High-pressure structural phases of titanium dioxide

Dewhurst, J. K.; Lowther, J. E.

doi:10.1103/physrevb.54.r3673

Cited by 100 publications

(71 citation statements)

References 12 publications

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“…The current HF and LDA calculations predict internal coordinates in excellent agreement with experimental observations 23 and in reasonable agreement with the results of recent PW-LDA calculations. 30 For baddeleyite, the computed lattice vectors are in excellent agreement ͑within around 1%͒ with those observed. 26 To our knowledge, there have been no experimental determination of the internal coordinates of this phase.…”

Section: B High-pressure Phasessupporting

confidence: 69%

“…The computed bulk modulus of rutile in the current work is in good agreement with experiment being only around 10% too high and is in excellent agreement with previous PW studies. 13,30,59 The discrepancy between the rutile bulk modulus computed in this study and that from the recent allelectron LCAO studies using very similar computational techniques is due to the fitting procedure used to compute the bulk modulus. In the current study, the Birch-Murnaghan equation of state 56 has been used to extract the bulk modulus, whereas the values from the previous LCAO studies were computed from a polynomial fit of the energy-volume curve.…”

Section: Resultsmentioning

confidence: 59%

“…For example, the existence of the fluorite phase of TiO 2 has only been tentatively assigned, and it is not certain whether the fluorite and pyrite phases can exist between baddeleyite and cotunnite or if they are post-cotunnite. Although there have been theoretical calculations of the fluorite structure 13,30 there have been no predictions of the structure or energetics of the pyrite or cotunnite phases. In order to understand the high-pressure phase diagram of TiO 2 , we have performed HF calculations of the rutile, anatase, columbite, baddeleyite, fluorite, pyrite, and cotunnite phases at pressures up to at least 70 GPa.…”

Section: B High-pressure Phasesmentioning

confidence: 99%

“…39 Several theoretical studies have been performed to assist in the identification of these phases. In particular, the cubic CaF 2 ͑fluorite͒ structure 30 and a modification of this form which is isostructural with FeS 2 ͑pyrite͒ have been proposed as candidate high-pressure phases. 31 Unfortunately, confirming the existence of these predicted structures by performing experiments at such high pressures poses many technical difficulties 22 which had, until recently, precluded the detailed determination of the post-baddeleyite phase.…”

Section: Introductionmentioning

confidence: 99%

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First-principles calculations of the phase stability ofTiO2

2002

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First-principles calculations of the crystal structures, bulk moduli, and relative stabilities of seven known and hypothetical TiO 2 polymorphs ͑anatase, rutile, columbite, baddeleyite, cotunnite, pyrite, and fluorite structures͒ have been carried out with the all-electron linear combination of atomic orbitals ͑LCAO͒ and pseudopotential planewave ͑PW͒ methods. The anatase versus rutile relative phase stability at 0 K and zero pressure has been investigated using high-quality basis sets and carefully controlled computational parameters. From the optimal crystal structures obtained with the Hartree-Fock theory at various pressures, the bulk modulus and phase transition pressures of various high-pressure polymorphs have been derived at the athermal limit. In most cases, the calculated unit cell data agree to within 2% of the corresponding experimental determination. Complete predicted structural data ͑unit cell constants and fractional atomic coordinates͒ are presented for the baddeleyite and pyrite forms. The calculated bulk moduli are within 10% of the most reliable experimental results. Both the all-electron LCAO and pseudopotential PW methods predict anatase to be more stable than rutile at 0 K and ambient pressure. The computed anatase-columbite, rutile-columbite, columbite-baddeleyite, and baddeleyite-cotunnite phase transitions appear in the same order as observed in experiments, and the transition pressures agree semiquantitatively with those measured. The pyrite and fluorite structures are predicted to be less stable than other polymorphs at pressures below 70 GPa in agreement with experiments. Finally, the elastic properties, compressibilities and phase transformations of the various polymorphs are discussed in terms of simple models based on the behavior of the constituent Ti-O polyhedra under compression.

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Section: B High-pressure Phasessupporting

confidence: 69%

Section: Resultsmentioning

confidence: 59%

Section: B High-pressure Phasesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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First-principles calculations of the phase stability ofTiO2

2002

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“…The stable phase of this material at normal conditions, rutile, has, among many others, the interesting property of being a crystallographic analog of stishovite SiO 2 , a significant highpressure quartz phase in the Earth's lower mantle. 7 The structural and elastic behavior of rutile TiO 2 at several p and T conditions has been recently investigated theoretically [8][9][10][11][12] and experimentally. 7,13,14 The theoretical bulk modulus at zero pressure (B 0 ) lies in the range 200-240 GPa and its first pressure derivative at zero pressure (B 0 Ј) between 4 and 6.…”

Section: Introductionmentioning

confidence: 99%

Spinodal equation of state for rutileTiO2

et al. 2003

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We present a general computational scheme to extend the spinodal equation of state ͓García Baonza et al., Phys. Rev. B 51, 28 ͑1995͔͒ to the interpretation of the cell parameters response to hydrostatic pressure in orthogonal lattices. As an important example, we analyze the pressure (p) -volume (V) -temperature ͑T͒ data of the rutile phase of TiO 2 . We show that results of ab initio perturbed ion calculations and very recent x-ray-diffraction experiments of isothermal compression on this system closely follow the spinodal conduct. The computational scheme permits the incorporation of temperature effects in the static calculation as well as in the room-temperature experimental data. Overall, we find highly consistent results and good theoryexperiment agreement for a significant series of observables, including structural parameters, pϪV diagram, bulk modulus, linear compressibilities, and thermal-expansion coefficient. The observed discrepancies in the pressure first derivative of the bulk modulus can be traced back to the difference between the theoretical and the experimental spinodal pressure.

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Pressure‐induced phase transition and elastic properties of TiO₂polymorphs

Liang

Liu

et al. 2009

Physica Status Solidi (b)

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A theoretical study was carried out by first‐principles calculations using plane‐wave pseudopotential method to investigate the crystal structures, relative stabilities, and elastic properties of seven known titanium dioxide (TiO2) polymorphs. Our calculated equilibrium structural parameters of TiO2 polymorphs are in good agreement with the experimental results. Firstly, it is worth to note that from our energy‐minimized generalized gradient approximation (GGA) calculations, the four phases of TiO2 – anatase, rutile, columbite, and baddeleyite – are seen to lie within a very close energy range (0.02 eV/atom) of each other, which implies easy phase transition between them. Secondly, on the basis of enthalpy versus pressure data obtained from our GGA calculations for high‐pressure forms, we demonstrate the phase transition pressure and the expected sequence of the phase transition of TiO2, which are in reasonable agreement with experimental observations. Finally, we calculate the elastic constants of all the TiO2 polymorphs, and based on them, the bulk modulus, shear modulus, Young's modulus, and Poisson's ratio are estimated. The results show that cotunnite‐type TiO2 is a potential low‐compressible material.

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High-pressure structural phases of titanium dioxide

Cited by 100 publications

References 12 publications

First-principles calculations of the phase stability ofTiO2

First-principles calculations of the phase stability ofTiO2

Spinodal equation of state for rutileTiO2

Pressure‐induced phase transition and elastic properties of TiO₂polymorphs

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High-pressure structural phases of titanium dioxide

Cited by 100 publications

References 12 publications

First-principles calculations of the phase stability ofTiO2

First-principles calculations of the phase stability ofTiO2

Spinodal equation of state for rutileTiO2

Pressure‐induced phase transition and elastic properties of TiO2polymorphs

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Product

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Pressure‐induced phase transition and elastic properties of TiO₂polymorphs