The trap states in the Sr_2MgS_2O_7 and (Sr,Ca)MgSi_2O_7 long afterglow phosphor activated by Eu~(2+) and Dy~(3+)

摘要

The excellent long afterglow phosphor Sr_2MgSi_2O_7:Eu~(2+),Dy~(3+) with the blue light and (Sr,Ca)MgSi_2O_7:Eu~(2+),Dy~(32+) emitting blue-green afterglow for more than 20 h under the UV excitation were prepared. The trap states in the samples are studied by thermoluminescence (TL) and photo-stimulated luminescence (PSL). The results of TL and PSL exhibit plenty of traps which are responsible for the long afterglow. TL study shows that a broad band appeal's at 330 and 357 K for (Sr,Ca)MgSi_2O_7;Eu~(2+),Dy~(3+) with the thermal depth of trap E_(TL) = 0.66eV and for Sr_2MgSi_2O_7:Eu~(2+)Dy~(3+) with the thermal depth of trap E_(TL) = 0.75 eV, respectively. PSL spectra reveals that the trapped carries also can be released by optical stimulation with the E_(PSL) = 1.56-1.94 eV. The relation between TL and PSL can be explained by the configuration coordinate mode.