Tunable SrAl2Si2O8: Eu phosphor prepared in air via valence state-controlled means

Abstract

SrAl2Si2O8: xEu (x=0.5–8%) phosphors were prepared by the high-temperature solid-state reaction in air atmosphere. The phenomenon of Eu2+/Eu3+ coexistence was observed and the color of the SrAl2Si2O8: xEu phosphor could shift from light pink to blue by controllable and reproducible means. Photoluminescence (PL), excitation (PLE) spectra, X-ray photoelectron spectroscopy (XPS), and the fluorescence decay curves were employed to detect the presence of Eu2+ and Eu3+ ions in the compound. Under ultraviolet excitation, the broad band emission peaked at 410nm originated from the transition of 4f65d–4f7 from Eu2+ and narrow band emissions peaked at 591nm, 614nm, 655nm, and 703nm are derived from the 4f–4f transition of Eu3+ ions, although the Eu3+ precursors were employed. The reduction mechanism from Eu3+ to Eu2+ in this compound was discussed in detail and verified by photoluminescence properties through changing the addition amount of Eu, temperature rise and holding time.