Efficient oxide phosphors for light upconversion; green emission from Yb3+ and Ho3+ co-doped Ln2BaZnO5 (Ln = Y, Gd)

The optical properties of Yb3+ and Ho3+ co-doped Y2BaZnO5, synthesized by solid-state reactions, are investigated in detail. Under 977 nm excitation ([similar]25 [times] 10-3 W mm-2), bright green upconversion emission is observed. Concentration dependence studies at room temperature show that relatively high infrared to visible upconversion efficiencies are obtained with values up to [similar]2.6%. The results of power dependence studies and temperature-dependent lifetime measurements allow us to determine the dominant upconversion mechanisms in Yb3+:Ho3+ co-doped Y2BaZnO5 oxides. The materials presented in this article constitute new and efficient upconversion phosphors which may find utility in a variety of applications.