UV resonance Raman studies of Group 6 transition-metal carbonyls: evidence of Jahn-Teller distortion in the excited states of the lowest allowed charge-transfer transitions

1990 ◽  
Vol 94 (10) ◽  
pp. 4055-4060 ◽  
Author(s):  
David. Adelman ◽  
Daniel P. Gerrity
2021 ◽  
Author(s):  
Muhammad Mominur Rahman ◽  
Scott McGuigan ◽  
Shaofeng Li ◽  
Lina Gao ◽  
Dong Hou ◽  
...  

<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>


2007 ◽  
Vol 244 (1) ◽  
pp. 156-161 ◽  
Author(s):  
F. Rodríguez ◽  
F. Aguado ◽  
R. Valiente ◽  
M. Hanfland ◽  
J. P. Itiè

1996 ◽  
Vol 442 ◽  
Author(s):  
A. A. Gutkin ◽  
M. A. Reshchikov ◽  
V. E. Sedov

AbstractWe have investigated polarization of photoluminescence from the VGaTeAs complexes in n-GaAs induced through resonant excitation by polarized light. Experimental data in temperature range from 77 to 240 K were described by classic one-dipole approximation within the model of the VGaTeAs complex subjected to the Jahn-Teller distortion in the ground and excited states. It is shown that depolarization of photoluminescence at temperatures over ∼ 120 K may be explained by concurrent action of i) thermal emission and back capture of holes bound to the complexes in the excited state and ii) reorientation of complex distortion during a life of this state. The model parameters have been estimated.


2021 ◽  
Vol 6 (1) ◽  
Author(s):  
A. S. McLeod ◽  
A. Wieteska ◽  
G. Chiriaco ◽  
B. Foutty ◽  
Y. Wang ◽  
...  

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.


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