Preparation of Ca4Mg5(PO4)6:Eu2+, Mn2+ phosphor and its photoluminescence properties

Eu2+ and Mn2+ singly doped and Eu2+/Mn2+-codoped Ca4Mg5(PO4)6 phosphors were synthesized via combustion synthesis. Mn2+-singly doped Ca4Mg5(PO4)6 phosphor exhibits a single red emission in the wavelength range of 500–700 nm due to the 4T1(4G)→6A1(6S) transition of Mn2+. Eu2+/Mn2+ co-doped phosphor emits two distinctive luminescence bands: a blue one centered at 442 nm originating from Eu2+ and a broad red-emitting one peaked at 609 nm from Mn2+. Energy transfers from Eu2+ to Mn2+ were discovered by directly observing significant overlap of the excitation spectrum of Mn2+ and the emission spectrum of Eu2+ as well as the systematic relative decline and growth of emission bands of Eu2+ and Mn2+, respectively. Based on the principle of energy transfer, the relative intensities of blue and red emission could be tuned by adjusting the contents of Eu2+ and Mn2+.