Elucidating the Factors That Cause Cation Diffusion Shutdown in Spinel-Based Electrodes

AbstractCation diffusion in the spinel solid solution (Fe1-xTix)3-δO4 (0≤ x ≤ 0.3) was investigated at 1200 ºC as a function of oxygen activity, aO2 and cationic composition, x. At different cationic compositions, cation tracer diffusion coefficients, D*Me of Me = Fe and Ti were measured as a function of oxygen activity. Plots of log DMe vs. loga0 show V-shaped curves, indicating that different types of point defects prevail at high anc low oxygen activities. Thermogravimetric experiments were conducted, using a high resolution microbalance, to determine the deviation from stoichiometry in (Fe1-xTix)3-δO4 at 1200 °C. δversus log aO2 curves are S-shaped. An analysis of the oxygen activity dependences of thecation diffusion coefficients and the deviation from stoichiometry with regardto the point defect structure suggests that at high oxygen activities cation vacancies are the predominant defects governing the deviation from stoichiometry and the diffusion ofcations. At low oxygen activities, and at small values of x, cation interstitials determine the deviation from stoichiometry, while they dominate for 0 ≤ x ≤ 0.3 inthe cation diffusion.

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Divalent cation diffusion in calcium fluorapatite

Journal of Materials Science ◽

10.1007/s10853-011-5712-4 ◽

2011 ◽

Vol 46 (23) ◽

pp. 7459-7465 ◽

Cited By ~ 4

Author(s):

Eleanor E. Jay ◽

Phillip M. Mallinson ◽

Shirley K. Fong ◽

Brian L. Metcalfe ◽

Robin W. Grimes

Keyword(s):

Divalent Cation ◽

Cation Diffusion

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Role of cation diffusion in the formation mechanism and properties of cobalt-doped n-type pyrite thin films

Journal of Materials Science ◽

10.1007/s10853-013-7272-2 ◽

2013 ◽

Vol 48 (14) ◽

pp. 4914-4924 ◽

Cited By ~ 7

Author(s):

P. Díaz-Chao ◽

J. R. Ares ◽

I. J. Ferrer ◽

C. Sánchez

Keyword(s):

Thin Films ◽

Formation Mechanism ◽

Cation Diffusion

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Analysis of experimental data on divalent cation diffusion kinetics in aluminosilicate garnets with application to timescales of peak Barrovian metamorphism, Scotland

Contributions to Mineralogy and Petrology ◽

10.1007/s00410-015-1175-y ◽

2015 ◽

Vol 170 (2) ◽

Cited By ~ 21

Author(s):

Xu Chu ◽

Jay J. Ague

Keyword(s):

Experimental Data ◽

Divalent Cation ◽

Diffusion Kinetics ◽

Cation Diffusion

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A complete ab initio thermodynamic and kinetic catalogue of the defect chemistry of hematite α-Fe2O3, its cation diffusion, and sample donor dopants

Physical Chemistry Chemical Physics ◽

10.1039/d1cp03394h ◽

2021 ◽

Author(s):

Shehab Shousha ◽

Sarah Khalil ◽

Mostafa Youssef

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Defect Formation ◽

Defect Chemistry ◽

Cation Diffusion ◽

Functional Theory ◽

Migration Barriers ◽

Hubbard U ◽

And Migration ◽

Formation Energies

This paper studies comprehensively the defect chemistry and cation diffusion in α-Fe2O3. Defect formation energies and migration barriers are calculated using density functional theory with a theoretically calibrated Hubbard U...

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Anion reorientations and cation diffusion in a carbon-substituted sodium nido-borate Na-7,9-C2B9H12: 1H and 23Na NMR studies

Zeitschrift für Physikalische Chemie ◽

10.1515/zpch-2021-3108 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Alexander V. Skripov ◽

Olga A. Babanova ◽

Roman V. Skoryunov ◽

Alexei V. Soloninin ◽

Terrence J. Udovic

Keyword(s):

Lattice Relaxation ◽

Activation Energies ◽

Spin Lattice Relaxation ◽

Relaxation Rates ◽

Cation Diffusion ◽

Relaxation Data ◽

Nmr Studies ◽

Spin Lattice ◽

Jump Rate ◽

Disordered Phase

Abstract Polyhydroborate-based salts of lithium and sodium have attracted much recent interest as promising solid-state electrolytes for energy-related applications. A member of this family, sodium dicarba-nido-undecahydroborate Na-7,9-C2B9H12 exhibits superionic conductivity above its order-disorder phase transition temperature, ∼360 K. To investigate the dynamics of the anions and cations in this compound at the microscopic level, we have measured the 1H and 23Na nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation rates over the temperature range of 148–384 K. It has been found that the transition from the low-T ordered to the high-T disordered phase is accompanied by an abrupt, several-orders-of-magnitude acceleration of both the reorientational jump rate of the complex anions and the diffusive jump rate of Na+ cations. These results support the idea that reorientations of large [C2B9H12]− anions can facilitate cation diffusion and, thus, the ionic conductivity. The apparent activation energies for anion reorientations obtained from the 1H spin-lattice relaxation data are 314 meV for the ordered phase and 272 meV for the disordered phase. The activation energies for Na+ diffusive jumps derived from the 23Na spin-lattice relaxation data are 350 and 268 meV for the ordered and disordered phases, respectively.

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Structural basis for the alternating access mechanism of the cation diffusion facilitator YiiP

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1715051115 ◽

2018 ◽

Vol 115 (12) ◽

pp. 3042-3047 ◽

Cited By ~ 19

Author(s):

Maria Luisa Lopez-Redondo ◽

Nicolas Coudray ◽

Zhening Zhang ◽

John Alexopoulos ◽

David L. Stokes

Keyword(s):

Large Scale ◽

Structural Basis ◽

Membrane Domains ◽

Cation Diffusion ◽

Cation Diffusion Facilitator ◽

X Ray ◽

Bacterial Membranes ◽

Helix Bundle ◽

Four Helix Bundle ◽

Alternating Access

YiiP is a dimeric antiporter from the cation diffusion facilitator family that uses the proton motive force to transport Zn2+ across bacterial membranes. Previous work defined the atomic structure of an outward-facing conformation, the location of several Zn2+ binding sites, and hydrophobic residues that appear to control access to the transport sites from the cytoplasm. A low-resolution cryo-EM structure revealed changes within the membrane domain that were associated with the alternating access mechanism for transport. In the current work, the resolution of this cryo-EM structure has been extended to 4.1 Å. Comparison with the X-ray structure defines the differences between inward-facing and outward-facing conformations at an atomic level. These differences include rocking and twisting of a four-helix bundle that harbors the Zn2+ transport site and controls its accessibility within each monomer. As previously noted, membrane domains are closely associated in the dimeric structure from cryo-EM but dramatically splayed apart in the X-ray structure. Cysteine crosslinking was used to constrain these membrane domains and to show that this large-scale splaying was not necessary for transport activity. Furthermore, dimer stability was not compromised by mutagenesis of elements in the cytoplasmic domain, suggesting that the extensive interface between membrane domains is a strong determinant of dimerization. As with other secondary transporters, this interface could provide a stable scaffold for movements of the four-helix bundle that confers alternating access of these ions to opposite sides of the membrane.

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