High-temperature X-ray diffraction study of crystallization and phase segregation on spinel-type lithium manganese oxides
- Department of Applied Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601 (Japan)
To study crystallization process of spinel-type Li{sub 1+x}Mn{sub 2-x}O{sub 4}, in-situ high-temperature X-ray diffraction technique (HT-XRD) was utilized for the mixture consisting of Li{sub 2}CO{sub 3} and Mn{sub 2}O{sub 3} as starting material in the temperature range of 25-700 deg. C. In-situ HT-XRD analysis directly revealed that crystallization process of Li{sub 1+x}Mn{sub 2-x}O{sub 4} was significantly affected by the difference in the Li/Mn molar ratio in the precursor. Single phase of stoichiometric LiMn{sub 2}O{sub 4} formed at 700 deg. C. The formation of single phase of spinel was achieved at the lower temperature than the stoichiometric sample as Li/Mn molar ratio in the precursor increased. Lattice parameter of the stoichiometric LiMn{sub 2}O{sub 4} at 25 deg. C was 8.24 A and expanded to 8.31 A at 700 deg. C, which corresponds to the approximately 3% expansion in the unit cell volume. From the slope of the lattice parameter change as a function of temperatures, linear thermal expansion coefficient of the stoichiometric LiMn{sub 2}O{sub 4} was calculated to be 1.2x10{sup -5} deg. C{sup -1} in this temperature range. When the Li/Mn molar ratio in Li{sub 1+x}Mn{sub 2-x}O{sub 4} increased (x > 0.1), the spinel phase segregated into the Li{sub 1+y}Mn{sub 2-y}O{sub 4} (x > y) and Li{sub 2}MnO{sub 3} during heating, which involved the oxygen loss from the materials. During the cooling process from 700 deg. C, and the segregated phase merged into Li{sub 1+x}Mn{sub 2-x}O{sub 4} with oxygen incorporation. Such trend directly observed by in-situ HT-XRD was supported by thermal gravimetric analysis as reversible weight (oxygen) loss/gain at higher temperature (500-700 deg. C). - Graphical abstract: Non-linear variation of lattice parameters of the Li excess LiMn{sub 2}O{sub 4} spinels was observed during cooling process from 700 to 25 deg. C.
- OSTI ID:
- 21372473
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 183; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALKALI METAL COMPOUNDS
CARBON COMPOUNDS
CARBONATES
CHALCOGENIDES
CHEMICAL ANALYSIS
COHERENT SCATTERING
CRYSTALLIZATION
DIFFRACTION
EXPANSION
GRAVIMETRIC ANALYSIS
HEATING
LATTICE PARAMETERS
LITHIUM CARBONATES
LITHIUM COMPOUNDS
MANGANESE COMPOUNDS
MANGANESE OXIDES
MINERALS
NONLINEAR PROBLEMS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
QUANTITATIVE CHEMICAL ANALYSIS
SCATTERING
SEGREGATION
SPINELS
STOICHIOMETRY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THERMAL ANALYSIS
THERMAL EXPANSION
THERMAL GRAVIMETRIC ANALYSIS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION