Valence fluctuations of 57Fe in disordered Li0.6FePO4

被引：23

作者：

Dodd, J. L. ^{[1
]}

Halevy, I. ^{[1
]}

Fultz, B. ^{[1
]}

机构：

[1] CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA

来源：

JOURNAL OF PHYSICAL CHEMISTRY C | 2007年 / 111卷 / 04期

关键词：

D O I：

10.1021/jp067710x

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The local electronic structure around iron ions in Li0.6FePO4 was studied by Fe-57 Mossbauer spectrometry at temperatures from 25 to 240 degrees 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 degrees 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 x 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 degrees 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.

引用

页码：1563 / 1566

页数：4

共 23 条

[1] Lithium extraction/insertion in LiFePO4:: an X-ray diffraction and Mossbauer spectroscopy study
Andersson, AS
Kalska, B
Häggström, L
Thomas, JO
[J]. SOLID STATE IONICS, 2000, 130 (1-2) : 41 - 52
[2] Reducing carbon in LiFePO4/C composite electrodes to maximize specific energy, volumetric energy, and tap density
Chen, ZH
Dahn, JR
[J]. JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 2002, 149 (09) : A1184 - A1189
[3] Electronically conductive phospho-olivines as lithium storage electrodes
Chung, SY
Bloking, JT
Chiang, YM
[J]. NATURE MATERIALS, 2002, 1 (02) : 123 - 128
[4] Crystal chemistry of the olivine-type LixFePO4 system (0 ≤ x ≤ 1) between 25 and 370°C
Delacourt, C
Rodríguez-Carvajal, J
Schmitt, B
Tarascon, JM
Masquelier, C
[J]. SOLID STATE SCIENCES, 2005, 7 (12) : 1506 - 1516
[5] Toward understanding of electrical limitations (electronic, ionic) in LiMPO4 (M = Fe, Mn) electrode materials
Delacourt, C
Laffont, L
Bouchet, R
Wurm, C
Leriche, JB
Morcrette, M
Tarascon, JM
Masquelier, C
[J]. JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 2005, 152 (05) : A913 - A921
[6] The existence of a temperature-driven solid solution in LixFePO4 for 0 ≤ x ≤ 1
Delacourt, C
Poizot, P
Tarascon, JM
Masquelier, C
[J]. NATURE MATERIALS, 2005, 4 (03) : 254 - 260
[7] Phase diagram of LixFePO4
Dodd, JL
Yazami, R
Fultz, B
[J]. ELECTROCHEMICAL AND SOLID STATE LETTERS, 2006, 9 (03) : A151 - A155
[8] Small polaron hopping in LixFePO4 solid solutions:: Coupled lithium-ion and electron mobility
Ellis, Brian
Perry, Laura K.
Ryan, Dominic H.
Nazar, L. F.
[J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2006, 128 (35) : 11416 - 11422
[9] FULTZ B, 2000, METHODS MAT RES
[10] Approaching theoretical capacity of LiFePO4 at room temperature at high rates
Huang, H
Yin, SC
Nazar, LF
[J]. ELECTROCHEMICAL AND SOLID STATE LETTERS, 2001, 4 (10) : A170 - A172

← 1 2 3 →