Tl₂NaScCl₆: A New Tl-based Elpasolite Crystalline Scintillator

A scintillator for X-ray and gamma-ray detection must possess high light yield, good energy resolution, and high effective atomic number. In this study, we fabricated Tl₂NaScCl₆ crystals using the vertical Bridgman method and investigated their luminescence, scintillation properties, and scintillation mechanisms. The photoluminescence and X-ray-induced radioluminescence (XRL) spectra reveal broad emission bands peaking at 410 and 430 nm, respectively. The temperature dependence of the intensity of XRL spectra follows the Arrhenius equation, indicating that the luminescence of the Tl₂NaScCl₆ crystals is a self-trapped exciton emission or exciton-related emission. The light yield and energy resolution calculated from the ¹³⁷Cs-gamma-ray pulse-height spectra are 20000 photons/MeV and 5.3%, respectively. These results suggest that Tl₂NaScCl₆ crystals are promising scintillators for X- and gamma-ray detection.