Structural and electronic properties of SrAl2O4:Eu2+ from density functional theory calculations

• Persistent phosphor SrAl2O4:Eu2+ was synthesized and studied.
• Ab initio calculations of its electronic properties were performed.
• Lowest position of the Eu 4f states in the band gap was determined.
• Position of the Eu 4f states agrees with the charge transfer transition.

A stoichiometric micro-sized powder SrAl2O4:Eu2+ was synthesized by traditional solid state reaction at 1250 °C. Low-temperature spectroscopic measurements revealed two luminescence bands at 450 nm and 512 nm; their origin was discussed. Theoretical calculations of the structural and optical properties of SrAl2O4:Eu2+ in the framework of the density functional theory (DFT) were carried out; the obtained results were compared with the corresponding experimental data. For the first time, the position of the lowest 4f states of Eu in the host’s band gap was calculated for both available Sr positions to be at about 4.5–5 eV above the top of the valence band. Reliability of this result is confirmed by good agreement with the experimental value of the O(2p)–Eu(4f) charge transfer energy, which is equal to about 4.9 eV.

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