A General View of the Lower Boundary of Existence of $\gamma$-$\mathrm{Zr(M)O}_{2-x}$

On the basis of analysis of the interaction between the defects of a crystal lattice of zirconium dioxide doped with inovalent cations, the conditions are found for which there are no relatively large single-charged anions of oxygen in interstitial sites of the lattice. Under the assumption that this is enough for the existence of cubic modification of the lattice, the position of the bottom phase boundary of its monophase existence (depending on doping level, temperature, and the partial pressure value of oxygen in ambient medium) is determined. It is demonstrated that such a description fits well with the experimental data and provides a physical explanation for detected phenomena of the existence of “low-temperature cubic modification” of zirconium dioxide. A qualitative description of the boundary positions of the existence domain of pure zirconium dioxide in cubic modification is proposed.