Cost-effective synthesis of Ca-α-sialon:Eu2+ phosphors by a direct silicon nitridation route

The direct silicon nitridation method was used to synthesize Ca-α-sialon:Eu2+ phosphors. From a low cost CaCO3–AlF3–Si mixture, pure α-sialon phase was produced at a low temperature of 1250 °C. The crystallinity of the obtained phosphors can be markedly improved by increasing the firing temperature or post-annealing. Solid–gas reactions occur easily, according to thermodynamic analysis, leading to loss of silicon and enhancing the replacement of Sisingle bondN bonds by Alsingle bondN bonds. The produced Ca-α-sialon:Eu2+ phosphors feature high purity, uniform and discrete particle morphology with a particle size of 1–2 μm and good luminescence properties with a yellow emission that peaks at 580 nm under n-UV or blue light excitation.