Thermoelectric properties of Ru and In substituted misfit-layered Ca3Co4O9
| Autor: | Nina Vogel-Schäuble, Gesine Saucke, Leyre Sagarna, Kailash Mogare, Anke Weidenkaff, Sascha Populoh, Lassi Karvonen |
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| Rok vydání: | 2013 |
| Předmět: |
010302 applied physics
Materials science Oxide Analytical chemistry 02 engineering and technology Crystal structure Atmospheric temperature range 021001 nanoscience & nanotechnology Thermoelectric materials 01 natural sciences chemistry.chemical_compound chemistry Electrical resistivity and conductivity Seebeck coefficient 0103 physical sciences Thermoelectric effect Crystallite 0210 nano-technology |
| Zdroj: | Materials Research Society Symposium Proceedings |
| ISSN: | 1946-4274 0272-9172 |
| Popis: | As an approach to improve the thermoelectric properties of the polycrystalline Ca3Co4O9 misfit-layered oxide, substitutions of Co2+…4+ with the heavier cations Ru3+/4+ and In3+ were tested. Polycrystalline samples Ca3Co4-xRuxO9 and Ca3Co4-xInxO9 (0 < x < 0.21) were prepared via a solid-state-reaction route. For each sample the crystal structure was analyzed and a complete thermoelectric characterization was done within a temperature range of 300 K < T < 1125 K.Both substitution strategies resulted in a significant decrease of the thermal conductivity (κ). For the In3+-substituted samples the decrease of the Seebeck coefficient (α) balanced the κ reduction so that no overall enhancement of the figure of merit (ZT) was found. The Ru3+/4+ substitution reduced the p-type carrier concentration and thus increases the electrical resistivity (ρel), while α became larger at low temperatures. Despite the reduction of the power factor, a small enhancement in ZT was observed in the case of x = 0.1 Ru substitution, due to the strong κ reduction. Considering the observed preferred orientation of the Ru-substituted crystallites, a maximum value of ZT = 0.14 perpendicular to the pressing direction is found at T = 1125 K, indicating that Ru substitution is a promising strategy for a further ZT improvement. |
| Databáze: | OpenAIRE |
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