浮区法生长Lu_2Si_2O_7:Ce晶体的缺陷、光学和闪烁性能研究

Defect Optical and Scintillation Properties of Lu_2Si_2O_7:Ce Single Crystal Grown by Floating Zone Method

通过浮区法制备得到LPS：0.5%Ce单晶样品,并对其包裹体、开裂、闪烁和光学性能进行了研究,获得了晶体的电子探针谱、透过谱、77~500 K下的紫外激发发射谱、X射线激发发射谱和77~500 K下的衰减时间谱。研究发现晶体中存在解理开裂和热应力开裂,同时存在两种类型的包裹体,分别包含[Si3O9]6-、23[SiO]n阴离子团和过量的SiO2。由于采用空气为生长气氛,样品中部分Ce3＋被氧化为Ce4＋。浮区法LPS：0.5%Ce表现出较高的发光效率,约为32000 ph/MeV。随着温度的升高,样品的紫外激发发射谱逐渐向长波方向移动,发射谱谱线随着温度的升高展宽,导致自吸收的增加。衰减时间的温度转变点位于450 K,表明LPS：Ce闪烁晶体适用于高温环境,是一种性能优异的闪烁晶体。

Floating zone （Fz） method was employed to grow the Lu2Si2O7 （LPS）：0.5%Ce single crystal. The crack, de- fect, optical and scintillation properties of LPS：Ce were studied. The electron probe microanalysis （EPMA）, transmittance spectrum, X-ray excited luminescence （XEL） spectra, photoluminescence spectra and decay curves （from 77 K to 500 K） were recorded. The cleavage and thermal stress cracks are detected in the as-grown crystal. Two kinds of inclusions are found through the EPMA： one is [Si3O9]6- and [SiO3 ]n 2- anion radicals and the other is the excess SiO2. Part of Ce3＋ in the LPS：Ce sample was oxidized into Ce4＋ in the air growth atmosphere. Fz grown LPS：0.5%Ce sample presents high luminescence efficiency, which is 32000 ph/MeV. As the temperature increases, the photoluminescence curves move towards the longer wavelength direction and broaden, leading to the increasing self-absorption. The rollover point of the decay time locates at 450 K, indicating that the LPS：Ce scintillator is a kind of high performance scintillator which can be applied in the high temperature environment.