Attempts to further enhance ZT in skutterudites via nano-composites

Gerda Rogl (Korresp. Autor*in), Andrij Grytsiv, Fainan Failamani, Markus Hochenhofer, Ernst Bauer, Peter Rogl

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed

Abstract

Skutterudites are known as excellent thermoelectric p- and n-type materials and have already achieved good efficiencies for the conversion of heat to electricity, but nevertheless researchers try to further enhance the figure of merit, ZT. In the present work the aim was to mix p- and n-type skutterudite powders with additives in order to produce an evenly dispersed distribution of sub micron grains, preferable small nano-particles, which enhance the scattering of the heat carrying phonons of different wavelengths and reduce thermal conductivity without changing electrical resistivity and Seebeck coefficient. Various quantities of three groups of materials (a) nonmetallic oxides (Al 2O 3), (b) metallic oxides (Cu 2O and La 1.85Sr 0.15CuO 4) and (c) metallic borides (Fe 2.25Co 0.75B and Ta 0.8Zr 0.2B) were added to industrially produced p-type (DD yFe 3CoSb 12) and n-type ((Mm,Sm) yCo 4Sb 12) skutterudite powders. First the influence of pre-sieving and various ball milling conditions before hot pressing were studied, using Al 2O 3as additive. As a consequence of these studies pre-sieved powders and high-energy ball milling were used for all following experiments. The goal, to enhance ZT was not reached with Al 2O 3and Cu 2O. La 1.85Sr 0.15CuO 4was successful for the n-type, Fe 2.25Co 0.75B for the p-type skutterudites, although ZT-enhancement was small, but with Fe 2.25Co 0.75B the maximum ZT could be shifted to lower temperatures, a valuable information for device production. Much better results in respect to ZT values were gained with adding 0.5, 1.0 and 1.5 wt.% Ta 0.8Zr 0.2B to p-type DD yFe 3CoSb 12. In this series it was possible to enhance ZT (from ZT ∼ 1.2 to ZT ∼ 1.3) as well as to significantly increase the thermal-electrical conversion efficiency η. In addition, we found that all boride additives enhanced the hardness, elastic moduli and fracture resistance.

OriginalspracheEnglisch
Seiten (von - bis)682-696
Seitenumfang15
FachzeitschriftJournal of Alloys and Compounds
Jahrgang695
DOIs
PublikationsstatusVeröffentlicht - 25 Feb. 2017

ÖFOS 2012

  • 104011 Materialchemie
  • 210006 Nanotechnologie

Zitationsweisen