Upconversion emission enhancement of TiO2 coated lanthanide-doped Y2O3 nanoparticles

To investigate the upconversion emission, this paper synthesizes Tm3+ and Yb3+ codoped Y2O3 nanoparticles, and then coats them with TiO2 shells for different coating times. The spectral results of TiO2 coated nanoparticles indicate that upconversion emission intensities have respectively been enhanced 3.2, 5.4, and 2.2 times for coating times of 30, 60 and 90 min at an excitation power density of 3.21 × 102 W · cm−2, in comparison with the emission intensity of non-coated nanoparticles. Therefore it can be concluded that the intense upconversion emission of Y2O3:Tm3+, Yb3+ nanoparticles can be achieved by coating the particle surfaces with a shell of specific thickness