Photoluminescence properties and energy transfer of Ba2Lu(BO3)2Cl : Eu2+/Eu3+,Tb3+phosphors

Novel green-emitting Ba 2 Lu(BO 3 ) 2 Cl : Eu 2+ /Eu 3+ ,Tb 3+ phosphors were synthesized via a solid-state reaction. It was found that Eu 3+ could be detected when the so-called Ba 2 Lu(BO 3 ) 2 Cl : Eu 2+ ,Tb 3+ were prepared in a reducing atmosphere. Through efficient energy transfer processes between Eu 2+ , Tb 3+ and Eu 3+ , the emission intensities of Tb 3+ and Eu 3+ were significantly enhanced due to the spectra overlap. The lifetime of Eu 2+ in Ba 1.97− y Lu(BO 3 ) 2 Cl : 0.03Eu 2+ /Eu 3+ , y Tb 3+ phosphors was 1.32 µs in the absence of Tb 3+ ( y = 0) and then it decreased to 0.62 µs ( y = 0.3). The proposed schematic diagram for energy transfer processes indicated that an effective resonance type energy transfer occurred between Eu 2+ and Tb 3+ (η T = 53%); however, the energy transfer between Tb 3+ and Eu 3+ was attributed to the charge transfer from Tb 3+ to Eu 3+ . Accordingly, Tb 3+ ions exhibited characteristic green emission peaks corresponding to the strong excitation band of Eu 2+ ions (300–450 nm), matching well with the dominant emission band of near ultraviolet (n-UV, 350–420 nm) light-emitting diodes. The present green-emitting Ba 2 Lu(BO 3 ) 2 Cl : Eu 2+ /Eu 3+ ,Tb 3+ phosphors exhibit potential as a kind of phosphor-converted materials for n-UV white light-emitting diodes.