skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Novel high-pressure phase of ZrO{sub 2}: An ab initio prediction

Abstract

The high-pressure behavior of the orthorhombic cotunnite type ZrO{sub 2} is explored using an ab initio constant pressure technique. For the first time, a novel hexagonal phase (Ni{sub 2}In type) within P6{sub 3}/mmc symmetry is predicted through the simulation. The Ni{sub 2}In type crystal is the densest high-pressure phase of ZrO{sub 2} proposed so far and has not been observed in other metal dioxides at high pressure before. The phase transformation is accompanied by a small volume drop and likely to occur around 380 GPa in experiment. - Graphical abstract: Post-cotunnite Ni{sub 2}In type hexagonal phase forms in zirconia at high pressure. - Highlights: • A post-cotunnite phase is predicted for ZrO{sub 2} through an ab initio simulation. • Cotunnite ZrO{sub 2} adopts the Ni{sub 2}In type structure at high pressure. • The Ni{sub 2}In type structure is the densest high-pressure phase of ZrO{sub 2} proposed so far. • The preferred mechanism in ZrO{sub 2} differs from the other metal dioxides.

Authors:
Publication Date:
OSTI Identifier:
22486811
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 230; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CERAMICS; CRYSTALS; HCP LATTICES; INDIUM ALLOYS; NICKEL BASE ALLOYS; ORTHORHOMBIC LATTICES; PHASE TRANSFORMATIONS; PRESSURE DEPENDENCE; PRESSURE RANGE GIGA PA; ZIRCONIUM OXIDES

Citation Formats

Durandurdu, Murat, E-mail: murat.durandurdu@agu.edu.tr. Novel high-pressure phase of ZrO{sub 2}: An ab initio prediction. United States: N. p., 2015. Web. doi:10.1016/J.JSSC.2015.07.010.
Durandurdu, Murat, E-mail: murat.durandurdu@agu.edu.tr. Novel high-pressure phase of ZrO{sub 2}: An ab initio prediction. United States. doi:10.1016/J.JSSC.2015.07.010.
Durandurdu, Murat, E-mail: murat.durandurdu@agu.edu.tr. 2015. "Novel high-pressure phase of ZrO{sub 2}: An ab initio prediction". United States. doi:10.1016/J.JSSC.2015.07.010.
@article{osti_22486811,
title = {Novel high-pressure phase of ZrO{sub 2}: An ab initio prediction},
author = {Durandurdu, Murat, E-mail: murat.durandurdu@agu.edu.tr},
abstractNote = {The high-pressure behavior of the orthorhombic cotunnite type ZrO{sub 2} is explored using an ab initio constant pressure technique. For the first time, a novel hexagonal phase (Ni{sub 2}In type) within P6{sub 3}/mmc symmetry is predicted through the simulation. The Ni{sub 2}In type crystal is the densest high-pressure phase of ZrO{sub 2} proposed so far and has not been observed in other metal dioxides at high pressure before. The phase transformation is accompanied by a small volume drop and likely to occur around 380 GPa in experiment. - Graphical abstract: Post-cotunnite Ni{sub 2}In type hexagonal phase forms in zirconia at high pressure. - Highlights: • A post-cotunnite phase is predicted for ZrO{sub 2} through an ab initio simulation. • Cotunnite ZrO{sub 2} adopts the Ni{sub 2}In type structure at high pressure. • The Ni{sub 2}In type structure is the densest high-pressure phase of ZrO{sub 2} proposed so far. • The preferred mechanism in ZrO{sub 2} differs from the other metal dioxides.},
doi = {10.1016/J.JSSC.2015.07.010},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 230,
place = {United States},
year = 2015,
month =
}
  • Ab-initio total energy calculations have been performed in lutetium nitride (LuN) as a function of hydrostatic compression to understand the high pressure behavior of this compound. Our calculations predict a phase transition from ambient rocksalt type structure (B1 phase) to a tetragonal structure (B10 phase) at ~ 240 GPa. The phase transition has been identified as first order in nature with volume discontinuity of ~ 6%. The predicted high pressure phase has been found to be stable up to at least 400 GPa, the maximum pressure up to which calculations have been performed.Further, to substantiate the results of static lattice calculations analysismore » of lattice dynamic stability of B1 and B10 phase has been carried out at different pressures. Apart from this, we have analyzed the lattice dynamic stability CsCl type (B2) phase around the 240 GPa, the pressure reported for B1 to B2 transition in previous all-electron calculations by Gupta et al. 2013. We find that the B2 structure is lattice dynamically unstable at this pressure and remains unstable up to ~ 400 GPa, ruling out the possibility of B1 to B2 phase transition at least up to ~ 400 GPa. Further, the theoretically determined equation of state has been utilized to derive various physical quantities such as zero pressure equilibrium volume, bulk modulus, and pressure derivative of bulk modulus of B1 phase at ambient conditions.« less
  • The design of vapor recovery processes requires very accurate vapor-liquid equilibria data. In this work, the problem is attacked from both an experimental and a correlational viewpoint, and the methane-n-hexane system is chosen for study. A predictive model for vapor-liquid equilibrium aids in the interpretation of the experimental measurements, and data acquired in this study agree closely with the theoretical predictions. Maximum deviation between calculated and experimental equilibrium ratios (y/sub i//x/sub i/) is 8.5% with average absolute deviations of 3% for n-hexane and 0.1% for methane. Several procedures are described for checking the accuracy of experimental VLE data when amore » heavy vapor is present at low concentrations in the gas phase. Several potential sources of experimental error also are identified and discussed. (26 refs.)« less
  • The possibility that free SiO{sub 2} may exist at the core mantle boundary motivates a first-principles investigation of the equation of state and possible phase transitions of stishovite using periodic Hartree-Fock theory. Using a moderately extended basis set, the calculated equation of state is shown to be in close agreement with experimental results taken under hydrostatic conditions. When fit to a third-order Birch-Murnaghan equation, the Hartree-Fock total energies give V{sub 0} = 46.1 A{sup 3}, K{sub 0} = 328 GPa, and K{prime} = 4.0. Moreover, the calculated equation of state is very close to that recently obtained using the linearizedmore » augmented plane wave method. The bonding in stishovite is unchanged by compression to 80% of its zero-pressure volume (corresponding to a pressure near 110 GPa). The possibility that stishovite might transform to a denser phase at high pressure is investigated by calculating the free energy of SiO{sub 2} in the modified-fluorite and {alpha}-PbO{sub 2} structures. The enthalpy of SiO{sub 2} with the fluorite and modified-fluorite structure is too high to allow those structures to be adopted. The 0 K enthalpy of silica in the {alpha}-PbO{sub 2} structure is within 10 kJ/mol of that of stishovite, and a transition to such a structure cannot be ruled out in the temperature regime of the lower mantle. However, the density of {alpha}-PbO{sub 2} structure SiO{sub 2} is only 2% greater than that of stishovite. 41 refs., 9 figs., 2 tabs.« less
  • Sm{sub 2}O{sub 3} was compressed at room temperature up to 44.0 GPa and then decompressed back to ambient pressure. In situ X-ray diffraction was used to monitor the structural changes in the sample. A cubic to hexagonal phase transformation was observed in Sm{sub 2}O{sub 3} for the first time. After decompression back to ambient pressure, the hexagonal phase was not quenchable and transformed to a monoclinic phase. Ab initio Density-Functional-Theory (DFT) calculations were performed to obtain theoretical data for comparison with the experimental results and elucidation of the transformation mechanism. A possible phase transformation mechanism that is consistent with themore » experimental results and theoretical calculations is proposed.« less
  • The phase stabilities of Y2Ti2O7 and Y2Zr2O7 under high pressure were investigated by ab initio methods. Pyrochlore-structured Y2Ti2O7 and defect-fluorite Y2Zr2O7 exhibit different responses to high pressure. Both the defect-fluorite and defect-cotunnite structures are energetically more stable at high pressure in Y2Ti2O7, but comparison with experimental results suggest that only the transformation to the defect-fluorite structure is kinetically favored. For Y2Zr2O7, the defect-fluorite phase should undergo a structural transformation to the defect-cotunnite state under high pressure.