Fabrication of transparent Y 2 O 3 ceramics by two‐step spark plasma sintering

Transparent Y 2 O 3 ceramics were successfully fabricated by spark plasma sintering applying a two‐step pressure and heating profile. Through the shrinkage curve of the single‐step SPS profile, it was confirmed that shrinkage occurred at 800°C–1250°C, and it was selected as the two‐step pressure profile. After the first‐step SPS stage at 1250°C, the second‐step SPS stage, which had the highest real in‐line transmittance, was completed at 1500°C. The two‐step SPS profile improved the shrinkage behavior and was able to achieve sufficient densification without excessive coarsening. As a result, the normalized real in‐line transmittance to 1 mm was 80.6% at 1100 nm, which is close to the theoretical transmittance of 81.6%. The two‐step pressure and heating profile in the SPS process was a significant advantage in manufacturing ceramics that were transparent and had sufficient densification.