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

For the first time, we have synthesized orthorhombic phase KSc ₂F₇:20%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 β-NaYF₄:20%Yb/2%Er (NaYF₄:Yb/Er) nanorods that usually give strong green UC luminescence, strong red UC emission was observed in KSc₂F ₇: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.