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(Y_1−xEu_x)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(Y_1−xEu_x)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(Y_1−xEu_x)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(Y_0.75Eu_0.25)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.