2015 年 123 巻 1441 号 p. 888-891
We have synthesized Mn4+-doped mixed tetragermanate phases in the Li2Ge4O9–LiNaGe4O9 system, i.e., Li(Li,Na)Ge4O9, by a glass-ceramic technique using stoichiometric precursor glasses, and have examined the effect of substitution of Na on their photoluminescence properties. The tetragermanate phases indicated clear red emission based on a 2E→4A2 transition, and the entire substitution resulting in an LiNaGe4O9 phase provided an improvement of quenching temperature for the emission. Furthermore, the LiNaGe4O9 phase synthesized by solid-state reaction showed a high internal quantum yield and red color purity, demonstrating it to be a possible candidate as a rare-earth-free red phosphor.