Zero-Dimensional Lead-Free Metal Halide Scintillator Suitable for Extreme Environments and X-Ray Imaging

Scintillators are widely used for radiation detection in various fields, such as medical imaging, nondestructive testing, and crystallography. X-ray-generating systems typically emit large amounts of heat and require a high thermal stability of scintillators, particularly for nondestructive testing or radiation detection performed under harsh conditions. Therefore, highly stable scintillators must be developed for application in extreme environments. Herein, we developed new zero-dimensional lead-free monoclinic phases of Cs₃TbCl₆ and Rb₃TbCl₆ metal halides. Surprisingly, Cs₃TbCl₆ and Rb₃TbCl₆ have retained over 90% of their original PL properties at 250°C. Cs₃TbCl₆ and Rb₃TbCl₆ polycrystals exhibit high light yields of 56,800 and 88,800 photons/MeV, respectively. Cs₃TbCl₆ and Rb₃TbCl₆ polycrystals also show low detection limits of 149.65 and 115.38 nGyairs^–1 due to their structural–optical properties, respectively. Furthermore, the fabricated thick films of Cs₃TbCl₆ and Rb₃TbCl₆ are applied to our homemade X-ray imaging system, and preferable spatial resolutions are obtained as compared with a commercial Gd₂O₂S:Tb³⁺ film.