Order-disorder transition in the complex lithium spinel Li{sub 2}CoTi{sub 3}O{sub 8}
- Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom)
Li{sub 2}CoTi{sub 3}O{sub 8} has an ordered Li{sub 2}BB'{sub 3}O{sub 8} spinel structure, space group P4{sub 3}32, at room temperature with 3:1 ordering of Ti and Li on the octahedral sites, and Li, Co disordered over the tetrahedral site. Rietveld refinement of variable temperature neutron powder diffraction data has shown an order-disorder phase transition in Li{sub 2}CoTi{sub 3}O{sub 8} which commences at {approx}500 deg. C with Li and Co mixing on the tetrahedral and 4-fold octahedral sites and is complete at a first order structural discontinuity at {approx}915 deg. C. The fraction of Ti on the 12-fold octahedral site exhibits a small decrease with increasing temperature, which may suggest that the disordering involves all three cations. Above 930 deg. C, the structure, space group Fd3-barm, has Li, Co and Ti sharing a single-octahedral site and Li, Co sharing a tetrahedral site, although Co still exhibits a preference for tetrahedral coordination. A labelling scheme for ordered and partially ordered 3:1 spinels is devised which focuses on the occupancy of the Li,B cations. - Graphical abstract: Rietveld refinement of variable temperature neutron powder diffraction data shows an order-disorder phase transition in Li{sub 2}CoTi{sub 3}O{sub 8} commencing at {approx}500 deg. C with Li,Co mixing on tetrahedral and octahedral sites. This becomes complete at a first-order structural discontinuity at {approx}915 deg. C. Above 930 deg. C, the structure, space group Fd3-barm, has Li, Co and Ti sharing a single-octahedral site and Li, Co sharing a tetrahedral site.
- OSTI ID:
- 21015852
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 6 Vol. 180; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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