Lattice vibrations and cubic to tetragonal phase transition in ZrO2

Negita, Keishi

doi:10.1016/0001-6160(89)90289-7

Cited by 63 publications

(26 citation statements)

References 15 publications

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“…The dispersion curves incorporate contributions from long-range dipole-dipole interactions, which leads to the splitting of the longitudinal-and transverse-optical modes in the vicinity of Γ 42 . Consistent with past group theoretical 19 and first-principles 20,43 lattice dynamical studies, the cubic form of ZrO 2 is predicted to be dynamically unstable. This is manifested by the imaginary frequencies (represented in Figure 2 as negative frequencies) in the calculated dispersion curves at the X wave vector.…”

Section: Resultssupporting

confidence: 67%

“…While it is now well established that cubic ZrO 2 is dynamically unstable with respect to a cooperative oxygen shuffle at zero Kelvin 19,20,22,24,43,[59][60][61] , this work predicts that tetragonal ZrO 2 also becomes dynamically unstable at volumes typical of its equilibrium volume at high temperature. The stability of cubic ZrO 2 at very high temperatures has been attributed to large anharmonic vibrational excitations that, on average, give the crystal cubic symmetry.…”

Section: Discussionmentioning

confidence: 71%

“…Several orthorhombic polymorphs become stable at high pressures [16][17][18] . It is well known that cubic ZrO 2 is dynamically unstable at zero Kelvin with respect to a cooperative oxygen shuffle that takes it to the tetragonal form [19][20][21][22][23][24] . The emergence of cubic ZrO 2 at high temperatures has been attributed to large anharmonic vibrational fluctuations that on average impart the crystal with cubic symmetry 21,25 .…”

Section: Introductionmentioning

confidence: 99%

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Effects of strain on the stability of tetragonalZrO2

et al. 2016

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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.

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Section: Resultssupporting

confidence: 67%

Section: Discussionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

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Effects of strain on the stability of tetragonalZrO2

et al. 2016

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“…Thus, in c ~ t transition in zirconia, 48/16 = 3 variants are expected. This result was experimentally verified by Nagita [29], Heuer and co-workers [30,31] and Sakuma [32]. Analogous conclusions can be derived for the t ~ m transition in zirconia.…”

Section: Ultrafine Particles In Tem Andsupporting

confidence: 68%

Electron microdiffraction studies of zirconia particles

Srinivasan¹,

Davis²,

Rice

et al. 1992

J Mater Sci

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A batch of zirconia was prepared at a pH of 2.95 using a sol-gel technique. The crystal structures formed during 500 ~ calcination was followed by X-ray diffraction. The tetragonal phase was the major component after the initial calcination period of 15.5 h; however, it gradually transformed to the monoclinic crystal form during 200 h of calcination at 500 ~ Electron microdiffraction was employed in the present investigation to determine the crystal structure of individual particles, and to identify whether these particles contained twin variants. A technique has been developed to get a dispersion of agglomerated particles by condensing and spreading the beam on the agglomerates at 200 kV. The data revealed that some of the individual zirconia particles are featureless and some of them appear to contain single or multiple twin variants.

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“…The eigenvector of this mode involves displacements of oxygen anions along the ⟨1 0 0⟩ direction breaking the cubic symmetry which, upon full relaxation of the cell and internal coordinates, results in the observed tetragonal phase 22 . Other first principles DFT calculations, for some representative defect structures, have suggested that the X-point imaginary phonon is stabilised as the Y 2 O 3 concentration is increased from 0 to 10.4 mol% 23 .…”

Section: Introductionmentioning

confidence: 99%

Chemical Descriptors of Yttria-Stabilized Zirconia at Low Defect Concentration: An ab Initio Study

et al. 2015

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Keywords: solid oxide fuel cell, yttria stabilised zirconia, cubic zirconia, bixbyite yttria, ab initio, density functional theory, empirical potential, Born-Mayer-Huggins, point charge model, phonons, harmonic approximation. been observed in either X-ray or neutron diffraction experiments. The prediction of local defect structure and the interaction between defects is therefore of great interest. This has not been possible to date as the number of possible defect topologies is very large and to perform reliable total energy calculations for all of them would be prohibitively expensive. Previous theoretical studies have only considered a selection of representative structures. In this study, a comprehensive search for low energy defect structures using a combined classical modelling and density functional theory approach is used to identify the low energy isolated defect structures at the dilute limit, 3.2mol%. Through analysis of energetics computed using the best available Born-Mayer-Huggins empirical potential model, a point charge model, DFT, and a local strain energy estimated in the harmonic approximation, the main chemical and physical descriptors that correlate to the low energy DFT structures are discussed. It is found that the empirical potential model reproduces a general trend of increasing DFT energetics across a series of locally strain relaxed structures, but is unreliable both in predicting some incorrect low energy structures, and 3 in finding some meta-stable structures to be unstable. A better predictor of low energy defect structures is found to be the total electrostatic energy of a simple point charge model calculated at the unrelaxed geometries of the defects. In addition, the strain relaxation energy is estimated effectively in the harmonic approximation to the imaginary phonon modes of undoped c-ZrO 2 , but is found to be unimportant in determining the low energy defect structures. These results allow us to propose a set of easily computed descriptors that can be used to identify the low energy YSZ defect structures, negating the combinatorial complexity and number of defect structures that need to be considered. Abstract

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Lattice vibrations and cubic to tetragonal phase transition in ZrO2

Cited by 63 publications

References 15 publications

Effects of strain on the stability of tetragonalZrO2

Effects of strain on the stability of tetragonalZrO2

Electron microdiffraction studies of zirconia particles

Chemical Descriptors of Yttria-Stabilized Zirconia at Low Defect Concentration: An ab Initio Study

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