Interaction of Hydrogen Atoms with Grain Boundaries in Palladium Bicrystals

Иевлев, В. М.; Prizhimov, A. S.; Boldyreva, A. V.

doi:10.1134/s0020168518050047

Cited by 5 publications

(4 citation statements)

References 9 publications

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“…Additionally, studies carried out on various types of grain boundaries over nickel found an enhanced hydrogen diffusion along large-angle boundaries (LAGB) [24]. This was also shown, using molecular dynamics simulations, in work by Ievlev et al [25], who reported that the different types of GBs have a different effect of absorption activity for hydrogen. While discussing hydrogen permeation tests, Oudriss et al [26] suggested that high-energy boundaries (consisting of large-angle boundaries-LAGB) act as fast diffusion paths while low-energy grain boundaries (consisting of low-angle boundaries) act as hydrogen trapping sites, lowering in this way the hydrogen flux.…”

Section: Introductionmentioning

confidence: 61%

Palladium Membrane with High Density of Large-Angle Grain Boundaries to Promote Hydrogen Diffusivity

et al. 2022

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A higher density of large-angle grain boundaries in palladium membranes promotes hydrogen diffusion whereas small-angle grain boundaries suppress it. In this paper, the microstructure formation in 10 µm thick palladium membranes is tuned to achieve a submicronic grain size above 100 nm with a high density of large-angle grain boundaries. Moreover, changes in the grain boundaries’ structure is investigated after exposure to hydrogen at 300 and 500 °C. To attain large-angle grain boundaries in Pd, the coating was performed on yttria-stabilized zirconia/porous Crofer 22 APU substrates (intended for use later in an ultracompact membrane reactor). Two techniques of plasma sprayings were used: suspension plasma spraying using liquid nano-sized powder suspension and vacuum plasma spraying using microsized powder as feedstock. By controlling the process parameters in these two techniques, membranes with a comparable density of large-angle grain boundaries could be developed despite the differences in the fabrication methods and feedstocks. Analyses showed that a randomly oriented submicronic structure could be attained with a very similar grain sizes between 100 and 500 nm which could enhance hydrogen permeation. Exposure to hydrogen for 72 h at high temperatures revealed that the samples maintained their large-angle grain boundaries despite the increase in average grain size to around 536 and 720 nm for vacuum plasma spraying and suspension plasma spraying, respectively.

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Section: Introductionmentioning

confidence: 61%

Palladium Membrane with High Density of Large-Angle Grain Boundaries to Promote Hydrogen Diffusivity

et al. 2022

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“…The size of Cu clusters is in the range between 0.5 and 1.5 nm. The molecular dynamic study of hydrogen atom diffusion in the thin Pd foil model [28] showed the retention of hydrogen atoms in structure defects. Therefore, hydrogen atoms are expected to be retained by the local deviations from the β-phase structure distributed in the "ordered" structure.…”

Section: Resultsmentioning

confidence: 99%

“…The Cu-Pd50 sample also has a <110>α texture; the heat treatment gives a recrystallized microstructure with a crystal lattice parameter (3.7440(9) Å) corresponding to the specified elemental composition of the α-phase [8]. Figure 5 shows the X-ray diffraction The molecular dynamic study of hydrogen atom diffusion in the thin Pd foil model [28] showed the retention of hydrogen atoms in structure defects. Therefore, hydrogen atoms are expected to be retained by the local deviations from the β-phase structure distributed in the "ordered" structure.…”

Section: Resultsmentioning

confidence: 99%

“…The decrease in the electrical conductivity characteristic of two-component solid solutions occurs for near-equiatomic compositions [29], which can be attributed to electron scattering at cluster boundaries (the limiting case of the classical size effect of electrical conductivity [30]). The phase separation of this type can also account for low hydrogen permeability of the near-equiatomic disordered Pd-Cu structure: the hydrogen atoms are retained at the phase boundary like at a grain boundary [28].…”

Section: Resultsmentioning

confidence: 99%

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Dependence of the Atomic Structure of Solid Solutions in the Pd-Cu System Ordered According to the B2 Type on the Composition

et al. 2022

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Owing to exceptionally high selectivity, membranes based on palladium alloys are widely used for obtaining high-purity hydrogen. An important issue for providing high hydrogen permeability of the membranes is to form the required phase composition. The structural organization of the solid solutions consisting of Cu–36.4 at .% Pd and Cu–50 at .% Pd were studied by X-ray diffraction (XRD), electron diffraction (ED), high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDXS). It was found that the former composition can be ordered in the temperature range of 300–400 °C and in the heating (up to 800 °C)–cooling cycle. In the presence of excess Cu atoms (27.2%), this structure can be represented by CsCl type structural units (β-phase) and distributed body center cubic (BCC) copper structural units in the corresponding concentration dose. The formation of a single crystal ordered phase within the mosaic blocks of the disordered phase was established. Experimental evidence was obtained for the separation of the α-phase solid solution in the elemental composition; the very low rate of ordering inherent in this system was attributed to this effect. The hydrogen permeability of a foil of the equiatomic composition was described.

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On the Nature of the Decrease in the Rate of the B2 Ordering Process in a Cu–Pd Solid Solution as the Equiatomic Composition Is Approached

Ievlev,

Pavlov,

Solntsev

et al. 2023

Inorg Mater

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Interaction of Hydrogen Atoms with Grain Boundaries in Palladium Bicrystals

Cited by 5 publications

References 9 publications

Palladium Membrane with High Density of Large-Angle Grain Boundaries to Promote Hydrogen Diffusivity

Palladium Membrane with High Density of Large-Angle Grain Boundaries to Promote Hydrogen Diffusivity

Dependence of the Atomic Structure of Solid Solutions in the Pd-Cu System Ordered According to the B2 Type on the Composition

On the Nature of the Decrease in the Rate of the B2 Ordering Process in a Cu–Pd Solid Solution as the Equiatomic Composition Is Approached

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