Thermal Stability Study of BaAl₂Si₂O₈:Eu²⁺ Phosphor Using Its Polymorphism for Plasma Display Panel Application

We have evaluated the thermal stability of BaAl 2 Si 2 O 8:Eu 2+ (BAS:Eu 2+ ) phosphor using its polymorph property and hexagonal and monoclinic crystal structure, depending upon firing temperature for plasma display panel application. When BAS:Eu 2+ samples having each characteristic crystal structure were baked at 500 °C in air for 30 min, the baked monoclinic BAS:Eu 2+ showed the same photoluminescence (PL) intensity as the fresh one, whereas the baked hexagonal one lost its PL intensity significantly, corresponding to about 34%. From analyses of electron spin resonance on Eu 2+ and Rietveld refinement, the difference of thermal stability between hexagonal and monoclinic BAS:Eu 2+ could be ascribed to both the crystal structure of host materials and the average interatomic distances between the Eu 2+ ion and oxygen which plays the key role of shield for Eu 2+ ions against an oxidation atmosphere.