Effect of processing route on the bipolar contribution to the thermoelectric properties of n-type eutectic Bi22.5Sb7.5Te70 alloy

Femi, Olu Emmanuel and Akkiraju, Karthik and Murthy, BS and Ravishankar, N and Chattopadhyay, K (2016) Effect of processing route on the bipolar contribution to the thermoelectric properties of n-type eutectic Bi22.5Sb7.5Te70 alloy. In: JOURNAL OF ALLOYS AND COMPOUNDS, 682 . pp. 791-798.

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Abstract

Narrow bandgap thermoelectric materials based on bismuth-telluride exhibit bipolar conduction that is detrimental to their overall thermoelectric performance. Through fabrication of composites of (Bi,Sb)(2)Te-3 matrix with embedded random colony of (Bi,Sb)(2)Te-3/Te lamellar (eutectic) with different length scales through a combination of different processing routes such as normal flame melting, cryomilling followed by spark plasma sintering and melt-spinning techniques followed by spark plasma sintering, interfacial charge defects and selective potential barrier were created leading to the injection of excess electron and activation of energy filtering effect of minority carriers. The selective-filtering of charge carriers lead to the delay in the onset of bipolar conduction to a higher temperature as a result of an increase in the band gap. This was found to be responsible for shifting the Peak ZT and the optimum operating regime of our alloys to a higher temperature. Changes in microstructure length scale from normal flame-melting to melt-spinning plus spark plasma sintering resulted in 20% reduction in the total thermal conductivity. (C) 2016 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF ALLOYS AND COMPOUNDS
Publisher:	ELSEVIER SCIENCE SA
Additional Information:	Copy right for this article belongs to the ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND
Keywords:	Thermoelectric; Bipolar-conduction; Energy filtering; BiSbTe; Low temperature milling; Melt-spinning
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	25 Aug 2016 10:17
Last Modified:	25 Aug 2016 10:17
URI:	http://eprints.iisc.ac.in/id/eprint/54316

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