Muthiah, Saravanan and Singh, R. C. and Pathak, B. D. and Avasthi, Piyush Kuma and Kumar, Rishikesh and Kumar, Anil and Srivastava, A. K. and Dhar, Ajay (2018) Significant enhancement in thermoelectric performance of nanostructured higher manganese silicides synthesized employing a melt spinning technique. Nanoscale, 10 (4). pp. 1970-1977. ISSN 2040-3364

PDF - Published Version Restricted to Registered users only Download (3502Kb) | Request a copy

Abstract

The limited thermoelectric performance of p-type Higher Manganese Silicides (HMS) in terms of their low figure-of-merit (ZT), which is far below unity, is the main bottle-neck for realising an efficient HMS based thermoelectric generator, which has been recognized as the most promising material for harnessing waste-heat in the mid-temperature range, owing to its thermal stability, earth-abundant and environmentally friendly nature of its constituent elements. We report a significant enhancement in the thermoelectric performance of nanostructured HMS synthesized using rapid solidification by optimizing the cooling rates during melt-spinning followed by spark plasma sintering of the resulting melt-spun ribbons. By employing this experimental strategy, an unprecedented ZT similar to 0.82 at 800 K was realized in spark plasma sintered 5 at% Al-doped MnSi1.73 HMS, melt spun at an optimized high cooling rate of similar to 2 x 10(7) K s(-1). This enhancement in ZT represents a similar to 25% increase over the best reported values thus far for HMS and primarily originates from a nano-crystalline microstructure consisting of a HMS matrix (20-40 nm) with excess Si (3-9 nm) uniformly distributed in it. This nanostructure, resulting from the high cooling rates employed during the melt-spinning of HMS, introduces a high density of nano-crystallite boundaries in a wide spectrum of nano-scale dimensions, which scatter the low-to-mid-wavelength heat-carrying phonons. This abundant phonon scattering results in a significantly reduced thermal conductivity of similar to 1.5 W m(-1) K-1 at 800 K, which primarily contributes to the enhancement in ZT.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Royal Society of Chemistry.
Subjects:	Chemistry Materials Science Applied Physics/Condensed Matter Nanoscience/ Nanotechnology
Divisions:	UNSPECIFIED
Depositing User:	Mr. Yogesh Joshi
Date Deposited:	27 Sep 2019 08:17
Last Modified:	27 Sep 2019 08:17
URI:	http://npl.csircentral.net/id/eprint/3945

Actions (login required)

View Item