scholarly journals Chemical Modulation of Local Transition Metal Environment Enables Reversible Oxygen Redox in Mn-Based Layered Cathodes

2021 ◽  
Author(s):  
Muhammad Mominur Rahman ◽  
Scott McGuigan ◽  
Shaofeng Li ◽  
Lina Gao ◽  
Dong Hou ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Layer ◽  
Chemical Transformations ◽  
Teller Distortion ◽  
Structural Stabilization ◽  
Factors Affecting ◽  
Jahn Teller ◽  
Chemical Modulation ◽  
Jahn Teller Distortion ◽  
Layered Cathodes

<p>Oxygen redox plays a prominent role in enhancing the energy density of Mn-based layered cathodes. However, understanding the factors affecting the reversibility of oxygen redox is nontrivial due to the complicated concurrent structural and chemical transformations. Herein, we show that local Mn‒O symmetry induced structural and chemical evolutions majorly dictate the reversibility of oxygen redox of Na<sub>x</sub>Li<sub>y</sub>Mn<sub>1-y</sub>O<sub>2</sub> in Na cells. We find that Na<sub>x</sub>Li­<sub>y</sub>Mn<sub>1-y</sub>O<sub>2</sub> with Jahn-Teller distorted MnO<sub>6</sub> octahedra undergoes severe Mn dissolution during cycling, which destabilizes the transition metal layer resulting in poor Li retention and irreversible oxygen redox. Jahn-Teller distortion of MnO<sub>6</sub> octahedra can be suppressed by modulating the local charge of Mn and Mn‒O distance through Mg/Ti dual doping. This leads to reduced Mn dissolution resulting in more reversible oxygen redox. Such stabilization significantly improves the electrochemical performance of Mg/Ti dual doped Na<sub>x</sub>Li<sub>y</sub>Mn<sub>1-y</sub>O<sub>2</sub>. Through this work, we show that promoting reversible oxygen redox can benefit from structural stabilization at local length scale, and that modifying the chemical environment through doping chemistry is an efficient strategy to promote local structural stability and thus, oxygen redox.</p>

scholarly journals Chemical Modulation of Local Transition Metal Environment Enables Reversible Oxygen Redox in Mn-Based Layered Cathodes

2021 ◽  
Author(s):  
Muhammad Mominur Rahman ◽  
Scott McGuigan ◽  
Shaofeng Li ◽  
Lina Gao ◽  
Dong Hou ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Layer ◽  
Chemical Transformations ◽  
Teller Distortion ◽  
Structural Stabilization ◽  
Factors Affecting ◽  
Jahn Teller ◽  
Chemical Modulation ◽  
Jahn Teller Distortion ◽  
Layered Cathodes

<p>Oxygen redox plays a prominent role in enhancing the energy density of Mn-based layered cathodes. However, understanding the factors affecting the reversibility of oxygen redox is nontrivial due to the complicated concurrent structural and chemical transformations. Herein, we show that local Mn‒O symmetry induced structural and chemical evolutions majorly dictate the reversibility of oxygen redox of Na<sub>x</sub>Li<sub>y</sub>Mn<sub>1-y</sub>O<sub>2</sub> in Na cells. We find that Na<sub>x</sub>Li­<sub>y</sub>Mn<sub>1-y</sub>O<sub>2</sub> with Jahn-Teller distorted MnO<sub>6</sub> octahedra undergoes severe Mn dissolution during cycling, which destabilizes the transition metal layer resulting in poor Li retention and irreversible oxygen redox. Jahn-Teller distortion of MnO<sub>6</sub> octahedra can be suppressed by modulating the local charge of Mn and Mn‒O distance through Mg/Ti dual doping. This leads to reduced Mn dissolution resulting in more reversible oxygen redox. Such stabilization significantly improves the electrochemical performance of Mg/Ti dual doped Na<sub>x</sub>Li<sub>y</sub>Mn<sub>1-y</sub>O<sub>2</sub>. Through this work, we show that promoting reversible oxygen redox can benefit from structural stabilization at local length scale, and that modifying the chemical environment through doping chemistry is an efficient strategy to promote local structural stability and thus, oxygen redox.</p>

Structure of the clinopyroxene-type compound CaCuGe2O6 between 15 and 800 K

2005 ◽  
Vol 61 (4) ◽  
pp. 367-380 ◽  
Author(s):  
Günther J. Redhammer ◽  
Gerold Tippelt ◽  
Michael Merz ◽  
Georg Roth ◽  
Werner Treutmann ◽  
...  
Keyword(s):  
Phase Transition ◽  
Magnetic Susceptibility ◽  
Magnetic Phase ◽  
Metal Layer ◽  
Lattice Parameters ◽  
Zigzag Chain ◽  
Two Dimensional ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Distortion

CaCuGe2O6 shows a strongly distorted clinopyroxene-type structure with P21/c symmetry at 298 K. The Cu2+ ion at the M1 site is coordinated by six O atoms forming an octahedron, which deviates significantly from ideal geometry. Individual M1 sites are connected via common edges to form an infinite zigzag chain parallel to the crystallographic c axis. The Ca2+ ion at M2 shows a sevenfold coordination. M2 sites are connected to the M1 chain via three common edges, thereby forming a metal layer within the bc plane. Besides the strong Jahn–Teller distortion of the Cu site, the structure of the title compound differs from `normal' clinopyroxenes by a distortion of alternate layers of Ge sites. While the Ge(A) site is fourfold coordinated by O atoms, forming infinite chains of corner-sharing chains parallel to the c axis, the Ge(B) site exhibits a fivefold coordination, thereby forming a true two-dimensional layer of edge-sharing GeO5 bipyramids. Decreasing the temperature causes a magnetic phase transition at 40 K, as monitored by a broad maximum in the magnetic susceptibility and by discontinuities in the lattice parameters. Increasing the temperature causes variations in bond lengths, edge lengths and bond angles. Most prominent is the increase of one bond length of the Ge(B) site and the increase of the tetrahedral bridging angle of the Ge(A) site. At 660 K a crystallographic phase transition is observed where the symmetry changes from P21/c to C2/c. The transition is accompanied by large changes in the lattice parameters which are indicative of distinct topological changes of several structural building units. The high-temperature C2/c structure is similar to that of the germanate clinopyroxene CaMgGe2O6.

scholarly journals Nano-imaging of strain-tuned stripe textures in a Mott crystal

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
A. S. McLeod ◽  
A. Wieteska ◽  
G. Chiriaco ◽  
B. Foutty ◽  
Y. Wang ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Oxides ◽  
Electrical Current ◽  
Teller Distortion ◽  
Self Organized ◽  
Imaging Results ◽  
Insulator Metal Transition ◽  
Jahn Teller ◽  
Nano Imaging ◽  
Jahn Teller Distortion

AbstractThe 4d transition metal perovskites Can+1RunO3n+1 have attracted interest for their strongly interacting electronic phases showing pronounced sensitivity to controllable stimuli like strain, temperature, and even electrical current. Through multi-messenger low-temperature nano-imaging, we reveal a spontaneous striped texture of coexisting insulating and metallic domains in single crystals of the bilayer ruthenate Ca3(TixRu1-x)2O7 across its first-order Mott transition at $$T \approx 95$$ T ≈ 95 K. We image on-demand anisotropic nucleation and growth of these domains under in situ applied uniaxial strain rationalized through control of a spontaneous Jahn-Teller distortion. Our scanning nano-susceptibility imaging resolves the detailed susceptibility of coexisting phases to strain and temperature at the transition threshold. Comparing these nano-imaging results to bulk-sensitive elastoresistance measurements, we uncover an emergent “domain susceptibility” sensitive to both the volumetric phase fractions and elasticity of the self-organized domain lattice. Our combined susceptibility probes afford nano-scale insights into strain-mediated control over the insulator-metal transition in 4d transition metal oxides.

The first-row transition-metal series of tris(ethylenediamine) diacetate complexes [M(en)3](OAc)2 (M is Mn, Fe, Co, Ni, Cu, and Zn)

2017 ◽  
Vol 73 (6) ◽  
pp. 442-446 ◽  
Author(s):  
Duyen N. K. Pham ◽  
Mrittika Roy ◽  
James A. Golen ◽  
David R. Manke
Keyword(s):  
Transition Metal ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
The Other ◽  
Asymmetric Unit ◽  
Teller Distortion ◽  
Dimensional Network ◽  
Jahn Teller ◽  
Jahn Teller Distortion ◽  
Cu And Zn

The crystal structures of the first-row transition-metal series of tris(ethylenediamine-κ2 N,N′)metal(II) diacetate, [M(C2H8N2)3](CH3CO2)2, with M = Mn, Fe, Co, Ni, Cu, and Zn, are reported. The complexes are all isostructural, crystallizing in a centrosymmetric triclinic cell and possessing an asymmetric unit composed of one [M(en)3]2+ cation and two symmetrically independent acetate anions. In the unit cell, the two complex cations are inversion-generated enantiomers, possessing the energetically favoured Δ(λλλ) and Λ(δδδ) configurations. The complex cations and acetate anions combine through a series of N—H...O hydrogen bonds to generate a three-dimensional network in the crystals. The other notable feature of the series is a significant Jahn–Teller distortion for the d 9 Cu2+ complex.

Electronic Structures in LaTiO3/LaAlO3 Multilayers

2013 ◽  
Vol 771 ◽  
pp. 7-11 ◽  
Author(s):  
Er Jun Kan
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Density Functional ◽  
Orbital Ordering ◽  
Crystal Field Theory ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Important Direction ◽  
Jahn Teller Distortion

We demonstrate the existence of a hidden degree of freedom controlling the orbitalordering in [LaTiO1/[LaAlO5 multilayers with comprehensive density-functional theorycalculations. The orbitals of two-dimensional (2D) 3d1state of Ti atoms in the multilayers alwayscontain large dxy components, which is unexpected from crystal field theory (first Jahn-Tellerdistortion). The competition between first and second Jahn-Teller distortion induces variousmagnetic properties. Thus, transition-metal oxides/non-transition-metal oxides multilayers mayprovide an important direction to manipulate the spin and orbital ordering in magnetic materials.

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  
Keyword(s):  
High Harmonic ◽  
Open Shell ◽  
Spin Coupling ◽  
High Symmetry ◽  
Teller Distortion ◽  
Spectral Window ◽  
X Ray ◽  
Jahn Teller ◽  
X Ray Absorption ◽  
Jahn Teller Distortion

We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of<br>the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys.<br>Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence<br>of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation.<br>The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron<br>in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of<br>the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to<br>be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller<br>effect in benzene cation.<br>

Jahn-Teller Effect in Hexahydroxocuprate(II) Complexes

1995 ◽  
Vol 60 (9) ◽  
pp. 1429-1434
Author(s):  
Martin Breza
Keyword(s):  
Hydrogen Bonding ◽  
Quantum Chemical ◽  
Potential Surface ◽  
Hydroxyl Group ◽  
Chemical Calculation ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Extremal Values ◽  
Jahn Teller Distortion

Using semiempirical CNDO-UHF method the adiabatic potential surface of 2[Cu(OH)6]4- complexes is investigated. The values of vibration and vibronic constants for Eg - (a1g + eg) vibronic interaction attain extremal values for the optimal O-H distance. The Jahn-Teller distortion decreases with increasing O-H distance. The discrepancy between experimentally observed elongated bipyramid of [Cu(OH)6]4- in Ba2[Cu(OH)6] and the compressed one obtained by quantum-chemical calculation is explainable by hydrogen bonding of the axial hydroxyl group.

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