Improvement of X-ray storage properties of C12A7:Tb3+ photo-stimulable phosphors through controlling encaged anions

Lanthanide-doped oxide photo-stimulable (PS) phosphors (C12A7:Tb3+) with different encaged anions (O2-, H-, OH- and e(-)) have been prepared by a combustion method in combination with treatment under different conditions. Electron spin resonance (ESR) and Fourier transform IR (FTIR) transmittance data confirm the existences of encaged electrons, O-2(-) (indicating the existence of encaged O-2(-) anions) and OH- anions in C12A7:Tb3+. PS luminescence, thermoluminescence (TL), X-ray storage properties and luminescent kinetics analysis show that the more encaged OH- anions appear in C12A7, the shallower the depths of the two deeper traps (E-trap1 = similar to 0.72 eV and E-trap2 = similar to 0.95 eV), the smaller the glow-peak intensity ratio (I-trap2/I-trap1), the shorter the X-ray storage time and the lower the quality of X-ray imaging become. Our results suggest that, among all the anions, encaged OH- anions in C12A7:Tb3+ play a key role in influencing X-ray storage properties of PS phosphors. High-quality X-ray image with a resolution of similar to 15 line pairs per mm (lp/mm) has been obtained by reducing encaged OH- anions in PS phosphors. The C12A7:Tb3+ PS phosphor is a potential candidate material for computed radiography system and erasable/rewritable optical memory media. (C) 2016 Elsevier B.V. All rights reserved.