In this letter, a yellow oxynitride phosphor $\alpha \text{-}\mathrm{SiAlON}$ with compositions of ${\mathrm{Ca}}_{0.625}{\mathrm{Eu}}_x{\mathrm{Si}}_{0.75-3x}{\mathrm{Al}}_{1.25+3x}{\mathrm{O}}_x{\mathrm{N}}_{16-x}$ ($\mathrm{Ca}\text{-}\alpha \text{-}\mathrm{SiAlON}:\mathrm{Eu}$ , $x=0–25$ ) was prepared by gas pressure sintering. The diffuse reflection spectrum, photoluminescence spectrum, and chromaticity of the powder phosphors were presented. It absorbs light efficiently in the UV–visible spectral region, and shows a single intense broadband emission at $583–603\mathrm{nm}$ . This phosphor may become a good candidate for creating white light, typically warm white light, when coupled to a blue light-emitting diode $\left({\lambda }_{\mathrm{em}}=450\mathrm{nm}\right)$ .

Green α-sialon:Yb2+ and red Sr2Si5N8:Eu2+ oxynitride/nitride phosphors have been demonstrated as potential downconversion luminescent materials for white light-emitting diodes (LEDs). In this letter, the authors attempt to fabricate white LEDs by combining α-sialon:Yb2+ and Sr2Si5N8:Eu2+ with a blue LED die and report their optical properties. These two phosphors lend themselves for use in 2-phosphor-converted white LEDs with promising properties: a wide range of tunable correlated color temperature (2700–6700K), acceptable color rendering index (82–83), and luminous efficacy (17–23lm∕W). These LEDs are acceptable for general lighting.