Synthèse et caractérisation microstructurale de poudres nanométriques à base de Bi2Te3 et Sb2Te3 : contribution à l'état de l'art des nanocomposites thermoélectriques

Abstract : The study of thermoelectric nanostructured and nanocomposite materials is expanding because of the interest to multiply the number of interfaces and to decrease the size of the objects in order to improve the thermoelectric performance. We developed a new method to prepare thermoelectric n type (Bi0.95Sb0.05)2(Te0.95Se0.05)3 and p type (Bi0.2Sb0.8)2Te3 nanopowders, from the laser fracture in a liquid medium of powders of micrometric size. The developed cell preparation makes it possible to obtain per day approximately 200 mg of crystallized nanometric powders having the crystallographic structure of the initial powders and whose mean size lies between 7 and 12 nm. The mechanisms concerned in obtaining the nanoparticules were approached. They strongly depend on the density of energy of the laser beam. The nanopowders then were mechanically mixed with the micrometric powders of comparable nature and were cold pressed. The thermoelectric properties (electrical resistivity, thermoelectric power, thermal conductivity) of the nanocomposites were evaluated at room temperature. The first results show that even if the thermoelectric power is maintained in nanostructured and nanocomposite materials and that the total thermal conductivity can, in a completely exceptional way, being decreased by a factor two, the electrical resistivity obtained is hitherto too high to lead to high values of the dimensionless thermoelectric figure of merit, with regard to conventional bulk materials of same composition
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Voravit Kosalathip. Synthèse et caractérisation microstructurale de poudres nanométriques à base de Bi2Te3 et Sb2Te3 : contribution à l'état de l'art des nanocomposites thermoélectriques. Autre. Institut National Polytechnique de Lorraine, 2008. Français. ⟨NNT : 2008INPL033N⟩. ⟨tel-01753021⟩

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