X-ray scintillators are crucial for medical, industrial, and security imaging systems. However, achieving dual-mode of real-time and delayed imaging within a single matrix still faces challenges. Herein, LiGa 5 O 8 : Tb 3+ was successfully synthesized by the high-temperature solid-phase method. By controlling the atmosphere and optimizing the Li + /Ga 3+ ratio, the trap structure of LiGa 5 O 8 : Tb 3+ spinel phosphors is effectively adjusted, which achieved excellent dual-mode imaging. The air-synthesized Li 1.6 Ga 5 O 8 :4 %Tb 3+ exhibits intense X-ray excited persistent luminescence (X-PersL, 595 nm), while the sample of LiGa 5 O 8 :Tb 3+ reduced in H 2 /N 2 shows enhanced radioluminescence (RL) without X-PersL. This precise manipulation of anti-occupancy defects controls the charge trapping/detrapping dynamics, enabling switchable RL (real-time imaging) and X-PersL (delayed imaging) modes through the single Tb 3+ ions emission. The result resolves the incompatibility between prompt and persistent X-ray responses in conventional scintillators. The defect-regulation method establishes a universal strategy for developing scintillators compatible with complex operational demands, advancing high-performance X-ray imaging technologies.
Incorporation of lanthanide ions (Ln 3+ ) can remarkably enhance the structural stability and optical properties of lead-free perovskite NCs. Herein, we have established the relationship between the intrinsic emission of Cs 2 AgInCl 6 host and the Ln 3+ by Eu 3+ , Tb 3+ doping in Cs 2 AgInCl 6 NCs, realizing tunable luminescence of NCs in the visible region. Experimental studies and density functional theory (DFT) calculations analysis show that Eu 3+ and Tb 3+ occupy the sites of In 3+ in Cs 2 AgInCl 6 , the defect formation energy for Cs 2 AgInCl 6 :Ln 3+ is larger than the pristine Cs 2 AgInCl 6 , resulting in a more stable cubic double perovskite structure. The optical band gap increases with the increase in Ln 3+ doping percentage. Turning excitation from 250 nm to 300 nm, the broad self-trapped excitons (STEs) emission is more remarkable, and the narrow Ln 3+ emission is less notable. The emitted color can be adjusted from white to red and to green light by altering the doping concentration of Eu 3+ or Tb 3+ and excitation wavelength. This work promotes the design and optoelectronic application of desired lead-free perovskites.
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