Transmission electron microscopy and electron diffraction study of the short-range ordering structure of α-LiFeO₂

Abstract

The basic structure of alpha-LiFeO2, lithium iron oxide, is a cubic NaCl-type structure with a lattice constant of 0.42 nm; some short-range ordering characterized by octahedral clusters exists. The local structure of the short-range ordering was investigated by transmission electron microscopy and electron diffraction. A new short-range ordering structure was found in local areas. The local structure has a cubic lattice with a doubled lattice constant. The occupation factors of cations on Wyckoff sites 4(a) and 4(b) are different from those on 24(d) sites, but the stoichiometric composition in cubic clusters is the same as the macroscopic composition. The number of pairs in which iron cations exist in nearest-neighbor sites and next nearest-neighbor sites is reduced in the structure. This means that a magnetic interaction between the iron cations is reduced by cation ordering even without spin ordering at room temperature.

Structural phase transformation and Fe valence evolution in FeOxF2−x/C nanocomposite electrodes during lithiation and de-lithiation processes

“…In the lithiated rocksalt a-LiFe 3+ O 2 phase, Fe and Li occupy the same 4b lattice sites while O occupies the 4a lattice sites. 43 Substitution of O by F may occur with a corresponding reduction of the Fe valence state. For Li 1.4 Fe 2+ O 1.4 F 0.6 described in eqn (2b), only 1Li can occupy the 4b lattice sites with the remaining 0.4Li possibly located in the octahedral of tetrahedral interstitial sites.…”

Hidden structural and chemical order controls lithium transport in cation-disordered oxides for rechargeable batteries

“…The formation of SRO can be understood as a preferred local arrangement of species, resulting in non-vanishing patterns in reciprocal space. [26][27][28][29] Notably, the diffuse scattering patterns are completely different, both in shape and orientation, for the two materials, indicating significant difference in SRO. Based on previous characterization of SRO in oxides and alloys, the SRO patterns in LMTO is characteristic of octahedral cation clusters similar to the [Li 3 Fe 3 ] in cubic-LiFeO 2 [30] ,…”

Epitaxial growth of β-Ga2O3 nanocolumns on MgO substrate

“…5(b), the size of small crystals is smaller than coherent length of incident electrons. The coherent length of electrons of 300 keV energy is estimated as 12 nm [24], and the size of the crystals in the mixed layer is estimated as 4-6 nm. Such small nanocrystals of b and g forms are mixed with the same crystal orientations like as mosaic.…”