Eu~(2+)-doped CsBr photostimulable X-ray storage phosphors - analysis of defect structure by high-frequency EPR

摘要

Eu~(2+)-doped CsBr in form of needle image plates is a promising alternative to the granular Eu~(2+):BaFBr X-ray storage phosphor with respect to photo-stimulated luminescence, yield and spatial resolution. However, in order to understand the corresponding mechanisms on an atomic scale, the defect structure of Eu~(2+)-doped CsBr photostimulable X-ray storage phosphors has to be analyzed. By means of high-frequency electron paramagnetic resonance (EPR) spectroscopy, three types of defects have been observed - an electrically neutral dimeric (Eu_(Cs)~· - O_(Br)~')~× defect complex and a neutral trimeric (V_(Br)~× - Eu_(Cs)~·- V_(Cs)~')~× defect complex (F_z-center), as well as acceptor-type F-centers (V_(Br)~·) that are generated by the trapping of electrons at initially neutral bromine vacancies.