Fabrication of Al2O3GAGG:Ce composite ceramic phosphors with excellent color quality for high-power laser-driven lighting

The application of high-power laser-driven lighting is limited by the insufficient heat dissipation of phosphor converters and the poor color quality of white light. In this study, the Al2O3(Gd,Ce)3(Al,Ga)5O12 (Al2O3GAGG:Ce) composite ceramics were designed to improve thermal performance of phosphors, while maintaining excellent color rendering under high-power laser excitation. Dense composite ceramics were fabricated by pre-sintering at 1600 °C in air followed by HIP at 1700 °C through the investigation of the phase evolution and sintering process. The emission spectrum of GAGG:Ce shows a red shift of 31 nm and a high full width at half maximum (FWHM) of 128 nm. Meanwhile, the thermal conductivity was increased to 13.2 W·m−1K−1 by addition of Al2O3, which is 72% higher than that of single-phase GAGG:Ce ceramic. Therefore, warm white light with high color rendering index (CRI) of 71.4 and low correlated color temperature (CCT) of 4352 K was attained under excitation of high-power LDs.