Orthorhombic KSc2F7:Yb/Er nanorods: controlled synthesis and strong red upconversion emission

For the first time, we have synthesized orthorhombic phase KSc2F7:20% Yb/2% Er (KSc2F7:Yb/Er) nanorods and further studied the crystal structure and morphology evolution, as well as their upconversion (UC) properties under varying F- contents and reaction temperatures. Different from beta-NaYF4:20% Yb/2% Er (NaYF4:Yb/Er) nanorods that usually give strong green UC luminescence, strong red UC emission was observed in KSc2F7:Yb/Er nanorods under 980 nm laser excitation. Their UC mechanisms are further analyzed and compared. This study provides a novel type of rare earth nanorods with strong red UC emissions which have great potential in high resolution 3-dimensional bioimaging, color displays, solid-state lasers, and photocatalysis.