Understanding Deviations in Hydrogen Solubility Predictions in Transition Metals through First-Principles Calculations

Lee, Kyoungjin; Yuan, Mengyao; Wilcox, Jennifer

doi:10.1021/acs.jpcc.5b05469

Cited by 40 publications

(35 citation statements)

References 91 publications

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“…The already available related DFT studies are focused on various features of the system under consideration: (i) One of the first questions addressed concerns the type of sites for hydrogen absorption in pure Pd. In agreement with experiment [9], the theory indicates that the octahedral (O) absorption sites are energetically more favorable than the tetrahedral (T) sites at H/Pd ratios up to 1 [10][11][12][13]. In addition, the theory was used to clarify the specifics of the band structure [12] and phonon dispersion of PdH [12,14,15], the dynamics of H diffusion [16], the effect of lattice strain on H diffusion [11], the energetics of subsurface H absorption [17,18], and the effect of vacancies on H absorption [14,19].…”

Section: Introductionsupporting

confidence: 75%

“…In addition, the theory was used to clarify the specifics of the band structure [12] and phonon dispersion of PdH [12,14,15], the dynamics of H diffusion [16], the effect of lattice strain on H diffusion [11], the energetics of subsurface H absorption [17,18], and the effect of vacancies on H absorption [14,19]. (ii) For pure Au, DFT is in favor of H absorption on the T sites, whereas the H location in the O sites is predicted to be unstable [13,19]. (iii) For a Pd-Au alloy, the theory was used to scrutinize the arrangement of atoms [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Suppression of hysteresis in absorption of hydrogen by a Pd-Au alloy

Mamatkulov

Zhdanov

2020

Phys. Rev. E

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Hydrogen absorption by Pd exhibits hysteresis loops (provided the temperature is not too high) and represents one of the classical examples of first-order phase transitions in metals. Experiments indicate that addition of even a small amount of Au is able to suppress hysteresis. From this perspective, we analyze the energetics of hydrogen in a Pd-Au alloy by using extensive density-functional-theory (DFT) calculations. The dependence of the hydrogen binding energy on the number (n) of Au atoms forming an adsorption site is found to be appreciably nonlinear. With the DFT input for statistical calculations, we reproduce special features of the hydrogen absorption isotherms and explain the rapid decrease of the corresponding critical temperature with increasing Au fraction. The key factor here is that the phase transition is related primarily to absorption in sites formed only by Pd. With increasing Au amount, the fraction of such sites rapidly decreases, the distance between H atoms located there becomes on average larger, the interaction between them becomes weaker, and accordingly the driving force for the phase transition decreases. It is of interest that all these effects can be illustrated by taking only the configurations with n 2 into account. This means that in the context under consideration the fine details of the dependence of the hydrogen binding energy on n are in fact not too important.

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Section: Introductionsupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Suppression of hysteresis in absorption of hydrogen by a Pd-Au alloy

Mamatkulov

Zhdanov

2020

Phys. Rev. E

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“…For determining the H solubility at a given site, (zero-point) vibrations can be important [34]. Our study, however, is primarily concerned with trapping energies of hydrogen, i.e., the difference in the solution enthalpy of hydrogen for different sites and regions of steel materials comprising ferritic and austenitic metal matrices, carbide precipitates, as well as the carbide/matrix interface.…”

Section: Methodsmentioning

confidence: 99%

The Role of κ-Carbides as Hydrogen Traps in High-Mn Steels

Timmerscheidt

Dey

Bogdanovski

et al. 2017

Metals

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Abstract:Since the addition of Al to high-Mn steels is known to reduce their sensitivity to hydrogen-induced delayed fracture, we investigate possible trapping effects connected to the presence of Al in the grain interior employing density-functional theory (DFT). The role of Al-based precipitates is also investigated to understand the relevance of short-range ordering effects. So-called E2 1 -Fe 3 AlC κ-carbides are frequently observed in Fe-Mn-Al-C alloys. Since H tends to occupy the same positions as C in these precipitates, the interaction and competition between both interstitials is also investigated via DFT-based simulations. While the individual H-H/C-H chemical interactions are generally repulsive, the tendency of interstitials to increase the lattice parameter can yield a net increase of the trapping capability. An increased Mn content is shown to enhance H trapping due to attractive short-range interactions. Favorable short-range ordering is expected to occur at the interface between an Fe matrix and the E2 1 -Fe 3 AlC κ-carbides, which is identified as a particularly attractive trapping site for H. At the same time, accumulation of H at sites of this type is observed to yield decohesion of this interface, thereby promoting fracture formation. The interplay of these effects, evident in the trapping energies at various locations and dependent on the H concentration, can be expressed mathematically, resulting in a term that describes the hydrogen embrittlement.

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“…anisotropy switching for Co/Pt, low solubility of H in Pt [42] significantly limits its practical applications.…”

Section: Effect Of H Insertion At the Interface Of Various Fm/nm Trilayersmentioning

confidence: 99%

Hydrogen tunes magnetic anisotropy by affecting local hybridization at the interface of a ferromagnet with nonmagnetic metals

Klyukin

Beach

Yildiz

2020

Phys. Rev. Materials

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Ionic control of magnetic properties, dubbed magneto-ionics, has gained much attention in recent years due to the sizable effects that can be induced by electrically controlled ion motion. Here we assess the mechanism by which hydrogen affects magnetic anisotropy in representative ferromagnetic/nonmagnetic metal layers. We take Co/Pd film as a model system that is widely used in spintronics. First-principles calculations demonstrate that the magnetic moment can be switched by 90 • via hydrogen insertion at the Co/Pd interface. This control results from hydrogen-induced changes in magnetic anisotropy originating from modifications to the electronic structure. Accumulation of hydrogen at the Co/Pd interface affects the hybridization between neighboring Co and Pd layers, leading to a decrease of the perpendicular anisotropy component, and eventually changes the net magnetic anisotropy to in-plane. Hydrogen penetration into the interior Co layers has the opposite effect, promoting perpendicular magnetic anisotropy. These changes are governed by competing contributions of the d xy ; d x 2 +y 2 and the 3d z 2 ; 3d zy states, which are mainly responsible for the perpendicular and the in-plane magnetocrystalline anisotropy, respectively. By using this understanding, we predict that hydrogen accumulation at Fe/V interfacial layers causes the opposite spin reorientation effect, promoting perpendicular magnetic anisotropy.

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Understanding Deviations in Hydrogen Solubility Predictions in Transition Metals through First-Principles Calculations

Cited by 40 publications

References 91 publications

Suppression of hysteresis in absorption of hydrogen by a Pd-Au alloy

Suppression of hysteresis in absorption of hydrogen by a Pd-Au alloy

The Role of κ-Carbides as Hydrogen Traps in High-Mn Steels

Hydrogen tunes magnetic anisotropy by affecting local hybridization at the interface of a ferromagnet with nonmagnetic metals

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