The Study On Preparation And Luminescence Of Dy³⁺ Doped CaYAl₃O₇ Yellow Emitting X-ray Phosphors

At present,digital X-ray imaging technology（DR）has been widely used in the field of medical imaging due to its advantages of real-time imaging,low radiance,and clear imaging.Among them,the scintillation screen in the DR imaging system is made of X-ray phosphor,so the performance of X-ray phosphor is very important for DR imaging.In this thesis,the self-propagating combustion method and heat treatment are used to prepare different concentrations of Dy³⁺-doped Ca YAl₃O₇ X-ray phosphors.Studies have shown that under the excitation of 348 nm ultraviolet light or X-ray,the emission spectrum of Ca YAl₃O₇:Dy³⁺X-ray phosphor has two emission peaks at 480 nm and 573 nm,which are attributed to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 of Dy³⁺respectively.When the Dy³⁺doping concentration is 4%,it has the maximum luminous intensity.Among them,the yellow light emission of 573 nm can match the sensitive wavelength range of common CCD,and there is no afterglow after ultraviolet light and X-ray irradiation.Because dysprosium has a larger atomic number than yttrium,it has stronger X-ray absorption ability,so in order to improve the X-ray absorption ability of Ca YAl₃O₇:Dy³⁺X-ray phosphor.In this paper,Ca Dy Al₃O₇ X-ray phosphors were prepared by the self-propagating combustion method combined with heat treatment,we have studied the influence of different temperature（800℃,900℃,1000℃,1100℃）treatment on the optical properties of the sample,and found that as the sintering temperature increases,the luminous intensity of the sample becomes stronger.This paper compares the luminescence characteristics of Ca YAl₃O₇:Dy³⁺X-ray phosphors in the two doping modes of Ca Y_0.96Al₃O₇:Dy³⁺_0.04and Ca Dy Al₃O₇.The study shows that the samples doped in the two modes have no afterglow after UV and X-ray irradiation.And Ca Y_0.96Al₃O₇:Dy³⁺_0.04 X-ray phosphor has stronger luminous intensity,more uniform particle size,and better thermal stability.We made the best-performing Ca Y_0.96Al₃O₇:Dy³⁺_0.04 X-ray phosphor into a thin film,and carried out X-ray imaging research on it,the X-ray radiation dose is 1468μGy·s^-1in the experiment,and we can see the hollow slits from the imaging pictures.This indicates that Dy³⁺doped Ca YAl₃O₇ X-ray phosphor has potential applications in medical imaging.