Luminescence properties and energy transfer of a red-emitting Ca_3 (PO_4)_2:Sm~(3+), Eu~(3+) phosphor

摘要

A series of Sm~(3+), Eu~(3+) and Sm~(3+)-Eu~(3+) doped Ca_3(PO_4)_2 were prepared by a high temperature solid-state method. Their luminescent properties were studied by pho-toluminescence emission, excitation spectra and decay curves. Under excitation with a wavelength at 403 nm, Ca_3(PO_4)_2:Sm~(3+) emits red-orange light, and the dominated peak situates at 602 nm which is due to the ~4G_(5/2) → ~6H_(7/2) transition of Sm~(3+). Ca_3(PO_4)_2:Eu~(3+) produces red light under the 394 nm excitation, and the strongest peak centers at 613 nm, which is assigned to ~5D_0 → ~7F_2 transition of Eu~(3+). The energy transfer from Sm~(3+) to Eu~(3+) in Ca_3(PO_4)_2 host has been studied and demonstrated to be a resonant type via a dipole-quadrupole interaction mechanism. The critical distance of Sm~(3+)-Eu~(3+) in Ca_3(PO_4)_2 is calculated to be 13.5 A. With the increase of Eu~(3+) doping content, the energy transfer efficiency (Sm~(3+) → Eu~(3+)) obtained from decay curves gradually increases to 30.7 %. Moreover, the emitting color of Ca_3(PO_4)_2:Sm~(3+), Eu~(3+) can be tuned by appropriately adjusting the relative doping composition of Sm~(3+)/Eu~(3+).