Spray pyrolysis synthesis of MAl sub(2)O sub(4):Eu super(2+) (M=Ba, Sr) phosphor for UV LED excitation

The UV excited green emitting Eu super(2+)-activated BaAl sub(2)O sub(4) and SrAl sub(2)O sub(4) phosphors were prepared by ultrasonic spray pyrolysis at low temperature. The morphologies of phosphors were spherical and approximately 1 mu m size with non-aggregation. The BaAl sub(2)O sub(4):Eu super(2+) and SrAl sub(2)O sub(4):Eu super(2+) 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 Eu super(2+). 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 BaAl sub(2)O sub(4):Eu super(2+) phosphor LEDs showed the CIE coordinate of (0.171, 0.432) in bluish-green emission, and SrAl sub(2)O sub(4):Eu super(2+) phosphor LEDs showed that of (0.224, 0.518) in green emission.