Luminescence properties and energy transfer of a red-emitting Ca3 (PO4)2:Sm3+, Eu3+ phosphor

Abstract

A series of Sm3+, Eu3+ and Sm3+–Eu3+ doped Ca3(PO4)2 were prepared by a high temperature solid-state method. Their luminescent properties were studied by photoluminescence emission, excitation spectra and decay curves. Under excitation with a wavelength at 403 nm, Ca3(PO4)2:Sm3+ emits red–orange light, and the dominated peak situates at 602 nm which is due to the 4G5/2 → 6H7/2 transition of Sm3+. Ca3(PO4)2:Eu3+ produces red light under the 394 nm excitation, and the strongest peak centers at 613 nm, which is assigned to 5D0 → 7F2 transition of Eu3+. The energy transfer from Sm3+ to Eu3+ in Ca3(PO4)2 host has been studied and demonstrated to be a resonant type via a dipole–quadrupole interaction mechanism. The critical distance of Sm3+–Eu3+ in Ca3(PO4)2 is calculated to be 13.5 A. With the increase of Eu3+ doping content, the energy transfer efficiency (Sm3+ → Eu3+) obtained from decay curves gradually increases to 30.7 %. Moreover, the emitting color of Ca3(PO4)2:Sm3+, Eu3+ can be tuned by appropriately adjusting the relative doping composition of Sm3+/Eu3+.