Gamma-irradiation applied to the synthesis of the nanocrystalline GdOS:Pr powders for imaging applications.

Nanocrystalline GdOS:Pr powders were successfully synthesized by the co-participation method. The changes of size, shape and luminescence properties of these nanocrystalline powders were studied under different gamma doses (0-50 kGy) during the synthesizing process. Also, the structural, morphology and luminescence properties of these nanocrystalline powders were characterized using the X-ray diffraction, field emission scanning electron microscopy, energy dispersion of X-ray spectroscopy, photoluminescence, and thermoluminescence. The XRD results confirmed that the nanocrystalline GdOS:Pr powders have a pure hexagonal structure with the high crystallinity at a temperature of 900 °C, and the gamma radiation doses have no effect on the structure. The SEM images showed that the nanocrystalline GdOS:Pr powders have a spherical shape and are agglomerated when the irradiation dose increases. These nanopowders, which were prepared at an irradiation dose of 40 kGy, show the lowest crystallite size and hence the highest intensity of emission peaks at the wavelengths of 506, 515 and 671 nm, which are corresponded to the transitions of the P-H, P-H and P-F of Pr ions, respectively. The X-ray radiography image was obtained by the screen of GdOS:Pr nanopowders (prepared at 40 kGy gamma dose), coupled with a radiographic film. The TL glow curves of the sample, prepared at 40 kGy gamma dose, were recorded under the X-ray irradiation in the times of 5 and 10 min. The heating rate and preheat temperature were obtained 2 and 50 °C, respectively. The obtained results were investigated in details.