The Bond-Energy Method in Site Occupancy and Property of High Concentration Eu³⁺ in Sr₂CeO₄ Phosphors

The low concentration of Eu³⁺ doped Sr₂CeO₄ phosphors has been widely studied in recent years and in this paper, we researched the properties of high concentration Eu³⁺ doped in Sr₂CeO₄. The Sr₂Ce_(1-Eu_4- (x = 0, 1%, 10%, 20%) phosphors were obtained by traditional solid-state reaction. Photoluminescence (PL) spectra are characterized the property of samples. PL spectra illustrate that the concentration of Eu³⁺ increased, the intensity of ⁵D₀-⁷F₁, ⁵D₀-⁷F₂ increased and intensity of Sr₂CeO₄ host emission intensity was decreased. The phenomenon can be ascribed to the energy transfer from Ce⁴⁺ to Eu³⁺. When the concentration of Eu³⁺ is 20%, the completely red emission can be obtained even if no other ions are doped under the excitation wavelength of 350 nm, it is proved that Eu³⁺ occupied Ce sites rather than Sr site in Sr₂CeO₄ samples. The conclusion we make is due to the value of |ΔE^Eu_Ce-O| and |ΔE^Eu_Sr-O| calculated by bond-energy method, the smaller the value, the easier it is for the doped ions Eu³⁺ to enter the site.