Color-tunable luminescence and energy transfer properties of Ca1.5Sr1.5(PO4)2: Dy3+, Tb3+ phosphor via hydrothermal synthesis

Ca1.5Sr1.5(PO4)(2): Dy3+, Tb3+ phosphors were obtained by hydrothermal synthesis. XRD and SEM verify Dy3+ and Tb3+ into Ca1.5Sr1.5(PO4)(2): Dy3+, Tb3+ and the change of morphology in the process of Sr2+ ion occupying Ca2+ sites. The optimum doping concentrations of Dy3+ and Tb3+ were in 0.02 mol% and 0.04 mol%, and the corresponding mechanism exchange interaction and quadrupole-quadrupole mechanism, respectively. The emission spectra of Ca1.5Sr1.5(PO4)(2): Dy3+, Tb3+ phosphors excited at 368 nm were composed of emission peaks at 481 nm, 573 nm of Dy3+ and at 487 nm, 543 nm, 584 nm, 621 nm of Tb3+. Energy transfer mechanism was dipole dipole mechanism. The emission intensity of Dy3+ retained about 74.50% and Tb3+ was 75.19% at 500 K comparing with the initial temperature of 300 K. The Ca1.5Sr1.5(PO4)(2): Dy3+, Tb3+ phosphors had better thermal stability, and the activation energy was estimated to be 0.14 - 0.15 eV. The color of phosphors tuned from white light to green-white light. The Ca1.5Sr1.5(PO4)(2): Dy3+, Tb3+ phosphors provide a strategy for tunable luminescence in LED with UV chip.