COLOR TUNABLE PERSISTENT LUMINESCENCE IN M2MgSi2O7:Eu2+,Dy3+ (M=Ca,Sr,Ba) PHOSPHOR WITH CONTROLLED MICROSTRUCTURE

Color tunable, highly intense, long persistent M2MgSi2O7 (M=Ca, Sr, Ba) phosphors were prepared by one pot hydrothermal method. The phosphor particles were well controlled by the solution pH of the mixture that tuned the luminescence intensities significantly. Compared with the conventional solid state method, narrow particles size distribution, homogeneous and agglomeration free particles were achieved by hydrothermal method. The underlined mechanism of particles formation in regard to the pH of the starting mixture was proposed. Fine tuning of fluorescence and afterglow color was achieved by changing host cations. Bluish green, green and yellowish-green afterglow were observed in the Sr2MgSi2O7:Eu2+,Dy3+, Ba2MgSi2O7:Eu2+,Dy3+ and Ca2MgSi2O7:Eu2+,Dy3+ phosphors, respectively. The afterglow duration was found to be in the order Ca2MgSi2O7 > Ba2MgSi2O7 > Sr2MgSi2O7 and was discussed in term of the trap depths in the respective hosts. Optimum Eu2+ activator and Dy3+ trapping centers were estimated for intense afterglow with longer persistent duration. These yellowish-green afterglow phosphors which are difficult to realize might have potential applications due to superior water resistant properties.