Luminescent properties and energy transfer of orange-emitting phosphor Ca10Na(PO4)7: Eu2+, Mn2+ for NUV LEDs

Color-tunable Ca10Na(PO4)7: Eu2+, Mn2+ phosphors were firstly synthesized via high-temperature solid-state method. At 350 nm NUV excitation, Ca10Na(PO4)7: Eu2+, Mn2+ emits a broad yellow band and a intense red band, which nearly covers the entire visible region. The mechanism of Eu2+ ⟶ Mn2+ energy transfer is found to be a quadrupole–quadrupole interaction, and the corresponding critical transfer distance is calculated as 8.24 Å. Emission color of Ca10Na(PO4)7: Eu2+, Mn2+ can be easily modulated from yellow to reddish-orange by adjusting the Mn2+ content. Results indicated that Ca10Na(PO4)7: Eu2+, Mn2+ might be promising for NUV LED application as an orange-emitting phosphor.