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

We report on the phase formation of a Ba-2(Gd,Tb)(2)Si4O13 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 D-5(4)-F-7(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 Ba-2(Gd,Tb)(2)Si4O13 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 Ba2Tb2-ySi4O13: yEu (y = 0-0.12) solid-solution phosphors under investigation.