X-ray imaging and storage based on a NaF modified Y3Al2Ga3O12:Ce phosphor†

Abstract

Scintillators possessing remarkable capabilities for converting high-energy irradiation into visible emission can be utilized to achieve indirect X-ray detection. Defect levels of oxide phosphors can effectively capture electron–hole pairs induced by ionizing radiation for carrier storage. Here, we fabricated a series of Y₃Al_xGa_(5−x)O₁₂:Ce phosphors with a broad trap depth distribution using the molten salt method by introducing aliovalent Na⁺ and F⁻ ions into lattices. We found that charge carriers excited by X-ray irradiation are distributed at shallower defect levels than those excited by 450 nm blue light. We propose the photophysical mechanisms of the two excitation modes: high-energy electrons induced by ionizing radiation are transferred to the shallow traps through the conduction band, while photogenerated electrons are transferred to the deep traps, which are close to the excited state of the luminescence center. Flexible thin films prepared by embedding Y₃Al₂Ga₃O₁₂:Ce powder into polydimethylsiloxane (PDMS) are utilized as a scintillator screen, and X-ray imaging in real-time, time-lapse and storage modes has been achieved. This work reveals the mechanisms of ionizing radiation-induced carrier charging and further develops the application of oxide phosphors in X-ray imaging and information storage.