Novel upconversion phenomenon of Nd~(3+) sensitized by Yb(3+) in Nd~(3+)-Yb~(3+)-co-doped β-Na(Y_(1.5)Na_(0.5)F_6

摘要

Hexagonal phase Na(Y_(1.5)Na_(0.5))F_6 co-doped with Yb~(3+) and Nd~(3+) was synthesized and its structure was studied by XRD and Raman methods. The Raman scattering spectrum illustrates it is a host with low phonon energy. Emissions in green (~4G_(7/2) → ~4I_(9/2)), yellow (~4G_(7/2) → ~4I_(11/2)), red (~4G_(7/2) → ~4I_(13/2)). and infrared (~4F_(5/2) → ~4I_(9/2). ~4F_(3/2) → ~4I_(9/2)) were observed and were the direct result of emissions of the Nd~(3+) ion. The luminescence intensity ratio (I_(863)/I_(804)) gradually decreased with the increase of excitation power. The long lifetime of 863 nm infrared emission was proved. The upconversion mechanism was deduced to be energy transfer from the Yb~(3+) to Nd~(3+) under 980 nm excitation, by analyzing the energy level structures of Nd~(3+) and Yb~(3+) ions and measuring the power dependence of upconverted emission intensities.