Synthesis and photoluminescence characteristics of high color purity Ba3Y4O9:Eu3+ red-emitting phosphors with excellent thermal stability for warm W-LED application.

Abstract

Single phase Eu3+-activated Ba3Y4O9 (Ba3(Y1−xEux)4O9) red-emitting phosphors with different Eu3+ 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 Ba3(Y1−xEux)4O9 phosphors exhibited a strong red emission at 614 nm due to the 5D0 → 7F2 transition of Eu3+ ions. The optimal doping concentration of Eu3+ ions in Ba3(Y1−xEux)4O9 was found to be x = 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 Ba3(Y0.75Eu0.25)4O9 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 Ba3Y4O9:Eu3+ phosphor may be a suitable candidate as a red phosphor for white light-emitting diodes under effective excitation at near-ultraviolet and blue light.