水热法制备ZnS:Cu,Tm超细X射线发光粉

研究了水热法合成的ZnS: Cu,Tm超细X射线发光粉及其光致发光(PL)和X射线激发发光(X-ray excited luminescence,XEL)光谱特性.200 ℃水热处理12 h直接合成样品的纳米晶粒径约15 nm,尺寸分布窄,分散性好,具有纯立方相的类球形结构.氩气保护下900 ℃退火1 h后的样品存在一定的团聚,但团聚后尺寸为200—600 nm,为超细X射线发光粉,此时样品为纯六方相的类球形为主的结构.所有样品的PL和XEL光谱均为宽带谱.水热法直接合成样品的XEL强度最强时,样品的Cu/Zn,Tm/Cu比值分别为3×10^-4和2.在此比值条件下,900 ℃退火1 h样品的XEL发光最强,此时其两个峰值分别位于453,525 nm.发光强度增强的同时粒径很小,对提高成像系统分辨率非常有意义.通过比较PL光谱与XEL光谱特性,讨论了PL和XEL光谱的发光机理和其不同的激发机理. 关键词： ZnS:Cu Tm 水热法 X射线激发发光

X-ray excited luminescence property of ZnS:Cu,Tm fine particles synthesized by hydrothermal method

The ZnS:Cu,Tm X-ray phosphor fine particles synthesized by hydrothermal method has been reported for first time and its photoluminescence (PL) and X-ray excited luminescence (XEL) properties have been studied in detail also. The direct hydrothermal treatment at 200 ℃ for 12h samples average gain size is about 15 nm; the synthesized spherical-like nanocrystals with well dispersity and narrow gain size distribution show cubic structure. The after annealing in Argon at 900 ℃ for 1h samples agglomerate size is about 200—600 nm and roughly spherical fine particles show pure hexagonal structure. The PL and XEL spectra of all of samples show a broad emission band and an intense emission band in the range of 400—600 nm. The maximum XEL intensity of sample directly synthesized by hydrothermal treatment is observed for Cu/Zn and Tm/Cu are 3×10^-4 and 2, respectively. In this condition, the strongest PL and XEL emission is observed for the direct synthesized sample further annealing in Argon at 900℃ for 1h sample and the XEL peak center about 453 nm and 525 nm, respectively. The Samples with highly luminescence efficiencies and the smaller size could enhance the resolution of imaging systems. The difference between PL and XEL spectrum is due to its different excitation mechanism. The luminescence mechanism and different excitation mechanism of PL and XEL have been discussed.