New rock salt-related oxides Li3M2RuO6 (M=Co, Ni): Synthesis, structure, magnetism and electrochemistry

Laha, S and Moran, E and Saez-Puche, R and Alario-Franco, MA and Dos Santos-Garcia, AJ and Gonzalo, E and Kuhn, A and Garcia-Alvarado, F and Sivakumar, T and Tamilarasan, S and Natarajan, S and Gopalakrishnan, J (2013) New rock salt-related oxides Li3M2RuO6 (M=Co, Ni): Synthesis, structure, magnetism and electrochemistry. In: JOURNAL OF SOLID STATE CHEMISTRY, 203 . pp. 160-165.

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Abstract

We describe the synthesis, crystal structure, magnetic and electrochemical characterization of new rock salt-related oxides of formula, Li3M2RuO6 (M=Co, Ni). The M=Co oxide adopts the LiCoO2 (R-3m) structure, where sheets of LiO6 and (Co-2/Ru)O-6 octahedra are alternately stacked along the c-direction. The M=Ni oxide also adopts a similar layered structure related to Li2TiO3, where partial mixing of Li and Ni/Ru atoms lowers the symmetry to monoclinic (C2/c). Magnetic susceptibility measurements reveal that in Li3Co2RuO6, the oxidation states of transition metal ions are Co3+ (S=0), Co2+ (S=1/2) and Ru4+ (S=1), all of them in low-spin configuration and at 10 K, the material orders antiferromagnetically. Analogous Li3Ni2RuO6 presents a ferrimagnetic behavior with a Curie temperature of 100 K. The differences in the magnetic behavior have been explained in terms of differences in the crystal structure. Electrochemical studies correlate well with both magnetic properties and crystal structure. Li-transition metal intermixing may be at the origin of the more impeded oxidation of Li3Ni2RuO6 when compared to Li3CO2RuO6. Interestingly high first charge capacities (between ca. 160 and 180 mAh g(-1)) corresponding to ca. 2/3 of theoretical capacity are reached albeit, in both cases, capacity retention and cyclability are not satisfactory enough to consider these materials as alternatives to LiCoO2. (C) 2013 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF SOLID STATE CHEMISTRY
Publisher:	ACADEMIC PRESS INC ELSEVIER SCIENCE
Additional Information:	copyright for this article belongs to Elsevier
Keywords:	Ruthenium oxides; Rock salt structures; Magnetism; Electrochemistry
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	07 Nov 2013 06:00
Last Modified:	07 Nov 2013 06:00
URI:	http://eprints.iisc.ac.in/id/eprint/47693

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