Photoluminescent properties and Judd-Ofelt analysis of Eu3+-doped NaMg(PO3)3 red phosphor

A series of novel red-emitting Na1-xMg(PO3)3: xEu3+ phosphors were successfully synthesized using the high-temperature solid-state method. The crystal structure, photoluminescence spectra, decay lifetime and quantum efficiency of the phosphors were investigated as a function of Eu3+ concentration. A dominant red emission peak centered at 612 nm along with an intense 5D0→7F4 transition at 699 nm indicates that Eu3+ occupies low symmetry sites in NaMg(PO3)3 host lattice, which was confirmed by Judd-Ofelt analysis. The crystallographic site-occupations of Eu3+ were investigated by the site-selective excitation and emission spectra in the 5D0→7F0 region, which indicates that Eu3+ ion in NaMg(PO3)3 prefers to occupy the crystallographic site of C3 symmetry. The emission intensity is closely dependent on Eu3+ concentration with critical concentration of 8 mol%. NaMg(PO3)3: Eu3+ phosphor exhibits good thermal stability (67.2% at 473 K).