β-NaYF4：Yb，Er上转换发光纳米晶的制备及表面性能

利用热分解法制备出β-NaYF4：20mol％Yb，2mol％Er上转换发光纳米晶，并采用两种方法对产物进行后处理。分别用X-射线衍射仪（XRD）、扫描电子显微镜（SEM）、荧光光谱（FL）、傅立叶红外光谱仪（FT—IR）对产物的结构、形貌、发光性质及表面性能进行了表征。结果表明，制备的NaYF4：20mol％Yb，2mol％Er纳米晶为六方相，粒径分布均匀为25nm左右，在980nm红外光激发下，呈现强的上转换发光。两种后处理方法对纳米晶的上转换发光强度及表面性能均产生了影响，但其形貌及晶相无变化。

Synthesis and Surface Properties of β- NaYF4 ： Yb, Er Up -conversion Luminescent Nano - crystals

β - NaYF4 ： 20 mol % Yb, 2 mol % Er up - conversion luminescent nano - crystals were synthesized by a thermal decomposition process. And two methods were used to wash the products. The crystalline phase, morphology, optical properties and surface properties of the samples were characterized by X -ray diffraction （XRD）, scanning electron microscopy （SEM）, fluorescence spectrum （FL） and Fourier transform infrared （FT- IR） spectrometer, respectively. The results confirmed that the synthesized NaYF4：20mo1% Yb, 2mol% Er nano- crystals were hexagonal phase. The grain size of β - NaYF4 ： 20mol% Yb, 2mol% Er was about 25nm, and its distribution was uniform. Under 980 -nm excitation, both samples exhibited bright up - conversion luminescence. No change was observed between them by XRD spectra and SEM images. But the intensity of up - conversion luminescence and surface properties were influenced by the different processes of washing products.