Enhanced Thermoelectric Performance in the Ba0.3Co4Sb12/InSb Nanocomposite Originating from the Minimum Possible Lattice Thermal Conductivity

Sanyukta Ghosh; Gyan Shankar; Anirudha Karati; Katharina Werbach; Gerda Rogl; Peter Rogl; Ernst Bauer; B S Murty; Satyam Suwas; Ramesh Chandra Mallik

doi:10.1021/acsami.0c17254

Enhanced Thermoelectric Performance in the Ba_0.3Co₄Sb₁₂/InSb Nanocomposite Originating from the Minimum Possible Lattice Thermal Conductivity

ACS Appl Mater Interfaces. 2020 Oct 28;12(43):48729-48740. doi: 10.1021/acsami.0c17254. Epub 2020 Oct 19.

Authors

Sanyukta Ghosh¹, Gyan Shankar², Anirudha Karati³, Katharina Werbach⁴, Gerda Rogl^{4

5}, Peter Rogl⁴, Ernst Bauer⁵, B S Murty⁶, Satyam Suwas², Ramesh Chandra Mallik¹

Affiliations

¹ Thermoelectric Materials and Devices Laboratory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
² Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, India.
³ Department of Chemistry, Indian Institute of Technology, Chennai 600036, India.
⁴ Institute of Materials Chemistry, University of Vienna, Waehringerstrasse 42, Wien 1090, Austria.
⁵ Institute of Solid State Physics, TU-Wien, Wien 1040, Austria.
⁶ Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Chennai 600036, India.

PMID: 33073561
DOI: 10.1021/acsami.0c17254

Abstract

The thermoelectric efficiency of skutterudite materials can be improved by lowering the lattice thermal conductivity via the uniform dispersion of a nanosized second phase in the matrix of filled Co₄Sb₁₂. In this work, nanocomposites of Ba_0.3Co₄Sb₁₂ and InSb were synthesized using ball-milling and spark plasma sintering. The thermoelectric transport properties were studied from 4.2 to 773 K. The InSb nanoparticles of ∼20 nm were found to be dispersed in the Ba_0.3Co₄Sb₁₂ grains with a few larger grains of about 10 μm due to the agglomeration of the InSb nanoparticles. The +2 oxidation state of Ba in Co₄Sb₁₂ resulted in a low electrical resistivity, ρ, value of the matrix. The enhancement of the Seebeck coefficient, S, and the electrical resistivity values of Ba_0.3Co₄Sb₁₂ with the addition of InSb can be credited to the energy-filtering effect of electrons with low energy at the interfaces. The power factor of the composites could not be enhanced compared to the matrix because of the very high ρ value. A minimum possible lattice thermal conductivity (0.45 W/m·K at 773 K) was achieved due to the combined effect of rattling of Ba atoms in the voids and enhanced phonon scattering at the interfaces induced by nanosized InSb particles. As a result, the (InSb)_0.15 + Ba_0.3Co₄Sb₁₂ composite exhibited improved thermoelectric properties with the highest zT of 1.4 at 773 K and improved mechanical properties with a higher hardness, higher Young's modulus, and lower brittleness.

Keywords: Cahill and Pohl’s model; EBSD; nanocomposite; skutterudites; thermoelectric materials.