Facile Fabrication of Highly Transparent Yttria Ceramics with Fine Microstructures by a Hot‐Pressing Method

In this study, we report highly transparent yttria ceramics fabricated by a facile hot-pressing method with tantalum foil shielding which effectively prevents the ceramic samples from carbon contamination caused by the graphite mold used during the process. The hot-pressed sample was already highly transparent without a post-annealing step or hot isostatic pressing. For a 2-mm-thick specimen doped with 1 at.% ZrO2, the in-line transmittance reaches 74.4% at 400 nm and 81.1% at 1100 nm. The sample shows a very fine microstructure with an average grain size of about 1 μm owing to the low sintering temperature of only 1600°C. The study results indicate that it is possible to produce transparent yttria ceramics with excellent optical transparency using the economical and convenient hot-pressing method.