Transparent Sialon phosphor ceramic plates for white light emitting diodes applications

Abstract

Wide visible light emitting Sialon phosphor ceramic plates (PCPs) have been reported for Eu2+ doped, and Gd3+ and Pr3+ co-doped systems fabricated by hot press sintering technique. The phase dependent luminescence for Eu2+ doped PCPs is also presented in this work. Intense greenish-yellow luminescence at 552 nm wavelength under blue light excitation with the highest luminous efficacy of 58.78 lm/W was observed for β-Sialon PCP. Whereas, α-Sialon phase containing PCPs with Eu2+ show orange luminescence at 590 nm wavelength under 460 nm wavelength excitation. The co-doping of Gd3+ with Eu2+ cations enhance the α-Sialon phase as well as transparency and even with a minimum content of Eu2O3 (2 wt%) shows intense orange luminescence with luminous efficacy of 46.10 lm/W which is the highest among the orange emitting PCPs. The Gd3+ co-doped with Pr3+ without Eu2+ PCP shows wide visible emission from cyan to red excited by 460 nm wavelength. Further, Gd3+and Pr3+ were co-doped with Eu2+ shows orange emission with a red shoulder emission. The PCPs coupled with 450 nm blue LED produces cool white light, day light and warm light corresponding to their phases and co-dopants.