Characteristics of α′- and β-Sr2SiO4:Eu2+ phosphor powders prepared by spray pyrolysis

α′- and β-Sr2SiO4:Eu2+ phosphor powders were prepared by spray pyrolysis from the spray solutions with and without NH4Cl flux. The phosphor powders prepared from the spray solutions with the addition amount of NH4Cl flux between 2 and 5 wt% of phosphor had regular polyhedron structures and main crystal structure of β-Sr2SiO4. On the other hand, the phosphor powders prepared from the spray solution with high addition amount of NH4Cl flux as 6 wt% of phosphor had irregular morphology and crystal structure of α′-Sr2SiO4. The mean size of the β-Sr2SiO4 phosphor powders with regular polyhedron structure was 5.2 μm. The β-Sr2SiO4:Eu2+ phosphor powders had higher photoluminescence intensities than the α′-Sr2SiO4:Eu2+ phosphor powders. The β-Sr2SiO4:Eu2+ phosphor powders prepared from the spray solution with 5 wt% NH4Cl flux of phosphor had the maximum photoluminescence intensity. The wavelengths of the emission spectra showing the maximum peak intensities changed from 543.2 to 561.8 nm when the addition amount of NH4Cl flux was increased from 2 to 6 wt% of phosphor.