Investigation of the phosphorescence, persistent decay and structure properties of Eu2+: strontium aluminate doped with Nd3+, B3+ or Dy3+

Luminescent sources based on crystalline materials doped with transition metal or rare-earth cations are known as persistent phosphors, and they can continue to emit light even after the excitation source has disappeared. The present study aims to prepare strontium aluminate with varying weight percentages of Eu²⁺, RE³⁺ (RE = Dy³⁺, Nd³⁺, or B³⁺) oxides by the solid-state preparation followed by firing under active carbon at 1250 °C.The produced phosphors were examined using FTIR spectroscopy, mechano-luminescent measurement, scanning electron microscopy (SEM), and X-ray diffraction (XRD). A bulk density and apparent porosity measurement was also used to assess the impact of the firing temperature at 1250 °C. Photoluminescence characteristics were examined concerning the kind of trivalent oxides doped in strontium aluminate. The results showed that for samples containing 0.15 weight% of Eu₂O₃ and 0.15 weight% of RE₂O₃, SrAl₂O₄ formed with Eu^{+ 2}, RE³⁺ as a single phase. However, RESr₂AlO₅ was formed together with a minor amount of SrAl₂O₄ when the Eu₂O₃ contents decreased at the expense of the RE₂O₃ contents. Additionally, it was observed that the Eu³⁺ was converted into Eu²⁺ for every sample. Every sample had porous behavior, and the bulk density was increased by the inclusion of RESr₂AlO₅ in addition to SrAl₂O₄. Transitions from the 4f⁶ and 5d¹ configurations of the emission center (Eu²⁺ ions) to the 4f⁷ configuration result in a broad band at peaks of 517 nm in the emission spectra of all the samples. Samples containing RESr₂AlO₅ exhibit high phosphor color characteristics, forming red-orange phosphors encircled by green phosphor rings. Compared to samples containing Nd₂O₃ and B₂O₃, those containing Dy₂O₃ phosphor have the highest decay time values.