Stabilization of moisture-reactive raw materials for improved synthesis of Ca-α-SiAlON:Eu2+ phosphor

• The moisture-reactive starting materials of Ca-α-SiAlON:Eu2+ were stabilized.
• Preheated materials exhibited significantly enhanced resistance against oxidation.
• Preheating process prevented compositional change out of single α-SiAlON region.
• Oxygen contamination deteriorated PL intensity and particle homogeneity.
• In case of high m-value and λexc > 460 nm, preheating effects were more conspicuous.

The raw materials needed to make the Ca-α-SiAlON:Eu2+ phosphor contain highly moisture-reactive Ca3N2. Exposing them to a preheating process prior to high-temperature synthesis stabilized the raw materials against oxidation. Preheating above 1200 °C in a tube furnace directly connected to a glove box, resulted in the formation of intermediate phases such as CaAlSiN3, which provided higher moisture resistance to the raw materials. We found that even after exposure to a humid environment, the preheated samples maintained PL characteristics similar to the conventional unexposed samples, while the PL intensity and particle homogeneity of the un-preheated samples were severely deteriorated.

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