Pitfalls of local and quantitative phase analysis in partially stabilized zirconia

The addition of selected elements into the host structure of ZrO₂ stabilizes the tetragonal and cubic phases of zirconia, which are, in their undoped binary form, only stable at high temperatures. From the crystallographic point of view, the increasing amount of the stabilizer causes a continuous transition of the tetragonal zirconia to its cubic modification. In partially stabilized zirconia, local concentration gradients of the stabilizer are frequently present as a consequence of the production process, which results in a coexistence of zirconia domains having different degrees of tetragonality. The presence of the local concentration gradients in such samples and the continuous nature of the phase transformation are features important for many technological applications, but their analysis is not straightforward. Furthermore, these features complicate the quantitative phase analysis in partially stabilized zirconia. For the example of zirconia partially stabilized by magnesium, this contribution illustrates the capabilities and limitations of X-ray and electron backscatter diffraction. In particular, the ability of these experimental methods to reveal the gradual lattice distortion that is associated with the cubic to tetragonal phase transformation in zirconia and the reliability of the quantitative phase analysis are discussed. In this context, it is shown to what extent the choice of the microstructure model influences the result of the phase analysis.