Structure and properties of a novel cobaltate La.sub.0.30./sub.CoO.sub.2./sub..

0365147 - FZÚ 2012 RIV US eng J - Článek v odborném periodiku
Knížek, Karel - Hejtmánek, Jiří - Maryško, Miroslav - Šantavá, Eva - Jirák, Zdeněk - Buršík, Josef - Kirakci, Kaplan - Beran, Přemysl
Structure and properties of a novel cobaltate La_0.30CoO₂.
Journal of Solid State Chemistry. Roč. 184, č. 8 (2011), s. 2231-2237. ISSN 0022-4596. E-ISSN 1095-726X
Grant CEP: GA ČR GA203/09/1036; GA ČR GA202/09/0421
Výzkumný záměr: CEZ:AV0Z10100521; CEZ:AV0Z40320502; CEZ:AV0Z10480505
Klíčová slova: thermoelectric cobaltates * La_xCoO * Na_xCoO₂ * X-ray and neutron diffraction * LDA calculations
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
Impakt faktor: 2.159, rok: 2011

The layered cobaltate La0.30CoO2 was prepared from NaxCoO2 precursor by a solid-state ionic exchange and was characterized by means of X-ray and neutron diffraction,magnetic,thermalandelectric transport measurements.The compound consists of hexagonal sheets of edge-sharing CoO6 octahedra interleaved by lanthanum monolayers.Compared to Na+ in the parent system,the La3+ ions occupy only one-third of available sites,forming a 2 dimensional superstructure.The deviation from the ideal stoichiometry La1/3CoO2 introduces extra hole carriers into the diamagnetic LS Co3+ matrix making the sample Pauli paramagnetic.The temperature dependence of the electrical conductivity in La0.30CoO2 follows Mott´s T-1/3 law up to about 400K,which is in contrast with the standard metallic behavior in the Na+ homolog possessing the same formal doping.The experiments are complemented by electronic structure calculations for La0.30CoO2 and related NaxCoO2 systems.
Trvalý link: http://hdl.handle.net/11104/0006582