Synthesis, structure and luminescence of a high-purity and thermal-stable Sr9LiMg(PO4)7: Eu3+ red phosphor

Abstract Eu3+-activated Sr9LiMg(PO4)7 phosphors, which presented bright red emissions mainly from the 5D0→7F2 transition of Eu3+ ions upon the near-ultraviolet excitation, were successfully synthesized in ambient atmosphere. The crystal structure, phase constitution, photoluminescent behaviors, decay time, internal quantum efficiency and thermal stability of the resultant phosphors were investigated in detail. Eu3+ ions are found to tend to occupy multiple Sr2+ sites, which are 7, 8 and 10-coordinated. The optimal doping concentration is 7 mol% and the electrical multipolar interaction contributed to the non-radiative energy transfer between Eu3+ ions in Sr9LiMg(PO4)7 host lattices. Temperature-dependent PL spectra indicated Sr9LiMg(PO4)7: Eu3+ possess excellent emission and color stability at elevated temperature. Fabricated single-chromatic LED prototype emit bright red light under 20 mA bias current, which demonstrates that Sr9LiMg(PO4)7: Eu3+ phosphor is of great potential as converted phosphor in NUV LED application.