利用水热法，制备了具有不同形貌的NaYF4∶20%Yb3+,1%Tm3+上转换发光粒子。利用扫描电子显微镜、X射线衍射分析、发光光谱测量等手段对样品进行了形貌、晶相和发光性质的表征。结果表明，通过调控反应物的浓度，可以实现NaYF4基质从立方相到六角相的晶相转变。在980 nm红外光的激发下，六角相的NaYF4∶20%Yb3+,1%Tm3+上转换发光粒子发出蓝紫色可见光。通过分析反应物浓度对产物晶相的影响，为制备晶相可控的上转换发光材料提供了新的实验依据。

A series of NaYF4∶20%Yb3+, 1%Tm3+ upconversion particles (UCPs) with different morphology were prepared by the facile hydrothermal approach. The morphology, crystalline phase and optical properties were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and luminescent spectra. XRD patterns and SEM images showed that the UCPs crystalline phase tansformed from cubic phase to hexagonal phase by controlling the reactants concentration. Pumped with 980 nm diode laser, the UCPs emitted bright violet/blue upconversion luminescence. By analyzing the effect of reactants concentration on the products crystalline phase, the crystal growth mechanism of NaYF4 was studied in detail. Significantly, our research work would provide more experimental data for controlling the crystalline phase of the upconversion luminescent materials.