Luminescence Reducing Mechanism of Cd Doped Y_2O_2S:Ti,Cd Long Afterglow Phosphor

摘要

Y_(1.97-x)Ti_(0.03)Cd_xO_2S (0 ≤ x ≤ 0.06) phosphors with long afterglow were synthesized by solid-state reaction. The photoluminescence spectra, decay curves, thermoluminescnece spectra and Chromaticity coordinate curves were investigated. Results showed that the luminescence and afterglow intensity of Y_(1.97-x)Ti_(0.03)Cd_xO_2S (0 ≤ x≤ 0.06) reduced gradually with increasing Cd~(2+) ion content while the shape and position of emission peak remain unchanged. The Chromaticity coordinate of present phosphor keeps at (0.5497,0.4415). Furthermore, based on the results of thermoluminescence curves of Ti, Cd single doped and co-doped Y_2O_2S phosphors, the doped Cd ion reduces the inherent trap depth of Ti single doped Y_2O_2S:Ti, and induces simultaneously a new trap level in Y_2O_2S:Ti,Cd phosphor. Thus, it was proposed that the introduced new structure defect by Cd~(2+) ions should be responsible for the reducing luminescence and afterglow property.