Optical and thermal quenching properties of Al-doped Ba 1.98 SiO 4 :0.02Eu 2+ phosphor synthesized with different Si 3 N 4 /SiO 2 ratio

An intense emission green color phosphor of Al-doped Ba1.98SiO4:0.02Eu2+ synthesized with different Si3N4/SiO2 ratio was prepared by conventional sintering method. The X-ray diffraction patterns, the photoluminescence, scanning micrograph and thermal quenching properties of Ba1.98SiO4:0.02Eu2+ with different Si3N4/SiO2 ratio were investigated in detail. As the Si3N4/SiO2 ratio increases, the emission intensity enhanced gradually until the optimum Si3N4/SiO2 ratio reached 3/2. The PL intensity with Si3N4/SiO2 = 3/2 is about four times of the initial intensity of Ba1.98SiO4:0.02Eu2+ phosphor and the reason was discussed clearly. Furthermore, when we introduced Al3+ ions into the host, the samples exhibited outstanding optical properties and smaller thermal quenching behavior compared with Ba1.98SiO4:0.02Eu2+ phosphor. The emission intensity of Ba1.98Si1−xAlxO4:0.02Eu2+ series increased until x reached 7% and the emission intensity of x = 0.07 is 5 times of the originated intensity of Ba1.98SiO4:0.02Eu2+ synthesized without Si3N4. The smaller thermal quenching behavior of Al-doped phosphors was studied clearly, too. All the results suggested that Al-doped Ba1.98SiO4:0.02Eu2+ phosphor synthesized with Si3N4/SiO2 = 3/2 can be a candidate green phosphor for WLEDs.