Vacancy formation energies in metals: A comparison of MetaGGA with LDA and GGA exchange–correlation functionals

Medasani, Bharat; Harańczyk, Maciej; Canning, Andrew; Asta, Mark

doi:10.1016/j.commatsci.2015.01.018

Cited by 83 publications

(67 citation statements)

References 45 publications

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“…We find that E v is equal to 1.985 eV using the LDA and 3 × 3 × 3 supercell, similar to the results obtained with the GGA. This is also confirmed by E v values for hcp-Ti evaluated by Medasani et al 16 using both the LDA and GGA.…”

Section: Methodssupporting

confidence: 76%

“…The difference between vacancy formation energy values is probably due to the choice of approximation for the exchange and correlation functional. In fact, Medasani et al 16 have shown that E v is 2.18 eV when calculated using GGA-PBEsol. All these approximations to the exchange and correlation functional appear to overestimate the experimental data for the vacancy formation energy.…”

Section: A Self-diffusionmentioning

confidence: 99%

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Diffusion anisotropy of poor metal solute atoms in hcp-Ti

Scotti

Mottura

2015

The Journal of Chemical Physics

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Atom migration mechanisms influence a wide range of phenomena: solidification kinetics, phase equilibria, oxidation kinetics, precipitation of phases, and high-temperature deformation. In particular, solute diffusion mechanisms in α-Ti alloys can help explain their excellent high-temperature behaviour. The purpose of this work is to study self- and solute diffusion in hexagonal close-packed (hcp)-Ti, and its anisotropy, from first-principles using the 8-frequency model. The calculated diffusion coefficients show that diffusion energy barriers depend more on bonding characteristics of the solute rather than the size misfit with the host, while the extreme diffusion anisotropy of some solute elements in hcp-Ti is a result of the bond angle distortion.

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Section: Methodssupporting

confidence: 76%

Section: A Self-diffusionmentioning

confidence: 99%

Diffusion anisotropy of poor metal solute atoms in hcp-Ti

Scotti

Mottura

2015

The Journal of Chemical Physics

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“…40 Energies of Ti vacancies are obtained in a similar range with different exchangecorrelation functionals, 41 which are overestimated than that reported in experiment (1.55 eV in ref. 42 and 1.27 eV from positron annihilation spectroscopy in ref.…”

Section: Resultsmentioning

confidence: 71%

Insight into point defects and impurities in titanium from first principles

et al. 2018

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Titanium alloys find extensive use in the aerospace and biomedical industries due to a unique combination of strength, density, and corrosion resistance. Decades of mostly experimental research has led to a large body of knowledge of the processing-microstructure-properties linkages. But much of the existing understanding of point defects that play a significant role in the mechanical properties of titanium is based on semi-empirical rules. In this work, we present the results of a detailed self-consistent first-principles study that was developed to determine formation energies of intrinsic point defects including vacancies, self-interstitials, and extrinsic point defects, such as, interstitial and substitutional impurities/dopants. We find that most elements, regardless of size, prefer substitutional positions, but highly electronegative elements, such as C, N, O, F, S, and Cl, some of which are common impurities in Ti, occupy interstitial positions.

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“…Migration barriers have been calculated with the nudged-elastic band (NEB) method with the climbing image algorithm [81]. Elastic energy corrections for image interactions associated with supercells were made 094105-4 [46] using the method of Varvenne et al [65]. The elastic interaction energy is computed from the pressure and the deviatoric stress computed ab initio within supercells with fixed volume and fixed (cubic) shape.…”

Section: First-principles Calculationsmentioning

confidence: 99%

“…This is particularly the case for diffusion in iron where an Arrhenius plot does not show a simple linear relation in the ferromagnetic state. Density functional theory (DFT) calculations have proven successful in predicting experimental data such as lattice parameters [46,47], elastic properties [48,49], and energy barriers for diffusion, e.g., diffusivities in aluminum [50], magnesium [51,52], and nickel [53]. Many impurity diffusivities in bcc iron [54][55][56][57][58][59][60][61] have been calculated with DFT methods, but oftentimes only experimentally fitted data, such as activation energy for diffusion, have been compared with the computed results.…”

Section: Introductionmentioning

confidence: 99%

First-principles analysis of solute diffusion in dilute bcc Fe- X alloys

2017

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The diffusivities of substitutional impurity elements in iron have been computed with ab inito electronic density functional techniques, using exchange-correlation functional PW91. Excess entropies and the attempt frequency for a jump were determined by calculating phonon frequencies in the harmonic approximation. The influence of the degree of spontaneous magnetization on diffusivity is taken into account by means of the Girifalco model. The activation energy for diffusion has been determined by computing the vacancy formation energy, impurity-vacancy binding energies, migration barrier energies, and the effective energy associated with correlation of vacancy-mediated jump. For each type of impurity atom these contributions have been evaluated and analyzed up to and including the fifth nearest-neighbor shell of the impurity atom. It is found that impurities that have a low migration energy tend to have high effective energy associated with vacancy migration correlation, and vice versa, so that the total diffusion activation energies for all impurities are surprisingly close to each other. The strong effect of vacancy migration correlation is found to be associated with the high migration energy for iron self-diffusion, so that movement of vacancies through the iron bulk is in all cases, except cobalt, the limiting factor for impurity diffusion. The diffusivities calculated with the PW91 functional show good agreement with most of the experimental data for a wide range of elements.

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Vacancy formation energies in metals: A comparison of MetaGGA with LDA and GGA exchange–correlation functionals

Cited by 83 publications

References 45 publications

Diffusion anisotropy of poor metal solute atoms in hcp-Ti

Diffusion anisotropy of poor metal solute atoms in hcp-Ti

Insight into point defects and impurities in titanium from first principles

First-principles analysis of solute diffusion in dilute bcc Fe- X alloys

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