Study on Irradiation Damage of Bi-Doped PbWO4 Crystal |
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Authors: | LIANG Ling GU Mu DUAN Yong MA Xiao-Hui LIU Feng-Song WU Xiang-Hui QIU Long-Qing CHEN Ming-Nan LIAO Jing-Ying SHEN Ding-Zhong ZHANG Xin GONG Bo XUE Xuan-Ping |
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Institution: | Department of Physics,Tongji University,Shanghai 200092,China2 Laboratory of Functional Inorganic Materials,Chinese Academy of Sciences,Shanghai 200050,China3 Shanghai Key Laboratory of Metal-Functional Materials,Shanghai 200940,China |
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Abstract: | The luminescence and point defects of pure lead tungstate crystals (PbWO4) and Bismuth (Bi) doping crystal (PbWO4:Bi)grown by modified Bridgman method are studied. It is found that irradiation results in the great change of the transmission and X-ray excited emission after γ-ray irradiation about 4 Mrad dose. The defects in PbWO4 crystal have been studied by means of positron annihilation lifetime and X-ray photoelectron spectra. The results show that Bi dopant suppresses the concentrations of positron capture centers and low-valent oxygen ions.After γ-ray irradiation,in the pure crystal the concentration of lead vacancy (VPb) is decreased and that of low-valent oxygen increased; on the contrary,in Bi dopant crystal the concentrations of positron capture centers increased and that of low-valent oxygen ions suppressed. It is tentatively proposed that Bi3+ dopants would mainly occupy the sites of lead vacancies resulted from Pb volatilization. And irradiation changes the chemical valence of Bi element,which is Bi3+→Bi5+.The Bi5+ will replace the lattice W6+ ions and it will cause some (WO4)2- replaced by (BiO3+VO)-. |
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