Structure and properties of a novel cobaltate La{sub 0.30}CoO{sub 2}

Journal Article · Mon Aug 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.06.021· OSTI ID:21580172

Knizek, K ^[1]; Hejtmanek, J; Marysko, M; Santava, E; Jirak, Z ^[1]; Bursik, J; Kirakci, K ^[2]; Beran, P ^[3]

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1. Institute of Physics ASCR, 162 00 Prague 6 (Czech Republic)
2. Institute of Inorganic Chemistry ASCR, 250 68 Rez near Prague (Czech Republic)
3. Nuclear Physics Institute ASCR, 250 68 Rez near Prague (Czech Republic)

The layered cobaltate La{sub 0.30}CoO{sub 2} was prepared from Na{sub x}CoO{sub 2} precursor by a solid-state ionic exchange and was characterized by means of X-ray and neutron diffraction, magnetic, thermal and electric transport measurements. The compound consists of hexagonal sheets of edge-sharing CoO{sub 6} octahedra interleaved by lanthanum monolayers. Compared to Na{sup +} in the parent system, the La{sup 3+} ions occupy only one-third of available sites, forming a 2-dimensional superstructure. The deviation from the ideal stoichiometry La{sub 1/3}CoO{sub 2} introduces extra hole carriers into the diamagnetic LS Co{sup 3+} matrix making the sample Pauli paramagnetic. The temperature dependence of the electrical conductivity in La{sub 0.30}CoO{sub 2} follows Mott's T{sup -1/3} law up to about 400 K, which is in contrast with the standard metallic behavior in the Na{sup +} homolog possessing the same formal doping. The experiments are complemented by electronic structure calculations for La{sub 0.30}CoO{sub 2} and related Na{sub x}CoO{sub 2} systems. - Graphical abstract: Optimized superstructure of La{sub 0.3}CoO{sub 2} obtained by LDA calculation. Highlights: > A novel layered cobaltate La{sub 0.30}CoO{sub 2} was prepared by a solid-state ionic exchange. > La{sup 3+} ions are ordered and form a 2-dimensional superstructure. > Electrical conductivity of variable range hopping type up to 400 K.

• OSTI ID: 21580172
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 8; Other Information: DOI: 10.1016/j.jssc.2011.06.021; PII: S0022-4596(11)00347-1; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COBALT IONS
ELECTRIC CONDUCTIVITY
ELECTRONIC STRUCTURE
ION EXCHANGE
LANTHANUM
LANTHANUM IONS
NEUTRON DIFFRACTION
PARAMAGNETISM
SODIUM IONS
SOLIDS
TEMPERATURE DEPENDENCE
TWO-DIMENSIONAL CALCULATIONS
X-RAY DIFFRACTION
CHARGED PARTICLES
COHERENT SCATTERING
DIFFRACTION
ELECTRICAL PROPERTIES
ELEMENTS
IONS
MAGNETISM
METALS
PHYSICAL PROPERTIES
RARE EARTHS
SCATTERING