Synthesis and Upconversion Luminescence of LaF3 : Yb3+, Er3+/SiO2 Core/Shell Microcrystals

LaF3: Yb3+, Er3+ microcrystals were synthesized by a hydrothermal method, and then, the LaF3: Yb3+, Er3+ microcrystals were coated with silica. Phase identification of LaF3: Yb3+, Er3+ and LaF3: Yb3+, Er3+/SiO2 was performed via XRD. The TEM image showed that the size of LaF3: Yb3+Er3+ was 150 nm and LaF3: Yb3+, Er3+/SiO2 presented clearly a core/shell structure with 20 nm shell thickness. The upconversion spectra of LaF3: Yb3+, Er3+ and LaF3: Yb3+, Er3+/SiO2 in solid state and in ethanol were studied with a 980 nm diode laser as the excitation source. The upconversion spectra showed that the silica shell had little effect on the properties of fluorescence of the LaF3: Yb3+, Er3+ microcrystals. At the same time, the green luminescence photo of LaF3: Yb3+, Er3+/SiO2 in the PBS buffer was obtained, which indicated that the LaF3: Yb3+, Er3+/SiO2 could be used in biological applications.