Neutron diffraction study of the beta' and gamma phases of LiFeO{sub 2}

Journal Article · Tue Sep 15 00:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.06.029· OSTI ID:21370590

Barre, Maud ^[1]; Catti, Michele ^[1]

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1. Dipartimento di Scienza dei Materiali, Universita di Milano Bicocca, via Cozzi 53, 20125 Milano (Italy)

The beta, beta', gamma and alpha phases of LiFeO{sub 2}, synthesized as powders, were annealed at different temperatures and characterized by X-ray measurements. The beta' and gamma modifications were also studied by time-of-flight neutron diffraction (ISIS Facility, UK). The structure of the beta' phase was refined in the monoclinic C2/c space group (a=8.566(1), b=11.574(2), c=5.1970(5) A, beta=146.064(5){sup o}) to wR{sub p}=0.071-0.080 (data from four counter banks). Fe and Li atoms are ordered over two of the four independent sites, and partially disordered over the other two. The ordered Li has a distorted tetrahedral coordination. The gamma structure was refined at RT (a=4.047(1), c=8.746(2) A) and at 570 deg. C (a=4.082(3), c=8.822(6) A) in the I4{sub 1}/amd symmetry, showing full order with Li in octahedral coordination at RT, and in a split-atom configuration at high temperature. On annealing, the beta' polymorph was found to transform to gamma at 550 deg. C, thus suggesting that it is a metastable phase. Electrostatics is discussed as the driving force for the alpha->beta'->gamma ordering process of LiFeO{sub 2}. - Graphical abstract: Crystal structure of beta'-LiFeO{sub 2} (monoclinic C2/c). Lithium and iron atoms are both ordered (blue and yellow balls) and partially disordered (green balls) over four independent sites. The beta' phase transforms to fully ordered gamma (tetragonal I4{sub 1}/amd) at 550 deg. C.

• OSTI ID: 21370590
• Journal Information: Journal of Solid State Chemistry, Vol. 182, Issue 9; Other Information: DOI: 10.1016/j.jssc.2009.06.029; PII: S0022-4596(09)00290-4; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
IRON OXIDES
LITHIUM IONS
LITHIUM OXIDES
MONOCLINIC LATTICES
NEUTRON DIFFRACTION
ORDER-DISORDER TRANSFORMATIONS
SPACE GROUPS
TEMPERATURE RANGE 0400-1000 K
TETRAGONAL LATTICES
TIME-OF-FLIGHT METHOD
X RADIATION
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
ELECTROMAGNETIC RADIATION
HEAT TREATMENTS
IONIZING RADIATIONS
IONS
IRON COMPOUNDS
LITHIUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RADIATIONS
SCATTERING
SYMMETRY GROUPS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS