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

•Color tunable SrAl2Si2O8: xEu phosphors were prepared in air atmosphere.•The presence of Eu2+ and Eu3+ ions in this compound were detected.•The reduction mechanism from Eu3+ to Eu2+ in this compound was discussed.•The luminescence properties associated with the local surrounding of phosphor were investigated.

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 410 nm originated from the transition of 4f65d–4f7 from Eu2+ and narrow band emissions peaked at 591 nm, 614 nm, 655 nm, and 703 nm 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.

Graphical abstractA multi-color-emitting phosphor of valence-varied Eu doped SrAl2Si2O8 with the aid of incomplete reduction at air atmosphere is demonstrated and its luminescence properties can be tuned through controllable addition of doped ions and the local surrounding.Figure optionsDownload full-size imageDownload high-quality image (86 K)Download as PowerPoint slide