Persistent luminescence of Eu and Dy doped barium aluminate (BaAl2O4:Eu,Dy) materials

Polycrystalline Eu²⁺ and Dy³⁺ doped barium aluminate materials, BaAl₂O₄:Eu²⁺,Dy³⁺, were prepared with solid state reactions at temperatures between 700 and 1500 °C. The influence of the thermal treatments on the stability, homogeneity and structure as well as to the UV-excited and persistent luminescence of the materials was investigated by X-ray powder diffraction, SEM imaging and infrared spectroscopies as well as by steady state luminescence spectroscopy and persistent luminescence decay curves, respectively. The IR spectra of the materials prepared at 250, 700, and 1500 °C follow the formation of BaAl₂O₄ composition whereas the X-ray powder diffraction of compounds revealed how the hexagonal structure was obtained. The morphology of the materials at high temperatures indicated important aggregation due to sintering. The luminescence decay of the quite narrow Eu²⁺ band at ca. 500 nm shows the presence of persistent luminescence after UV irradiation. The dopant (Eu²⁺) and co-dopant (Dy³⁺) concentrations affect the crystallinity and luminescence properties of the materials.