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Title: On Thermodynamic and Kinetic Mechanisms for Stabilizing Surface Solid Solutions

Abstract

Many processes for energy storage rely on transformations between phases with strong separation tendencies. In these systems, performance limitations can arise from undesirable chemical and mechanical factors associated with the phase separation behavior. Solid solutions represent a desirable alternative, provided the conditions for their formation are known. In the present work, we invoke linear stability theory and diffuse-interface mesoscopic simulations to demonstrate that solid solutions can be stabilized near surface layers of phase-separating systems. Two factors are found to drive surface solid-solution formation: surface relaxation of solution self-strain energy and anisotropy of diffusion mobility. Using a strongly phase-separating LiXFePO4 particle as a model system, we show that the relaxation of the solution self-strain energy competes against the relaxation of the coherency strain energy to stabilize surface solid solutions. Our theoretical understanding also suggests that highly anisotropic diffusion mobility can provide an alternative kinetic route to achieve the same aim, with stabilizing behavior strongly dependent on the specific alignment of the surface orientation. Our findings provide fundamental guidance for manipulating solid-solution behavior in nanoscale structures, in which surface effects become especially significant. Beyond energy storage materials, our findings have important implications for understanding solid-solution formation in other phase-separating systems from metalmore » alloys to ceramics.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Materials Science Division
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Office (EE-3F)
OSTI Identifier:
1581486
Report Number(s):
LLNL-JRNL-765417
Journal ID: ISSN 1944-8244; 955594
Grant/Contract Number:  
AC52-07NA27344; 12-ERD-053; 18-FS-038
Resource Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 11; Journal Issue: 51; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 25 ENERGY STORAGE; phase stability; surfaces; solid solution; linear stability theory; diffuse-interface model

Citation Formats

Heo, Tae Wook, and Wood, Brandon C. On Thermodynamic and Kinetic Mechanisms for Stabilizing Surface Solid Solutions. United States: N. p., 2019. Web. doi:10.1021/acsami.9b14104.
Heo, Tae Wook, & Wood, Brandon C. On Thermodynamic and Kinetic Mechanisms for Stabilizing Surface Solid Solutions. United States. doi:10.1021/acsami.9b14104.
Heo, Tae Wook, and Wood, Brandon C. Tue . "On Thermodynamic and Kinetic Mechanisms for Stabilizing Surface Solid Solutions". United States. doi:10.1021/acsami.9b14104.
@article{osti_1581486,
title = {On Thermodynamic and Kinetic Mechanisms for Stabilizing Surface Solid Solutions},
author = {Heo, Tae Wook and Wood, Brandon C.},
abstractNote = {Many processes for energy storage rely on transformations between phases with strong separation tendencies. In these systems, performance limitations can arise from undesirable chemical and mechanical factors associated with the phase separation behavior. Solid solutions represent a desirable alternative, provided the conditions for their formation are known. In the present work, we invoke linear stability theory and diffuse-interface mesoscopic simulations to demonstrate that solid solutions can be stabilized near surface layers of phase-separating systems. Two factors are found to drive surface solid-solution formation: surface relaxation of solution self-strain energy and anisotropy of diffusion mobility. Using a strongly phase-separating LiXFePO4 particle as a model system, we show that the relaxation of the solution self-strain energy competes against the relaxation of the coherency strain energy to stabilize surface solid solutions. Our theoretical understanding also suggests that highly anisotropic diffusion mobility can provide an alternative kinetic route to achieve the same aim, with stabilizing behavior strongly dependent on the specific alignment of the surface orientation. Our findings provide fundamental guidance for manipulating solid-solution behavior in nanoscale structures, in which surface effects become especially significant. Beyond energy storage materials, our findings have important implications for understanding solid-solution formation in other phase-separating systems from metal alloys to ceramics.},
doi = {10.1021/acsami.9b14104},
journal = {ACS Applied Materials and Interfaces},
number = 51,
volume = 11,
place = {United States},
year = {2019},
month = {11}
}

Journal Article:
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This content will become publicly available on November 26, 2020
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