Vacuum-sintered Al2O3:Cr3+ transparent ceramics as cost-effective alternatives to single-crystal ruby

Al2O3:Cr3+ ruby is one of the most popular materials for lasers because it has unique optical and physical properties. How to obtain Al2O3:Cr3+ efficiently and economically remains a challenge. In this study, Al2O3:Cr3+ transparent ceramics were prepared through a traditional solid-state process in a vacuum environment. A high transmittance of 76.8% at 1200 nm, approaching that of single crystals, can be reached in the pure Al2O3 transparent ceramic. The photoluminescence, micromorphology, thermal conductivity, and mechanical characteristics of Al2O3:Cr3+ transparent ceramics were studied. A ruby with a thermal conductivity of about 38 W m−1 K−1 and a high hardness of 1859 HV was prepared. These results indicate that Al2O3:Cr3+ transparent ceramics have broad prospects to serve as a substitute for Al2O3:Cr3+ single crystals in certain fields.