First-principles investigation of quantum mechanical effects on the diffusion of hydrogen in iron and nickel

Stefano, Davide Di; Mrovec, Matous; Elsässer, Christian

doi:10.1103/physrevb.92.224301

Cited by 53 publications

(35 citation statements)

References 54 publications

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“…[55]). Our results and the results of Di Stefano et al [56] suggest a possibility that the quantum effects can influence the H diffusion in fcc metals even at high temperatures (∼1000 K) due to the strong confinement of the H atom along its migration path. Nuclear quantum effects tend to remain at high temperature in systems with relatively stiff bonds, such as water vapor [57], diamond [58], and graphene [59,60], which lead to gradual convergence of structural and thermal properties to their classical limits.…”

Section: B Nuclear Quantum Effects On H Migrationsupporting

confidence: 72%

Mechanism of fast lattice diffusion of hydrogen in palladium: Interplay of quantum fluctuations and lattice strain

2018

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Understanding the underlying mechanism of the nanostructure-mediated high diffusivity of H in Pd is of recent scientific interest and also crucial for industrial applications. Here, we present a decisive scenario explaining the emergence of the fast lattice-diffusion mode of interstitial H in face-centered cubic Pd, based on the quantum mechanical natures of both electrons and nuclei under finite strains. Ab initio path-integral molecular dynamics was applied to predict the temperature-and strain-dependent free energy profiles for H migration in Pd over a temperature range of 150-600 K and under hydrostatic tensile strains of 0.0%-2.4%; such strain conditions are likely to occur in real systems, especially around the elastic fields induced by nanostructured defects. The simulated results revealed that, for preferential H location at octahedral sites, as in unstrained Pd, the activation barrier for H migration (Q) was drastically increased with decreasing temperature owing to nuclear quantum effects. In contrast, as tetrahedral sites increased in stability with lattice expansion, nuclear quantum effects became less prominent and ceased impeding H migration. This implies that the nature of the diffusion mechanism gradually changes from quantum-to classical-like as the strain is increased. For H atoms in Pd at the hydrostatic strain of ∼2.4%, we determined that the mechanism promoted fast lattice diffusion (Q = 0.11 eV) of approximately 20 times the rate of conventional H diffusion (Q = 0.23 eV) in unstrained Pd at a room temperature of 300 K.

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Section: B Nuclear Quantum Effects On H Migrationsupporting

confidence: 72%

Mechanism of fast lattice diffusion of hydrogen in palladium: Interplay of quantum fluctuations and lattice strain

2018

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“…The quantum tunneling effects, as described by different authors in the literature [44,45], were neglected here. The tunneling effect is a correction to the classical diffusivity which has to be taken into account at low temperature (below ambient temperature).…”

Section: Hydrogen Diffusivitymentioning

confidence: 99%

Theoretical study on hydrogen solubility and diffusivity in the γ-TiAl L10 structure

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2019

International Journal of Hydrogen Energy

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“…The energy path to escape a trap is typically asymmetric (e.g., qualitatively similar to that for H migration in fcc Ni), so that quantum-mechanical effects are not critical, as shown in Ref. 33. All migration barriers calculated here correspond to transition-state configurations that are either symmetry-dictated extrema or saddle points whose energies can be obtained using a standard structural relaxation.…”

Section: Computational Detailsmentioning

confidence: 99%

“…Atom positions were relaxed until the residual forces acting on the atoms were less than 10 −3 eV/Å and the total energy was converged to 10 −5 eV. An inclusion of quantum mechanical effects is crucial for a correct description of H diffusion in bcc Fe 33,51,52 , but in the case of H trapping, these effects should not affect significantly the escape rate of H from a trap. The energy path to escape a trap is typically asymmetric (e.g., qualitatively similar to that for H migration in fcc Ni), so that quantum-mechanical effects are not critical, as shown in Ref.…”

Section: Computational Detailsmentioning

confidence: 99%

“…Nowadays, the most reliable means for theoretical studies of materials properties at the atomic scale are first-principles calculations based on density functional theory (DFT) that can be applied to virtually every material. Binding and activation energies of hydrogen within the bulk matrix or the precipitate can be determined relatively easily using DFT, without the need of additional assumptions or simplifications 32,33 . To accurately capture the interaction of H with the simplest imperfections of crystals, such as atomic vacancies [34][35][36] or symmetric tilt or twist grain boundaries 37,38 , is a more challenging but still doable task for DFT computations.…”

Section: Introductionmentioning

confidence: 99%

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First-principles investigation of hydrogen interaction with TiC precipitates inα-Fe

et al. 2016

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A correct description of hydrogen diffusion and trapping is the prerequisite for an understanding of the phenomenon of hydrogen embrittlement. In this study, we carried out extensive first-principles calculations based on density functional theory to investigate the interaction of H with TiC precipitates that are assumed to be efficient trapping agents mitigating HE in advanced high-strength steels. We found that there exists a large variety of possible trapping sites for H associated with different types of interfaces between the TiC particle and the Fe matrix, with misfit dislocations and other defects at these interfaces, and with carbon vacancies in TiC. The most efficient trapping by more than 1 eV occurs at carbon vacancies in the interior of TiC particles. However, these traps are difficult to populate at ambient temperatures since the energy barrier for H entering the particles is high. H trapping at the semicoherent interfaces between the TiC particles and the Fe matrix is moderate, ranging from 0.3 to 0.5 eV. However, a sufficiently large concentration of the carbide particles can significantly reduce the amount of H segregated at dislocation cores in the Fe matrix. A systematic comparison of the obtained theoretical results with available experimental observations reveals a consistent picture of hydrogen trapping at the TiC particles that is expected to be qualitatively valid also for other carbide precipitates with the rock-salt crystal structure.

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First-principles investigation of quantum mechanical effects on the diffusion of hydrogen in iron and nickel

Cited by 53 publications

References 54 publications

Mechanism of fast lattice diffusion of hydrogen in palladium: Interplay of quantum fluctuations and lattice strain

Mechanism of fast lattice diffusion of hydrogen in palladium: Interplay of quantum fluctuations and lattice strain

Theoretical study on hydrogen solubility and diffusivity in the γ-TiAl L10 structure

First-principles investigation of hydrogen interaction with TiC precipitates inα-Fe

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