Color-tunable up-conversion emission in Y2O3:Yb3+, Er3+ nanoparticles prepared by polymer complex solution method.

Powders of Y2O3 co-doped with Yb3+ and Er3+ composed of well-crystallized nanoparticles (30 to 50 nm in diameter) with no adsorbed ligand species on their surface are prepared by polymer complex solution method. These powders exhibit up-conversion emission upon 978-nm excitation with a color that can be tuned from green to red by changing the Yb3+/Er3+ concentration ratio. The mechanism underlying up-conversion color changes is presented along with material structural and optical properties. PACS: 42.70.-a, 78.55.Hx, 78.60.-b.