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用非真空Bridgman方法制备了掺有Tb杂质的氟化铅 (PbF2 ∶Tb)晶体 ,掺杂浓度从 0 0 0 8at.%至0 6at.%。在室温下测量了该晶体的吸收和发射光谱 ,发现该晶体在X 射线和紫外线激发下均能够发出比较强的荧光。PbF2 ∶Tb晶体的光吸收起源于Tb3 + 离子的 4f-4f跃迁 ,而其光发射则源于Tb3 + 离子的电子分别从其激发态5D3 和5D4 能级跃迁到基态7FJ(J=6,5,4 ,3 ,2 )。荧光强度随掺杂浓度的提高而提高 ,当Tb3 + 离子浓度较低时 ,以5D3 →7FJ 跃迁发射为主 ,当Tb3 + 离子浓度较高时 ,则以5D4 →7FJ 跃迁发射为主。在同一晶体中 ,发光强度随中心所占晶格位置的改变而改变 ,反映出Tb3 + 离子在PbF2 晶体中的分布具有分凝系数大于 1的特征。推测Tb3 + 离子在PbF2 晶体中占据Pb格位 ,同时产生间隙F-离子缺陷来平衡电价。
The lead fluoride (PbF2: Tb) crystals doped with Tb impurities were prepared by a non-vacuum Bridgman method with a doping concentration of 0 0 0 8 at.% To 0 6 at.%. The absorption and emission spectra of the crystal were measured at room temperature. It was found that the crystal could emit relatively strong fluorescence under X-ray and UV-ray excitation. The light absorption of PbF2: Tb crystal originates from the 4f-4f transition of Tb3 + ion, while the light emission of PbF2: Tb crystal results from the transition of the excited states 5D3 and 5D4 to the ground state 7FJ (J = 6,5 , 4, 3, 2). Fluorescence intensity increases with the increase of doping concentration. When Tb3 + ion concentration is low, 5D3 → 7FJ transition emission is dominant, while when Tb3 + ion concentration is high, 5D4 → 7FJ transition emission is dominant. In the same crystal, the luminescence intensity changes with the change of the lattice position occupied by the center, which shows that the distribution of Tb3 + ions in the PbF2 crystal has the characteristic that the segregation coefficient is greater than one. It is speculated that Tb3 + ions occupy Pb sites in the PbF2 crystal and produce interstitial F- ion defects to balance the electricity price.