Luminescence and Energy Transfer in Europium and Bismuth Codoped Trisodium Yttrium Silicates

Bi³⁺ and Eu³⁺ doped Na₃YSi₂O₇ phosphors are prepared with solid state reactions. The luminescence properties of Bi³⁺ and Eu³⁺ in Na₃YSi₂O₇ and the energy transfer (ET) from Bi³⁺ to Eu³⁺ are investigated in detail. The ET mechanism is also discussed. Bi³⁺ in Na₃YSi₂O₇ emits near-ultraviolet (UV) light in a broad band peaking at 394 nm which can be attributed to the transition from excited states ³P_{0, 1} to ground state ¹S₀ under the excitation of UV light with a wavelength of 309 nm. Eu³⁺ in Na₃YSi₂O₇ emits orange and red light. The co-doping of Bi³⁺ into Eu³⁺ doped Na₃YSi₂O₇ introduces an intense absorption band from 270 to 350 nm due to ET from Bi³⁺ to Eu³⁺. The sensitization effect of Bi³⁺ on Eu³⁺ makes it possible that Bi³⁺ and Eu³⁺ co-doped Na₃YSi₂O₇ could be used in AlGaN-based UV light emitting diodes as a red phosphor.