Effects of strain on the stability of tetragonalZrO2

Abstract

The tetragonal form of ZrO2 is used in a wide range of technologies. In this study, we systematically explore the effect of strain on the relative stability of symmetrically equivalent tetragonal variants of ZrO2 using first-principles density functional theory. We focus in particular on the role that strain plays in altering metastability and causing dynamical instabilities as these properties affect the mechanisms of ferroelastic switching. We also discover the emergence of a dynamical instability in tetragonal ZrO2 at its high temperature equilibrium volume. This indicates that the high temperature thermodynamic properties of tetragonal ZrO2 have important anharmonic vibrational contributions that cannot be captured with the quasi-harmonic approximation. Finally, we determine that the instability of tetragonal ZrO2 at large volumes leads to a new orthorhombic phase having a P 212121 space group.

Order parameters for symmetry-breaking structural transitions: The tetragonal-monoclinic transition in ZrO2

“…This monoclinic structure is very closely related to the orthorhombic polymorph identified in Ref. 44 , which was obtained by relaxing an unstable phonon mode of the volume-expanded tZrO 2 crystal. That orthorhombic structure can be constructed by stacking the (e − 5 , 1) → (e − 4 , 1) midpoint structure with its (001) m shear-compensating twin, doubling the periodicity of the cell.…”

Oxygen self-diffusion mechanisms in monoclinic ZrO2 revealed and quantified by density functional theory, random walk analysis, and kinetic Monte Carlo calculations

“…First, all experimental studies listed here were not conducted on single-crystal ZrO 2 . References [1] and [2] measured conductivity via an 18 O diffusion experiment on ZrO 2 spheres, and Ref. [3] by measuring the oxidation rate of nonstoichiometric ZrO 2 powder to stoichiometric ZrO 2 .…”

“…In particular, such knowledge could guide design by, e.g., aliovalent doping and controlling operating environmental conditions. Experimental [12][13][14] and computational [15][16][17][18][19][20] studies have been carried out to atomistically resolve the structure, valence states, and defect chemistry in ZrO 2 . Zirconium-oxygen system phase stability has been examined by first-principles studies, and a range of suboxide structures with oxygen dissolved into the metal phase have been identified [20].…”

Theoretical and experimental investigations of mechanical properties for polymorphous YTaO4ceramics

“…Furthermore, the ferroelastic domain is only detected in M phase . The underlying roles of high‐temperature ferroelastic transformation and ferroelastic domain in YTaO 4 is to enhance materials' toughness, analogous to that of ZrO 2 . Intriguingly, recent researches reveal that there are large miscibility between ZrO 2 and YTaO 4 given their crystallographic relationship .…”

“…21,22 The underlying roles of high-temperature ferroelastic transformation and ferroelastic domain in YTaO 4 is to enhance materials' toughness, analogous to that of ZrO 2 . 23 Intriguingly, recent researches reveal that there are large miscibility between ZrO 2 and YTaO 4 given their crystallographic relationship. 17,18 The YTaO 4 -ZrO 2 pseudo-binary phase diagram from room temperature to 1600°C shows, over the entire compositional range, there are three regimes including YTaO 4 solid solution, ZrO 2 solid solution, and two-phase region.…”