Below its Jahn-Teller transition temperature, , NaNiO has a monoclinic layered structure consisting of alternating layers of edge-sharing NaO and Jahn-Teller-distorted NiO octahedra. Above where NaNiO is rhombohedral, diffraction measurements show the absence of a cooperative Jahn-Teller distortion, accompanied by an increase in the unit cell volume. Using neutron total scattering, solid-state Nuclear Magnetic Resonance (NMR), and extended X-ray absorption fine structure (EXAFS) experiments as local probes of the structure we find direct evidence for a displacive, as opposed to order-disorder, Jahn-Teller transition at . This is supported by molecular dynamics (AIMD) simulations. To our knowledge this study is the first to show a displacive Jahn-Teller transition in any material using direct observations with local probe techniques.
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http://dx.doi.org/10.1021/jacs.4c09922 | DOI Listing |
Nanomaterials (Basel)
December 2024
School of Materials and Metallurgy, Guizhou University, Guiyang 550025, China.
The P2-NaMnO cathode material has long been constrained by phase transitions induced by the Jahn-Teller (J-T) effect during charge-discharge cycles, leading to suboptimal electrochemical performance. In this study, we employed a liquid phase co-precipitation method to incorporate Ti during the precursor MnO synthesis, followed by calcination to obtain NaTiMnO materials. We investigated the effects of Ti doping on the structure, morphology, Mn concentration, and Na diffusion coefficients of NaTiMnO.
View Article and Find Full Text PDFMolecules
November 2024
Atomic and Molecular Collisions Laboratory, CEFITEC-Centre of Physics and Technological Research, Department of Physics, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
We report absolute high-resolution vacuum ultraviolet (VUV) photoabsorption cross-sections of carbon tetrachloride (CCl) in the photon energy range 5.0-10.8 eV (248-115 nm).
View Article and Find Full Text PDFJ Phys Condens Matter
December 2024
Department of Physics, Zhejiang University of Science and Technology, Hangzhou 310023, People's Republic of China.
ACS Phys Chem Au
November 2024
Rosalind Franklin Institute, Harwell OX11 0QX, Oxfordshire, United Kingdom.
Efficient photoredox chemical transformations are essential to the development of novel, cost-effective, and environmentally friendly synthetic methodologies. The concept of the entatic state in bioinorganic catalysis proposes that a preorganized structural configuration can reduce the energy barriers associated with chemical reactions. This concept provides one of the guiding principles to enhance catalytic efficiency by maintaining high-energy conformations close to the reaction's transition state.
View Article and Find Full Text PDFChem Mater
November 2024
Department of Materials, Oxford University, Oxford OX1 3PH, U.K.
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