147Pm激发的ZnS：Cu,Cl发光粉的研究

以高纯ZnS粉末为基质,采用高温转相、扩散,以及表面涂敷工艺,制得了¹⁴⁷Pm激发的ZnS:Cu,Cl发光粉。分析了ZnS:Cu,Cl的晶体结构,测量了ZnS:Cu,Cl的激发光谱、发射光谱、发光亮度。其晶体结构主要是六方纤锌矿型结构,激发光谱峰值波长为341nm,发射光谱峰值波长为513nm,初始发光亮度达到312mcd/m₂。由激发光谱的峰值波长341nm推算得到六方ZnS晶体的禁带宽度为3.64eV。分析了¹⁴⁷Pm激发的ZnS:Cu,Cl发光粉的发光寿命,其发光寿命达到5年以上。还探讨了该放射性发光粉的发光机理。¹⁴⁷Pm激发的ZnS:Cu,Cl的稳定发光,实际上是激发过程与复合过程的准平衡。ZnS:Cu,Cl的绿色发光来源于深施主-深受主对的复合发射。实验结果的分析表明,ZnS:Cu,Cl中深施主-深受主之间的能级间隔约为2.42eV。

Studies on the 147Pm-excited ZnS:Cu,Cl Luminescent Powders

The ¹⁴⁷Pm-excited ZnS:Cu,Cl luminescence powders are the important radioactive luminescence materials. They are used widely in the feeble illumination. Now they are investigated and produced only at Tsinghua University in China. The preparation and the luminescence properties of ¹⁴⁷Pm-excited ZnS:Cu, Cl luminescent powders are investigated in this paper. The ZnSpowders with high pureness were used as the matrices. It is a direct bandgap semiconductor. Firstly the ZnSpowders were mixed with CuCl₂ and the flux uniformly. Then the homogeneous mixtures were calcinated in the furnace for 1.5 hours at 1150℃ to make the ZnS:Cu,Cl powders. At the same time it changed to the hexagonal crystals. Finally the ZnS:Cu,Cl powders were coated with SiO₂, Na₂SiO₃ and ¹⁴⁷Pm₂O₃. So the ¹⁴⁷Pm-excited ZnS:Cu,Cl luminescent powders were prepared. We detected the excitation spectrum and the emission spectrum of ZnS:Cu,Cl. The excitation spectrum of the ZnS:Cu,Cl tells that the maximal excitation intensity is at 341 nm. On the basis of that, we calculated the bangap energy of ZnS. It is about 3.64 eV. The emission spectrum of the ZnS:Cu, Cl tells that the maximal emission intensity is at 513 nm. The maximal brightness of the ¹⁴⁷Pm-excited ZnS:Cu, Cl is 312 mcd/m². The analyses tell that the luminescence lifetime of this phosphor is longer than₅ years. The luminescence mechanism of the ¹⁴⁷Pm-excited ZnS:Cu,Cl is discussed in this paper too. The stable luminescence of the ¹⁴⁷Pm-excited ZnS:Cu,Cl is based on the quasi-equilibrium between the excitation and the recombination processes. The green luminescence of ZnS:Cu,Cl comes from the deep donors to the deep acceptors recombination emission. We calculated the energy level between the deep donors and the deep acceptors of ZnS:Cu, Cl according to the experiment results. It is about 2.42 eV.