Luminescence properties and energy transfer of Ce3+/Tb3+ co-doped Ca9La(PO4)5(SiO4)F2 phosphor

Emission-tunable phosphors Ca9La(PO4)5(SiO4)F2:Ce3+,Tb3+ with apatite structure were synthesized by a solid-state reaction. The phase structure, photoluminescence (PL) properties, lifetimes and the PL thermal stability were investigated, respectively. The phosphor exhibited an asymmetric broad-band blue emission (Ce3+) with peak at 403 nm and the line-type green emission with peak at 543 nm (Tb3+). The varied color of the phosphors from blue to green can be achieved by properly tuning the relative ratio of Ce3+/Tb3+ through the energy transfer from Ce3+ to Tb3+ ions. The critical distance was calculated to be 8.78 Å by using the concentration quenching method. When the temperature turned up to 150 °C, the emission intensity of Ca9La(PO4)5(SiO4)F2:Ce3+,Tb3+ phosphor was 77% of its initial value at room temperature, which indicated the good thermal stability of the sample. All the properties indicate that the Ca9La(PO4)5(SiO4)F2:Ce3+,Tb3+ phosphor has potential application of color-tunable w-LEDs.