Photoluminescence of Eu³⁺ activated Ba₂SnO₄ under ultraviolet–vacuum ultraviolet excitation

A novel red emitting phosphor, Eu³⁺-doped Ba₂SnO₄, has been synthesized by solid-state reaction. Photoluminescence (PL) excitation spectrum of Ba₂Sn_0.925Eu_0.075O₄ shows the strongest broad band from 220 to 280 nm due to the charge transfer (CT) band of Eu³⁺–O2⁻, and the band centered at 180 nm could be caused by the CT band of Ba²⁺–O2⁻. The band (110–130 nm) could be attributed to SnO₆8⁻ octahedron band absorption. It is found that under 254 nm excitation, Ba₂Sn_1−xEu_xO₄ (0.025 ≤ x ≤ 0.125) exhibits a strong emission at around 592 nm, and with the increase in Eu³⁺, the phosphors present orange to red luminescence due to the decreasing of the site symmetry of Eu³⁺. The maximum PL intensity has been obtained for 7.5 mol% concentration of Eu³⁺ in Ba₂SnO₄. On the other hand, under 147 nm excitation, the phosphors do not emit effectively because of inefficient absorption in vacuum ultraviolet (VUV) region.