+3价离子掺杂钨酸铅晶体发光性能和微观缺陷的研究

The scintillation characteristics and point defects of PbWO_4 crystal by doping with trivalent ions

通过透射光谱、x射线激发发射光谱 (XSL)的测试 ,研究了Bridgman法生长的几种不同 +3价离子掺杂钨酸铅晶体的发光性能 ,并利用正电子湮没寿命谱 (PAT)和x光电子能谱 (XPS)的实验手段 ,对不同钨酸铅晶体的微观缺陷进行研究 .实验表明 ,不同的 +3价离子掺杂 ,对钨酸铅晶体发光性能的改善不同 ,并使得晶体中正电子俘获中心和低价氧的浓度发生不同变化 .其中掺镧晶体的正电子俘获中心和低价氧浓度均上升 ,而掺钇和掺铋晶体的正电子俘获中心和低价氧浓度均下降 ,掺锑晶体则出现了正电子俘获中心浓度上升、低价氧浓度下降的情况 .提出 +3价离子在钨酸铅晶体中的掺杂作用机理并不相同 ,晶体中La3+ 将替代Pb2 + 的格位 ,Y3+ 和Bi3+ 将占据铅空位 ,而锑可以以Sb3+ 替代Pb2 + 格位和Sb5+ 替代W6 +

The influence of doping with different trivalent ions (La 3+,Y 3+,Bi 3+,Sb 3+)on the properties of lead tungstate crystals (PWO) has been investigated. Transmission, emission, positron annihilation lifetime and x-ray photoelectron spectra of different trivalent ions doped and undoped PWO are reported. The scintillation characteristics of the La-doped、Y-doped、Bi-doped、Sb-doped PWO crystals are discussed by comparing with the result of undoped PWO crystal. All the trivalent ions but Bi 3+ doping gave a significant improvement in luminescence property of PWO obviously. The defects in PWO crystals caused by trivalent-ion dopants have been studied by means of positron annihilation lifetime and x-ray photoelectron spectra. The results can be stated as follows: La dopant can increase the concentrations of both lead vacancy (V Pb) and the low-valent oxygen; Y and Bi dopant can decrease the concentrations of both V Pb and low-valent oxygen; and Sb dopant can increase the concentration of V Pb but decrease the concentration of low-valent oxygen. We consider that the La ions will replace the lattice Pb 2+, the Y and Bi ions will occupy the lead vacancy; and the Sb ions have two valence states (+3 and +5), which will replace the lattice Pb 2+ and W 6+ ions, respectively.