Fabrication of stable monoclinic zirconia-based ceramics

Recently ZrO2-based ceramics gained attention due to their shape memory properties. In order to use the power of shape recovery in shape memory materials, it is essential to access the twinned low symmetry phase in the temperature regime of the desired application. However, creating stable monoclinic phase is difficult in bulk ZrO2 due to volume expansion during phase transformations after sintering. Therefore, the material is often stabilized in the tetragonal phase by addition of yttria, which leads to transformation temperatures far below room temperature. In this article, we describe the sintering temperature and time as well as pre-processing steps for a successful formation of a stable, twinned monoclinic phase at room temperature in bulk ceramic 1-x Y0.5Ta0.5O2 + x Zr0.5Hf0.5O2 (0.6 < x <= 1).

Automated summary

This article discusses the successful formation of a stable twinned monoclinic phase in ZrO2-based ceramics, as well as the impact of yttria addition and sintering conditions on this process.