The improved scintillation performances and X-ray imaging of Lu₂O₃:Pr³⁺ nanoparticles induced by Sm3+doping

Lu2(1-x)Pr2xO3 nanoscintillators (x = 0.0005, 0.001, 0.0015, 0.003, 0.005) with excellent red emission and a response time of 185.7 mu s were synthesized by a coprecipitation method. It is found that both photoluminescence and radioluminescence intensities show an initial rising and then decreasing trend with increasing Pr3+ concentration and the strongest intensity can be obtained at x = 0.001. By determining the average distance between Pr and O, the radiative transition processes from P-3(0) and D-1(2) to H-3(4) and nonradiative transition process from P-3(0) to D-1(2) can be confirmed. Meanwhile, the afterglow level of Lu2O3:Pr3+ nanoscintillators with an average size of 112.3 nm was found to be 2190 ppm. Based on the spectral data and density functional theory calculations, the afterglow can be related to Pr-Lu traps due to the presence of Pr4+ in Lu2O3:Pr. When Sm3+ ions were doped into Lu2O3:Pr3+, it is found that it leads to the decreased creation of Pr4+, the reduced afterglow level and the improved radioluminescence. By means of Lu2O3:Pr3+, Sm3+ nanoparticles being dispersed into polymethyl methacrylate (PMMA) polymer, PMMA-Lu2O3:Pr3+, Sm3+ composite films with fast response time and radiation resistance were prepared by a rotating coating method. The static X-ray imaging with a spatial resolution of 5.5 lp/mm using the composite film as an imaging screen was realized at extremely low safe dose of 4.6 mu Gy. Meanwhile, for the broken electric wire used as an object, the clear X-ray image can be observed. Our results suggest that Lu2O3:Pr3+, Sm3+ nanoscintillators have potential applications in medical imaging and nondestructive testing.