Energy transfer and luminescence properties of Sr[1-3(x+y)/2]Al₂B₂O₇:xEu³⁺, yBi³⁺ phosphor.

Sr[1-3(x+y)/2]Al2B2O7:xEu(3+), yBi(3+) (x=0-5 mol% and y=0-5 mol%) phosphors are synthesized by a solid-state reaction method in air, and their crystal structure, fluorescence lifetime, and luminescence properties are investigated. The optimal composition is determined to be (Sr0.94Eu0.03Bi0.01)Al2B2O7. The PLE band peaks within the range 200-550 nm are due to O(2-)→Eu(3+) charge transfer band, (7)F0→(5)H3, (5)D4, (5)L7, (5)L6, (5)D3, (5)D2, and (5)D1 transitions, respectively. The strongest PL band peak under excitation 394 nm light is at ∼615 nm owing to (5)D0→(7)F2 transition of Eu(3+) ion. The PL intensity of Eu(3+), Bi(3+) co-doped SrAl2B2O7 phosphor is 1.3 times that of Eu(3+) doped SrAl2B2O7 phosphor due to the energy transfer between Eu(3+) and Bi(3+) ions, which is explained by the energy level diagrams of Bi(3+) and Eu(3+) ions. The CIE chromaticity coordinates of Sr0.955Al2B2O7:0.03Eu(3+) and Sr0.94Al2B2O7:0.03Eu(3+), 0.01Bi(3+) phosphors under excitation 394 nm light are (x=0.6292, y=0.3702) and (x=0.6284, y=0.3711), respectively. These phosphors will be used as reddish orange emitting phosphor candidate for white LED with ∼394 nm near ultraviolet LED chip.