Transparent caesium bromide storage‐phosphors for radiation imaging

Abstract Semi‐transparent discs of polycrystalline CsBr:Eu²⁺ storage phosphor for X‐ray imaging have been produced using a room temperature milling/pressing technique, and have been studied using infrared, and photoluminescence spectroscopies, together with scanning electron microscopy. The pressed discs are very sensitive to water vapour, and scanning electron microscopy shows that material undergoes a complete recrystallization following exposure to humid air for a few minutes through a room temperature hydration/crystallization process. Discs prepared by a simple mixture of CsBr and EuBr₂ show photostimulated luminescence (PSL) at 440 nm without further processing, and the conversion efficiency is sufficient that X‐ray imaging can be demonstrated. Discs which have been prepared by first sintering at 600 °C, then pressed, and finally hydrated at room temperature show very strong PSL with a conversion efficiency of ∼36 pJ mR⁻¹ mm⁻³. A model is proposed for the generation of the active PSL centres in CsBr by the milling/hydration process.