Tunable Blue–Red Emission and Energy‐Transfer Properties of Mg3(PO4)2:Eu2+,Mn2+ Phosphors

Abstract A series of Eu 2+ ‐doped and Eu 2+ /Mn 2+ ‐codoped Mg 3 (PO 4 ) 2 phosphors were synthesized by the combustion‐assisted synthesis method. Under UV excitation, Mg 3 (PO 4 ) 2 :Eu 2+ presents a broad emission band, which can be decomposed into two symmetrical bands centered at λ = 427 and 467 nm, owing to the substitution of two kinds of Mg 2+ sites by Eu 2+ ions. In Mg 3 (PO 4 ) 2 :Eu 2+ ,Mn 2+ phosphors, the excitation spectra monitored at the red emission of the Mn 2+ ions is similar to that monitored at the blue emission of the Eu 2+ ions, which illustrates the possibility of energy transfer from the Eu 2+ ions to the Mn 2+ ions. The variations of the emission spectra and decay lifetimes further demonstrate the existence of energy transfer from the Eu 2+ ions to the Mn 2+ ions under UV excitation. The energy‐transfer mechanism is dominated by electric dipole–dipole interactions, which can be validated by the agreement of the critical distances obtained from the concentration‐quenching (9.69 Å) and spectrum‐overlap methods (8.04 Å). The 4 T 1 → 6 A 1 emission band of the Mn 2+ ions in Mg 3 (PO 4 ) 2 :0.04Eu 2+ , y Mn 2+ shows a redshift as a function of the Mn 2+ concentration ( y ), which has been discussed in relation to the exchange interactions between Mn 2+ –Mn 2+ pairs.