Calculations of vacancy formation and migration energies offcc Cs by the LMTO-method: Application to self diffusion

1993 ◽  
Vol 92 (4) ◽  
pp. 469-473 ◽  
Author(s):  
D. Fuks ◽  
J. Pelleg ◽  
S. N. Rashkeev ◽  
S. Dorfman
Keyword(s):  
Vacancy Formation ◽  
Self Diffusion ◽  
Lmto Method ◽  
And Migration

Vacancy diffusion along twist grain boundaries in copper

1991 ◽  
Vol 6 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Miki Nomura ◽  
Sing-Yun Lee ◽  
James B. Adams
Keyword(s):  
Grain Boundaries ◽  
Activation Energies ◽  
Vacancy Formation ◽  
Embedded Atom Method ◽  
Vacancy Diffusion ◽  
High Angle ◽  
Self Diffusion ◽  
Embedded Atom ◽  
And Migration ◽  
Formation Energies

Vacancy diffusion along two different high-angle twist grain boundaries (Σ5 and Σ13) was studied using the Embedded Atom Method (EAM). Vacancy formation energies in all the possible sites were calculated and found to be directly related to the degree of coincidence with the neighboring crystal planes. Optimal migration paths and migration energies were determined and found to be very low. The activation energies for self-diffusion at the boundaries were found to be less than half of the bulk value.

scholarly journals A comprehensive first-principles study of pure elements: Vacancy formation and migration energies and self-diffusion coefficients

2016 ◽  
Vol 109 ◽  
pp. 128-141 ◽  
Author(s):  
Shun-Li Shang ◽  
Bi-Cheng Zhou ◽  
William Y. Wang ◽  
Austin J. Ross ◽  
Xuan L. Liu ◽  
...  
Keyword(s):  
First Principles ◽  
Diffusion Coefficients ◽  
Vacancy Formation ◽  
Self Diffusion ◽  
First Principles Study ◽  
And Migration

Atomistic Modeling of Interfacial Diffusion in the Lamellar Li0 TiAl

1999 ◽  
Vol 578 ◽  
Author(s):  
M. Nomura ◽  
D. E. Luzzi ◽  
V. Vitek
Keyword(s):  
Atomistic Simulation ◽  
Effective Activation Energy ◽  
Surprising Result ◽  
Atomistic Modeling ◽  
Many Body ◽  
Interfacial Diffusion ◽  
Self Diffusion ◽  
Diffusion Mechanisms ◽  
And Migration ◽  
Lamellar Interfaces

AbstractAtomistic simulation employing many-body central-force potentials was performed to elucidate the diffusion mechanisms in the bulk and at lamellar interfaces assuming a vacancy mechanism. First the self- diffusion of Ti and Al in stoichiometric structures was studied. It was found that the diffusion was faster along lamellar interfaces than in the bulk; the effective activation energy for the diffusion coefficient is about ∼15% lower. The simulations were then extended to investigate diffusion along lamellar boundaries with segregated Ti which is likely in Ti rich alloys. The surprising result is that diffusion remains practically unchanged when compared with the stoichiometric case. The reason is that while the path controlling the diffusion is different, the corresponding effective formation and migration energies are practically the same as in the stoichiometric case.

Vacancy Formation Energy and Kinetic Properties of Liquid Metals

2021 ◽  
Vol 880 ◽  
pp. 43-48
Author(s):  
Yuri N. Starodubtsev ◽  
V.S. Tsepelev
Keyword(s):  
Diffusion Coefficient ◽  
Kinematic Viscosity ◽  
Formation Energy ◽  
Liquid Metals ◽  
Linear Regression Analysis ◽  
Vacancy Formation Energy ◽  
Vacancy Formation ◽  
Kinetic Properties ◽  
Self Diffusion ◽  
Self Diffusion Coefficient

We investigated the relationship of the vacancy formation energy with kinematic viscosity and self-diffusion coefficient in liquid metals at the melting temperature. Formulas are obtained that relate experimental values of the vacancy formation energy, kinematic viscosity, and self-diffusion coefficient to the atomic size and mass, the melting and Debye temperatures. The viscosity and self-diffusion parameters are introduced. The ratio of these parameters to vacancy formation energy is equal to dimensionless constants. It is shown that the formulas for viscosity and self-diffusion differ only in dimensionless constants; the values of these constants are calculated. Linear regression analysis was carried out and formulas with the highest adjusted coefficient of determination were identified. The calculated values of the self-diffusion coefficient for a large number of liquid metals are presented.

Lithium tracer diffusion in near stoichiometric LiNi0.5Mn1.5O4 cathode material for lithium-ion batteries

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Daniel Uxa ◽  
Harald Schmidt
Keyword(s):  
Cathode Material ◽  
Secondary Ion Mass Spectrometry ◽  
Lithium Ion ◽  
Tracer Diffusion ◽  
Side Reactions ◽  
Battery Materials ◽  
Self Diffusion ◽  
Thermally Activated ◽  
Average Grain Size ◽  
And Migration

Abstract The compound LiNi0.5Mn1.5O4 is used as novel cathode material for Li-ion batteries and represents a variant to replace conventional LiMn2O4. For a further improvement of battery materials it is necessary to understand kinetic processes at and in electrodes and the underlying diffusion of lithium that directly influences charging/discharging times, maximum capacities, and possible side reactions. In the present study Li tracer self-diffusion is investigated in polycrystalline sintered bulk samples of near stoichiometric LiNi0.5Mn1.5O4 with an average grain size of about 50–70 nm in the temperature range between 250 and 600 °C. For analysis, stable 6Li tracers are used in combination with secondary ion mass spectrometry (SIMS). The tracer diffusivities can be described by the Arrhenius law with an activation enthalpy of (0.97 ± 0.05) eV, which is interpreted as the sum of the formation and migration energy of a thermally activated Li vacancy.

The analysis of self-diffusion and migration of rough spheres in nonlinear shear flow using a traction-corrected boundary element method

2008 ◽  
Vol 598 ◽  
pp. 267-292 ◽  
Author(s):  
MARC S. INGBER ◽  
SHIHAI FENG ◽  
ALAN L. GRAHAM ◽  
HOWARD BRENNER
Keyword(s):  
Boundary Element Method ◽  
Shear Flow ◽  
Boundary Element ◽  
Particle Migration ◽  
Self Diffusion ◽  
Centre Of Gravity ◽  
Particle Pairs ◽  
And Migration ◽  
Nonlinear Shear ◽  
Element Method

The phenomena of self-diffusion and migration of rough spheres in nonlinear shear flows are investigated using a new traction-corrected boundary element method (TC-BEM) in which the near-field asymptotics for the traction solution in the interstitial region between two nearly touching spheres is seamlessly coupled with a traditional direct boundary element method. The TC-BEM is extremely accurate in predicting particle trajectories, and hence can be used to calculate both the particle self-diffusivity and a newly defined migration diffusivity for dilute suspensions. The migration diffusivity is a function of a nonlinearity parameter characterizing the shear flow and arises from the net displacement of the centre of gravity of particle pairs. This net displacement of the centre of gravity of particle pairs does not occur for smooth particles, nor for rough particles in a linear shear flow. An explanation is provided for why two-particle interactions of rough spheres in a nonlinear shear flow result in particle migration.

Determination of the Activation Energy for Formation and Migration of Thermal Vacancies in 401.0 Casting Aluminum Alloy

2013 ◽  
Vol 337-338 ◽  
pp. 1-4
Author(s):  
N.A. Kamel ◽  
S.A. Aly ◽  
A.A. Ibrahim ◽  
E.A. Badawi
Keyword(s):  
Aluminum Alloy ◽  
Formation Enthalpy ◽  
Electrical Measurements ◽  
Quenching Rate ◽  
Self Diffusion ◽  
A Value ◽  
Casting Aluminum Alloy ◽  
Casting Aluminum ◽  
And Migration

Electrical techniques have been used to study the thermal vacancies in 401.0 casting aluminum alloy. Quenching experiments were usually performed on thin specimens to ensure a uniform quenching rate throughout the specimen. After grinding, polishing and etching, samples of 401.0 were homogenized for 12h at 673K and annealed for 90min., before quenched in water (277K) and then subjected to electrical measurements. From such measurements it is possible to deduce the vacancy formation enthalpy, which in combination with the results of self-diffusion measurements, give a value for the migration enthalpy of the vacancy.

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