浮区法生长Lu2Si2O7:Ce晶体的缺陷、光学和闪烁性能研究

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-、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。

Defect Optical and Scintillation Properties of Lu2Si2O7:Ce Single Crystal Grown by Floating Zone Method

Floating zone (Fz) method was employed to grow the Lu₂Si₂O₇ (LPS):0.5%Ce single crystal. The crack, defect, 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 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.