Effect of Mg and Ti doping on the luminescence of Y2O2S:Eu

The Y₂O₂S:Eu³⁺,Mg²⁺,Ti^IV (x_Eu = 0.028, x_Mg = 0.086, x_Ti = 0.03) materials were prepared with the flux fusion method. According to X-ray powder diffraction, the materials had the hexagonal crystal structure. The emission of Y₂O₂S:Eu³⁺,Mg²⁺,Ti^IV was centered at 627 nm (λ_exc : 250 nm) due to the ⁵D₀ → ⁷F₂ transition of Eu³⁺. The excitation spectra (λ_em : 627 nm) showed broad bands at 240 and 320 nm due to the O²⁻ → Eu³⁺ and S²⁻ → Eu³⁺ charge transfer transitions, respectively. The latter band can also overlap with the Ti → Eu³⁺ energy transfer. In the excitation spectra with synchrotron radiation, in addition to the O²⁻ → Eu³⁺ and S²⁻ → Eu³⁺ charge transfer transitions, excitation over the band gap was observed at 4.8 eV (258 nm). The red persistent luminescence due to the ⁵D₀ → ⁷F₂ emission from Eu³⁺ residing in the regular Y³⁺ site of the host was ca. 10 min with 1 min fluorescent lamp irradiation. In addition, a very broad band was observed at 600 nm probably due to the Ti³⁺ emission.