Ce³⁺-activated Tl₂GdCl₅: Novel halide scintillator for X-ray and γ-ray detection

Luminescence and scintillation properties of the Tl₂GdCl₅:Ce³⁺(5%) crystal are reported in this study. The luminescence properties are studied under the excitation of X-rays. An intense Ce³⁺ emission is observed in the range of 350–500 nm with a peak at 389 nm. Scintillation properties including light output, decay time, and energy resolution, are studied under the excitation of 662-keV γ-rays from a ¹³⁷Cs source. A light output of 53,000 ± 5000 photons/MeV and energy resolution of 5% full-width-at-half-maximum (FWHM) are obtained at room temperature. The decay-time analysis reveals three exponential decay time constants of 32 ns (76%), 271 ns (10%), and 1.6 μs (14%). Owing to its high effective atomic number (Z_eff = 71) and high density (ρ = 5.10 g/cm³), the grown crystal exhibits a higher detection efficiency for X- and γ-rays. These findings reveal that the proposed compound could be employed for the development of radiation scintillation detector for various applications.