PbF2:Gd晶体的发光强度与发光均匀性研究

以Ｘ射线荧光光谱分析为手段，测试了用Ｂridgman方法生长的ＰbF2:Gd晶体中Ｇd离子沿生长方向的分布。发现该晶体在Ｘ射线激发下的发光强度与Ｇd在ＰbF2晶体中的含量变化均从结晶开始端至结晶结束端逐渐降低，表明ＰbF2:gD晶体的发光是不均匀的。这种不均匀性源于Ｇd离子在ＰbF2晶体中的分布不均匀性，通过在ＰbF2:Gd晶体中掺入一定量的碱金属离子，可以比较有效地改善Ｇd离子在ＰbF２晶体中的不均匀分布，使晶体的发光均匀性和透光率得到明显提高，其中以Ｎa离子的均匀化效果为最好，推测Ｎa离子的作用是消除了ＰbF2:Gd晶体中因子Ｇd离子的掺杂而造成的间隙Ｆ离子，从而使晶体中的缺陷浓度大大降低。

Luminescence intensity and Uniformity of PbF2:Gd Crystals

Gd doped lead fluoride crystals were grown by modified Bridgman methods. Under X-ray excitation, their emission intensities peaked at 278nm and 312nm increase with the doping amount of Gd³⁺ ions, but decrease from the beginning part to the finishing end of the crystallization along the growth direction. The concentration of Gd³⁺ ions in the PbF_2 crystal, analyzed by X-ray fluorescence spectrophotometer, also decreases in the same direction as emission intensity does. The correspondence between Gd content and luminescence intensity of PbF₂:Gd crystal demonstrates that the non-uniformity of luminescence intensity results from the in-homogeneous distribution of Gd³⁺ ions in the crystal. It was found that by co-doping suitable amount of alkali metal ions, such as Na⁺ and K⁺, with Gd ion into PbF₂ crystal, the difference of luminescent intensities and Gd³⁺ concentration from the bottom to the top of the crystal become smaller and the transmittance is higher than that of the single doping crystal. Especially, the uniformization effect of Na⁺ ions is better than that of K⁺ ions. It shows that the role of