Green-emissive Ce3+:Lu3Al5O12–Al2O3 nanoceramics elaborated via glass crystallization for high-power laser lighting applications

Abstract

Transparent Ce:Lu₃Al₅O₁₂ (Ce:LuAG) phosphor ceramics are regarded as the most promising green color conversion materials in the next-generation of laser diode (LD) lighting. However, the insufficient scattering of incident blue laser and poor heat quenching seriously prevent the application of transparent Ce:LuAG phosphor ceramics in high-quality LD-driven lighting, especially at high input power density. In view of this, a biphasic Ce:LuAG–Al₂O₃ green phosphor ceramic is proposed in this study. Using an excessive Al₂O₃ component design strategy, the Al₂O₃ secondary phase is in situ generated in the resulting ceramic material via the full bulk glass crystallization method. The in situ generated Al₂O₃ secondary phase can serve as a light scattering center and has good thermal conductivity. Therefore, the luminescence properties and thermal stability of transparent Ce:LuAG–Al₂O₃ phosphor ceramics are greatly enhanced compared to Ce:LuAG. An ultrahigh luminous flux (LF) of 5124.7 lm and an excellent luminous density of 4235.5 lm mm⁻² are achieved in LD-driven lighting under 450 nm high power density laser excitation (29.83 W mm⁻²), which has been almost the best performance of transparent Ce:LuAG ceramics in LD lighting to date. A maximum luminous efficiency of 247.9 lm W⁻¹ (4.38 W mm⁻²) is also obtained. These results demonstrate that the transparent Ce:LuAG–Al₂O₃ nanoceramics prepared in this work are promising green-emitting color converters to achieve high-brightness and excellent luminous density for high power LD lighting. The excessive Al₂O₃ component design strategy could also further drive the development of garnet-based transparent ceramics in the field of high-power LD lighting.