X-ray storage phosphors

In X-ray storage phosphors an image is formed and stored by generation of room temperature stable radiation-induced electron and hole trap centres. The image is read-out by recording a photo-stimulated luminescence (PSL) from a doped activator, generally stimulating the electron trap centres. The best-known and hitherto most efficient X-ray storage phosphor is BaFBr:EuZ+. However, the exact mechanism of its functioning is not yet understood. The present discussion of the storage and read-out mechanisms is critically reviewed. New results about the role of oxygen Contamination of BaFBr:Eu2+ are presented: if there is much less oxygen present than Edc, then the PSL efficiency decreases and the stimulation energy increases. A new efficient X-ray storage phosphor is presented: Cs2NaYF6 doped with trivalent rare earth activators. Its properties are described and preliminary results on X-radiation-induced radiation damage centres in undoped Cs2NaYF6 are presented.