Crystal structure and photoluminescence of (Ba _(1-x-y)Sr _yEu _x) _9Sc _2Si _6O _(24)

摘要

Divalent europium-doped alkaline earth metal silicate phosphors, (Ba _(1-x-y)Sr _yEu _x) _9Sc _2Si _6O _(24) (x=0.005-0.1, y=0-0.95), have been successfully prepared by solid-state reaction at 1350 °C. The analysis of X-ray diffraction shows that the compounds are in a single phase at the proper concentration of Sr ~2. At room temperature, the Eu ~(2+)- activated Ba _9Sc _2Si _6O _(24) phosphor exhibits a single emission band peaking at about 506 nm. With the increasing content of Sr ~2, the luminescent intensity of (Ba _(1-x-y)Sr _yEu _x) _9Sc _2Si _6O _(24) weakens, and the emission peak shifts towards red. Luminescence concentration quenching occurs when Eu ~(2+) content x is more than 1 mol in (Ba _(1-x-y)Sr _yEu _x) _9Sc _2Si _6O _(24) (y=0/0.2). At low temperatures (Ba _(0.9-y)Sr _yEu _(0.1)) _9Sc _2Si _6O _(24) (y=0/0.2) phosphors have two emission bands corresponding to different Eu ~(2+) crystallographic sites. The high energy peak (P _1) is quenched at room temperature, while the low energy peak (P _2) weakens much more slowly owing to the energy transfer from P _1 to P _2.