六角柱形NaErF_(4)和NaErF_(4)@NaYF_(4)核壳微粒制备及多色上转换荧光调控性能EI北大核心CSCD

采用简单的水热法合成了六角柱形NaErF_(4)和NaErF_(4)@NaYF_(4)核壳上转换发光材料,利用扫描电镜(SEM)、X射线粉末衍射(XRD)和荧光光谱(PL)等表征对材料的形貌、结构和上转换发光性能进行了研究。结果表明,纯NaErF_(4)样品为六角柱形,边长和厚度均为1μm左右,样品表面光滑。随着NaYF_(4)壳层的包覆,六角相NaErF_(4)周围出现了大量的立方相NaYF_(4)纳米颗粒,得到了NaErF_(4)@NaYF_(4)核壳结构。荧光光谱表明,通过在六角柱形NaErF_(4)表面包覆NaYF_(4)壳层,可以有效增强上转换发光强度,其中,位于527,543,663 nm处的3个发射峰分别对应于Er^(3+)的^(2)H_(11/2)→^(4)I_(15/2)、^(4)S_(3/2)→^(4)I_(15/2)和^(4)F_(9/2)→^(4)I1_(5/2)能级跃迁。随着壳层中Y∶F比例的增加,立方相NaYF_(4)的晶体衍射峰逐渐增强;同时,对应的NaErF_(4)@NaYF_(4)样品发射光谱中红绿比(R/G)逐渐增大,发光颜色也从绿色、经黄绿色逐渐向黄色过渡,实现了多色发光。

Preparation and Polychromatic Upconversion Luminescence of Hexagonal NaErF4 and NaErF4@NaYF4 Core-shell Particles

Hexagonal NaErF₄ and NaErF₄@NaYF₄ core-shell upconversion luminescent materials were synthesized by simple hydrothermal method.The morphology,structure and upconversion luminescence properties of the obtained materials were studied by scanning electron microscopy(SEM),X-ray powder diffraction(XRD)and fluorescence spectroscopy(PL).The results show that the pure NaErF₄ sample has hexagonal column morphology with smooth surface,and the side length and thickness are both 1μm.With the coating of NaYF₄ shell,a large number of cubic NaYF₄ nanoparticles appeared around hexagonal NaYF₄ particles,and the NaErF₄@NaYF₄ core-shell materials were obtained.The luminescence spectra show that the upconversion luminescence intensity can be effectively enhanced by coating NaYF₄ shell on the surface of hexagonal NaErF₄.The three emission peaks at 527,543,663 nm correspond to ²H_11/2→⁴I_15/2,⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 energy level transitions of Er³⁺,respectively.Meanwhile,with the increase of the molar ratio of Y∶F in the shell of NaErF₄@NaYF₄ sample,the crystal diffraction peak of cubic NaYF₄ increases gradually,moreover,the red green ratio(R/G)gradually increases in the emission spectrum of the sample,and the luminescence color gradually transits from green to yellow,realizing multi-color luminescence.