Tunable luminescence and energy transfer properties in Na3Bi(PO4)2:Eu3+, Tb3+, Dy3+, Sm3+ phosphors with high thermal stability

Abstract

Na3Bi(PO4)2:Eu3+/Tb3+/Dy3+/Sm3+ phosphors were synthesized via a high-temperature solid-state reaction method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), diffuse reflection, photoluminescence (PL) and fluorescent decay curves were utilized to characterize the obtained phosphors. Under n-UV excitation, Na3Bi(PO4)2:Eu3+/Tb3+/Dy3+/Sm3+ samples show the characteristic f-f emissions and present red, green, yellow and orange emission, respectively. When Tb3+, Dy3+ and Sm3+ were co-doped into the Na3Bi(PO4)2:Eu3+ phosphors, tunable emission colors can be obtained and can be efficiently adjusted by varying the doping ions and the doping concentration. The energy transfer mechanisms were investigated in detail and demonstrated that there is an efficient energy transfer from Tb3+, Dy3+ and Sm3+ to Eu3+ via a dipole-dipole interaction mechanism. Additional, as the temperature increases from RT to 150°C, the PL intensity of Tb3+-Eu3+, Dy3+-Eu3+ and Sm3+-Eu3+ co-doped phosphors decreased to 86%, 85% and 88%, respectively, which prove good thermal stability. All the CIE coordinates of as-prepared phosphors are displayed and show abundant colors, making these materials have potential applications for n-UV-excited white-LEDs.