Phase-tunable synthesis and upconversion photoluminescence of rare-earth-doped sodium scandium fluoride nanocrystals

Monodisperse rare-earth-doped NaxScF3+x nanocrystals have been synthesized via the co-thermolysis of trifluoroacetates. They can be easily tuned from monoclinic-phase (Na3ScF6) to hexagonal-phase (NaScF4) just through changing the ratio of Na(CF3COO) to Sc(CF3COO)(3). The obtained samples show bright upconversion photoluminescence. Furthermore, luminescence with a wide spectrum of colors, including white, has been achieved by the appropriate blend of NaScF4:Yb3+/Er3+ and NaScF4:Yb3+/Tm3+ nanocrystals