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On The LixNi0.70Fe0.15Co0.15O2 System: An X-Ray Diffraction and Mössbauer Study

2001; Elsevier BV; Volume: 159; Issue: 1 Linguagem: Inglês

10.1006/jssc.2001.9137

1095-726X

G. Prado, L. Fournès, Claude Delmas,

Semiconductor materials and interfaces

The structural modifications and redox processes occurring during lithium deintercalation from the quasi-stoichiometric Li0.97(Ni0.70Fe0.15Co0.15)1.03O2 phase were studied by X-ray diffraction and Mössbauer spectroscopy. A solid solution is observed in the whole deintercalation domain (0.08≤x≤0.97); Rietveld refinement of the XRD pattern shows a strong decrease of the M–O bond distance upon lithium deintercalation. The Mössbauer study shows that nickel and iron ions are simultaneously oxidized, a large number of the iron ions being stabilized in the high-spin tetravalent state. Comparison with the data obtained in the Lix(Ni,Fe)O2 system emphasizes the effect of the small cobalt ions on the facility to oxidize iron ions.