制备了一系列Na1-xKxErF4@NaLuF4的核壳纳米结构, 核中K+掺杂摩尔分数变化范围为0%～8%。XRD分析结果揭示这些具有不同K掺杂浓度的纳米粒子均为β-相纳米结构。研究结果表明: 随着K+浓度的增加, 纳米结构中Er3+～650 nm处的红带发光强度呈现先增强后减弱的规律, 当K+摩尔分数为4%时, Na0.96K0.04ErF4@NaLuF4纳米晶的发光强度达到最大, 为未掺杂K+的NaErF4@NaLuF4纳米晶发光强度的3.7倍。其发光增强的原因在于K+的掺杂降低了Er3+微环境晶场宇称对称性, 提高了Er3+离子4F9/2→ 4I5/2能级辐射跃迁几率, 进而增强了Er3+的650 nm红带的上转换发光强度。

The nanostructures composing of Na1-xKxErF4@NaLuF4 core@shell were synthetized with 0%-8% K+ doping mole fraction in the cores. XRD results reveal that all of the nanoparticles are the hexagonal structure. The research results show that the intensity of UCL at ~650 nm increases at first and then decreases with K+ concentration under 980 nm excitation. The intensity is enhanced 3.7 times with 4% K+ doping, compared with that of NaErF4@NaLuF4 core@shell without K+ doping. Furthermore, the slopes of relationship between UCL intensity and pumping power are from 1.91 to 1.76, for the two nanostructures undoped and doped with 4% K+, respectively. Our results suggest that the strategy of K+ doping in NaErF4@NaLuF4 nanoparticles is an efficient solution to improve the luminescence efficiency of NaErF4@NaLuF4 nanosystem.