Local structure modification for identifying the site preference and characteristic luminescence property of Eu2+ ions in full-color emission phosphors Sr18Mg3(PO4)14:Eu2+

Abstract An understanding on the site preference of luminescence centers in phosphors serves as a starting point to illustrate the relationship between structure and luminescence. Till now, various methods such as theoretical calculation or modern testing techniques are employed to analyze their luminescent behavior and intrinsic mechanism. The present study proposes a local structure modification method to confirm the site occupation of Eu2+ ions in a whitlockite-type phosphor Sr18Mg3(PO4)14: Eu2+. The result shows that Eu2+ ions can not only occupy Sr2+ sites but also substitute partial Mg2+ sites in Sr18Mg3(PO4)14. Owing to this, three emission bands centered at 420 (blue), 520 (green) and 620 nm (red) are simultaneously observed upon ultraviolet light excitation, resulting in a full color emission in Sr18Mg3(PO4)14: Eu2+ phosphors. Meanwhile, the detailed structure information of Sr18Mg3(PO4)14 are renewedly evaluated and the optical spectroscopy property, decay curves and thermal quenching behavior as well as related mechanism of Sr18Mg3(PO4)14: Eu2+ are studied in detail. Finally, an ultraviolet light pumped white LED is fabricated with suitable CCT of 4663 K and high Ra of 82. The current analysis provides a deep insight into the origin of Eu2+ luminescence and its relationship with local lattice environment, which paves a new avenue to identify the site preference of luminescence centers.