Luminescence of Eu2+ Ions in CsMgPO4 Phosphor: Anomalous Emission and its Origin

Eu 2+ -doped CsMgPO 4 phosphors were synthesized by the conventional high-temperature solid-state reaction. The phase formations of the phosphors were confirmed by X-ray powder diffraction measurements. The photoluminescence excitation and emission spectra, the temperature dependent (10–300 K) luminescence intensities and the decay curves of the phosphor were measured. The Eu 2+ -doped CsMgPO 4 shows a red emission band peaking at around 650 nm from 4f 6 5d 1 →4f 7 transitions of Eu 2+ ions. The luminescence nature of CsMgPO 4 :Eu 2+ is greatly different from the other Eu 2+ doped AB PO 4 orthophosphates ( A and B are mono- and divalent cations, respectively) and is characterized by the red-shifted emission, the larger Stokes shift and a lower luminescence quenching temperature. The anomalous luminescence properties of CsMgPO 4 :Eu 2+ are ascribed to impurity trapped exciton emission.