Photoluminescent properties of Eu3+-Eu2+ activated MAl2SixO2x+4 (M=Mg, Ca, Sr, Ba) phosphors prepared in air

In this paper, MAl2SixO2x+4:Eu2+/Eu3+ (Eu2+ + Eu3+ = 2%, molar ratio; M = Mg, Ca, Sr, Ba; x = 0, 0.5, 1, 1.5, 2) phosphors with different SiO2 concentrations (the ratio of SiO2 to MAl2O4 is n%, n = 0, 50, 100, 150, 200, respectively) were prepared by high-temperature solid-state reaction under atmospheric air conditions. Their structures and photoluminescent properties were systematically researched. The results indicate that Eu3+ ions have been reduced and Eu2+ ions are obtained in air through the self-reduction mechanism. The alkaline earth metal ions and doping SiO2 strongly affect the crystalline phase and photoluminescent properties of samples, including microstructures, relative intensity of Eu2+ to Eu3+, location of emission lines/bands. It is interesting and important that the emission color and intensities of europium-doped various phosphors which consist of aluminosilicate matrices prepared under atmospheric air conditions could be modulated by changing the kinds of alkaline earth metal and the content of SiO2.