K离子掺杂增强NaErF4体系上转换发光

Enhancement of NaErF_4 Nanostructure Upconversion Luminescence with K^+ Doping

制备了一系列Na_(1-x)K_xErF_4@NaLuF_4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!-相纳米结构。研究结果表明:随着K^+浓度的增加,纳米结构中Er^(3+)~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,Na_(0.96)K_(0.04)ErF_4@NaLuF_4纳米晶的发光强度达到最大,为未掺杂K^+的NaErF_4@NaLuF_4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Er^(3+)微环境晶场宇称对称性,提高了Er^(3+)离子~4F_(9/2)→~4I_(5/2)能级辐射跃迁几率,进而增强了Er^(3+)的650 nm红带的上转换发光强度。

Abstract： The nanostructures composing of Na 1- x K x ErF 4@NaLuF 4 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 NaErF 4@NaLuF 4 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 NaErF 4@NaLuF 4 nanoparticles is an efficient solution to improve the luminescence efficiency of NaErF 4@NaLuF 4 nanosystem.