Syntheses and optical properties of monodisperse BaLnF5 (Ln = La–Lu, Y) nanocrystals

Single phase cubic BaLnF5 (Ln = La–Lu, Y) nanocrystals are successfully synthesized via a common facile solvothermal route using oleic acid as surfactant. It is found that the smaller the Ln3+ radius, the easier to precipitate the undesired BaLn2F8 phase in the reaction system along with the formation of BaLnF5. In this case, the appropriate reaction temperature is required to obtain single BaLnF5 nanophase. Measurements on the up-conversion emission behaviors of the Yb3+/Er3+ (Tm3+): BaLaF5 and Yb3+/Er3+ (Tm3+): BaLuF5 nanocrystals demonstrate that BaLnF5 are desirable up-conversion hosts. In addition, the Ce3+/Ln3+ (Ln = Tb, Eu, Dy, Sm): BaGdF5 nanocrystals are found exhibiting multicolor down-conversion emissions.

► Pure cubic BaLnF5 (Ln = La–Lu, Y) nanocrystals were successfully synthesized.
► Through control the experiment condition to suppress the undesired BaLn2F8 phase.
► The morphologies and micro-structures of these nanocrystals were characterized.
► The up- or down- conversion luminescence of BaLnF5 (Ln = La, Lu, Gd) were characterized.