退火对提拉法生长Lu_2Si_2O_7∶Ce晶体闪烁性能的影响

Effect of Annealing Treatments on Scintillation Properties of Lu_2Si_2O_7∶Ce Grown by Czochralski Method

Lu2Si2O7:Ce(LPS:Ce)表现出较高的光输出,平均值约26000photons/MeV(简写为ph/MeV),但通过提拉法获得的晶体发光效率很低.实验对LPS:Ce晶体进行了不同气氛下的退火,研究退火条件对LPS:Ce的发光效率等闪烁性能的影响.发现在Ar气氛下退火对LPS:Ce发光效率的提高没有作用,在空气气氛下退火后可显著提高LPS:Ce的发光效率.通过不同退火工艺的比较,确定了提高LPS:Ce发光效率的最佳退火制度:空气气氛下,退火温度1400℃,退火时间根据样品的大小决定,样品越大,需要的退火时间越长.同时讨论了退火过程中,LPS:Ce吸收谱和UV-ray激发发射谱的变化趋势.

Although the Lu2Si2O7∶Ce（LPS∶Ce） has a high light yield about 26000ph/MeV, the LPS∶Ce crystals grown by Czochralski（Cz） process usually display a low light yield. In present work, annealing treatments in different conditions were carried out on Cz grown LPS∶Ce with low luminescence efficiency, in order to investigate the effect of annealing treatment conditions on scintillation properties of LPS∶Ce, such as luminescence efficiency, absorption spectrum. It is found that annealing in argon atmosphere has a negligible effect on the scintillation properties of LPS∶Ce; annealing in air can dramatically improve the luminescence efficiency of LPS∶Ce. The optimized annealing mechanism is determined through the comparison between different annealing treatment： atmosphere of air; annealing temperature of 1400℃; annealing time depending on the dimension of the sample. The larger dimension is the longer annealing time. The change trend of charge transfer band in the absorption spectrum and UV-ray excitation and emission property of LPS∶Ce crystal are also discussed.