PHOTOSTIMULATION REDSHIFT FOR NONSTOICHIOMETRIC BA1-XSRXFBR-EU2+

The oxygen-free x-ray storage phosphor BaFBr, doped with Sr2+ and havi ng Br- vacancies due to fluorine excess, is shown to have a high photo stimulability shifted appreciably to lower photon energy compared to n ondoped BaFBr because of the predominant generation of F-A(Sr2+) cente rs on the Br- sublattice upon room-temperature x irradiation. The F-A( Br-,Sr2+) centers are less stable than unperturbed F(Br-) centers3. Th erefore, the redshift of the photostimulability disappears upon therma l activation above room temperature. From the failure to observe an F center infrared emission, it is concluded that F and F-A centers are s patially correlated to hole centers of yet unknown nature. (C) 1996 Am erican Institute of Physics.