焦硅酸镥(Lu2Si2O7:Ce)闪烁晶体的生长与发光性能研究

铈掺杂的焦硅酸镥晶体(简写为LPS:Ce)是新近发现的一种具有潜在应用价值的无机闪烁晶体.本文用提拉法成功地生长出尺寸为φ15mm×40mm的LPS:Ce晶体.XRD结构测试表明,该晶体属于单斜晶系,C2/m空间群,晶体中分布有少量的LPS和石英颗粒包裹体.对从毛坯中切割出的无色透明晶体样品在室温下分别进行了透射光谱、紫外激发、X射线激发发射光谱和衰减时间测试.结果表明,铈(Ce3+)离子掺杂使LPS晶体的紫外吸收边从175nm红移到350nm,紫外和X射线激发的荧光光谱中都可以分解出384nm和412nm两个发射峰,它们分别对应于电子从铈(Ce3+)离子的5d轨道向4f轨道的两个能级(2F5/2和2F7/2)的辐射跃迁,从衰减曲线中可以拟合出一个38.75ns的时间常数.这些发光特征与该晶体独特的晶体结构密切相关.

Growth and Luminescence Properties of Lutetium Pyrosilicate (Lu2Si2O7:Ce) Scintillation Crystals

Cerium-doped lutetium pyrosilicate (LPS:Ce) crystal is a new found inorganic scintillator with promising scintillation properties. A boule with dimension of φlSmm × 40mm was grown successfully by using the Czochralski method. It's crystal structure was determined to be monoclinic with space group of C2/m and some inclusions was found to be composed of LPS and quartz. The optical transmission, UV and X-ray excited emission spectra, as well as decay curves were measured at room temperature. The cutoff edge of LPS:Ce crystals shifts to 350nm after doped with cerium ions. Two emissions peaks, 384nm and 412nm can be fitted into in the UV and X-ray excited emission spectra. The decay time of the fluorescence can be fitted with one exponential terms, 38.75ns, these two emission result from the transition of electrons from 5d to two ground levels (2F5/2 and 2F7/2)of Cerium ions(Ce3+)in the LPS crystals. The difference of luminescence between LPS: Ce and LSO: Ce can be explained from the difference of the crystal structure of these two types of crystals.