Synthesis and optical characterization of Eu2+,Tb3+-codoped Sr3Y(PO4)3 green phosphors

A series of Eu²⁺,Tb³⁺-codoped Sr₃Y(PO₄)₃ (SYP) green phosphors were synthesized by high-temperature solid–state reaction. Several techniques, such as X-ray diffraction, UV–vis spectrum, and photoluminescence spectrum, were used to investigate the obtained phosphors. The present study investigates in detail photoluminescence excitation and emission properties, energy transfer between the two dopants, and effects of doping ions on optical band gap. SYP:0.05Eu²⁺ phosphor shows an intense and broad excitation band ranging from 220 to 400 nm and exhibits a bright green emission band with CIE chromaticity coordinates (0.189, 0.359) under 350 nm excitation. Green emission of SYP:0.03 Tb³⁺ is intensified by codoping with Eu²⁺, and energy transfer mechanism between them is demonstrated to be a dipole–dipole interaction. Upon 350 nm excitation, SYP:Eu²⁺,Tb³⁺ phosphors exhibits two dominating bands peaking at 466 and 545 nm, which are assigned to 4f⁶5d¹→4f⁷ transition of Eu²⁺ ions and ⁵D₄→⁷F₅ transition of Tb³⁺ ions, respectively. Optimal doping concentrations of Eu²⁺ and Tb³⁺ in the SYP host are 5 mol% and 15 mol%, respectively. Results indicate that SYP:Eu²⁺,Tb³⁺ phosphors are potentially used as green-emitting phosphors for white light-emitting diodes.