High temperature stability of Eu2+-activated nitride red phosphors

Abstract The novel nitride-based luminescent materials have received much attention since the end of the last century. In this paper, the commercial Eu 2+ -activated nitride red phosphors, Sr 1.95 Si 5 N 8 :Eu 0.05 , Sr 1.85 Si 5 N 8 :Eu 0.15 and Ca 0.99 AlSiN 3 :Eu 0.01 phosphors were annealed at different temperatures (beyond 300 °C) to investigate the dependence of their luminescence performance and structure variability on the temperature. By photoluminescence spectra, X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TG-DSC) analysis, the high temperature stability of the hosts and activator of the three samples were disclosed. With the annealing temperature increasing, the activator Eu 2+ ions were firstly oxidized and then host in Sr 1.95 Si 5 N 8 :Eu 0.05 and Sr 1.85 Si 5 N 8 :Eu 0.15 , but for Ca 0.99 AlSiN 3 :Eu 0.01 , only the oxidation of the host could be observed, which would lead to the luminescence degradation and even failure of these phosphors. The activator Eu 2+ ions were much more stable in CaAlSiN 3 :Eu than Sr 2 Si 5 N 8 :Eu due to their crystal surroundings, and its concentration also influenced the temperature stability of Sr 2 Si 5 N 8 :Eu.