The demand for scintillators with ultrafast decay times, high spatial resolutions, and high stabilities is increasing due to the development of ultrafast hard X-ray detection, hard X-ray imaging, and high-energy physics facilities. γ-CuI single crystals, which exhibit ultrafast luminescence and high stopping power for hard X-rays, hold great promise for such applications. However, slow luminescence and poor stability caused by surface iodine deficiencies hinder the practical use of γ-CuI. Herein, we treated a γ-CuI single crystal by iodine annealing and SiO2 coating and investigated its crystal structure and luminescence properties in detail. Iodine annealing significantly enhanced the near-band-edge emission of the γ-CuI crystal with an ultrafast decay time of less than 1 ns, while completely suppressing the slow luminescence. Moreover, the SiO2 film effectively prevented the oxidation and decomposition of surface iodine, leading to substantial improvement in luminescence stability. The γ-CuI crystal demonstrated an ultrahigh spatial resolution of 1.5 μm in X-ray imaging, highlighting its potential for ultrafast hard X-ray imaging applications. This study provides insight into the growth, optimization, and application of γ-CuI crystals, advancing the field of scintillator materials.
Shuangqiang Yue,Mu Gu,Xiaolin Liu,Juannan Zhang,Shiming Huang,Bo Liu,Chen Ni
γ-CuI single crystal was grown via evaporation method in ZnI 2 acetonitrile solvent. The ZnI 2 plays a unique role which can not only increase the solubility of CuI in acetonitrile but also introduce the Zn and I ions in the crystal. The γ-CuI crystal grown in ZnI 2 acetonitrile is regular and transparent. Its size reaches up to 18 × 11 × 2 mm 3 which is larger than that of the crystal grown in pure acetonitrile. In terms of the photoluminescence , the intensity of the emission at 411 nm of the crystal grown with ZnI 2 as a cosolute is much higher than that of the crystal grown without ZnI 2 , which implies that the crystallinity of the crystal can be improved by ZnI 2 doping. The X-ray excited luminescence of the crystal shows that the emission at 435 nm can be significantly enhanced and the emission near 680 nm can be suppressed by introducing Zn and I in the natural non-stoichiometry γ-CuI crystal. The nature of the phenomena is discussed. The decay time of the emission at 435 nm similar to that of the emission at 411 nm is faster than the detection limit of the instrument, i.e. less than 1 ns, and the average decay time of the emission near 680 nm is about 183 ns. The results can provide a useful guide to optimize the scintillation properties of γ-CuI single crystal.
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