A low sintering temperature glass based on SiO 2 –P 2 O 5 –ZnO–B 2 O 3 –R 2 O system for white LED s with high color rendering index

A low sintering temperature glass based on the SiO 2 –P 2 O 5 –ZnO–B 2 O 3 –R 2 O (R=K and Na) system was studied as a matrix for embedding phosphors to fabricate color tunable white LEDs. The proposed system, which uses no heavy‐metal elements and can be sintered at 500°C, incorporates thermally weak commercial phosphors such as CaAlSiN 3 :Eu 2+ to produce phosphor‐in‐glasses (PiGs). Changing the mixing ratio of glass to phosphors affected the photo‐luminescence spectra and color coordinates of the PiGs when mounted on a blue LED. The color rendering index (CRI) and color correlated temperature (CCT) of the LED s were also varied with the mixing ratio, providing color tunable white LED s. A high CRI , up to 93, as well as highly improved thermal stability were obtained, along with a low sintering temperature compared to other glass systems, suggesting the practical feasibility of the proposed system.