Following irradiation of non-stoichiometric BaF1.1Br0.9, a new intrinsic hole center, as well as the F(Br-) center, was detected by electron paramagnetic resonance. The powder electron paramagnetic resonance line of this new center could be simulated by assuming the presence of an F2- molecule on a fluoride site. The new hole center was stable at room temperature and was the anti-center of the F(Br-) center in F center generation. Magic angle spinning nuclear magnetic resonance experiments on non-stoichiometric BaF1.1Br0.9 revealed not only resonances of 19F on normal lattice sites, but also resonances which were due to 19F on Br sites (so-called F antisites). There were some 10% of F antisites in the non-stoichiometric powder; corresponding to the excess F determined by chemical analysis. The generation of F(Br-) electron trap-hole trap pairs, upon X-irradiation, originated at the F antisites.

Generation of F Centers and Hole Centers in the Non-Stoichiometric X-Ray Storage Phosphor BaFBr. S.Schweizer, J.M.Spaeth, T.J.Bastow: Journal of Physics - Condensed Matter, 1998, 10[40], 9111-22