Luminescence thermal stability improvement mechanism of Ba2SiO4: Eu2+ with Mg2+ cation substitution

Ba₂SiO₄: Eu is a most attractive phosphor for its high luminescent intensity. However, the luminescence thermal stability should be further improved for the lighting/displaying application. In this work, Ba₂SiO₄:Eu²⁺ luminescence thermal stability had increased after Mg²⁺ cation substitution. The mechanism has then been explored. The improvement is associated with a larger Edc (Energy gap between the relaxed lowest 5d level and the bottom of the conduction band). Based on Dorenbos ionization quenching model, the bigger Edc means the bigger ∆E (luminescence thermal quenching barrier). The density functional theory calculation and photoluminescent spectra show a smaller Edf (Energy for Eu²⁺4f⁶5d→4f⁷ electronic transition) after Mg²⁺ substitution, which leads to a smaller Edc (Edc=Eg-Ef-Edf). The work provides a new strategy for improving luminescence thermal stability, and also gives a theoretical/experimental explanation.