Ca_3Y_2Si_3O_(12)∶Tm^(3+),Yb^(3+)上转换发光粉的制备与发光性能研究

Synthesis and Luminescence Properties of Ca_3Y_2Si_3O_(12)∶Tm^(3+),Yb^(3+) Upconversion Phosphors

采用高温固相法成功制备了Ca_3Y_2Si_3O_(12)∶Tm^(3+),Yb^(3+)上转换蓝色发光材料。在980 nm红外激光器激发下,发光粉呈现强烈的蓝光(475 nm)和近红外光(810 nm)以及较弱的红光(650 nm)发射,分别归因于Tm^(3+)离子的~1G_4→~3H_6、~3H_4→~3H_6和~1G_4→~3F_4能级跃迁。随着Yb^(3+)离子浓度的增加,发光粉上转换发射强度和发光亮度均呈现先增强后减弱的变化趋势。在最佳掺杂浓度下(Yb^(3+)摩尔分数为15%),蓝、红光强度分支比为12∶1,色坐标为(0.129 2,0.152 3)。在3.9 W/cm^2激发功率密度下,发光亮度可达6.8 cd/m^2。上述结果证实,所制备发光粉呈现优异的蓝光上转换发射特性并具有潜在的应用价值。发光强度和激发光功率关系表明,所得上转换发射为三光子和双光子吸收过程。借助Tm-Yb体系能级结构详细讨论了上转换发射的跃迁机制。

Ca3Y2Si3O（12）∶Tm3＋,Yb3＋ up-conversion phosphors were synthesized by solid-state reaction method at 1 400 ℃,and the up-conversion luminescence（ UCL） properties of the phosphor were studied under 980 nm excitation. The phosphor exhibits strong blue light（ 475 nm） and near infrared light（ 810 nm）,as well as weak red（ 650 nm） light,which correspond to 1G4→3H6,3H4→3H6 and 1G4→3F4 transitions of Tm3＋ ion,respectively. The UCL intensity and brightness of the phosphor increased firstly and then decreased with the increasing Yb3＋ concentration,and the optimum concentration is 15%. Under the best doping concentration（Yb3＋ mole fraction of 15%）,the intensity ratio of blue and red emissions is calculated to be 12∶1,and the chromaticity coordinate of the phosphor locates at the blue region（ 0. 129 2,0. 152 3）. Furthermore,the brightness of the phosphor can reach 6. 8 cd/m2 as the exciting power density is increased to be 3. 9 W/cm2. These measurement results indicate that the phosphor exhibits excellent blue UCL property and application potential. The dependence of the UCL intensity on excitation power proves that the observed emissionsare obtained via three and two absorption processes. The transition mechanism of the phosphor excited at 980 nm is discussed in detail.