Tunable Color of Eu ²⁺ / Mn ²⁺ Coactivated Na ₅ Ca ₂ Al ( PO ₄ ) ₄ via Energy Transfer

Abstract

Eu 2+ and Eu 2+ / Mn 2+ ‐activated Na 5 Ca 2 Al ( PO 4 ) 4 phosphors have been synthesized by the combustion method. X‐ray powder diffraction profiles, luminescence spectra, chromaticity variation, and energy transfer of Na 5 Ca 2 Al(PO 4 ) 4 :Eu 2+ , Mn 2+ were investigated as a function of the Eu 2+ and Mn 2+ concentrations in Na 5 Ca 2 Al ( PO 4 ) 4 . The Na 5 Ca 2 Al ( PO 4 ) 4 : Eu 2+ , Mn 2+ phosphors can be effectively excited at wavelength ranging from 300 to 430 nm, which matches well with that for near‐ultraviolet ( UV ) light‐emitting diode ( LED ) chips. Under excitation at 354 nm, Na 5 Ca 2 Al ( PO 4 ) 4 : Eu 2+ , Mn 2+ not only exhibits blue‐green emission band attributed to 4 f 6 5 d 1 →4 f 7 of Eu 2+ but also gives an orange emission band attributed to 4 T 1 → 6 A 1 of Mn 2+ . The emission color of the phosphor can be systematically tuned from blue‐green through white and eventually to orange by adjusting the relative content of Eu 2+ and Mn 2+ through the principle of energy transfer. The results indicated that Na 5 Ca 2 Al ( PO 4 ) 4 : Eu 2+ , Mn 2+ may serve as a potential color‐tunable phosphor for near UV white‐light LED .