The structures and luminescence properties of Sr4Gd3Na3(PO4)6F2:Ce3+,Tb3+ green phosphors with zero-thermal quenching of Tb3+ for WLEDs

Abstract

In this paper, novel green-emitting Sr₄Gd₃Na₃(PO₄)₆F₂:Ce³⁺,Tb³⁺ phosphors with zero-thermal quenching of Tb³⁺ have been prepared and investigated. X-ray diffraction together with Rietveld structure refinement was employed to give an insight into the structures of the samples. The luminescence spectra at 300 K and 80 K confirmed that the Ce³⁺ ions in Sr₄Gd₃Na₃(PO₄)₆F₂:Ce³⁺ were distributed randomly on the cation sites and gave intense emission. Utilizing the Ce³⁺ → Tb³⁺ energy transfer, intense green emitting Sr₄Gd₃Na₃(PO₄)₆F₂:Ce³⁺,Tb³⁺ had been obtained. The energy migration mechanism of Ce³⁺ in Sr₄Gd₃Na₃(PO₄)₆F₂:Ce³⁺ and the energy transfer mechanism of Ce³⁺ → Tb³⁺ in Sr₄Gd₃Na₃(PO₄)₆F₂:Ce³⁺,Tb³⁺ were determined by the analysis of photoluminescence spectra and decay curves. Sr₄Gd₃Na₃(PO₄)₆F₂:Ce³⁺,Tb³⁺ exhibited a thermal-induced enhancement of Tb³⁺ emission at 25–300 °C, indicating an excellent thermal stability. Moreover, utilizing our prepared Sr₄Gd₃Na₃(PO₄)₆F₂:0.06Ce³⁺,0.15Tb³⁺ phosphor, green and white emitting LED devices have been fabricated. Our investigation indicated the potential application of prepared green phosphors in UV WLEDs and a feasible method to explore highly thermally stable phosphors utilizing the high thermal stability of donors together with energy transfer from donors to acceptors.