Fabrication of textured thermoelectric layered cobaltites with various rock salt-type layers by using β-Co(OH)2platelets as reactive templates

Itahara, Hiroshi; Xia, Changtai; Sugiyama, Jun; Tani, Toshihiko

doi:10.1039/b309804d

Cited by 110 publications

(132 citation statements)

References 21 publications

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“…This evolution of the resistivity values is consistent with the reduction of the amount of the secondary phases observed in the SEM images and also with the apparent density values for all the samples. Furthermore, for samples obtained by the polymer solution method, ρ is nearly temperature independent and it is close to the values obtained for textured materials (~ 15 mW.cm at 275 ºC) [7] or single crystals (~ 18 mW.cm at room temperature) [14]. (125 mV/K at 275 ºC) [7] or single crystals (110 mV/K at room temperature) [14].…”

Section: Sintered Materials Characterizationsupporting

confidence: 49%

“…Crystallographically, these cobaltites are composed of two different layers, with an alternate stacking of a common conductive CdI 2 -type CoO 2 layer, with a two-dimensional triangular lattice, and an insulating block layer, with the rocksalt-type (RS) structure. The two sublattices (RS block and CdI 2 -type CoO 2 layer) possess common a-and c-axis lattice parameters and b angles but different b-axis length, causing a misfit along the b-direction [6][7][8] that gives their common name: misfit cobaltites.…”

Section: Introductionmentioning

confidence: 99%

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Mejora de las propiedades termoeléctricas de Bi2Sr2Co1.8Ox por métodos de síntesis en disolución

Torres¹,

Sotelo²,

Rasekh³

et al. 2012

Bol. Soc. Esp. Ceram. Vidr.

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Several solution synthetic methods, sol-gel and a polymeric route, have been studied in order to obtain Bi 2 Sr 2 Co 1.8 O x ceramics with improved thermoelectric properties, compared to the classical solid state reaction. The products obtained by these different methods have been compared using DTA-TGA, powder X-ray diffraction, scanning electron microscopy, and thermoelectric characterizations. All the samples obtained by solution synthesis show higher homogeneity and lower content of secondary phases. The main differences in thermoelectrical properties are due to the decrease of electrical resistivity in samples obtained by solution methods, compared with the solid state obtained samples. Between them, the decrease is especially high for those samples prepared by the polymer solution method. Therefore, the polymeric solution synthesis route is shown to yield a power factor four times higher than the obtained for the solid state and sol-gel methods at room temperature.Keywords: Processing, Electrical properties, Microstructure, Thermopower, Cobaltites. Mejora de las propiedades termoeléctricas de Bi 2 Sr 2 Co 1.8 O x por métodos de síntesis en disoluciónSe han obtenido cerámicas termoeléctricas Bi 2 Sr 2 Co 1.8 O x utilizando varios métodos de síntesis, el clásico por estado sólido, sol-gel y de matriz polimérica. Se han comparado los productos obtenidos por las diferentes vías a través de técnicas de DTA-TGA, difracción de rayos X en polvo, microscopía electrónica de barrido y de caracterización termoeléctrica. Todas las muestras obtenidas por los métodos en disolución poseen una mayor homogeneidad y menor contenido de fases secundarias. La principal diferencia en las propiedades termoeléctricas es debida a la disminución de la resistividad eléctrica en las muestras obtenidas por medio de métodos en disolución, comparado con las que se obtienen por estado sólido. Entre ellas, la reducción de la resistividad es mucho mayor para las que se obtienen por el método de matriz polimérica. Además, los materiales obtenidos por este último método poseen un factor de potencia, a temperatura ambiente, cuatro veces mayor que el obtenido en las sintetizadas por los otros dos métodos estudiados.

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Section: Sintered Materials Characterizationsupporting

confidence: 49%

Section: Introductionmentioning

confidence: 99%

Mejora de las propiedades termoeléctricas de Bi2Sr2Co1.8Ox por métodos de síntesis en disolución

Torres¹,

Sotelo²,

Rasekh³

et al. 2012

Bol. Soc. Esp. Ceram. Vidr.

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show abstract

“…This misfit system exhibits a large thermopower TEP 300 ~150 µV/K and a rather low resistivity value [5][6][7]. Due to its high structural anisotropy, the alignment of plate-like grains by mechanical and/or chemical processes is necessary to attain macroscopic properties comparable to the intrinsic crystallographic ones.…”

Section: Introductionmentioning

confidence: 99%

Neutron diffraction texture analysis and thermoelectric properties of BiCaCoO misfit compounds

Guilmeau¹,

Pollet²,

Grebille³

et al. 2008

Materials Research Bulletin

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Sintered, textured and single crystal products of the layered misfit [Bi 0.81 CaO 2 ] 2 [CoO 2 ] 1.69 cobaltite have been successfully synthesized and characterized. Based on structure and texture models, the orientation distribution of the hot-forged sample was successfully analysed by neutron diffraction. The results gave a clear description of the fiber texture with c-axes of the plate-like grains aligned parallel to the hot-forging direction. In terms of transport properties, the decrease of the electrical resistivity according to the degree of alignment and crystallinity of the materials evidenced the important role of the texturation and the strong anisotropy existing in these misfit layered cobaltites.

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“…These layers show an alternate stacking of a common conductive CdI 2 -type hexagonal CoO 2 layer with a two-dimensional triangular lattice and a block layer composed of insulating rock-salt-type (RS) layers. The two sublattices (RS block and CdI 2 -type CoO 2 layer) possess common a-and c-axis lattice parameters and β angles, but different b-axis length, causing a misfit along the b-direction [10,11]. Furthermore, it has also been found that the Seebeck coefficient values are governed by the incommensurability ratio and/or the charge of the RS block layer between the CoO 2 ones [9].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Ca 3 Co 4 O 9 thermoelectric properties by Cr for Co substitution

Díez¹,

Torres

Rasekh³

et al. 2013

Ceramics International

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Fabrication of textured thermoelectric layered cobaltites with various rock salt-type layers by using β-Co(OH)₂platelets as reactive templates

Cited by 110 publications

References 21 publications

Mejora de las propiedades termoeléctricas de Bi<sub>2</sub>Sr<sub>2</sub>Co<sub>1.8</sub>O<sub>x</sub> por métodos de síntesis en disolución

Mejora de las propiedades termoeléctricas de Bi<sub>2</sub>Sr<sub>2</sub>Co<sub>1.8</sub>O<sub>x</sub> por métodos de síntesis en disolución

Neutron diffraction texture analysis and thermoelectric properties of BiCaCoO misfit compounds

Enhancement of Ca 3 Co 4 O 9 thermoelectric properties by Cr for Co substitution

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