Effects of annealing atmosphere on the luminescent efficiency of ZnTe:O phosphors

The effect of the annealing atmosphere on the luminescent efficiency of ZnTe:O phosphors for X-ray imaging applications was studied. The phosphors were doped by ball-milling bulk ZnTe crystals in an O2 atmosphere and annealed in various atmospheres: vacuum, N2 or forming gas (95%N2/5%H2). All samples exhibited a deep red emission centered at 680 nm.The samples annealed in forming gas atmosphere exhibited an X-ray luminescent efficiency five times higher than the samples annealed in vacuum or N2 atmospheres, which was attributed to the removal of surface tellurium oxides.