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Effect of annealling temperature on spectra and trap concentration of SrAl_2O_4: Eu~(2+),Dy~(3+) luminescent material

The long afterglow luminescent materials Sr 0. 96 Al 2 O 4 : Eu 0. 02,Dy 0. 02,B 0. 08 were synthesized via solid-state reaction. The effects of the second annealling temperature on crystal structure,excitation spectra,emission spectra,decay curves,Raman spectra and thermoluminescence spectra of the long afterglow phosphors were discussed. The results show that the concentrations of electrons trapped in Dy Sr ˙ increase with enhancing the second annealling temperature,which is advantageous to improve the long afterglow properties. As the second annealling temperature increasing,the variations of the Ramam spectura values are well coincident with the variations of the V O ˙˙ concentrations,which demonstrates the validity of the model of electron trap for the long afterglow luminescent materials. The sample with the second annealling temperature of 1400 ℃ for 6 h possesses the highest brightness within the testing period,which results from the largest concentration of electrons trapped in Dy Sr ˙ and the proper decay time constant.