Melt synthesis of oxide phosphors with K₂NiF₄ structures: CaLa_{1− x} Eu _x GaO₄

摘要

In order to synthesize compounds of various Perovskite-related structures, we have utilized a novel “melt synthesis technique” for phosphors rather than the conventional solid state reaction techniques. The solid state reactions require multi-step processes of heating/cooling with intermediate grindings to make homogeneous samples. However, for the melt synthesis, it is possible to make a homogeneous sample in a single step within a short period of time (1–60 s) due to the liquid phase reaction in the molten samples, which were melted by strong light radiation in an imaging furnace. In this study, we have prepared a red-phosphor CaLaGaO₄:Eu3+ which has a perovskite—related layered K₂NiF₄ structure. Well-crystallized CaLa_1−x Eu _x GaO₄ samples with the K₂NiF₄ structure have been obtained up to x = 0.25, but there was the formation of an olivine phase when x = 0.5–1.0. The red emission at 618 nm increased with the increasing value of x up to x = 0.25.