Bonding Nature of LiCoO₂ by Topological Analysis of Electron Density from X-ray Diffraction

Abstract

Electron density distributions of LiCoO 2 have been determined by Maximum Entropy method (MEM) and multipole modeling from synchrotron x-ray powder diffraction data. The localization of Co-3d electrons was clearly visualized in the deformation MEM density. An electron density by multipole modeling was investigated by the Bader's topological analysis to reveal bonding characteristics and interactions between the constituted atoms.

Spatial distribution of electrons near the Fermi level in the metallic LaB6 through accurate X-ray charge density study

“…The experimental procedure we developed has been widely applied to accurate charge density studies of materials such as α-boron20, TiO 2 21, Al 2 O 3 21, CoSb 3 2223, silicon24 and diamond2425. The technique successfully determined the detailed charge density features which were quantitatively comparable to those determined theoretically17202122232425. Recently, the charge density studies from ultra-high resolution synchrotron radiation powder diffractions have been reported using an all-in-vacuum diffractometer installed at PETRA-III26.…”

“…We have developed the high quality measurement method of X-ray powder diffraction data at SPring-8 powder diffraction beamline16. We recently achieved to measure diffraction data available to d -spacing range d  > 0.29 Å for charge density study of LiCoO 2 17. The diffraction data were successfully analyzed by a maximum entropy method (MEM)18 and a multipole refinement19.…”

Interlayer Modulation of Layered Transition Metal Compounds for Energy Storage

“…The layered transition metal compounds are mainly divided into transition metal oxides, transition metal hydroxides, transition metal chalcogenides, and transition metal carbides and/or nitrides. They are composed of alternately stacked layer units, which are combined by at least one main type of interaction, including the ionic/covalent bond, − the hydrogen bond, , and the van der Waals (vdW) force. , The ionic bond is a type of chemical bond between two oppositely charged ions. − And the covalent bond is a strong interaction formed by several adjacent atoms sharing electrons . They are relatively strong interlayer forces, indicating that the interlayer spacing in this kind of compound is relatively small.…”

Multiple powder diffraction data for an accurate charge density study using synchrotron radiation x-ray

“…In this case, we can avoid saturating the IP and measure very high counting statics data in high angle region with increasing x-ray exposure time. The exposure time for high angle data is normally more than four times longer than normal low angle data [4,[6][7][8]. The dataset prepared by this procedure was mainly used for the accurate charge density study.…”

“…The MEM charge densities at the bond midpoints of silicon and diamond were almost equal to theoretical values within 0.05 eÅ −3 . The method was also applied to a thermoelectric binary-skutterudite CoSb 3 [6], an α-rhombohedral boron [7], and a lithium cobalt dioxide, LiCoO 2 [8]. In the case of the structure determination from powder diffraction, the complicated structures of pharmaceuticals [9] and crystalline molecular electrolyte [3] have been solved by using multiple powder data.…”