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

• SrAl2B2O7:Eu3+, Bi3+ phosphor is synthesized by a solid-state reaction method in air.
• Energy transfer between Eu3+ and Bi3+ ions is observed.
• The energy transfer mechanism is explained.
• CIE chromaticity coordinate of SrAl2B2O7:Eu3+, Bi3+ phosphor under excitation 394 nm light is calculated.

Sr[1−3(x+y)/2]Al2B2O7:xEu3+, yBi3+ (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 O2− → Eu3+ charge transfer band, 7F0 → 5H3, 5D4, 5L7, 5L6, 5D3, 5D2, and 5D1 transitions, respectively. The strongest PL band peak under excitation 394 nm light is at ∼615 nm owing to 5D0 → 7F2 transition of Eu3+ ion. The PL intensity of Eu3+, Bi3+ co-doped SrAl2B2O7 phosphor is 1.3 times that of Eu3+ doped SrAl2B2O7 phosphor due to the energy transfer between Eu3+ and Bi3+ ions, which is explained by the energy level diagrams of Bi3+ and Eu3+ ions. The CIE chromaticity coordinates of Sr0.955Al2B2O7:0.03Eu3+ and Sr0.94Al2B2O7:0.03Eu3+, 0.01Bi3+ 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.

PL spectra of Sr0.97Al2B2O7:0.03Eu3+ and Sr0.96Al2B2O7:0.03Eu3+, 0.01Bi3+ phosphors sintered at 1000 °C (λex = 394 nm), their CIE chromaticity coordinates, and picture under 254 nm UV lamp.Figure optionsDownload as PowerPoint slide