Fabrication, characterization, and optimization of the composite long afterglow material Sr2MgSi2O7:Eu2+, Dy3+@ SrAl2O4:Eu2+, Dy3+

In order to improve the water resistance of SrAl2O4:Eu2+, Dy3+, the composite long afterglow material Sr2MgSi2O7:Eu2+, Dy3+@ SrAl2O4:Eu2+, Dy3+ was prepared by covering uniform and stable Sr2MgSi2O7 sol on SrAl2O4:Eu2+, Dy3+ powder, which was synthesized via traditional solid-state method. The effects of various factors, such as the amount of ammonia, the molar ratio of Sr2MgSi2O7:SrAl2O4 and the content of H3BO3, on the structure and luminescent properties of Sr2MgSi2O7:Eu2+, Dy3+@ SrAl2O4:Eu2+, Dy3+ were investigated by the response surface method. The results show that the influence extent on both the initial afterglow brightness and water resistance are as follows:the amount of ammonia > the content of H3BO3 > the molar ratio of Sr2MgSi2O7:SrAl2O4. When the amount of ammonia, the molar ratio of Sr2MgSi2O7:SrAl2O4 and the content of H3BO3 is 1.64 mL, 11.10, and 0.006 mol, respectively, both the brightness and water resistance of Sr2MgSi2O7:Eu2+, Dy3+@ SrAl2O4:Eu2+, Dy3+ are improved, the water resistance is 0.835 (51.82% higher than that of pure SrAl2O4) and the initial afterglow brightness can reach 2793 mcd/m(2) (91.69% higher than that of pure SrAl2O4), which were in good agreement with the predicted optimum value of 0.867 and 2720 mcd/m(2), respectively. Under the optimization conditions, the synergistic action of SrAl2O4 with excellent afterglow properties and Sr2MgSi2O7 with high water resistance plays an important role in improving the water resistance without sacrificing brightness. Finally, the water-based light-emitting inks with SMSA as fluorescent pigment exhibit excellent luminescent properties in the dark.