Site regulation and luminescence properties of Eu3+, Eu2+ in (La, Mg):SrAl12O19 matrix.

The partially and equivalent substitution of La + Mg → Sr + Al in SrAl12O19 lattice is an effective strategy to provide trivalent sites, reduce the site occupation splitting of Al and stabilize the entire lattice. When excited by 397 nm, the Eu3+ activated La, Mg:SrAl12O19 (ASL) phosphor shows intense linear emission through the 5D0→7F4 transition at 707 nm when compared with SrAl12O19:Eu3+. Especially, the Eu, Mg co-doped Sr1-xLaxMgxAl12-xO19 with certain amount of x = 1/3 exhibits the significant intense photoluminescence, which was demonstrated through a lattice evolutional model. Eu2+ in the host with 1/3 ratio of (La, Mg) substitution shows broad blue emission and as short fluorescence lifetime as 248 ns. The temperature-depended fluorescence quenching behavior confirms the essence of strong electric-phonon coupling originated from distorted and polarized crystal field around Eu2+/Sr2+ site. Basing on site regulation of SrAl12O19 matrix, our study provides a reference for exploration on efficient rare earth ions activated luminescent laser or scintillation materials.