Highly Transparent Lu‐α‐SiAlON

Abstract

Novel Lu‐α‐SiAlON ceramics were produced by hot pressing mixtures of Si 3 N 4 , Lu 2 O 3 , AlN, and Al 2 O 3 at 1950°C for 2 h in a nitrogen atmosphere. The resultant SiAlON was fully dense and possessed a uniform, equiaxed microstructure with a grain size of ∼1 μm, which resulted in a high hardness of >19 GPa. In addition to high hardness, the sample showed very high optical transparency in the visible light region, with >70% transmission at higher wavelengths. This high transparency was attributed to the uniform, dense microstructure and lack of residual grain‐boundary phase.