Er^3+,Yb^3+共掺杂NaY(WO4)2上转换荧光粉的制备及其发光性能

Preparation and Upconversion Luminescence Properties of Er^(3+)/Yb^(3+) Co-doped NaY(WO_4)_2 Phosphors

应用传统水热法合成出具有四方白钨矿结构的NaY(WO_4)_2微米颗粒及一系列Er^(3+)/Yb^(3+)共掺杂NaY(WO_4)_2上转换荧光粉。利用XRD、SEM、TEM、HRTEM、粒度分布和上转换发光光谱对样品的物相、形貌及上转换发光性能进行分析表征。结果表明,p H值对于制备具有同一形貌的纯相NaY(WO_4)_2微米颗粒发挥重要作用。随着pH值的升高,可以完成从八面体到拟立方体再到片状颗粒的形貌转变。在980 nm近红外光激发下,观测到525及553 nm处的强绿光发射,对应Er^(3+)的~2H_(11/2)→~4I_(15/2)与~4S_(3/2)→~4I_(15/2)跃迁,以及650~680 nm范围内的弱红光发射,对应Er^(3+)的~4F_(9/2)→~4I_(15/2)跃迁,且绿、红光上转换发射均属于双光子过程。此外,通过调节NaY(WO_4)_2∶Er^(3+),Yb^(3+)荧光粉中Yb^(3+)的浓度,可实现对绿光色度的有效控制。

NaY(WO4)2 microparticles with tetragonal scheelite structure and Er3+/Yb3+co-doped NaY(WO4)2 phosphors were synthesized by traditional hydrothermal method.The crystal structure,morphology and up-conversion luminescence properties of the samples were discussed detailedly via XRD,SEM,TEM,HRTEM,particle size distribution and up-conversion luminescence spectrum.The results indicated that the pH values played an important role in the synthesis of pure phase NaY(WO4)2 microparticles with regular morphology.As pH value increased,the morphology of the samples could generate a transition from octahedrons,quasi-cubes to plate particles and a possible morphological formation mechanism of NaY(WO4)2 was proposed.Er3+/Yb3+co-doped NaY(WO4)2 samples show strong green(2H11/2→4I15/2(525 nm)and 4S3/2→4I15/2(553 nm)of Er3+)and weak red(650~680 nm:4F9/2→4I15/2 of Er3+)up-conversion emission under 980 nm laser diode excitation,and the two-photon process was confirmed to be responsible for the green and red up-conversion emissions.Moreover,by adjusting the doping concentration of Yb3+in NaY(WO4)2∶Er3+,Yb3+phosphors,the color-tunable and high-purity green were exhibited by the CIE color coordinates of NaY(WO4)2∶Er3+,Yb3+phosphors.