Journal
RSC ADVANCES
Volume 11, Issue 42, Pages 26421-26431Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/d1ra04270j
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Funding
- Spanish Ministry of Science, Innovation and Universities [MAT2017-84496-R]
- MICINN [PRE2018-083398]
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Rare-earth metals have been filled in CoSb3 thermoelectric skutterudite under high-pressure conditions, leading to a phase segregation with different unit-cell sizes. This results in a dramatic decrease in total thermal conductivity and a substantial enhancement in power factor with charge transfer promoted by the filler.
CoSb3 thermoelectric skutterudite has been filled with rare-earth metals (M = La, Ce, Yb) and partially doped with Sn in specimens of MxCo4Sb12-ySny stoichiometry. This has been achieved under high-pressure conditions at 3.5 GPa in a piston-cylinder hydrostatic press. A structural investigation using synchrotron X-ray diffraction data reveals a phase segregation in twin skutterudite phases with filling fraction fluctuation and different unit-cell sizes. As a result of three effects acting as phonon scatterers, namely the rattling effect of M at the wide 8a cages of the cubic Im3 structure, the phase segregation, and the intrinsic disorder introduced by Sn substitution at the Sb sublattice, the total thermal conductivity (kappa) dramatically falls to reach minimum values under 2 W m(-1) K-1, well below those typically exhibited by other thermoelectric materials based upon single-filled skutterudites. The power factor is substantially enhanced to 1.11 mW m(-1) K-2 in Yb0.5Co4Sb11.6Sn0.4 with respect to the unfilled composition, as a result of the charge transfer promoted by the filler.
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