Optimization of crystal growth and properties of γ-CuI ultrafast scintillator by the addition of LiI

[Display omitted] •Large and transparent γ-CuI single crystal with the size over 20 mm was successfully obtained for the first time.•The intensities of near-band-edge emissions of γ-CuI single crystal are greatly enhanced by Li and I dopants.•The 430 nm emission decay time is less than 450 ps under pulsed X-ray irradiation. Large-sized γ-CuI single crystals with ultrafast scintillation property were grown in LiI acetonitrile solvent through evaporation technique. The LiI exhibits unique properties to γ-CuI single crystal preparation. One is that it increases the solubility of CuI in the solvent, which gives rise to a largest-sized (23 × 14 × 2 mm3) single crystal with the high optical transmission (over 60%) in the wavelength region of 435–800 nm. The other feature is that it acts as an effective isoelectronic dopant and improves the molar ratio of copper to iodine, which greatly enhances the near-band-edge emissions (411 and 432 nm) and suppresses the broadband emission (680 nm). The decay time of the fast emission under pulsed X-ray excitation is shorter than 450 ps. The results will give a guidance for optimizing the properties of γ-CuI single crystal as an ultrafast scintillator.