Re-examining the Chevrel phase Mo6S8 cathode for Mg intercalation from an electronic structure perspective
Florian Thöle1, Liwen F Wan, David Prendergast
1Materials Theory, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland.
Physical Chemistry Chemical Physics : PCCP
|August 19, 2015
Summary
Magnesium intercalation in Chevrel phase Mo6S8 shows metallic behavior with localized electronic screening. This screening shields Mg(2+) ion charges, facilitating ion diffusion within the material.
Area of Science:
- Materials Science
- Solid State Physics
- Computational Materials Science
Background:
- Chevrel phases, like Mo6S8, are ternary molybdenum chalcogenides with unique electronic properties.
- Understanding ion intercalation is crucial for developing advanced battery materials.
Purpose of the Study:
- To investigate the electronic response of Mo6S8 during magnesium intercalation.
- To elucidate the mechanism of charge screening and its effect on ion diffusion.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- Analysis of electronic structure and charge distribution.
Main Results:
- The metallic ground state of Mo6S8 was confirmed.
- Strongly localized electronic screening of Mg(2+) ions was observed.
- The screening cloud effectively shields Mg(2+) charge within a unit cell length scale.
Conclusions:
- Localized electronic screening in Mo6S8 plays a key role in accommodating intercalated Mg ions.
- This phenomenon facilitates Mg ion diffusion, suggesting potential for Chevrel phases in energy storage applications.
Related Concept Videos
02:42Valence Bond Theory
11.7K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
11.7K
02:48Ionic Bonding and Electron Transfer
54.3K
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.
54.3K
02:58Crystal Field Theory - Octahedral Complexes
31.9K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
31.9K
02:27Predicting Molecular Geometry
47.1K
VSEPR Theory for Determination of Electron Pair Geometries
47.1K
03:45Formation of Complex Ions
26.8K
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
26.8K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
49.8K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
49.8K