The role of cation ordering and disordering on mass transport in complex oxides

Kreller, Cortney R.; Uberuaga, Blas P.

doi:10.1016/j.cossms.2021.100899

Cited by 14 publications

(13 citation statements)

References 80 publications

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“…There is a need, once reasonable models of the disordered state have been established, to understand the structure-property relationship of those systems. Structural properties such as short-range order and percolation networks can have dramatic effects on transport and these relationships have received scant modeling attention ( Kreller and Uberuaga, 2021 ).…”

Section: Discussion and Outlookmentioning

confidence: 99%

“…The key question then is when is it critical to account for the short-range order to accurately understand and predict the properties of these materials. For example, it seems clear that the nature of the short-range order is essential for understanding mass transport in these materials ( Kreller and Uberuaga, 2021 ). However, it isn’t necessary to understand chemical trends in thermodynamic behavior.…”

Section: Discussion and Outlookmentioning

confidence: 99%

“…In contrast, pyrochlores that have high energy cost for the order-disorder transition would amorphize under irradiation ( Sickafus, 2000 ). Understanding the disordering process and its impact on properties is critical for a number of other applications, including ionic conductors ( Kreller and Uberuaga, 2021 ). We note that, in contrast, spinels (AB 2 O 4 ), which have a crystal structure related to rocksalt and have ordered cation vacancy sites, show opposite correlation between disordering energies and amorphization resistance compared to pyrochlores ( Uberuaga et al, 2015 ), i.e., spinels that are more difficult to disorder exhibiting higher resistance to amorphization.…”

Section: Introductionmentioning

confidence: 99%

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Modeling Disorder in Pyrochlores and Other Anion-Deficient Fluorite Structural Derivative Oxides

2021

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Their very flexible chemistry gives oxide materials a richness in functionality and wide technological application. A specific group of oxides that have a structure related to fluorite but with less oxygen, termed anion-deficient fluorite structural derivatives and with pyrochlores being the most notable example, has been shown to exhibit a diversity of useful properties. For example, the possibility to undergo a transition from an ordered to disordered state allows these oxides to have high radiation tolerance. Atomistic-scale calculations in the form of molecular dynamics (MD) and density functional theory (DFT) have been extensively used to understand what drives this order/disorder transition. Here we give a brief overview of how atomistic-scale calculations are utilized in modeling disorder in pyrochlores and other anion-deficient fluorite structural derivatives. We discuss the modeling process from simple point defects to completely disordered structures, the dynamics during the disordering process, and the use of mathematical models to generate ordered solid-solution configurations. We also attempt to identify the challenges in modeling short range order and discuss future directions to more comprehensive models of the disordered structures.

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Section: Discussion and Outlookmentioning

confidence: 99%

Section: Discussion and Outlookmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling Disorder in Pyrochlores and Other Anion-Deficient Fluorite Structural Derivative Oxides

2021

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“…Dimensionality is an important design concept in solid-state chemistry with functional properties intimately linked to features in the crystal structure, for example, the empirical link between high-temperature superconductivity and layered structures and low-energy migration pathways in superionic materials. 1 − 3 Layered cobalt double perovskites, LnBaCo 2 O 6−δ (Ln = lanthanides, Y), have been identified as promising electrode materials for solid oxide fuel cells 4 − 11 as electrocatalysts for oxygen evolution in alkaline solution 12 , 13 and also have interesting magnetic and thermoelectric properties. 14 − 16 The strong performance in electrochemical applications is linked to their high electronic and ionic conduction, high surface oxygen exchange rates, and catalytic selectivity.…”

Section: Introductionmentioning

confidence: 99%

Insights into Oxygen Migration in LaBaCo₂O_6−δ Perovskites from In Situ Neutron Powder Diffraction and Bond Valence Site Energy Calculations

2022

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Layered cobalt oxide perovskites are important mixed ionic and electronic conductors. Here, we investigate LaBaCo 2 O 6−δ using in situ neutron powder diffraction. This composition is unique because it can be prepared in cubic, layered, and vacancy-ordered forms. Thermogravimetric analysis and diffraction reveal that layered and disordered samples have near-identical oxygen cycling capacities. Migration barriers for oxide ion conduction calculated using the bond valence site energy approach vary from E b ∼ 2.8 eV for the cubic perovskite to E b ∼ 1.5 eV for 2D transport in the layered system. Vacancy-ordered superstructures were observed at low temperatures, 350–400 °C for δ = 0.25 and δ = 0.5. The vacancy ordering at δ = 0.5 is different from the widely reported structure and involves oxygen sites in both CoO 2 and LaO planes. Vacancy ordering leads to the emergence of additional migration pathways with low-energy barriers, for example, 1D channels with E b = 0.5 eV and 3D channels with E b = 2.2 eV. The emergence of these channels is caused by the strong orthorhombic distortion of the crystal structure. These results demonstrate that there is potential scope to manipulate ionic transport in vacancy-ordered LnBaCo 2 O 6−δ perovskites with reduced symmetry.

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“…As the connection between the structure, chemistry, and properties of materials across length scales becomes clearer, it is recognized that many interesting phenomena can only be understood by embracing the role of such disorder ( Chaney et al, 2021 ). Multi-cation, or complex oxides are an ideal class of materials to study such phenomena, since their structure-property relationships are not only related to the composition and structure, but are correlated to the extent of disorder within the cation and anion sublattices ( Kreller and Uberuaga, 2021 ; Mullens et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Probing Multiscale Disorder in Pyrochlore and Related Complex Oxides in the Transmission Electron Microscope: A Review

et al. 2021

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Transmission electron microscopy (TEM), and its counterpart, scanning TEM (STEM), are powerful materials characterization tools capable of probing crystal structure, composition, charge distribution, electronic structure, and bonding down to the atomic scale. Recent (S)TEM instrumentation developments such as electron beam aberration-correction as well as faster and more efficient signal detection systems have given rise to new and more powerful experimental methods, some of which (e.g., 4D-STEM, spectrum-imaging, in situ/operando (S)TEM)) facilitate the capture of high-dimensional datasets that contain spatially-resolved structural, spectroscopic, time- and/or stimulus-dependent information across the sub-angstrom to several micrometer length scale. Thus, through the variety of analysis methods available in the modern (S)TEM and its continual development towards high-dimensional data capture, it is well-suited to the challenge of characterizing isometric mixed-metal oxides such as pyrochlores, fluorites, and other complex oxides that reside on a continuum of chemical and spatial ordering. In this review, we present a suite of imaging and diffraction (S)TEM techniques that are uniquely suited to probe the many types, length-scales, and degrees of disorder in complex oxides, with a focus on disorder common to pyrochlores, fluorites and the expansive library of intermediate structures they may adopt. The application of these techniques to various complex oxides will be reviewed to demonstrate their capabilities and limitations in resolving the continuum of structural and chemical ordering in these systems.

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The role of cation ordering and disordering on mass transport in complex oxides

Cited by 14 publications

References 80 publications

Modeling Disorder in Pyrochlores and Other Anion-Deficient Fluorite Structural Derivative Oxides

Modeling Disorder in Pyrochlores and Other Anion-Deficient Fluorite Structural Derivative Oxides

Insights into Oxygen Migration in LaBaCo₂O_6−δ Perovskites from In Situ Neutron Powder Diffraction and Bond Valence Site Energy Calculations

Probing Multiscale Disorder in Pyrochlore and Related Complex Oxides in the Transmission Electron Microscope: A Review

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The role of cation ordering and disordering on mass transport in complex oxides

Cited by 14 publications

References 80 publications

Modeling Disorder in Pyrochlores and Other Anion-Deficient Fluorite Structural Derivative Oxides

Modeling Disorder in Pyrochlores and Other Anion-Deficient Fluorite Structural Derivative Oxides

Insights into Oxygen Migration in LaBaCo2O6−δ Perovskites from In Situ Neutron Powder Diffraction and Bond Valence Site Energy Calculations

Probing Multiscale Disorder in Pyrochlore and Related Complex Oxides in the Transmission Electron Microscope: A Review

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Product

Resources

About

Insights into Oxygen Migration in LaBaCo₂O_6−δ Perovskites from In Situ Neutron Powder Diffraction and Bond Valence Site Energy Calculations