ZrO2 (Y2O3 stabilized ZrO2, 8 % +/- 0.5% mole Y2O3) Yttria-stabilized zirconia (YSZ) is a ceramic in which the crystal structure of zirconium dioxide is made stable at room temperature by an addition of yttrium oxide. These oxides are commonly called "zirconia" (ZrO2) and "yttria" (Y2O3), hence the name.