Luminescence enhancement of CaZnGe2O6:Tb3+ afterglow phosphors synthesized using ZnO nanopowders

CaZnGe2O6:Tb3+ afterglow phosphors were prepared by solid state reaction using organic coated ZnO nanopowders and their photoluminescence. X-ray luminescence and afterglow properties were investigated. The CaZnGe2O6:Tb3+ samples emit a green luminescence at 548 nm attributed to the D-5(4)-E-7(5) transition of Tb3+. It was observed that the replacement of bulk ZnO by ZnO nanopowder in the sample synthesis increases the luminescence intensity. By adjusting the mass ratio of bulk ZnO to nanopowder ZnO, the photoluminescence intensity, X-ray luminescence intensity, and afterglow efficiency are improved. The optimized sample made with a 0.71 ratio of nano ZnO to bulk ZnO has a factor of four enhancement in X-ray luminescence, photoluminescence and afterglow intensities in comparison with the sample made with 100% bulk ZnO. (C) 2011 Elsevier B.V. All rights reserved.