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

Femi, Olu Emmanuel ; Akkiraju, Karthik ; Murthy, B. S. ; Ravishankar, N. ; Chattopadhyay, K. (2016) Effect of processing route on the bipolar contribution to the thermoelectric properties of n-type eutectic Bi22.5Sb7.5Te70 alloy Journal of Alloys and Compounds, 682 . pp. 791-798. ISSN 0925-8388

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Official URL: http://www.sciencedirect.com/science/article/pii/S...

Related URL: http://dx.doi.org/10.1016/j.jallcom.2016.05.054

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)2Te3 matrix with embedded random colony of (Bi,Sb)2Te3/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.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Thermoelectric; Bipolar-Conduction; Energy Filtering; BiSbTe; Low Temperature Milling; Melt-Spinning
ID Code:105419
Deposited On:01 Feb 2018 16:41
Last Modified:01 Feb 2018 16:41

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