Preparation of SrAl 2 O 4 : Eu 2+ , Dy 3+ Powder by Combustion Method and Application in Anticounterfeiting.

Green emitting long afterglow phosphor SrAl₂O₄: Eu²⁺, Dy³⁺ was synthesized via the combustion method. The physical phase analysis was carried out by X-ray diffraction, the results show that the introduction of Eu²⁺ into the lattice of the matrix resulted in a broad green emission centered at 508 nm, which is ascribed to the characteristic 4f⁶5d¹ to 4f⁷ electronic dipole allowed transition of Eu²⁺ ions. The doping of Eu²⁺ and Dy³⁺ did not change the physical phase of the crystals. Dy³⁺, as a coactivator, does not emit light itself, but can generate holes to form a trap energy level, which acts as an electron trap center to capture some of the electrons generated by the excitation of Eu²⁺. After excitation has ceased, let them gradually to transfer to the ground state for long afterglow luminescence. Then, we investigate the optical characterizations of different samples excited by X-ray. We found that SrAl₂O₄: Eu²⁺, 0.5% Dy³⁺ has this higher luminous intensity and afterglow. Its fluorescence lifetime is about 720 ns, and its quantum yield can reach 15.18%. Through search engine marketing (SEM) and energy dispersive X-ray spectroscopy (EDX), it has been proved that the sample has been successfully synthesized and its component content has been confirmed. The Eg value calculated from the diffuse reflectance spectrum is 4.61eV. The prepared SrAl₂O₄: Eu²⁺, Dy³⁺ luminescent powder is combined with Polydimethylsiloxane substrate for anticounterfeiting application, which provides a novel idea and method for the development of the anticounterfeiting field. [ABSTRACT FROM AUTHOR]