Er^(3+)/Yb^(3+)共掺KLaF_4纳米晶的制备和上转换发光

Preparation and Upconversion Luminescence of Er^(3+)/Yb^(3+) Codoped KLaF_4 Nanocrystals

用水热法成功制备了Er3+/Yb3+共掺不同浓度比的KLaF4纳米晶,并在300℃氩气气氛下退火。利用X射线衍射谱(XRD)、透射电子显微镜(TEM)对样品的晶体结构和形貌进行了表征。测量了样品漫反射谱、980 nm激发下的上转换发射光谱和2H11/2能级的荧光寿命。研究结果表明:制备得到的样品为六方相的纳米棒,退火后纳米棒平均直径为28 nm,长为130 nm;在Er3+浓度一定的情况下,提高Yb3+掺杂量有利于增强973 nm附近光的吸收;980 nm的近红外光可上转换为较强的绿光和红光,且红绿光强度和2H11/2能级的平均荧光寿命均会随着Yb3+掺杂浓度的增加而下降。

KLaF4nanocrystals( NCs) co-doped with 2% Er3+( fixed) and varied Yb3+doping mole fractions( 10%,14%,18%) were synthesized by hydrothermal method. The samples were annealed in argon at 300 ℃ for 1. 5 h. The crystal structure and morphology of the samples were confirmed by X-ray diffraction( XRD) and transmission electron microscopy( TEM),respectively. The optical properties of the samples were evaluated by diffuse reflectance spectra and up-conversion photoluminescence spectroscopy with the average fluorescent lifetimes of2H11 /2level under laser excitation at 980 nm. The results show hexagonal KLaF4∶ Er3+,Yb3+NCs are successfully obtained,which have a longitude of about 130 nm and a diameter of 28 nm for the annealed sample. The diffuse reflection spectra indicate that the absorbtion at around 973 nm is enhanced with the increase of Yb3+mole fraction while Er3+mole fraction is fixed. The near-infrared light at 980 nm can be up-converted to green and red light. Furthermore,both the intensities of the red and green light and the average fluorescence lifetimes for 2H11 /2level were decreased with the increase of Yb3+ion concentration in KLaF4∶ Er3 +,Yb3 +NCs. In addition,the effect of Yb3+doping concertration on the intensity of up-conversion luminescence and the average fluorescence lifetimes for2H11 /2level were briefly clarified.