Effect of chemical treatment and trivalent doping on the surface structure and surface chemistry of Li1-xNi0.5-yMn1.5+yO4 spinel
MetadataShow full item record
The surface structure and surface chemistry of Li₁[subscript -x]Ni₀̣.₅[subscript -y]Mn₁.₅[subscript +y]O₄ was examined by first analyzing as-prepared Li[Mn₂]O₄, the basis cubic spinel structure without Ni or trivalent dopants. It was found that Li[Mn₂]O₄ undergoes a surface reconstruction, which results in the production of a thin, stable surface layer of Mn₃O₄, a subsurface region of Li₁[subscript -x][Mn₂]O₄ with retention of bulk Li[Mn₂]O₄. This observation is compatible with the surface disproportionation of Mn coupled with oxygen deficiency and a displacement of surface Li⁺ from the Mn₃O₄ surface phase to a subsurface layer. Li₁[subscript -x][Mn₂]O₄ was then subjected to chemical treatments to further understand and isolate the role of Li and oxygen in the surface reconstruction. An aqueous acid treatment, a non-aqueous chemical delithiation, and an oxygen plasma treatment were applied to Li[Mn₂]O₄. It was found that Mn₃O₄ is a robust surface phase in the Li₁[subscript -x][Mn₂]O₄ system regardless of the chemical treatment and level of lithiation. The surface Mn₃O₄ phase is cubic whereas bulk Mn₃O₄ undergoes a cooperative Jahn-Teller distortion to tetragonal symmetry. Thicker Mn₃O₄ surface layers are tetragonal. Analysis of as-prepared LiNi₀.₅Mn₁.₅O₄ revealed a surface composed of mixed Mn₃O₄ and a well-known Ni-rich rock-salt phase that occurs in the LiNi₀.₅Mn₁.₅O₄ system. Trivalent doping of LiNi₀.₅Mn₁.₅O₄ with Cr creates an ordered spinel/rock-salt phase that has not been previously observed in either the LiNi₀.₅Mn₁.₅O₄ or LiMn₂O₄ systems.
Showing items related by title, author, creator and subject.
Bentmann, Hendrik (2007-08)First principle calculations on the (112) surface of the group-IV elements diamond, silicon, germanium and α-tin were carried out within the framework of Density Functional Theory (DFT). We report chemical trends in surface ...
Exploration of a Polarized Surface Bidirectional Reflectance Model Using the Ground-Based Multiangle Spectropolarimetric Imager Diner, Diner J.; Xu, Feng; Martonchik, John V.; Rheingans, Brian E.; Geier, Sven; Jovanovic, Veljko M.; Davis, Ab; Chipman, Russell A.; McClain, Stephen C. (2012-12)Accurate characterization of surface reflection is essential for retrieval of aerosols using downward-looking remote sensors. In this paper, observations from the Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI) ...
Stevens, Robert Gardiner; 0000-0002-3242-8672 (2015-08)Previous scattering experiments have shown a dependence of reflectivity on the alignment of the angular momentum vector of molecular hydrogen incident on a surface of Pd(111), Isakson 2001. In these past experiments ...