In situ investigation of Ba-substitution effect on the Eu3+→Eu2+ conversion in SrAl2O4:Eu phosphor

SrAl2O4 is one of the most investigated phosphors for long lasting phosphorescence, mainly when activated with Eu2+ ions. Usually Eu2+ is obtained by the Eu3+ reduction during the material synthesis under a reducing atmosphere, such as H2 for example. In this paper, we investigated the effect of substituting Sr for Ba on the SrAl2O4:Eu2+ phosphor obtained by sol-gel route based on polyvinyl alcohol (PVA). Our results showed that SrAl2O4:Eu2+ phosphor obtained by this method presents higher Eu3+→Eu2+ conversion degree than samples obtained by the proteic sol-gel route, which was based on coconut water. Also, we observed that Ba-substitution does not change the temperature in which Eu3+ starts converting into Eu2+, which occurs between 700 and 800 °C. However, the Ba inclusion reduces the Eu3+→Eu2+ conversion.