Ho^(3+)离子掺杂单颗粒氟化物微米核壳结构的上转换发光特性  

Upconversion luminescence characteristics of Ho^(3+) ion doped single-particle fluoride micron core-chell structure

作　　者：高伟 孙泽煜 郭立淳 韩珊珊 陈斌辉 韩庆艳 严学文 王勇凯 刘继红 董军 Gao Wei;Sun Ze-Yu;Guo Li-Chun;Han Shan-Shan;Chen Bin-Hui;Han Qing-Yan;Yan Xue-Wen;Wang Yong-Kai;Liu Ji-Hong;Dong Jun(School of Electronic Engineering,Xi’an University of Posts&Telecommunications,Xi’an 710121,China)

机构地区：[1]西安邮电大学电子工程学院,西安710121

出　　处：《物理学报》2022年第3期163-174,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12004303,62005213);陕西省青年科技新星培育计划(批准号:2021KJXX-45);陕西省自然科学基金(批准号:2019JQ-864);陕西省重点研发计划(批准号:2020GY-101,2020GY-127);西安市科技计划(批准号:2020KJRC0107,2020KJRC0112);西安邮电大学研究生创新基金(批准号:CXJJLZ2019031)资助的课题。

摘　　要：构建核壳结构可有效降低材料的表面缺陷及实现掺杂离子的可控区域分布,已成为目前增强及调控材料发光特性的有效手段之一.为此,本文以外延生长技术,构建了一系列NaLnF_(4)(Ln=Y,Yb,Ho)@NaLnF_(4)(Ln=Y,Yb)核壳微米结构,并实现了Ho^(3+)离子上转换发光的增强及可控调节.借助共聚焦显微光谱测试系统,在980 nm近红外激光激发下,研究Ho^(3+)离子在不同单颗粒核壳结构中的上转换发光特性.结果表明,当包覆NaYF_(4)惰性壳时,NaYF_(4):Yb^(3+)/Ho^(3+)及NaYbF_(4):Ho^(3+)微米棒的上转换发射强度均得到了明显增强,而NaHoF_(4)@NaYF_(4)微米核壳结构的发射强度却没有发生明显的变化.当在其NaYF_(4)惰性壳中引入Yb^(3+)离子时,NaYF_(4):Yb^(3+)/Ho^(3+),NaYbF_(4):Ho^(3+)及NaHoF_(4)微米核壳结构的发射强度及红绿比均再次得到了明显增强.基于对其光谱特性及动力学过程的研究,其发射增强主要由于壳层中的Yb^(3+)离子通过能量迁移及传递过程有效地提高Ho^(3+)离子激发,进而在双向协同的作用下实现其发光有效增强及色彩调控.由此可见,对于微米晶体而言,构建其不同的核壳结构不仅可实现其发光有效增强,且可根据掺杂离子的不同及其区域分布实现光谱的精准调控,为拓展高效发光特性的微米晶体在防伪、微纳光电器件等领域的应用提供新途径.Constructing core-shell structures can effectively reduce the surface quenching effect of luminescent materials,which becomes an effective method to enhance upconversion luminescence.In this work,a series of NaLnF_(4)@NaLnF_(4)(Ln=Y^(3+),Yb^(3+),Ho^(3+))core-shell microcrystals is successfully synthesized based on epitaxial growth technology,thereby enhancing and regulating the upconversion emission of Ho^(3+) ions.The results of the XRD and SEM indicate that the NaLnF_(4)@NaLnF_(4)core-shell microcrystal possesses a pure hexagonal-phase crystal structure with a rod-like shape.Meanwhile,it is found that the epitaxial growth direction of the micro-shell is not affected by the crystal characteristics in the core,but determined by the crystal characteristics of the shell.Under 980 nm near-infrared laser excitation,the upconversion luminescence properties of single microrods with different core-shell structures are investigated via a confocal microscope spectroscopy.It is found that in the NaLnF_(4)micro-crystal,the coated NaYF_(4)inert shell can also effectively reduce the quenching effect on the surface of the micro-crystal for enhancing upconversion emission.When the Yb^(3+) ions are introduced into NaYF_(4)or NaYbF_(4)active shell that is coated,the Yb^(3+) ions in the shell can effectively transfer excitation energy to Yb^(3+) in the core through energy migration,and then establish new energy transfer channels,thereby realizing the Ho^(3+) ion luminescence enhancement.For NaHoF_(4)@NaYbF_(4)core-shell microrods,the Yb^(3+) in the shell can transfer more excitation energy to Ho^(3+) ions at the adjacent interface for enhancing the overall luminescence intensity,and its higher red-green ratio is mainly due to the cross-relaxation process occurring between the Ho^(3+) ions at high doping concentration of Ho^(3+) in the NaHoF_(4)core.Meanwhile,the luminescence process of the micron core-shell system is further confirmed based on the luminescence characteristics of different structures and the dynamic luminescence pr

关 键 词：上转换发光 微米核壳结构 发光调控 能量传递 单颗粒 

分 类 号：TB34[一般工业技术—材料科学与工程]