Europium-doped SiAlON and borosilicate glass composites for white light-emitting diode

The oxynitride phosphor Ca-α-SiAlON:Eu²⁺ has a high thermal tolerance. In this study, we prepared sodium borosilicate glass [4Na₂O-56B₂O₃-40SiO₂, mol. %], and examined its ability to host Ca-α-SiAlON:Eu²⁺ phosphor powder. We successfully used a melting method to fabricate glass-SiAlON phosphor composites, which can emit yellow light when irradiated with blue light (with a wavelength of 450 nm). The chromaticity of the composites, which was estimated from photoluminescence spectra, changed from blue to yellow with increasing SiAlON concentration and sample thickness. A 3 mm thick composite with 4 mass% SiAlON and a 2 mm thick composite with 5 mass% SiAlON generated near-white light. The quantum efficiency of the composites did not depend on the SiAlON concentration and was similar to that of the phosphor powder. The PL intensity decreased with increasing temperature, but the decrease was similar to that for SiAlON powder.