Studies on long lasting optical properties of Eu2+ and Dy3+ doped di-barium magnesium silicate phosphors

Di-barium magnesium silicate phosphors doped with europium and dysprosium were prepared under a weak reducing atmosphere.X-ray diffraction pattern of the sample was also done that confirmed the proper preparation of the phosphor.Scanning electron microscope(SEM) images confirmed that the sample has regular surface and uniform grain size distribution.Comparative studies of phosphorescence decay of BaMgSiO:Eu,Dyphosphors with different concentration of Dywere done.The phosphor with 0.5/1.5 mol%of Eu/Dy,exhibited optimum green color afterglow properties.This emission is expected to arise due to transition of Euions from any of the sublevels of 4f~65d~1configuration to ~8Slevel of the 4f7 configuration.For a suitable trap depth,the trap concentration is expected to be proportional to the concentration of Dy.These traps are responsible for holding the charge career for a reasonable time,subsequently for increasing the time of afterglow.Hence,optimum Dy3* concentration produces the longer afterglow duration with higher intensity of luminescence signals.Trap depth were also calculated using thermoluminescence glow curve which was indicative of formation of traps suitable for long afterglow.