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Coherent phase change in interstitial solutions : a hierarchy of instabilities
Citation Link: https://doi.org/10.15480/882.13353
Publikationstyp
Journal Article
Date Issued
2024-06-05
Sprache
English
TORE-DOI
Journal
Volume
11
Issue
21
Article Number
2308554
Citation
Advanced Science 11 (21): 2308554 (2024)
Publisher DOI
Scopus ID
Publisher
Wiley
Metal hydrides or lithium ion battery electrodes can take the form of interstitial solid solutions with a miscibility gap. This work discusses theory approaches for locating, in temperature-composition space, coherent phase transformations during the charging/discharging of such systems and for identifying the associated transformation mechanisms. The focus is on the simplest scenario, where instabilities derive from the thermodynamics of the bulk phase alone, considering strain energy as the foremost consequence of coherency and admitting for stress relaxation at free surfaces. The extension of the approach to include capillarity is demonstrated by an example. The analysis rests on constrained equilibrium phase diagrams that are informed by geometry- and dimensionality-specific mechanical boundary conditions and on elastic instabilities–again geometry-specific–as implied by the theory of open-system elasticity. It is demonstrated that some scenarios afford the analysis of chemical stability to be based entirely on a linear stability analysis of the mechanical equilibrium, which provides closed-form solutions in a straightforward manner. Attention is on the impact of the system geometry (infinitely extended or of finite size) and on the chemical (closed or open system) and mechanical (incoherent or coherent) boundary conditions. Transformation mechanism maps are suggested for documenting the findings. The maps reveal a hierarchy of instabilities, which depend strongly on each of the above characteristics. Specifically, realistic, finite-sized systems differ qualitatively from idealized systems of infinite extension. Among the transformation mechanisms exposed by the analysis are a uniform switchover to the other phase when the open system reaches its chemical spinodal, practical coherent nucleation, as well as chemo-elastically coupled spontaneous buckling modes, which may take the form of either, single-phase or dual-phase states.
Subjects
battery electrodes
Bitter-Crum theorem
coherent phase transformations
metal hydrides
open-system elasticity
phase transformation mechanisms
DDC Class
620.1: Engineering Mechanics and Materials Science
Publication version
publishedVersion
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Advanced Science - 2024 - Weissmüller - Coherent Phase Change in Interstitial Solutions A Hierarchy of Instabilities.pdf
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Main Article
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2.91 MB
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