Hf^(4+)共掺NaYF_4:Yb/Tm提高上转换发光性能研究  

Upconversion Performance Enhancement of NaYF_4: Yb/Tm by Codoping Hf^(4+) as Energy Migrator

作　　者：黄清明[1,2] 俞瀚[1] 张新奇[2] 曹文兵[1] 俞建长[1] 

机构地区：[1]福州大学材料科学与工程学院,福州350108 [2]福州大学测试中心,福州350002

出　　处：《化学学报》2016年第2期191-198,共8页Acta Chimica Sinica

基　　金：福建省自然科学基金(No.2013J05027)资助~~

摘　　要：利用X射线多晶衍射仪、场发射扫描电镜、场发射透射电镜、X射线光电子能谱和荧光光谱仪对相近半径离子Hf^(4+)和Zr^(4+)共掺六方Na YF_4:Yb^(3+)/Tm^(3+)的结构、形貌和上转换发光性能进行研究.结果表明Hf^(4+)和Zr^(4+)离子共掺六方Na YF_4:Yb^(3+)/Tm^(3+)可有效调控晶场的不对称性,Hf^(4+)相对于Zr^(4+)是个更好的掺杂离子,它在调控晶场的同时还参与Tm^(3+)离子上转换发光的能量传递过程,明显提高了短波500 nm以下发射带的荧光强度;而Zr4+离子仅扮演晶场调控角色而未能参与稀土离子Tm^(3+)的上转换发光过程,Tm^(3+)离子小于500 nm短波发射带的荧光强度没有得到明显的提高,仅提高802 nm发射带的荧光强度.该研究发现Hf^(4+)可作为蓄能离子参与稀土离子的上转换发光过程,有助于将Hf^(4+)作为蓄能离子和晶格操纵工具用于设计和制备其它高性能的稀土上转换发光材料.In this paper we report the infrared to visible upconversion（UC） luminescence properties of Hf^4＋ and Zr^4＋codoped Na YF4： Yb^3＋/Tm^3＋. Samples were synthesised by hydrothermal method. Concentration of Tm^3＋ and Yb^3＋ ions were fixed to be 2 mol% and 5 mol% for all samples, respectively. Na Y0.93-xYb0.05Tm0.02F4 was tridoped with 0, 2, 4, 6, 8 mol% Hf^4＋ or Zr^4＋ and corresponding samples were named as Hf0, Hf2, Hf4, Hf6, Hf8 and Zr0, Zr2, Zr4, Zr6, Zr8, respectively. In a typical procedure, trivalent nitrate stock solutions of 0.2 mol/L were prepared at first by dissolving the corresponding metal oxide in concentrated nitric acid or hydrofluoric acid at elevated temperatures. And then, a certain mole percentage of trivalent nitrate solutions were added into 20 m L 0.04 mmol EDTA aqueous solution. After vigorous stirring for 30 min, 25 m L ethanol solution containing 0.2 mmol Na F, 0.2 mmol NH4HF2 and corresponding stoichiometric amount Hf^4＋ or Zr^4＋ were dropwise added into the solution, and then p H value of solution was adjusted to 3.0 by addition 1 mol/L HF, and stirring continued for 30 min. Then the emulsion mixture was moved to PTFE-lined high pressure pot and incubated in oven at 180 ℃ for 12 h. The final products were collected, washed several times with water and ethanol alternately, and gathered by centrifugation, and then dried in oven at 60 ℃. Crystal microstructure, morphology and UC luminescence properties of samples were investigated by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and upconversion photoluminescence spectra. Results revealed the bond distance of F1-Y and F2-Y become close with the rising of Hf^4＋ or Zr^4＋ codoped concentration, indicating crystal field asymmetry of rare earth ions were tuned effectively by Hf^4＋ or Zr^4＋ codoping. Electron hypersensitive transition was promoted, and the intensity of 802 nm emission was enhanced obviously. Hf^4＋ ion was a be

关 键 词：上转换 铪掺杂 晶体场 能量转移 

分 类 号：TQ422[化学工程]