Interaction of hydrogen with defects in metals

Features of Valence Electron Density Distribution in Zr–H and Zr–He

“…Gray scale given in units e/(a.u.) 3 Figure 3 shows the calculated valence charge density distribution of the Zr−Hе system with octahedral coordination of the helium atom. Panels (a, d, g), (b, e, h), and (c, f, i) correspond to the p 1 , p 2 and p 3 planes, respectively.…”

“…The self-consistency process was carried out up to achieve the convergence of the charge density is not worse than 1⋅10 −7 e/a.u. 3 (e -the electron charge), which corresponds to the total energy convergence is not worse than 0.001 meV. The unit cells of the Zr-He and Zr-H systems contained the sixteen Zr atoms and one impurity atom, respectively, in the octahedral and tetrahedral interstices of hcp Zr.…”

“…Also as a result of (n, α) nuclear reactions in the materials of the technological constructions of the nuclear reactors are formed helium atoms. Accumulation of these impurities in the construction materials leads to hydrogen and helium embrittlements, a gas swelling and, as a consequence, to degradation of operating properties reactor frames [1][2][3]. To predict the mechanical properties of the used structural materials is necessary to understand the influence of these impurities on the properties of pure zirconium at the atomic level.…”

A Critical Review of Existing Hydrogen Diffusion Models Accounting for Different Physical Variables

“…is the binding energy of hydrogen to trap, and β = (RT) -1 is the Boltzmann's factor in terms of the gas constant R and temperature T. Then, e.g., for steels at usual HAF occurrence conditions T ≈ 300 K and θ L ∼ 10 -6 at utmost [3,6], reported values of E b , being approximately in the range from 0.25 to 1.5 eV [2,14,15] yield K ≥ ~ 10 4 and θ T /θ L ≥ ~10 4 . To this end, whenever L/T-partition of hydrogen in volume element d 3 x around a point x is in equilibrium, all partial concentrations C i (x,t) (i = 1,2,…) are related one to another via Eq.…”

Mechanism of Ni Film CVD with a Ni(ktfaa)2 Precursor on a Copper Substrate

“…[22] The hydrogen atoms are not fixed because the energy required to remove them from the adsorbed site is small (96 kJ mol ±1 ). [22] The adsorbed hydrogen atoms probably diffuse along the surface to the slow-moving large Ni(ktfaa) 2 chelate molecules and interact with them according to the Langmuir±Hinshelwood mechanism, as shown in Reaction 3.…”