Synthesis and photoluminescence characteristics of high color purity BaYO:Eu red-emitting phosphors with excellent thermal stability for warm W-LED application.

Single phase Eu-activated BaYO (Ba(Y Eu )O) red-emitting phosphors with different Eu doping concentrations were synthesized by a high temperature solid-state reaction method. The phase purity, crystal structure, photoluminescence properties, internal quantum efficiency, decay lifetimes, and thermal stability were investigated. Upon excitation at 396 nm near-ultraviolet light and 469 nm blue light, the Ba(Y Eu )O phosphors exhibited a strong red emission at 614 nm due to the D → F transition of Eu ions. The optimal doping concentration of Eu ions in Ba(Y Eu )O was found to be = 0.25. Furthermore, the critical distance was calculated to be 12.78 Å and the energy transfer mechanism for the concentration quenching effect was determined to be quadrupole-quadrupole interaction. In addition, the Commission Internationale de I'Eclairage (CIE) chromaticity coordinates of Ba(YEu)O phosphors were measured to be (0.6695, 0.3302) which located at the red region, and significantly, the high color purity was about 97.9%. The as-synthesized phosphors also possessed excellent thermal stability and the activation energy was determined to be 0.29 eV. Therefore, the investigated results indicated that the BaYO:Eu phosphor may be a suitable candidate as a red phosphor for white light-emitting diodes under effective excitation at near-ultraviolet and blue light.