采用柠檬酸钠辅助的水热方法制备了一系列不同Ca2+含量的Ca2+/Yb3+/Er3+共掺的NaYF4微米片。利用透射电子显微镜(TEM)、X射线衍射分析(XRD)、发光光谱等测量手段对样品进行了形貌、晶相、发光性质的表征。样品在980 nm激光泵浦下, 可以观察到强的上转换绿色荧光。在Ca2+的摩尔分数从0增加到8%的过程中, 紫外到可见的上转换发光随着Ca2+浓度的增加而显著增强。这是由于Ca2+的掺杂导致了晶体内部的不对称性, 同时也提高了晶体的结晶性。

Hexagonal NaYF4∶Yb/Er microcrystals were prepared by a facile trisodium citrate-assisted hydrothermal method. The microparticles were characterized by TEM, X-ray diffraction (XRD), and luminescent spectra. Intense green upconversion luminescence was observed under 980 nm excitation. By introducing Ca2+ dopants into the grain lattices, the upconversion luminescence intensity of NaYF4∶Yb/Er microcrystal was improved significantly. The enhancement is proposed to originate from a modification of the crystal structure and an improvement in the crystallinity of NaYF4∶Yb/Er microcrystals.