Zhang Yuepin

Optimum fluorescence emission around 1.8 mu m for LiYF4 single crystals of various Tm3+-doping concentrations

In this paper, optical spectra of LiYF4 single crystals doped with Tm3+ ions of various concentrations are reported. The emission intensity at 1.8 mu m first increases with increasing Tm3+ concentration, and reaches a maximum value when the concentration of Tm3+ is about 1.28 mol%, then it decreases rapidly as the concentration of Tm3+ further increases to 3.49 mol%. The emission lifetime at 1.8 mu m also shows a similar tendency to the emission intensity. The maximum lifetime of 1.8 mu m is measured to be 17.68 ms for the sample doped with Tm3+ of 1.28 mol%. The emission cross section of F-3(4) level is calculated. The maximum reaches 3.76 x 10(-21) cm(2) at 1909 nm. The cross relaxation (H-3(6), H-3(4) -> 3F(4), F-3(4)) between Tm3+ ions and the concentration quenching effect are mainly attributed to the change of emission with Tm3+ concentration. The largest quantum efficiency between Tm3+ ions is estimated to be similar to 147% from the measured lifetime and calculated radiative lifetime. All the results suggest that the Tm3+/LiYF4 single crystal may have potential applications in 2 mu m mid-infrared lasers.

Fluorescence properties of divalent and trivalent europium ions in CdWO4 single crystals grown by the Bridgman method

Optical absorption, excitation, and fluorescence were investigated in Eu ion-doped CdWO4 single crystal grown by a modified Bridgman method. The results indicate that Eu2+ and Eu3+ ions coexist in CdWO4 crystal and an energy transfer occurs between these Eu2+ and Eu3+ ions. When the crystal is excited by 266-nm light, the energy corresponding to the 4f65d to 8S7/2 transition of Eu2+ ions results in the excitation of the Eu3+ ions to the 5DJ level. The effect on fluorescence of annealing in oxygen at various temperatures was investigated. The excitation intensity of Eu2+ ions at 266 nm decreases as annealing temperature increases from 300 K to 1073 K, but it remains at a certain equilibrium level when the annealing temperature is further increased.

白光LED用Ba 2 LaF 7 : Pr 3+ 微晶玻璃的发光性能研究

采用高温熔制法制备得到50SiO2-10AlF3-5TiO2-30BaF2-4LaF3-Pr2O3(mol%)基质玻璃, 玻璃样品分别经640℃、660℃和690℃热处理后, 成功获得透明Ba2LaF7: Pr3+微晶玻璃且维持着较高的透明度。用XRD和TEM分析热处理前后样品的相变和结构变化, 并研究了热处理前后样品的光谱特性。结果表明: 玻璃经热处理后生成了Ba2LaF7微晶颗粒; 热处理前后样品光谱特性的变化表明: 热处理后掺杂的Pr3+离子逐渐进入到Ba2LaF7晶格位; 在波长443 nm的激发下, 660℃热处理过的样品实现了白光输出, 对应的三色坐标为(0.323, 0.343)。

Enhanced Luminescent Properties of Pr

采用高温熔制法制备得到50SiO2-10AlF3-5TiO2-30BaF2-4LaF3-Pr2O3(mol%)基质玻璃, 玻璃样品分别经640℃、660℃和690℃热处理后, 成功获得透明Ba2LaF7: Pr3+微晶玻璃且维持着较高的透明度。用XRD和TEM分析热处理前后样品的相变和结构变化, 并研究了热处理前后样品的光谱特性。结果表明: 玻璃经热处理后生成了Ba2LaF7微晶颗粒; 热处理前后样品光谱特性的变化表明: 热处理后掺杂的Pr3+离子逐渐进入到Ba2LaF7晶格位; 在波长443 nm的激发下, 660℃热处理过的样品实现了白光输出, 对应的三色坐标为(0.323, 0.343)。