Densification and optical properties of transparent Ho:YAG ceramics

Transparent Ho:YAG ceramics were successfully fabricated from commercial γ-Al2O3, Ho2O3 and Y2O3 powders by the solid-state reactive sintering method. The powders were mixed in ethanol with 0.5 wt.% tetraethyl orthosilicate (TEOS) added as a sintering aid. The milled slurry was dried and pressed, then sintered from 1650 to 1750 °C for up to 20 h for all Ho3+ levels studied (0.3–2.5 at.%). The densification, microstructure evolution, and optical properties of Ho:YAG ceramics were investigated. Specimens sintered at 1700 °C for 12 h were fully dense with an over 80% transmittance in the visible region. The grain boundary was clean and no secondary phase was observed.

► Commercial γ-Al2O3, Ho2O3 and Y2O3 powders were used as raw materials.
► Ho:YAG transparent ceramics got an average transmittance of above 80%.
► The grain boundary was clean and no secondary phase was observed.