Photoluminescence properties of Ca–α-SiAlON:Ce3+ phosphors as function of composition and microstructure

Cerium-doped Ca–α-SiAlON phosphors with Can−1.5xSi12−m−nAlm+nOnN16−n:Cex (m=2n, 0.8≤m≤2.4, and 0.02≤x≤0.40) nominal compositions have been synthesized by gas pressure sintering (GPS). The photoluminescence (PL) properties were studied in relation to phase composition, particle morphology, and microstructure. Continuous addition of Ce rare-earth (RE) could enhance the emission intensity of phosphors, which was partially attributed to the formation of increased amount of planar defects where dense doping of Ce ions is achieved. Such enhancement could hold up to x=0.32, above which the emission intensity fell slightly due to the formation of more secondary phases and a surface glassy phase rather than concentration quenching. Finally, possible ways to improve the luminescence properties of Ce-doped α-SiAlON phosphors were discussed through tailoring the composition and microstructure.