Yb :YAG晶体的闪烁特性

通过不同Yb³⁺掺杂浓度(5%~30%,原子数分数)的Yb:YAG晶体的阴极射线发光谱、衰减时间、光输出及其温度依赖关系的测量,研究了Yb:YAG晶体的闪烁性能.不同Yb³⁺掺杂浓度的Yb:YAG晶体具有不同的光输出和猝灭温度,光输出随Yb³⁺掺杂浓度的增大而降低,猝灭温度则随掺杂浓度的增大而升高.室温下Yb:YAG晶体的发光衰减时间较短,均小于50ns.Yb³⁺掺杂浓度为5%的Yb:YAG晶体具有较高的光输出和较低的猝灭温度.

Scintillation Properties of Yb : YAG Crystal with Different Yb3+ Doped Concentration

Emission spectra of Yb:YAG with Yb³⁺ doping level from 5% to 30% at room temperature and(97 K) were characterized by cathodoluminescence spectra and the results showed the strongest emission peak is at 335~350 nm at room temperature which attributes to charge transfer luminescence(CT→F_7/2) and shifted to shorter wavelength with decreasing temperature.Scintillation properties of Yb:YAG with different Yb³⁺ doping level were studied by measuring relative light output and decay time of Yb:YAG crystal.Measurements of relative light output and temperature dependence have been performed with α excitations and the results showed light output is related to Yb³⁺ doping level and crystal quality and the maximum achieved at low temperature for 5% Yb:YAG.The decay time and temperature dependence were measured by ²²Na excitation.The decay time of Yb:YAG crystal with different Yb³⁺ doping level at room temperature is less than 50ns and it is monotonically decreasing with increase of temperature above the temperature where maximum of light output achieved,and decay time is monotonically decreasing with decrease of temperature below that temperature.Quenching temperature of Yb:YAG crystal at which the emission intensity has dropped to half of its maximum was determined.The relative light output and quenching temperature of Yb:YAG crystal with different Yb³⁺ doping level are different.Relative light output decreases with the increase of Yb³⁺ concentrations,while quenching temperature increases with increase of Yb³⁺ concentration.5% Yb:YAG crystal has maximum relative light output and the lowest quenching temperature.We conclude from our measurements that Yb:YAG crystal should be possible for application in medical imaging at low temperature.