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

Single phase cubic BaLnF 5 (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 Ln 3+ radius, the easier to precipitate the undesired BaLn 2 F 8 phase in the reaction system along with the formation of BaLnF 5 . In this case, the appropriate reaction temperature is required to obtain single BaLnF 5 nanophase. Measurements on the up-conversion emission behaviors of the Yb 3+ /Er 3+ (Tm 3+ ): BaLaF 5 and Yb 3+ /Er 3+ (Tm 3+ ): BaLuF 5 nanocrystals demonstrate that BaLnF 5 are desirable up-conversion hosts. In addition, the Ce 3+ /Ln 3+ (Ln   =   Tb, Eu, Dy, Sm): BaGdF 5 nanocrystals are found exhibiting multicolor down-conversion emissions.