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Atomistic Modeling and Analysis of Hydride Phase Transformation in Palladium Nanoparticles

Sun, X. and Ariza, M. P. and Ortiz, M. and Wang, K. G. (2019) Atomistic Modeling and Analysis of Hydride Phase Transformation in Palladium Nanoparticles. Journal of the Mechanics and Physics of Solids, 125 . pp. 360-383. ISSN 0022-5096. http://resolver.caltech.edu/CaltechAUTHORS:20190107-130600369

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Abstract

Palladium-hydrogen (Pd-H) is a prototypical system for studying solute-induced phase transformation in various energy conversion and storage applications. While the behaviors of bulk Pd-H have been studied extensively, the detailed atomic picture of hydride phase transformation within individual Pd nanoparticles is still unclear. In this work, we employ a novel atomistic computational model, referred to as Diffusive Molecular Dynamics (DMD), to characterize the H absorption dynamics in Pd nanoparticles of spherical, octahedral and cubic shapes. The DMD model couples a non-equilibrium thermodynamic model with a discrete diffusion law, which allows it to reach diffusive time scales with atomic resolution. The model is capable of capturing the propagation of an atomistically sharp hydride phase boundary. A remarkable feature of the phase boundary structure that is predicted by the calculations is the emergence of misfit dislocations distributed over the interface. These dislocations relieve the elastic residual stresses induced by the change of volume that accompanies the phase transformation. Shape effects are also investigated in this work. More specifically, in both spherical and octahedral nanoparticles, we observe stacking faults during the H absorption process while the phase boundary in the cubic nanoparticle remains coherent. The spatial distribution of the stacking faults in the spherical sample is investigated in detail using an elastic core-shell model. We also identify the mechanisms that enable the movement of the stacking faults as they track the propagation of the phase boundary. Finally, we find that the rate of H absorption is reduced by the formation and movement of the stacking faults.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.jmps.2019.01.006DOIArticle
https://www.sciencedirect.com/science/article/pii/S0022509618306896PublisherArticle
Additional Information:© 2019 Elsevier Ltd. Received 12 August 2018, Revised 6 January 2019, Accepted 6 January 2019, Available online 7 January 2019. The authors gratefully acknowledge the support of the U.S. Office of Naval Research (ONR) under grant number N00014-17-1-2831, the Ministerio de Economía y Competitividad of Spain under grant number DPI2015-66534-R, and the U. S. Army Research Laboratory (ARL) through the Materials in Extreme Dynamic Environments (MEDE) Collaborative Research Alliance (CRA) under Award Number W911NF-11-R-0001.
Funders:
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-17-1-2831
Ministerio de Economía y Competitividad (MINECO)DPI2015-66534-R
Army Research Office (ARO)W911NF-11-R-0001
Subject Keywords:Hydrogen Absorption; Palladium Nanoparticles; Phase Transformation; Misfit Dislocations; Diffusive Molecular Dynamics
Record Number:CaltechAUTHORS:20190107-130600369
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190107-130600369
Official Citation:X. Sun, M.P. Ariza, M. Ortiz, K.G. Wang, Atomistic modeling and analysis of hydride phase transformation in palladium nanoparticles, Journal of the Mechanics and Physics of Solids, Volume 125, 2019, Pages 360-383, ISSN 0022-5096, https://doi.org/10.1016/j.jmps.2019.01.006. (http://www.sciencedirect.com/science/article/pii/S0022509618306896)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92117
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Jan 2019 23:21
Last Modified:16 Jan 2019 18:07

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