单分散LaF3纳米晶：形貌可控合成、激发功率诱导的多色上转换发射调控

In this paper, the monodispersed and high quality hexagonal phase LaF3 nanocrystals with different shape and size were synthesized by solvothermal method using oleic acid as stabilizing agent. The as-prepared LaF3 nanocrystals were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). XRD results demonstrate the crystal phase of the as-prepared LaF3 nanocrystals are hexagonal phase. TEM results reveal that the samples present high uniformity and monodispersity and are self-assembled into a two-dimensional ordered array. Moreover, the shape and size of the nanocrystals can be readily tuned by adjusting the NaF concentration. With increasing the concentration of NaF, the shape of LaF3 nanocrystals was changed from particle to rod and the size gradually increased. Moreover, high NaF concentration favors the formation of the one-dimensional nanorods. In addition, the LaF3 nanorystals co-doped with Yb3+/Er3+ can emit tunable visible light from yellow-white to yellow light with increasing the excitation power. Therefore, it is expected that these LaF3 nanocrystals with well controlled shape, size and upconversion luminesence have potential application in bioimaging field.