Development of two novel Eu²⁺-activated phosphors in the Na-Sc-Si-O system and their photoluminescence properties

Two novel Eu²⁺-activated phosphors in the Na-Sc-Si-O system were developed in this study, NaScSi₂O₆:Eu and Na ₃ScSi₃O₉:Eu. NaScSi₂O ₆:Eu²⁺ showed yellow emission with a peak at 555 nm under excitation at 220-430 nm. When flux-treatment was performed for NaScSi ₂O₆:Eu²⁺, we found the existence of a new phase. We then succeeded in synthesis of a high-purity sample of this new compound by a parallel solution synthesis method. It was revealed that the new phase was Na₃ScSi₃O₉ with isostructure to Na₃YSi₃O₉, and Eu²⁺-activated Na₃ScSi₃O₉ exhibited photoluminescence. Na ₃ScSi₃O₉:Eu showed green emission with a peak at 530 nm and a corresponding broad excitation band up to 500 nm. However, photoluminescence of Eu²⁺ was negligible for Na₃YSi ₃O₉:Eu because of the stabilization of Eu³⁺ at the Y³⁺ site.