On the mobility of interstitials

Gosar, P.

doi:10.1007/bf02733795

Cited by 29 publications

(7 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second, according to the classification in [16], the under-barrier transitions of an HA with the RC given by (24) should be called "active" jumps. In this case, any transitions with the RC given by (19) can be called "passive" jumps. We recall that E (p) contained in (19) is the activation energy of the lattice, not the activation energy of the migrating atom.…”

Section: Thermally Active Tunnel Transitions In Bcc Metalsmentioning

confidence: 98%

“…In this case, any transitions with the RC given by (19) can be called "passive" jumps. We recall that E (p) contained in (19) is the activation energy of the lattice, not the activation energy of the migrating atom.…”

Section: Thermally Active Tunnel Transitions In Bcc Metalsmentioning

confidence: 98%

“…Such an isotopic dependence of the diffusion coefficient D ∼ m −1/2 has been observed many times. For comparison, we give the results of other theories: D ∼ m −2 [8] and D ∼ m −1 [19]. We use (11) to write the isotopic ratio for the HA and its isotope in FCC metals as…”

Section: Classical (Fcc Metals) and Anomalous (Bcc Metals) Isotopic Ementioning

confidence: 99%

“…The point is that the minimum work w λλ = E (p) given by (18) for "passive" tunnel transitions, β −1 1 < θ D , depends on the isotope mass (Fig. 3) and the isotopic ratio, according to (19), becomes D(m) D(2m) = C 1 e β1(w λλ (2m)−w λλ (m)) .…”

Section: Classical (Fcc Metals) and Anomalous (Bcc Metals) Isotopic Ementioning

confidence: 99%

“…The over-barrier hopping with the RC given by (10) occurs in FCC metals because deep potential wells appear as a result of the action of Coulomb forces. Formation of deep wells in BCC metals is related to deformation effects, and a realization of two channels of transitions with the RC determined by formulas (19) and (24) is possible in a wide range of temperatures. To identify the mechanism of an elementary act in different temperature intervals, we present the results of numerical calculations of the activation energy for "passive" and "active" transitions.…”

Section: 1mentioning

confidence: 99%

See 4 more Smart Citations

Three Regimes of Diffusion Migration of Hydrogen Atoms in Metals

Kashlev

2005

Theor Math Phys

View full text Add to dashboard Cite

The classical diffusion theory cannot explain the temperature kink of the activation energy and the anomalous isotopic effect observed in the hydrogen atom migration in BCC metals. We present a theory based on the equations of quantum statistical mechanics that permits interpreting both these phenomena completely. We consider three possible mechanisms for an elementary act of hydrogen diffusion in metals: the over-barrier hopping, the thermally activated tunnel transition, and the tunneling due to decay of a local deformation near the hydrogen atom. Rate constant for the escape of light particles from the potential minimumMost of the quantum theories of hydrogen diffusion in metals [1]-[5] are based on the concept of the hopping conductivity of small-radius polarons [6]. The essential drawbacks of the polaron theory concerning hydrogen atom (HA) diffusion problems have been discussed in numerous papers, including [7]. Our goal here is to present a completely different approach to this problem, an approach sufficiently close to the basic concept of chemical kinetics [8].We consider the diffusion migration of light impurities in the one-dimensional crystal model. For the model potential, we use the potential of a symmetric well with two cells such that the distance between their minimums is d. The total system in this model can be divided into three subsystems: a thermostat including the lattice and electrons {1}, a light particle in the left-hand potential well {2}, and a light particle in the right-hand potential well {3}. The localized states of light particles at the interstitial sites of the crystal correspond to the equilibrium distribution in the configuration space. Such particles migrate jumplike because the lifetime of a particle at the temperature β −1 1 ∼ 10 3 K is 10 −8 to 10 −9 sec in order of magnitude, while the time of motion through the potential barrier is 10 −13 sec. It is clear that the total system under these conditions is sufficiently close to thermodynamic equilibrium. In the case of a weak particle-thermostat interaction, the general expression for the rate constant (RC) for the escape of particles from the potential minimum can be written as [9]We use the system of units where = k B = 1. Here, Ω is the eigenfrequency of particle oscillation in the well (subsystem {2} or {3}), ω s = Ωs is an energy level in the harmonic well, γ s = ω s /Ωτ 1 is the decay,

show abstract

Section: Thermally Active Tunnel Transitions In Bcc Metalsmentioning

confidence: 98%

Section: Thermally Active Tunnel Transitions In Bcc Metalsmentioning

confidence: 98%

Section: Classical (Fcc Metals) and Anomalous (Bcc Metals) Isotopic Ementioning

confidence: 99%

Section: Classical (Fcc Metals) and Anomalous (Bcc Metals) Isotopic Ementioning

confidence: 99%

Section: 1mentioning

confidence: 99%

See 3 more Smart Citations

Three Regimes of Diffusion Migration of Hydrogen Atoms in Metals

Kashlev

2005

Theor Math Phys

View full text Add to dashboard Cite

show abstract

Theory of the diffusion of hydrogen in metals

Stoneham

1972

Ber Bunsenges Phys Chem

View full text Add to dashboard Cite

This paper reviews the various theories of the motion of light interstitials in metals. It discusses the formulation of quantum theories and their relation to each other and to the classical theories. The physical assumptions are summarised, and a comparison of theory and experiment is made.The theory successfully predicts (1) the distinction between bcc and fcc host lattices, (2) the relation between activation energy and volume of solution in bcc hosts, (3) the absolute magnitudes of the activation energies, (4) the temperature dependence of the diffusion rate, (5) the existence of isotope effects in electro‐ and thermomigration, and (6) the Zener relations. Topics which are not yet understood are discussed.

show abstract

On the Theory of Thermally Activated Processes

Geszti

1967

Physica Status Solidi (b)

View full text Add to dashboard Cite

The range of validity of “rate theory” is investigated and a clear distinction is made between “directional” and complete thermalization. It is suggested that the first process determines the hopping character of the motion, while the second determines whether the usual quasi‐equilibrium description is applicable. Macroscopic diffusion is shown always to obey “rate theory”, while frequency‐dependent dielectric or anelastic loss may shown non‐equilibrium effects. In the case in which complete thermalization is slow (although directional thermalization may be fast) a succession of Lorentzian peaks is obtained instead of the single peak predicted by rate theory. Qualitative dynamic conditions are presented for slow thermalization behaviour.

show abstract

On the mobility of interstitials

Cited by 29 publications

References 10 publications

Three Regimes of Diffusion Migration of Hydrogen Atoms in Metals

Three Regimes of Diffusion Migration of Hydrogen Atoms in Metals

Theory of the diffusion of hydrogen in metals

On the Theory of Thermally Activated Processes

Contact Info

Product

Resources

About