Composite Al2O3-Ce:LuAG Phosphor Ceramics with High Luminous Efficacy and Thermal Conductivity for High-Brightness Laser Lighting

HighlightsHigh sintering activity Al2O3-Ce:LuAG nanopowders were prepared via a co-precipitation method.Ceramics vacuum-sintered at 1750 °C for 10 h exhibited excellent thermal stability (I450K/IRT= 96%).The thermal conductivity of the “1750 °C × 10 h” sample was 15.6 W·m−1·K−1at room temperature.Al2O3particles are uniformly dispersed in the Ce:LuAG matrix.Luminous efficacy reached 286 lm/W, with a saturation threshold at 18 W·mm−2.Despite the success of using Al2O3as a secondary phase in Ce:LuAG phosphor ceramics (PCs), there is still room for improvement in the compositional design of biphasic PCs, as well as in their luminescent and thermal performance. In this study, nanopowders with 40 wt.% Al2O3-0.4at.% Ce:LuAG stoichiometry were synthesized via a co-precipitation approach. Subsequently, a series of compositionally uniform PCs was successfully fabricated by adjusting the vacuum sintering temperature and dwelling time. The grain size distributions of the Al2O3and LuAG phases, as well as the evolution of porosity and pore size, were systematically analyzed and correlated with the sintering conditions. The addition of Al2O3has been demonstrated to enhance the thermal properties of ceramics. The thermal conductivity of the “1750 °C × 10 h” sample was 15.6 W·m−1·K−1at room temperature. Concurrently, it exhibited excellent thermal quenching behavior, retaining 96% of its luminescence intensity upon heating to 450 K. Its fluorescence lifetime was determined to be 21.06 ns. Under 450 nm laser excitation, the optimized PC attained a luminous efficacy of 286 lm·W−1at 1 W·mm−2. In addition, the luminous flux increased continuously with laser power from 1 to 20 W·mm−2without any sign of saturation, reaching a maximum of 2500 lm. The findings indicate that biphasic 40 wt.% Al2O3-0.4at.% Ce:LuAG PCs have potential as high-flux, green-color converters for next-generation high-power laser lighting. Furthermore, a laser illumination prototype device incorporating 40 wt.% Al2O3-0.4at.% Ce:LuAG ceramic samples and a 10 W blue laser was constructed. This device emits white light with an illumination range exceeding 500 m, thereby demonstrating its potential applications in laser-driven lighting.