Ba_5Zn_4Y_8O_(21)∶Er^(3+)/Yb^(3+)高效上转换发光粉的制备与发光性能

The synthesis and luminescence properties of efficient Ba_5Zn_4Y_8O_(21)∶Er^(3+)/Yb^(3+) upconversion phosphor

采用固相法成功制备了Ba_5Zn_4Y_8O_(2)∶Er^(3+),Yb^(3+)上转换发光粉。X射线衍射(XRD)和扫描电镜(SEM)测试结果表明,发光粉结晶良好,平均粒径1~5μm,呈碎颗粒状。在980nm激光器激发下,肉眼可见极其明亮的橙色发光。光谱测试结果证实,发光粉发射峰位于520~530,530~550和650~690nm间。其中,绿光发射源于Yb^(3+)→Er^(3+)两步能量传递对2H11/2、4S3/2能级的粒子布居,及随后向基态的跃迁。红光发射则主要与~4I_(11/2)(Er^(3+))+~4F_(7/2)(Er^(3+))→~4F_(9/2)(Er^(3+))+~4F_(9/2)(Er^(3+))交叉弛豫和~4S_(3/2)(Er^(3+))+~2F_(7/2)(Yb^(3+))→~4I_(13/2)(Er^(3+))+~2F_(5/2)(Yb^(3+))能量反传递、~4I_(13/2)→~4F_(9/2)激发态吸收及~4F_(9/2)→~4I_(15/2)跃迁有关。由于交叉弛豫和能量反传递可有效提高红光强度并削弱绿光发射,因此红光发射强度可达到绿光强度的6~13倍。在7%(摩尔分数)的Yb^(3+)掺杂条件下,Er^(3+)的最佳掺杂浓度为3%(摩尔分数)。提高激发光功率密度不仅可以使UCL增强,还可以进一步提高红绿光分支比。在高功率激发下,还观察到了三光子吸收产生的蓝光和蓝绿光发射。

A novel Ba5 Zn4 Y8 O21∶Er3＋,Yb3＋ upconversion phosphor has been synthesized by solid phase meth-od.XRD and SEM measurement results show that the phosphor crystalized well and presented granular appear-ance with average particle size of 1-5μm.Under the excitation of 980 nm laser,extremely bright orange lumi-nescence can be observed.Spectral test results confirm that the emission peaks are located in 520-530 nm,530-550 nm and 650-690 nm.The green emissions originate from the populations of 2 H11/2 and 4 S3/2 energy levels, and the subsequent transitions to the ground state.The red emission is mainly related to the cross relaxation of 4 I11/2 （Er3＋）＋4 F7/2 （Er3＋）→4 F9/2 （Er3＋）＋4 F9/2 （Er3＋）and the reverse energy transfer of 4 S3/2 （Er3＋）＋ 2 F7/2 （Yb3＋）→4 I13/2 （Er3＋）＋ 2 F5/2 （Yb3＋）,as well as the transitions of 4 I13/2→4 F9/2 and 4 F9/2→4 I15/2 .Due to the cross relaxation and reverse energy transfer,the red emission intensity can be effectively improved and the green emission can be reduced,so that the red emission intensity can reach 6-1 3 times of the green emission intensity. The best doping concentration of Er3＋ was 3mol% under the condition of 7mol% Yb3＋ doping content.Impro-ving the power density of excitation light can not only enhance the UCL,but also improve the intensity ratio of red and green light.Under high power excitation,the blue and blue-green emissions caused by three photon ab-sorption can also be observed.