2018年7期 电子期刊

采用自蔓延燃烧法制备了不同镨掺杂浓度的12CaO·7Al₂O₃：Pr³⁺（C12A7：Pr³⁺） X射线影像存储荧光粉。在232 nm激发下，发现Pr³⁺掺杂摩尔分数为0.3%的荧光粉位于486 nm的蓝光发射峰呈现最大的发光强度。对C12A7：0.3% Pr³⁺样品进行真空热处理后，C12A7笼中的O^2-基团数量减少，同时类F⁺色心的空笼子的数量增多，导致陷阱数目增加和光激励发光强度增大。热释发光实验表明：C12A7：0.3% Pr³⁺样品中存在两个深陷阱，陷阱深度分别约为0.69 eV和0.80 eV；经过真空热处理后的C12A7：0.3% Pr³⁺荧光粉，陷阱深度变深，陷阱数目增多，光存储性能变好。当吸收的X射线剂量为5.2 Gy时，可以实现分辨率较高的X射线成像。实验结果表明，镨掺杂C12A7荧光粉在计算机X射线摄影领域有潜在的应用前景。

Microstructure and Optical Properties of 12CaO·7Al2O3:Pr3+ Phosphors for High Quality X-ray Imaging

X-ray storage phosphors 12CaO·7Al₂O₃:Pr³⁺ (C12A7:Pr³⁺) with different doping concentrations were synthesized by a combustion method. For C12A7:0.3%Pr³⁺ phosphor, the strongest intensity of the emission peak at 486 nm, originating from ³P₀-³H₄ transition of Pr³⁺, can be obtained upon 232 nm excititation. After the annealing in vacuum, the number of encaged O^2- anions decreased, while the amount of empty cages increased. Thus, it led to the increased number of traps and the enhanced photo-stimulable luminescence(PSL). The thermoluminescence(TL) analysis showed that there existed two deep traps in the phosphors and the trap depths were~0.69 and~0.80 eV, respectively. In particular, the annealing in vacuum led to the deeper trap depths, the increased number of traps and the improved storage properties. Upon X-ray irradiation(applied dose:5.2 Gy), a blue image with high resolution was obtained by 808 nm stimulation. Our results suggested that the C12A7:Pr³⁺ phosphors have potential application in the field of computed radiography.