11:15 〜 11:30
▲ [14a-A35-9] Preparation of CaAlSiN3:Eu2+ Phosphor Ceramics
キーワード：luminescent ceramics, laser lighting, phosphor
As a blue-light excitable and efficient red phosphor, CaAlSiN3:Eu2+ plays a major role in high color rendering white light-emitting diodes (wLEDs) or wide color gamut LED backlights, but it cannot be used in high-power blue laser diode-driven displays and lighting due to the low thermal performance of the phosphor/silicone resin mixture. To apply CaAlSiN3:Eu2+ in solid state laser lighting devices, a bulk ceramic form is thus required to suffer from thermal attacks and high-flux density irradiation. However, the preparation of highly dense CaAlSiN3:Eu2+ luminescent ceramics still remains an unsolved great challenge due to the intrinsic low diffusion rate and high vapor pressure of the nitride host. Here, for the first time, optically translucent CaAlSiN3:Eu2+ ceramics with an interesting composite microstructure, where red-emitting phosphor particles with a core-shell structure are uniformly embedded in a non-luminescent α-Sialon matrix, are successfully synthesized by using Si3N4 and SiO2 as sintering additives. The luminescence ceramic is superior to the corresponding powder phosphor in terms of enhanced thermal stability (15% increase at 300°C) and thermal conductivity (4 Wm-1K-1). It has a high external quantum efficiency of 60% (87% of the powder phosphor) upon 450 nm excitation, and a luminous efficiency of 10.6 lmW-1 when irradiated under a blue laser flux density of 0.75 Wmm-2. The red-emitting translucent CaAlSiN3:Eu2+ ceramic is thus supposed to be a potential color converter for use in emerging laser lighting and display technologies.