Luminescence properties and energy transfer investigations of Sr3Gd(PO4)3:Ce3+,Tb3+ phosphors

Ce3+ and Tb3+ co-doped Sr3Gd(PO4)3 phosphors were synthesized by the solid-state method. The phase structure and luminescence properties of the phosphor samples were characterized by using powder X-ray diffraction (XRD), photoluminescence (PL) excitation and emission spectra, decay time, respectively. The obtained phosphor exhibits a strong excitation band between 200 and 400 nm, matching well with the dominant emission band of a ultraviolet (UV) light-emitting-diode (LED) chip. Effective energy transfer occurred from Ce3+ to Tb3+ in Sr3Gd(PO4)3 hosts due to the spectra overlap between the PL emission spectrum of Ce3+ ion and the PL excitation spectrum of Tb3+ ion. The energy transfer from Ce3+ and Tb3+ in Sr3Gd(PO4)3 host was demonstrated to be resonant type via a dipole–dipole interaction mechanism with the energy transfer critical distance of 1.87 nm. Furthermore, Sr3Gd(PO4)3:Ce3+,xTb3 can be systematically tuned to generate blue light to yellow–greenish light under UV excitation. It can serve as a potential color-tunable UV phosphor for white-light LED (w-LEDS) devices.

► The spectral overlap between Ce3+ and Tb3+ supports there is ET from Ce3+ to Tb3+.
► Sr3Gd(PO4)3:Ce3+,Tb3+could be excited by UV light and exhibited green emission.
► Decay times are estimated to be 43–8 ns for Ce3+ in Sr3Gd(PO4)3:Ce3+,Tb3+.
► The ET is a dipole–dipole interaction mechanism in Sr3Gd(PO4)3:Ce3+,Tb3+.