材料期刊网

采用固相法成功制备了 Ba5 Zn4 Y8 O21∶Er3＋,Yb3＋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980 nm 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650~690 nm间.其中,绿光发射源于Yb3＋→Er3＋两步能量传递对2 H11/2、4 S3/2能级的粒子布居,及随后向基态的跃迁.红光发射则主要与4 I11/2(Er3＋)＋4 F7/2(Er3＋)→4 F9/2(Er3＋)＋4 F9/2(Er3＋)交叉弛豫和4 S3/2(Er3＋)＋2 F7/2(Yb3＋)→4 I13/2(Er3＋)＋2 F5/2(Yb3＋)能量反传递、4 I13/2→4 F9/2激发态吸收及4 F9/2→4 I15/2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 Yb3＋掺杂条件下,Er3＋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.