Fig. 2. Radioluminescence (RL) characterisation of Cs₂Ag_0.6Na_0.4In_1-yBi_yCl₆ scintillators.

a Proposed mechanism of X-ray scintillation in a lead-free halide double-perovskite scintillator. b Schematic of RL spectra measurement using an integrating sphere and a spectrometer with a fixed X-ray source-to-sample distance. c Photographs of Cs₂Ag_0.6Na_0.4In_0.85Bi_0.15Cl₆ single crystals and powder under X-ray illumination (dose rate: 189 μGy_air s⁻¹, voltage: 50 kV). d RL spectra of Cs₂Ag_0.6Na_0.4In_1-yBi_yCl₆ powder with different Bi³⁺ contents under X-ray excitation with a dose rate of 189 μGy_air s⁻¹ at a voltage of 50 kV. e Stokes shift of Cs₂Ag_0.6Na_0.4In_1-yBi_yCl₆ with different Bi³⁺ contents. f RL spectra of Cs₂Ag_0.6Na_0.4In_0.85Bi_0.15Cl₆, LuAG:Ce and CsI:Tl wafers (dose rate: 189 μGy_air s⁻¹, voltage: 50 kV). g Attenuation efficiency and light yield of Cs₂Ag_0.6Na_0.4In_1-yBi_yCl₆ versus Bi³⁺ content. h Afterglow curves of Cs₂Ag_0.6Na_0.4In_0.85Bi_0.15Cl₆ and CsI:Tl