Oxygen-Doped ZnTe Phosphors for Synchrotron X-ray Imaging Detectors

摘要

ZnTe:O powder phosphors were successfully prepared by a dry synthesis process using gaseous doping and etching media. It was found that dry doping by O_(2) through ball-milling was an effective way to synthesize ZnTe:O powder phosphors and produced a red emission centered at 680 nm with a decay time of 1.1 (mu)s. The emission intensity of dry O_(2)-doped samples was three times more intense than from ZnO-doped samples, possibly due to a more uniform distribution of oxygen substitution on tellurium sites. The samples annealed in a 95percent N_(2)/5percent H_(2) forming gas atmosphere exhibited a x-ray luminescent efficiency five times higher than did powders annealed in vacuum or N_(2) atmosphere. This enhancement was attributed to the removal of surface tellurium oxides. ZnTe:O phosphor screens were prepared with x-ray luminescence efficiencies equivalent to 56percent of ZnSe:Cu,Ce,Cl and 76percent of Gd_(2)O_(2)S:Tb screens under 17-keV radiation. An x-ray imaging resolution of 2.5 lines/mm was resolved, the same as that measured for commercial ZnSe:Cu,Ce,Cl and Gd_(2)O_(2)S:Tb screens. These results indicate that ZnTe:O is a promising phosphor candidate for synchrotron x-ray imaging applications.