中文摘要：

利用酸洗改性对共沉淀法制得的油性β-NaYF_4：Yb~（3＋）,Tb~（3＋）@β-NaYF4纳米颗粒进行改性处理,获得水性β-NaYF4：Yb~（3＋）,Tb~（3＋）@β-NaYF4纳米颗粒.表征了制得样品的形貌和上转换荧光特性.结果表明制得的样品分散性好,形貌均一.在相同掺杂浓度和溶液浓度下,水性β-NaYF_4：Yb~（3＋）,Tb~（3＋）@β-NaYF4纳米颗粒溶液的上转换荧光强度比油性β-NaYF4：Yb~（3＋）,Tb~（3＋）@β-NaYF_4和水性β-NaYF4：Yb~（3＋）,Tb~（3＋）纳米颗粒溶液的双光子上转换荧光分别增强了1.1倍和37倍,三光子上转换荧光分别增强了1.5倍和3.9倍.水性β-NaYF4：Yb~（3＋）,Tb~（3＋）@β-NaYF_4纳米颗粒外层存在隔离壳层,导致改性处理既去除了油酸又获得较强的上转换荧光.

英文摘要：

The oleate-capped β-NaYF4 ： Yb3 ＋ , Tb3＋ @/3-NaYF4 nanoparticles were prepared by co-precipitation method. The water-soluble ligand-free β-NaYF4 ： Yb3 ＋ , Tb3＋ @β-NaYF4 core- shell nanoparticles were obtained from the oleate-capped nanoparticles by hydrochloric acid modifi- cation. The SEM images and upconversion luminescence spectra of samples were measured. The re- sults indicated that the ligand-free nanoparticles were uniform and can be well dispersed in water. With same solution concentration and rare-earth doping concentration, the upconversion emission in- tensity of ligand-freeβ-NaYF4 ： Yb3＋ , Tb3 ＋ @/3-NaYF4 core-shell nanoparticles reached 1.1 times/ 37 times （ two photons） and 1.5 times/3.9 times （ three photons） than that of oleate-capped/3- NaYF4： Yb3 , Tb3＋ @ β-NaYF4 nanoparticles and ligand-freeβ-NaYF4： Yb3 ＋ , Tb3＋ nanoparti- eles, respectively. Because of the core-shell structure of ligand-freeβ-NaYF4 ： Yb3＋ , Tb3＋ @β- NaYF4 nanoparticles, the oleate molecules were removed and stronger upconversion luminescence can be obtained after modification.