Valence Fluctuations of ^(57)Fe in Disordered Li_(0.6)FePO_4
- Creators
- Dodd, J. L.
- Halevy, I.
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Fultz, B.
Abstract
The local electronic structure around iron ions in Li_(0.6)FePO)4 was studied by ^(57)Fe Mössbauer spectrometry at temperatures from 25 to 240 °C. The equilibrium two-phase, triphylite plus heterosite, material was compared to a disordered solid solution that was obtained by quenching from a high temperature. Substantial electronic relaxations were found in the disordered solid solution compared to the two-phase material at temperatures of 130 °C and above. Fluctuations in the electric field gradient showed an approximately Arrhenius behavior, with an activation energy of 335 ± 25meV and a prefactor of 5 × 10^(11) Hz, whereas Arrhenius plots for the isomer shift showed activation energies of approximately 600 meV. It is suggested that these spectral relaxations are caused by the motions of Li^+ ions. A slight relaxation at 180 °C in 10% of the two-phase material can be attributed to defects in the heterosite and triphylite phases. Overall, the disordered solid solution phase shows faster electronic dynamics than the two-phase material.
Additional Information
© 2007 American Chemical Society. Received 20 November 2006. Published online 6 January 2007. Published in print 1 February 2007. The authors thank K. Amine, I. Belharouak, and Argonne National Laboratory for providing the LiFePO_4 material, and we also thank R. Yazami and L. F. Nazar for helpful discussions. This work was supported by the U.S. Department of Energy under Grant DE-FG03-00ER15035.Additional details
- Eprint ID
- 78051
- Resolver ID
- CaltechAUTHORS:20170609-091425287
- DE-FG03-00ER15035
- Department of Energy (DOE)
- Created
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2017-06-09Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field