Nb_2O_5掺杂对提高钨酸铅晶体发光性能的微观研究

Improvement of Luminescence Performance of PbWO_4 Crystal by Nb_2O_5-Doping

通过透射谱、X射线激发发射谱 (XSL)的测试 ,研究了布里奇曼 (Bridgman)法生长的掺铌钨酸铅晶体的发光性能 ,并利用正电子湮没寿命谱 (PAT)和X射线光电子能谱 (XPS)的实验手段 ,对其微观缺陷进行了深入研究。结果表明 ,铌掺杂能够有效地改善钨酸铅晶体的 35 0nm吸收带 ,提高钨酸铅晶体的发光快成分比例 ,并使得晶体中的正电子捕获中心浓度上升 ,低价氧浓度上升。提出掺铌钨酸铅晶体中Nb5+ 将占据W6+ 格位并使得晶体内部分(WO4) 2 -根团成为 (NbO3 +VO) -,由此可改善钨酸铅的发光性能。

The influence of niobium (Nb) doping on the properties of lead tungstate crystals (PWO) has been investigated. Transmission, emission, positron annihilation lifetime spectrum and X-ray photoelectron spectra (XPS) of PWO:Nb and undoped PWO were reported. The luminescence characteristics of the Nb-doped PWO crystal was discussed by comparing the results with that of pure PWO crystal. Nb doping improved the luminescence property of PWO and enhanced the percentage of its quick component. The defects in PWO crystal caused by Nb dopant has been studied by means of positron annihilation lifetime spectrum and X-ray photoelectron spectra. The results show that Nb dopant increases the concentration of lead vacancy (VPb) as well as the concentration of low-valent oxygen. The Nb5+ will occupy the lattice of W5+ and make some (WO4)2- change to (NbO3+VO)- which will result in the improvement of luminescence performance of PWO crystal.