Characteristics of Eu²⁺-doped Ca-α-SiAlON phosphor powders prepared by spray pyrolysis process

Eu²⁺-doped Ca-α-SiAlON phosphor powders with fine size and regular morphology were prepared by combining spray pyrolysis and the carbothermal reduction and nitridation processes. The precursor powders were prepared by spray pyrolysis from the spray solution with ethylenediaminetetraacetic acid, citric acid, and sucrose; they had large sizes, were hollow, and had thin wall structures. The precursor powders containing a carbon component turned into Ca-α-SiAlON phosphor powders after firing at 1450 °C under a H₂/N₂ mixture gas. The mean size of the phosphor powders was 5.1 μm. The phosphor powders had a broad excitation spectra range of 250-500 nm; this consisted of two broadbands centered at 305 and 400 nm. When excited by a 455-nm blue light, the emission spectra of the phosphor powders displayed a broadband in the range of 500-700 nm, which resulted in a yellow emission. The wavelength of the emission spectrum showing the maximum intensity was 576 nm.