Luminescence spectroscopy and energy transfer in Eu2+/Mn2+-doped KCaPO4 phosphors

Eu2+/Mn2+-doped KCaPO4 phosphors were prepared by conventional solid-state reaction. X-ray powder diffraction (XRD), SEM, photoluminescence excitation, and emission spectra, and the luminescence decay curves were measured. Mn2+ singly doped KCaPO4 shows the weak origin-red luminescence band peaked at about 590 nm. The Eu2+/Mn2+ co-doped phosphors emit two distinctive luminescence bands: a blue one centered at 480 nm originating from Eu2+ ions and a broad red-emitting one peaked at 590 nm from Mn2+ ions. The luminescence intensity from Mn2+ ions can be greatly enhanced with the co-doping of Eu2+ ions. The efficient energy transfer from Eu2+ to Mn2+ was verified by the photoluminescence spectra together with the luminescence decay curves. The resonance-type energy transfer via a dipole-quadrupole interaction mechanism was supported by the decay lifetimes. The emission colors could be tuned by changing the Mn2+-doping concentration.