Abstract: With the rapid development of silicon-based light detectors with high detection efficiency and long-wavelength sensitivity, the development of near-infrared scintillation crystals has become a hotspot. Especially, the Sm²⁺ doped europium-based halide crystals exhibit excellent near-infrared luminescence properties. In this paper, Cs₄EuI₆∶Sm near-infrared scintillation crystals with a size of cm-level were successfully prepared by Bridgman method. The composition and structure were discussed by XRD, XPS and ICP-OES methods, indicating that the Sm²⁺ was introduced and has no obvious effect on the crystal structure of the matrix. Under ultraviolet and X-ray excitation, the crystal has two luminescence centers (Eu²⁺ and Sm²⁺), and the emission peaks are located at 450 and 840 nm, respectively, corresponding to the 5d→4f luminescence of Eu²⁺ and Sm²⁺. The decay time of Eu²⁺ and Sm²⁺ is at the level of microsecond under ultraviolet excitation. The results show that the emission wavelength gradually varies from blue to near infrared as Sm²⁺ doping concentration increased. The effects of Sm²⁺ concentration on the luminescence properties, Eu²⁺-Sm²⁺ energy transfer and decay time of the crystals were also studied, which means that the luminescence properties can be tuned by adjusting the Sm²⁺ doping concenstration.

Key words: Cs₄EuI₆, Sm²⁺ doping, scintillation crystal, near infrared luminescence, Bridgman method, energy transfer