Christine Bellouard

Synthesis and properties of nearly single-shell nickel clusters in amorphous aluminium oxides

Abstract We introduce a new method for the synthesis of Al-Ni nanosized particles. After partial oxidation, this technique is able to produce ultrafine sub-nanometric nickel clusters dispersed with an amorphous aluminium oxide. Such clusters consist of about 15 nickel atoms which exhibit discrete electronic energy levels and superparamagnetism. A very significant enhancement of the catalytic properties is observed. We expect that division of metals down to such a reduced scale will lead us to new properties and to a technological breakthrough since upscaling this method to industrial production rate is straightforward.

Thermoelectric Properties of In x Co 4-y Ni y Sb 12 Skutterudite Compounds

In an effort to further understand the influence of Nd on the thermoelectric properties of the binary compound CoSb3 and try to optimize them through doping, we prepared and investigated NdxCo4-yNiySb12 compounds. The samples have been prepared by a conventional metallurgical route. Structural analysis have been carried out by X-ray diffraction. The chemical composition and micro-homogeneity have been checked by electron probe microanalysis. Measurements of the electrical resistivity, thermoelectric power, thermal conductivity and Hall coefficient have been performed. The influence of both Nd and Ni on the thermoelectric properties of the binary parent CoSb3 is presented and discussed. Nd plays the role of a dopant (n-type) and the presence of Ni contributes to decrease significantly the electrical resistivity.

Galvanomagnetic and Thermoelectric Properties of R3Cu3Sb4 Compounds

Zintl phases recently received a great attention for their thermoelectric potential and interesting results were reported on Yb₁₄MnSb₁₁ compounds [Brown, et al., 2006]. In this paper, we present results obtained with other Zintl phases, Y_1.5Gd_1.5Cu₃Sb₄, Y₃Cu₃Sb₄ and Gd₃Cu₃Sb ₄. They were synthesized in an induction furnace, followed by consequent annealing treatments. The crystallographic structure was checked by X-ray diffraction analysis. Resistivity and thermopower measurements were performed over a large temperature range going from 2 to 550 K. The low temperature thermal conductivity dependence of these materials was also determined between 10 to 300 K. Finally, the thermoelectric potential of these polycrystalline samples is discussed

Thermoelectric Properties of NdxCo4-yNiySb12 Skutterudite Compounds

In an effort to further understand the influence of Nd on the thermoelectric properties of the binary compound CoSb3 and try to optimize them through doping, we prepared and investigated NdxCo4-yNiySb12 compounds. The samples have been prepared by a conventional metallurgical route. Structural analysis has been carried out by X-ray diffraction. The chemical composition and micro-homogeneity have been checked by electron probe microanalysis. Measurements of the electrical resistivity, thermoelectric power, thermal conductivity and Hall coefficient have been performed. The influence of both Nd and Ni on the thermoelectric properties of the binary parent CoSb3 is presented and discussed. Nd plays the role of a dopant (n-type) and the presence of Ni contributes to decrease significantly the electrical resistivity

Low temperature thermoelectric properties of Ca/sub x/Co/sub 4/Sb/sub 12/ skutterudites

Electrical resistivity, thermoelectric power, thermal conductivity, and dimensionless figure of merit of the partially filled skutterudites CaxCo4Sb12, with x = 0, 0.03, 0.05, 0.08, and 0.20, have been studied in the low temperature range, from 4.2 to 300 K. The compounds have been prepared by a powder metallurgy route. We find that the insertion of Ca in the voids of the skutterudite structure has a dramatic effect on all the transport properties. Qualitative analysis of the physical properties was realized and the results are discussed as a function of the Ca filling fraction and compared to data obtained with other CoSb3 partially filled skutterudites.