Hydrothermal Growth\nof Double-Layer ZnO:Sc for X‑ray\nImaging Application

The\ndevelopment of high-speed imaging technology requires ultrafast\nscintillators. ZnO is an excellent scintillator whose near-band-edge\n(NBE) radiation attenuation can reach subnanosecond levels. Homogeneous\nand unique double-layered ZnO:Sc microcrystals (1% doping) were prepared\nby adding polyvinylpyrrolidone during a hydrothermal reaction. The\ngrowth process of double-layer ZnO:Sc microcrystals and the effects\nof Sc doping concentration on the morphology of ZnO:Sc microcrystals\nwere studied. ZnO:Sc tended to nucleate into twins in weakly basic\nhexamethylenetetramine. The <i>c</i>-axis growth of ZnO\nwas inhibited by Sc doping, and the growth pyramid of ZnO:Sc was in\naccordance with the Burton–Cabrera–Frank growth model\nin the (002) plane, according to the spiral dislocation. Sheet ZnO:Sc\nmicrocrystals were obtained under high-concentration Sc doping. After\nhydrogen annealing, the NBE intensity of 0.5%-doped ZnO:Sc microcrystals\nwas higher than that of ZnO, mainly owing to inhibition of defect\nluminescence and sheet morphology, which reduced the self-absorption\nof ZnO:Sc. The decay time of the ZnO:Sc microcrystals after hydrogen\nannealing under ultraviolet excitation was less than 1 ns. Combining\nthe annealed microcrystals with polydimethylsiloxane to form a flexible\ncomposite film enables the scintillation screen to be used for ultrafast\nX-ray detection with a spatial resolution of up to 16 lp/mm.