The formation and migration of non-equivalent oxygen vacancies in PrBaCo2−xMxO6−δ, where M = Fe, Co, Ni and Cu

2021 ◽  
Vol 23 (3) ◽  
pp. 2313-2319
Author(s):  
V. P. Zhukov ◽  
E. V. Chulkov ◽  
B. V. Politov ◽  
A. Yu. Suntsov ◽  
V. L. Kozhevnikov
Keyword(s):  
High Temperature ◽  
Ab Initio ◽  
Thermodynamic Functions ◽  
Oxygen Vacancies ◽  
Defect Formation ◽  
And Migration ◽  
Formation Energies

The ab initio calculated defect formation energies are used for assessment of high-temperature thermodynamic functions that govern the appearance of oxygen vacancies in PrBaCo2−xMxO6−δ.

A complete ab initio thermodynamic and kinetic catalogue of the defect chemistry of hematite α-Fe2O3, its cation diffusion, and sample donor dopants

2021 ◽  
Author(s):  
Shehab Shousha ◽  
Sarah Khalil ◽  
Mostafa Youssef
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Defect Formation ◽  
Defect Chemistry ◽  
Cation Diffusion ◽  
Functional Theory ◽  
Migration Barriers ◽  
Hubbard U ◽  
And Migration ◽  
Formation Energies

This paper studies comprehensively the defect chemistry and cation diffusion in α-Fe2O3. Defect formation energies and migration barriers are calculated using density functional theory with a theoretically calibrated Hubbard U...

scholarly journals Kinetic Monte Carlo Simulation of Oxygen Diffusion in Ytterbium Disilicate

MRS Advances ◽  
2016 ◽  
Vol 1 (17) ◽  
pp. 1203-1208 ◽  
Author(s):  
Brian S. Good
Keyword(s):  
Monte Carlo ◽  
High Temperature ◽  
Oxygen Diffusion ◽  
Density Functional ◽  
Defect Formation ◽  
Kinetic Monte Carlo ◽  
Interstitial Oxygen ◽  
Temperature Oxidation ◽  
Electron Volt ◽  
Formation Energies

ABSTRACTYtterbium disilicate is of interest as a potential environmental barrier coating for aerospace applications, notably for use in next generation jet turbine engines. In such applications, the transport of oxygen and water vapor through these coatings to the ceramic substrate is undesirable if high temperature oxidation is to be avoided. In an effort to understand the diffusion process in these materials, we have performed kinetic Monte Carlo simulations of vacancy-mediated and interstitial oxygen diffusion in Ytterbium disilicate. Oxygen vacancy and interstitial site energies, vacancy and interstitial formation energies, and migration barrier energies were computed using Density Functional Theory. We have found that, in the case of vacancy-mediated diffusion, many potential diffusion paths involve large barrier energies, but some paths have barrier energies smaller than one electron volt. However, computed vacancy formation energies suggest that the intrinsic vacancy concentration is small. In the case of interstitial diffusion, migration barrier energies are typically around one electron volt, but the interstitial defect formation energies are positive, with the result that the disilicate is unlikely to exhibit experience significant oxygen permeability except at very high temperature.

Ab initio Simulation of Vacancy Processes in Ni3Al

1998 ◽  
Vol 552 ◽  
Author(s):  
H. Schweiger ◽  
E. Moroni ◽  
W. Wolf ◽  
W. Püischl ◽  
W. Pfeiler ◽  
...  
Keyword(s):  
Activation Energy ◽  
Ab Initio ◽  
Point Defects ◽  
Nearest Neighbor ◽  
Defect Formation ◽  
Temperature Dependent ◽  
Ab Initio Simulation ◽  
Jump Model ◽  
Migration Barriers ◽  
Formation Energies

ABSTRACTProperties of point defects such as antisites and vacancies in Ni3A1 are studied by means of ab initio calculations for supercells. Temperature dependent quantitities such as defect formation energies are derived by means of a grandcanonical ensemble. Stimulated by experiments of residual resistivities suggesting an outstandingly large activation energy of 4.6 eV due to Al vacancies, several models for point like defects are treated in combination with calculated migration barriers for nearest neighbor jumps and also the six-jump model.

Defect Structure and Dynamics in Silicon

1985 ◽  
Vol 63 ◽  
Author(s):  
S. T. Pantelides ◽  
R. Car ◽  
P. J. Kelly ◽  
A. Oshiyama
Keyword(s):  
High Temperature ◽  
Defect Structure ◽  
Lattice Defects ◽  
Diffusion Data ◽  
Structure And Dynamics ◽  
Temperature Diffusion ◽  
Equilibrium Configurations ◽  
And Migration ◽  
Formation Energies

ABSTRACTThis paper gives a brief account of recent calculations of equilibrium configurations, formation energies, and migration energies of intrinsic lattice defects (vacancies, self-interstitials) and complexes of dopant impurities (phosphorus, aluminum) with these defects. The results have been used to provide a comprehensive interpretation of low- and high-temperature diffusion data.

scholarly journals An ab initio study of the effect of charge localization on oxygen defect formation and migration energies in magnesium oxide

2011 ◽  
Vol 467 (2131) ◽  
pp. 2054-2065 ◽  
Author(s):  
J. Mulroue ◽  
D. M. Duffy
Keyword(s):  
Density Functional ◽  
Oxygen Vacancies ◽  
Defect Formation ◽  
Frenkel Defect ◽  
Charge Localization ◽  
Migration Barriers ◽  
Pair Defect ◽  
Defect Energies ◽  
And Migration ◽  
Doubly Charged

Plane-wave density functional theory was used to study the properties of oxygen vacancies and interstitials, with different charge states, in MgO. The calculated properties were the relaxed configurations, the Frenkel defect formation energies and the energies of the migration barriers, and all properties were found to be strongly dependent on the defect charge state. The lowest energy configuration of the O 2− interstitial was found to be the cube centre; however, the O − and O 0 interstitials formed dumb-bell configurations. The Frenkel defect energies were also strongly dependent on the defect charge, with the neutral pair energy calculated to be 3 eV lower than the doubly charged Frenkel pair defect energy. The migration barriers of the oxygen vacancies were found to increase as the net charge of the oxygen vacancies decreased, which suggests that vacancies with trapped electrons are much less mobile than the F 2+ vacancies modelled by classical potentials. The migration of the oxygen interstitials showed particularly interesting behaviour. The O 0 interstitial was found to have a higher migration barrier than the O 2− interstitial but a very low barrier (0.06 eV) was found for the O − interstitial. The results have significant implications for the reliability of classical radiation damage simulations.

scholarly journals Determination of Vacancy Formation Energies in Binary UZr Alloys Using Special Quasirandom Structure Methods

2021 ◽  
Vol 8 ◽  
Author(s):  
Daniel Vizoso ◽  
Chaitanya Deo
Keyword(s):  
Large Scale ◽  
Nearest Neighbor ◽  
Defect Formation ◽  
Vacancy Formation ◽  
Random Structure ◽  
Local Configuration ◽  
Random Structures ◽  
And Migration ◽  
The Impact ◽  
Formation Energies

The use of predictive models to examine defect production and migration in metallic systems requires a thorough understanding of the energetics of defect formation and migration. In fully miscible alloys, atomistic properties will all have a range of values that are heavily dependent on local atomic configurations. In this work we have used the atomistic simulation tool Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to investigate the impact of first nearest neighbor configuration on vacancy formation energies at 0 K in γ-U-Zr alloys of varying Zr concentrations. The properties of randomly generated alloy microstructures were also compared with those produced as special quasi-random structures (SQS) using the “mcsqs” code within the Alloy Theoretic Automated Toolkit. Results have confirmed that local configuration can have a significant impact on measured properties and must be considered when characterizing miscible alloy systems. Results also indicated that the generation method of the random structure (i.e., via random species assignment or a method of enforced randomness) does not result in a measurable difference in average vacancy formation energies in miscible U-Zr systems.

Prediction of high-temperature point defect formation in TiO2 from combined ab initio and thermodynamic calculations

2007 ◽  
Vol 55 (13) ◽  
pp. 4325-4337 ◽  
Author(s):  
J. He ◽  
R.K. Behera ◽  
M.W. Finnis ◽  
X. Li ◽  
E.C. Dickey ◽  
...  
Keyword(s):  
High Temperature ◽  
Ab Initio ◽  
Point Defect ◽  
Defect Formation ◽  
Thermodynamic Calculations
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