products. The probability of quenching and nonradiative relaxation from F-4(7/2), H-2(11/2), and S-4(3/2) to F-4(9/2) could be increased as the number of defects introduced by the surfactant increases, and thus the ratio of red to green emission is also changed. The upconversion mechanism has been analyzed and discussed, which may be a new complement for upconversion luminescence. (C) 2014 AIP Publishing LLC.