980nm激发下Y2O2S：Ho3＋,Yb3＋纳米晶可见和红外发光特性研究  

Study on visible and infrared luminescence properties of Y_2O_2S:Ho^(3+),Yb^(3+) nanocrystals under 980 nm excitation

作　　者：张楠[1] 付姚[2] 罗昔贤[2] 邢明铭[2] 

机构地区：[1]辽宁师范大学物理与电子技术学院,辽宁大连116029 [2]大连海事大学物理系,辽宁大连116026

出　　处：《功能材料》2014年第12期12083-12087,共5页Journal of Functional Materials

基　　金：辽宁省高等学校优秀人才支持计划资助项目(LR2013020);辽宁省教育厅科学研究一般资助项目(L2013201);辽宁省博士科研启动基金资助项目(20121029);中央高校基本科研业务费专项资助项目(3132013103,3132013318)

摘　　要：采用共沉淀法,结合固-气硫化工艺制备出六角晶系结构的类球形Y2O2S∶Ho3+,Yb3+纳米晶,平均粒径约40nm。在980nm LD激发下,系统研究了纳米晶在450~1 500nm宽波段范围内的发光特性。根据上转换(UCL)和下转换(DCL)测试结果,Y2O2S∶Ho3+,Yb3+纳米晶发射峰位于545,655和1180nm,分别源于5F4/5S2→5I8、5 F5→5I8和5I6→5I8辐射跃迁。Yb3+离子的掺杂可显著提高Ho3+的上转换发光效率。由于纳米晶表面吸附产生的高能振动量子显著提高了5F4/5S2→5F5和5I6→5I7多声子弛豫的发生几率,使得655nm红光发射很难得到抑制。随Yb3+浓度不断增大,Yb3+→Ho3+能量传递效率提高。这不仅可以增大5F4/5S2和5I6能级的粒子布居数,使绿光和红外光发射增强,而且能在一定程度上抑制5I6→5I7多声子弛豫过程,间接削弱红光发射强度。但5F5能级的另一布居途径(5F4/5S2→5F5)使得Y2O2S∶Ho3+,Yb3+纳米晶的绿红光荧光分支比(IG/IR)值仅能达到3.75。当浓度高于6%(摩尔分数)时,(5F4/5S2,2F7/2)→(5I6,2F5/2)能量反传递过程导致绿光和红光发射大幅降低,而5I6能级布居数的增大却增强了红外发射强度。上述变化导致IG/IR增势减弱,红外/红光荧光分支比(IIR/IR)不断增大。Near-spherical Y2O2S∶Ho3＋,Yb3＋ nanocrystals（NCs）were prepared by coprecipitation method followed by a solid-gas sulfuration technic.The nanocrystals are in hexagonal structure,and the particle size was 40nm on average.Under the excitation of 980nm laser diode（LD）,more systematic researches on luminescence properties of Y2O2S∶Ho3＋,Yb3＋ NCs in a broad range from 450nm to 1 500nm have been performed.According to the luminescence measurement results,three different emissions located at 545,655,1 180nm can be observed,which are derived from5F4/5S2→5I8,5F5→5I8,5I6→5I8 transitions,respectively.The upconversion luminescence（UCL）efficiency of Ho3＋in the nanocrystals can be improved obviously by co-doping Yb3＋.However,because of the high-energy vibration quantum produced by surface adsorption,the 5F4/5S2→5F5 and 5I6→5I7 multi-phonon relaxations of Ho3＋are very efficient,and the red emission could be held up hardly.In addition,the increasing content of Yb3＋（no more than 6mol%）can not only improve the population of 5F4/5S2and 5I6energy levels,but also restrain the 5I6→5I7 multi-phonon relaxation in a certain degree,which results in an enhancement on green and infrared（IR）emissions,but a decrease on red emission.Nevertheless,the intensity ratio of green to red emission（IG/IR）obtained in Y2O2S∶Ho3＋,Yb3＋ NCs was only 3.75,which was much smaller than that of micron Y2O2S（46.6）.This was because of another possible populating process（5F4/5S2→5F5） of 5F5 energy level.When Yb3＋ content was higher than 6mol%,（5F4/5S2,2F7/2）→（5I6,2F5/2）inverse energy transmission make the green and red emission intensities decrease sharply,but this process was beneficial to the population of 5I6 energy level and leads to an enhancement on IR emission intensity.These changes weakens the IG/IRratio,and give rise to a remarkablely increase on IIR/IR.

关 键 词：Y2O2S∶Ho3+ YB3+ 纳米晶 上转换发光 下转换发光 跃迁机制 

分 类 号：O432.31[机械工程—光学工程]