The effect of the porosity on the Al2O3-YAG:Ce phosphor ceramic: Microstructure, luminescent efficiency, and luminous stability in laser-driven lighting

Solid-state laser lighting (SSL) fabricated by integrating laser diode with phosphor is a new development to achieve high luminance. Because of the high temperature caused by the laser, the phosphor-conversion apparatus is demanded to possess excellent thermal properties. In this paper, we utilized spark plasma sintering (SPS) to prepare the Al2O3-YAG:Ce phosphor ceramics with outstanding performances. Due to the high thermal conductivity and high transmittance, a high saturation input power (32 W/mm2) can be achieved for the sample with the lowest porosity. The correlated color temperature (CCT) and color rendering index (CRI) of composite ceramics with the lowest porosity are stable as the input power increases from 0.7 W/mm2 to 30.8 W/mm2. Nevertheless, the sample with the highest porosity shows the highest luminescence efficiency (305 lm/W) and luminous emittances (1796 lm/mm2), which can be ascribed to the scattering of the pore. •The Al2O3-YAG:Ce ceramics with different porosity were prepared.•The relationship between the luminous efficiency and the porosity is studied.•A stable CCT and CRI can be obtained for the ceramic with the low porosity.