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DC Field | Value | Language |
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dc.contributor.advisor | Greedan, John E. | en_US |
dc.contributor.author | Davidson, Jean Isobel | en_US |
dc.date.accessioned | 2014-06-18T16:42:05Z | - |
dc.date.available | 2014-06-18T16:42:05Z | - |
dc.date.created | 2010-10-13 | en_US |
dc.date.issued | 1996-12 | en_US |
dc.identifier.other | opendissertations/3401 | en_US |
dc.identifier.other | 4417 | en_US |
dc.identifier.other | 1603710 | en_US |
dc.identifier.uri | http://hdl.handle.net/11375/8176 | - |
dc.description.abstract | <p>This thesis discloses a newly discovered series of compounds, Li₂CryMn₂-yO₄, wherein 0.1≤y≤1.9. This series consists of two solid solutions regions with a cross-over occurring at a composition near y = 1.4. The chemical structure of these phases was identified by x-ray powder diffraction. Phases with y≥1.4 have an ordered rock salt structure in which the lithium and transition metal cations form alternating layers between the sheets of oxygen atoms. The phases with y<1.4 have a different rock salt related structure in which the lithium ions and transition metal ions are arranged in interleaving chains within the cubic-close-packed oxygen framework. The resulting structures are distorted from cubic symmetry by the presence of the Jahn-Teller ion, Mn³⁺. The compositions with y< 1.65 were found to be particularly useful as cathodes in lithium ion type, electrochemical cells. The chemical and ordered magnetic structure of three materials, orthorhombic LiMnO₂, 1T-Li₂NiO₂ and a low temperature form of LiFeO₂ were determined from neutron diffraction data. LT-LiFeO₂ and 1T-Li₂NiO₂ are metastable phases prepared by chimie douce synthetic methods. A detailed study of the magnetic properties of 1T-Li₂NiO₂ and orthorhombic LiMnO₂ revealed complex behaviour involving a competition between two- and three-dimensional ordering. Neutron diffraction was also employed to identify the chemical structure of Li₂NiMnO₄. The electrochemical behaviour of orthorhombic LiMnO₂, LT-LiFeO₂. Li₂NiMnO₄ and Li₂Ni₁.₅Mn₀.₅O₄ was investigated in lithium ion cells. Orthorhombic LiMnO₂ proved to be particularly useful as a cathode material as it undergoes a phase transition in situ to the lithiated spinel phase λ-Li₂Mn₂O₄. Consequently, orthorhombic LiMnO₂ provides a convenient, air stable precursor to the electrochemically useful, but not air stable, λ-Li₂Mn₂O₄ phase.</p> | en_US |
dc.subject | Chemistry | en_US |
dc.subject | Chemistry | en_US |
dc.title | Synthesis, structure and properties of selected lithiated transition metal oxides | en_US |
dc.type | thesis | en_US |
dc.contributor.department | Chemistry | en_US |
dc.description.degree | Doctor of Philosophy (PhD) | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
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fulltext.pdf | 6.5 MB | Adobe PDF | View/Open |
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