scholarly journals The Effect of Chemical Disorder on Defect Formation and Migration in Disordered MAXPhases

2019 ◽  
Author(s):  
Prashant Singh ◽  
Daniel Sauceda ◽  
Raymundo Arroyave
Keyword(s):  
Defect Formation ◽  
Chemical Disorder ◽  
And Migration

scholarly journals The effect of chemical disorder on defect formation and migration in disordered max phases

2020 ◽  
Vol 184 ◽  
pp. 50-58 ◽  
Author(s):  
Prashant Singh ◽  
Daniel Sauceda ◽  
Raymundo Arroyave
Keyword(s):  
Defect Formation ◽  
Max Phases ◽  
Chemical Disorder ◽  
And Migration

Is ReO3 a mixed ionic–electronic conductor? A DFT study of defect formation and migration in a BVIO3 perovskite-type oxide

2018 ◽  
Vol 20 (12) ◽  
pp. 8008-8015 ◽  
Author(s):  
J. P. Parras ◽  
A. R. Genreith-Schriever ◽  
H. Zhang ◽  
M. T. Elm ◽  
T. Norby ◽  
...  
Keyword(s):  
Defect Formation ◽  
Dft Study ◽  
Lithium Ions ◽  
Electronic Conductor ◽  
Hydronium Ions ◽  
Perovskite Type Oxide ◽  
Mixed Ionic Electronic Conductor ◽  
And Migration ◽  
Oxide Ions ◽  
Perovskite Type

Unexpected behaviour of the migration energetics of oxide ions, hydronium ions and lithium ions in perovskite-structured ReO3.

Computational studies of ice defects

2003 ◽  
Vol 81 (1-2) ◽  
pp. 325-332 ◽  
Author(s):  
P LM Plummer
Keyword(s):  
Defect Formation ◽  
Structural Evolution ◽  
Energy Difference ◽  
Electronic Energy ◽  
Energy Structure ◽  
Defect Site ◽  
And Migration ◽  
Dynamics Simulations ◽  
Small Clusters ◽  
Structure Calculations

Continuing our investigations of the energetics associated with defect formation and migration, both ab initio energy-structure calculations and molecular dynamics simulations are carried out on small clusters of water molecules containing one or more defects in hydrogen bonding. Previous studies in this series have identified structures containing defects that are stable at 0 K or that are transition states between such structures. However, results from this laboratory and elsewhere have shown that the energy required for the production or migration of a defect is more complex than merely the energy difference between the static structures. Cooperative motion of neighbors to the defect site can either increase or decrease the energy involved to produce or annihilate the defect. Thus, experimental measurements associated with the energy of defects in ice can differ substantially from those calculated using static models. By increasing the complexity of the model, the studies described in this report attempt to more realistically simulate a defect-containing ice system. The types of defects studied include ion and ion-pair defects. The initial structures are energetically stable — minima on the electronic energy surface — and contain one or more kinds of defects. Since the means and amount of energy injection can alter the migration path, the energy is introduced into the system in a variety of ways. The structural evolution of the ice system is then monitored as a function of time. PACS Nos.: 82.20Wt, 82.20Kh, 82.30Rs

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...

DECAHEDRAL AND ICOSAHEDRAL SYMMETRIES: AN APERIODIC MULTIPLE TWINNING MODEL WITH LINEAR STRAINS AND DENSITY INHOMOGENEITY

1992 ◽  
Vol 06 (10) ◽  
pp. 1623-1630 ◽  
Author(s):  
LUIGI G. CONTI
Keyword(s):  
Defect Formation ◽  
Defect Concentration ◽  
Concentration Gradients ◽  
Density Inhomogeneity ◽  
Pure Metals ◽  
And Migration ◽  
Multiple Twinning

The decahedral and icosahedral symmetries often observed in pure metals can be easily explained on the basis of an aperiodic multiple twinning model if defect concentration gradients are present. The different behavior of Au and Pt is discussed in detail in terms of defect formation volumes and migration thermodynamics.

Defect formation and migration in Nasicon Li1+xAlxTi2−x(PO4)3

2019 ◽  
Vol 21 (43) ◽  
pp. 24232-24238 ◽  
Author(s):  
Hamid R. Arjmandi ◽  
Steffen Grieshammer
Keyword(s):  
Defect Formation ◽  
And Migration

We investigate the formation and migration of various defects in Nasicon structured Li1+xAlxTi2−x(PO4)3.

scholarly journals Electric-field-assisted processing of ceramics: Nonthermal effects and related mechanisms

MRS Bulletin ◽  
2021 ◽  
Vol 46 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Olivier Guillon ◽  
Roger A. De Souza ◽  
Tarini Prasad Mishra ◽  
Wolfgang Rheinheimer
Keyword(s):  
Ion Transport ◽  
Electric Fields ◽  
Defect Formation ◽  
Heating Rates ◽  
Fast Heating ◽  
Plasma Sintering ◽  
Boundary Properties ◽  
Spark Plasma ◽  
Flow Through ◽  
And Migration

AbstractField-assisted processing methods, such as spark plasma sintering and flash sintering, have considerably expanded the toolbox of ceramic engineering. Depending on the conditions, substantial electric currents may flow through the material resulting in fast heating rates due to Joule heating. Here, we focus on nonthermal effects induced by electric fields during processing of fluorite- and perovskite-based ceramics. The fundamentals of how a field can directly modify defect formation and migration in crystals are discussed. In addition, the interplay of ion transport and electrical conductivity is considered, this interplay being crucial to understanding nonthermal effects caused by electric fields (as in memristive switching). Electrochemical reactions leading to new phases or reduction are also described, as are densification rates and sintering parameters that are significantly affected even though the sample temperature is held constant. Finally, as grain-boundary properties and segregation are changed by ion transport, we describe how both retardation and acceleration of grain growth can be achieved including graded microstructures.

scholarly journals Perturbed Angular Correlation Spectroscopy – A Tool for the Study of Defects and Diffusion at the Atomic Scale

2011 ◽  
Vol 311 ◽  
pp. 3-38 ◽  
Author(s):  
Matthew O. Zacate ◽  
Herbert Jaeger
Keyword(s):  
Angular Correlation ◽  
Defect Formation ◽  
Perturbed Angular Correlation ◽  
Correlation Spectroscopy ◽  
Atomic Scale ◽  
Perturbed Angular Correlation Spectroscopy ◽  
Migration Barriers ◽  
And Migration ◽  
Semiconducting Compounds ◽  
And Diffusion

This paper provides an introduction to perturbed angular correlation (PAC) spectroscopy in the context of its application in the study of point defects and diffusion. It emphasizes what we anticipate to be of interest to non-PAC specialists who are interested in understanding variations in how PAC results are presented by different research groups and in how physical quantities such as defect formation energies, association energies, and migration barriers can be extracted from analysis of PAC spectra. Numerous citations are included to emphasize the universality of the analysis methods across different classes of materials including metallic, ceramic, and semiconducting compounds.

Effect of Nb precipitate on defect formation and migration energies in bi-crystalline Zr

2019 ◽  
Vol 235 ◽  
pp. 121729 ◽  
Author(s):  
Divya Singh ◽  
Avinash Parashar ◽  
Rajeev Kapoor
Keyword(s):  
Defect Formation ◽  
And Migration

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.

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