Yttria-stabilized zirconia is known to not be completely stabilized in the pure cubic YSZ phase up to temperatures above 1000 °C (Ref. and publications therein), commonly used abbreviations in conjunction with yttria-stabilized zirconia are: The thermal expansion coefficients depends on the modification of zirconia as follows: By the addition of yttria to pure zirconia (e.g., fully stabilized YSZ) Y ions replace Zr on the cationic sublattice. Thereby, oxygen vacancies are generated due to charge neutrality: formula_4 with formula_5, meaning two Y ions generate one vacancy on the anionic sublattice. This facilitates moderate conductivity of yttrium stabilized zirconia for O ions (and thus
Zirconia Toughened Alumina offers several key properties. The mechanical robustness compared to alumina is attributed to the displacive phase transformation of the metastable tetragonal ziroconia grains when the material is stressed. The stress concentration at a crack tip can cause a transformation from a tetragonal crystal structure to a monoclinic one, which has an associated volume expansion of ziroconia. This volume expansion effectively pushes back the propagation of the crack and results in higher toughness and strength. A common specimen of Zirconia Toughened Alumina will have 10-20% zirconium oxides. The 20-30% increase in strength often meets the design criteria needed at a much