In-doped multifilled n-type skutterudites with ZT=1.8

Autor(en)

G. Rogl, A. Grytsiv, K. Yubuta, S. Puchegger, E. Bauer, C. Raju, R. C. Mallik, P. Rogl

Abstrakt

In this paper we maximize the thermoelectric (TE) figure of merit, ZT, of n-type skutterudites, (In, Sr, Ba, Yb)

_yCo

₄Sb

₁₂, via three different routes: (i) find the optimum fraction of In as fourth filler (ii) check the influence of powder particle, grain, and crystallite size on the TE properties and (iii) check thermal stability. Filled n-type (Sr, Ba, Yb)

_yCo

₄Sb

₁₂ was mixed in three different proportions with In

_0.4Co

₄Sb

₁₂, ball milled (regular or high-energy (HB) ball milling) and hot-pressed. Particle size analyses and SEM pictures of the broken surfaces of the hot pressed samples document that only HB produces uniform particles/grains with average crystallite sizes ∼100 nm, proven by transmission electron microscopy. X-ray Rietveld refinements combined with EDX indicate that in all cases indium entered the icosahedral voids of the skutterudite. Temperature dependent physical properties of all three regularly ball-milled samples show that increasing In-content infers an increasing electrical resistivity, increasing Seebeck coefficient but a decreasing total thermal conductivity. Although ZT (823 K) is in the same range as for the sample without In, the ZT values in the whole temperature range are higher and consequently the TE-conversion efficiency, η is at least 10% higher. Annealing the samples at 600 °C for three days shows minor changes in structure and thermoelectric properties, indicating TE stability. The HB sample, due to uniformly small particles, equally sized grains and crystallites, exhibits a high power factor (4.4 mW/m K

^-2 at 730 K) and a very low thermal conductivity leading to an outstanding high ZT = 1.8 at 823 K (η

_max = 17.5%).

Organisation(en)

Institut für Physikalische Chemie, Fakultätszentrum für Nanostrukturforschung

Externe Organisation(en)

Indian Institute of Science, Tohoku University, Technische Universität Wien

Journal

Acta Materialia

Band

95

Seiten

201-211

Anzahl der Seiten

11

ISSN

1359-6454

DOI

https://doi.org/10.1016/j.actamat.2015.05.024

Publikationsdatum

08-2015

Peer-reviewed

Ja

ÖFOS 2012

104017 Physikalische Chemie, 103018 Materialphysik, 210004 Nanomaterialien

Schlagwörter

ASJC Scopus Sachgebiete

Electronic, Optical and Magnetic Materials, Ceramics and Composites, Metals and Alloys, Polymers and Plastics

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/2b12912f-e6a1-472a-b312-a78b676933f2