Enhancement of Luminescence Efficiency of YO Nanophosphor via Core/Shell Structure.

We successfully fabricated YO:RE (RE = Eu, Tb, and Dy) core and core-shell nanophosphors by the molten salt method and sol-gel processes with YO core size of the order of 100~150 nm. The structural and morphological studies of the RE-doped YO nanophosphors are analyzed by using XRD, SEM and TEM techniques, respectively. The concentration and annealing temperature dependent structural and luminescence characteristics were studied for YO:RE core and core-shell nanophosphors. It is observed that the XRD peaks became narrower as annealing temperature increased in the core-shell nanophosphor. This indicates that annealing at higher temperature improves the crystallinity which in turn enhances the average crystallite size. The emission intensity and quantum yield of the Eu-doped YO core and core-shell nanoparticles increased significantly when annealing temperature is varied from 450 to 550 °C. No considerable variation was noticed in the case of YO:Tb and YO:Dy core and core-shell nanophosphors.