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Polaron-ion correlations in Li_xFePO_4 studied by x-ray nuclear resonant forward scattering at elevated pressure and temperature

Tracy, S. J. and Mauger, L. and Tan, H. J. and Muñoz, J. A. and Xiao, Yuming and Fultz, B. (2014) Polaron-ion correlations in Li_xFePO_4 studied by x-ray nuclear resonant forward scattering at elevated pressure and temperature. Physical Review B, 90 (9). Art. No. 094303. ISSN 1098-0121. http://resolver.caltech.edu/CaltechAUTHORS:20141016-125243303

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Abstract

Valence fluctuations of Fe^(2+) and Fe^(3+) were studied in a solid solution of Li_xFePO_4 by nuclear resonant forward scattering of synchrotron x rays while the sample was heated in a diamond-anvil pressure cell. The spectra acquired at different temperatures and pressures were analyzed for the frequencies of valence changes using the Blume-Tjon model of a system with a fluctuating Hamiltonian. These frequencies were analyzed to obtain activation enthalpies and an activation volume for polaron hopping. There was a large suppression of hopping frequency with pressure, giving an activation volume for polaron hopping of 5.8±0.7 Å^ 3. This large, positive value is typical of ion diffusion, which indicates correlated motions of polarons and Li^+ ions that alter the dynamics of both. Monte Carlo simulations were used to estimate the strength of the polaron-ion interaction energy.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1103/PhysRevB.90.094303DOIArticle
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.094303PublisherArticle
ORCID:
AuthorORCID
Fultz, B.0000-0002-6364-8782
Alternate Title:Polaron-ion correlations in LixFePO4 studied by x-ray nuclear resonant forward scattering at elevated pressure and temperature
Additional Information:© 2014 American Physical Society. Received 31 December 2013; Revised manuscript received 6 June 2014; Published 12 September 2014. We thank C. W. Li for discussions. Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT is supported by CIW, CDAC, UNLV, and LLNL through funding from DOE-NNSA, DOE-BES, and NSF. Use of the APS was supported by DOE-BES, under Contract No. DE-AC02-06CH11357. This work was supported as part of EFree, an Energy Frontier Research Center, under Award No. DE-SG0001057.
Funders:
Funding AgencyGrant Number
Carnegie Institution of WashingtonUNSPECIFIED
CDACUNSPECIFIED
University of Nevada, Las VegasUNSPECIFIED
Lawrence Livermore National Laboratory UNSPECIFIED
National Nuclear Security Administration (NNSA)UNSPECIFIED
Department of Energy (DOE)DE-AC02-06CH11357
NSFUNSPECIFIED
Department of Energy (DOE)DE-SG0001057
Classification Code:PACS: 71.38.−k; 72.20.Ee; 72.80.Sk; 76.80.+y.
Record Number:CaltechAUTHORS:20141016-125243303
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141016-125243303
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50450
Collection:CaltechAUTHORS
Deposited By: Joanne McCole
Deposited On:16 Oct 2014 22:39
Last Modified:08 Jan 2017 00:21

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