Fabrication of Transparent Lanthanum‐Doped Yttria Ceramics by Combination of Two‐Step Sintering and Vacuum Sintering

A new strategy for the sintering of transparent lanthanum‐doped yttrium oxide was presented. This method is the extension of the well‐accepted two‐step sintering process for the densification of nanomaterials. The samples were firstly sintered at an intermediate temperature T1 (1450°C) in air. Then the temperature decreased quickly to a lower point T2 (900°–1100°C) in air and held for more than 20 h in order to facilitate densification with limited grain growth. Nanocrystalline yttria ceramic with a high relative density was then obtained, which can be further densified at higher temperature T3 (>1700°C) in vacuum. After sintering, transparent yttria doped with 10% lanthanum ceramic was obtained with the grain size around 25 μm without annealing. The samples were densified mainly in air at low temperature, it is more easy for operation. The transmittance at 580 nm is 77%, which was equal or better than that from other sintering method for transparent yttria ceramics.