Effect of microstructure on the thermoelectric performance of La{sub 1−x}Sr{sub x}CoO{sub 3}

Journal Article · Mon Nov 14 23:00:00 EST 2016 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2016.08.015· OSTI ID:22658090

Viskadourakis, Z. ^[1]; Athanasopoulos, G. I. ^[2]; Kasotakis, E. ^[3]; Giapintzakis, J. ^[2]

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1. Crete Center for Quantum Complexity and Nanotechnology, University of Crete, P.O. Box 2208, GR7-1003 Heraklion (Greece)
2. Department of Mechanical and Manufacturing Engineering, University of Cypruss, 75 Kallipoleos Avenue, P.O. Box 20537, 1678 Nicosia (Cyprus)
3. Department of Materials Science and Technology, University of Crete, P.O. Box 2208, GR7-1003 Heraklion (Greece)

We present a case where the microstructure has a profound effect on the thermoelectric properties of oxide compounds. Specifically, we have investigated the effect of different sintering treatments on La{sub 1−x}Sr{sub x}CoO{sub 3} samples synthesized using the Pechini method. We found that the samples, which are dense and consist of inhomogeneously-mixed grains of different size, exhibit both higher Seebeck coefficient and thermoelectric figure of merit than the samples, which are porous and consist of grains with almost identical size. The enhancement of Seebeck coefficient in the dense samples is attributed to the so-called “energy-filtering” mechanism that is related to the energy barrier of the grain boundary. On the other hand, the thermal conductivity for the porous compounds is significantly reduced in comparison to the dense compounds. It is suggested that a fine-manipulation of grain size ratio combined with a fine-tuning of porosity could considerably enhance the thermoelectric performance of oxides. - Graphical abstract: The enhancement of the dimensionless thermoelectric figure ZT of merit is presented for two equally Sr-doped LaCoO3 compounds, possessing different microstructure, indicating the effect of the latter to the thermoelectric performance of the La{sub 1−x}Sr{sub x}CoO{sub 3} solid solution. - Highlights: • Electrical and thermal transport properties are affected by the microstructure in La{sub 1−x}Sr{sub x}CoO{sub 3} polycrystalline materials. • Coarse/fine grain size distribution enhances the Seebeck coefficient. • Porosity reduces the thermal conductivity in La{sub 1−x}Sr{sub x}CoO{sub 3} polycrystalline samples. • The combination of large/small grain ratio distribution with the high porosity may result to the enhancement of the thermoelectric performance of the material.

• OSTI ID: 22658090
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 243; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
COBALT OXIDES
DENSITY
DOPED MATERIALS
EXPERIMENTAL DATA
GRAIN BOUNDARIES
GRAIN SIZE
LANTHANUM COMPOUNDS
PERFORMANCE
POROSITY
POROUS MATERIALS
SOLID SOLUTIONS
STRONTIUM COMPOUNDS
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES