Triboluminescence and long-lasting phosphorescence of alkaline-earth metal aluminate polycrystals doped with rare-earth elements

Abstract

Long-lasting phosphorescent BaAl₂O₄:Eu²⁺, Dy³⁺, SrAl₂O₄:Eu²⁺, Dy³⁺ and CaAl₂O₄:Eu²⁺, Nd³⁺ polycrystals were prepared by the solid-state reaction. The polycrystalline samples of BaAl₂O₄:Eu²⁺, Dy³⁺ and SrAl₂O₄:Eu²⁺, Dy³⁺ exhibit intence triboluminescence, while CaAl₂O₄:Eu²⁺, Nd³⁺ polycrystals never show the triboluminescence. BaAl₂O₄ is a piezoelectric crystal, while CaAl₂O₄ is not a piezoelectric crystal. This suggests that the triboluminescence in these materials is produced by piezoelectricity.