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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Cottrino, Sandrine
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Topics
Publications (9/9 displayed)
- 2024Insights on the effect of process conditions on the optical properties of silver ion exchanged soda-lime silicate glass
- 2023In situ X-ray diffraction study of a TiO2 nanopowder Spark Plasma Sintering under very high pressurecitations
- 2023In situ X-ray diffraction study of a TiO2 nanopowder Spark Plasma Sintering under very high pressurecitations
- 2020Optimum in the thermoelectric efficiency of nanostructured Nb-doped TiO 2 ceramics: from polarons to Nb–Nb dimerscitations
- 2020Optimum in the thermoelectric efficiency of nanostructured Nb-doped TiO 2 ceramics: from polarons to Nb–Nb dimerscitations
- 2020Effect of High Pressure Spark Plasma Sintering on the Densification of a Nb-Doped TiO2 Nanopowdercitations
- 2020Effect of High Pressure Spark Plasma Sintering on the Densification of a Nb-Doped TiO2 Nanopowdercitations
- 2019Sol-gel preparation of doped-metal oxide nanostructures for the thermoelectric conversion of energy
- 2013Characterization by X-ray tomography of granulated alumina powder during in situ die compaction
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article
Optimum in the thermoelectric efficiency of nanostructured Nb-doped TiO 2 ceramics: from polarons to Nb–Nb dimers
Abstract
Rutile is the most common and stable polymorph form of titanium oxide TiO<sub>2</sub> at all temperatures. The doping of rutile TiO<sub>2</sub> with a small amount of niobium is reknown for being responsible for a large increase of the electrical conductivity by several orders of magnitude, broadening its technological interest towards new emerging fields such as the thermoelectric conversion of waste heat. The electronic conduction has been found to be of a polaronic nature with strongly localized charges around the Ti<sup>3+</sup> centers while, on the other side, the relatively high value of the thermal conductivity implies the existence of lattice heat carriers, i.e. phonons, with large mean free paths which makes the nanostructuration relevant for optimizing the thermoelectric efficiency. Here, the use of a high-pressure and high-temperature sintering technique has allowed to vary the grain size in rutile TiO<sub>2</sub> pellets from 300 to 170 nm, leading to a significant reduction of the lattice thermal conductivity. The thermoelectric properties (electrical conductivity, Seebeck coefficient and thermal conductivity) of Nb-doped rutile nanostructured ceramics, namely Nb<sub>x</sub>Ti<sub>1−x</sub>O<sub>2</sub> with x varying from 1 to 5%, are reported from room temperature to ∼900 K. With the incorporation of Nb, an optimum in the thermoelectric properties together with an anomaly on the tetragonal lattice constant c are observed for a concentration of ∼2.85%, which might be the fingerprint of the formation of short Nb dimers.