Photoluminescence tuning via energy transfer in Eu-doped Ba2(Gd,Tb)2Si4O13 solid-solution phosphors

Abstract

We report on the phase formation of a Ba₂(Gd,Tb)₂Si₄O₁₃ solid-solution, and the coexistence of Eu²⁺/Eu³⁺ was identified after Eu ion doping although the samples were prepared in a reducing atmosphere. Under 377 nm near-ultraviolet (UV) light excitation, Ba₂Tb₂Si₄O₁₃ exhibits the characteristic emission originating from Tb³⁺ corresponding to ⁵D₄–⁷F_6,5,4,3 transitions; whereas Ba₂Tb₂Si₄O₁₃:Eu emits bright red emission from Eu³⁺ with peaks around 594, 613 and 623 nm. Accordingly, photoluminescence tuning of Eu-doped Ba₂(Gd,Tb)₂Si₄O₁₃ phosphors has been realized from green, yellow, orange, to red emission light. Decay time and time-resolved luminescence results revealed that the tunable luminescence behavior should be ascribed to the existence of energy migration in the terbium subset, and successive energy transfer processes Eu²⁺–Eu³⁺(Tb³⁺) and Tb³⁺–Eu³⁺ appear to occur in the Ba₂Tb_2−ySi₄O₁₃:yEu (y = 0–0.12) solid-solution phosphors under investigation.