Characteristics of MgO-coated alkaline Earth selenide phosphor prepared by spray pyrolysis

Spherical submicron sized Eu2 +-activated SrSe and CaSe alkaline earth selenide phosphors were prepared by ultrasonic spray pyrolysis. The particle size decreased with decreasing precursor solution concentration, while the pyrolysis temperature had a negligible effect on the particles size and morphology. Due to the d-f transition of Eu2 +, SrSe:Eu2 + and CaSe:Eu2 + showed the broad band emission with maximum peaks at 565 and 608 nm, respectively. Further, the addition of 10 wt% NH4Cl flux helped to enhance the emission intensity by reducing the surface defects. MgO coating on selenide phosphor surface effectively improved the moisture stability without a significant loss in the luminescence intensity. 5-10 wt% MgO-coated SrSe: Eu2 +, and CaSe:Eu2 + nearly retained their initial luminescence intensity under water condition.