Spray pyrolysis synthesis of MAl2O4:Eu2+ (M=Ba, Sr) phosphor for UV LED excitation

The UV excited green emitting Eu2+-activated BaAl2O4 and SrAl2O4 phosphors were prepared by ultrasonic spray pyrolysis at low temperature. The morphologies of phosphors were spherical and ∼1 μm size with non-aggregation. The BaAl2O4:Eu2+ and SrAl2O4:Eu2+ were efficiently excited under UV range from 320 to 370 nm, and exhibited broad band emission at about 500 and 520 nm, respectively, corresponding to the 5d–4f transition of Eu2+. The detailed properties of crystal structure and luminescence behaviors were discussed by measurements of X-ray diffraction and photoluminescence. Phosphor conversion LEDs were fabricated by combining GaN-based 380 nm emitting UV LED as an optical pumping source with the prepared phosphors. The BaAl2O4:Eu2+ phosphor LEDs showed the CIE coordinate of (0.171, 0.432) in bluish-green emission, and SrAl2O4:Eu2+ phosphor LEDs showed that of (0.224, 0.518) in green emission.