Reduction of Thermal Conductivity Through Complex Microstructure by Dispersion of Carbon Nanofiber in p-Type Bi0.5Sb1.5Te3 Alloys

• Published in: Archives of metallurgy and materials Vol. 66; no. 3; pp. 803 - 808
• Main Authors: Sharief, P., Madavali, B., Sohn, Y., Han, J.H., Song, G., Song, S.H., Song, S.J.
• Format: Journal Article
• Language: English
• Published: Warsaw Polish Academy of Sciences 01.01.2021
• Subjects: Ball milling; bismuth telluride; Bismuth tellurides; Carbon fibers; carbon nano fiber; Composite materials; Diamond pyramid hardness; Dispersion; Electrical resistivity; Grain boundaries; Grain size; Heat conductivity; Heat transfer; Mechanical properties; Microstructure; Nanofibers; Plasma sintering; Raman spectroscopy; Seebeck effect; Sintering (powder metallurgy); Spark plasma sintering; Thermal conductivity; Thermoelectricity
• ISSN: 2300-1909; 1733-3490; 2300-1909
• DOI: 10.24425/amm.2021.136384

The influence of nano dispersion on the thermoelectric properties of Bi2Te3 was actively investigating to wide-spread thermoelectric applications. Herein this report, we have systematically controlled the microstructure of Bi0.5Sb1.5Te3 (BST) alloys through the incorporation of carbon nanofiber (CNF), and studied their effect on thermoelectric properties, and mechanical properties. The BST/x-CNF (x-0, 0.05, 0.1, 0.2 wt.%) composites powder was fabricated using high energy ball milling, and subsequently consolidated the powder using spark plasma sintering. The identification of CNF in bulk composites was analyzed in Raman spectroscopy and corresponding CNF peaks were recognized. The BST matrix grain size was greatly reduced with CNF dispersion and consistently decreased along CNF percentage. The electrical conductivity was reduced and Seebeck coefficient varied in small-scale by embedding CNF. The thermal conductivity was progressively diminished, obtained lattice thermal conductivity was lowest compared to bare sample due to induced phonon scattering at interfaces of secondary phases as well as highly dense fine grain boundaries. The peak ZT of 0.95 achieved for 0.1 wt.% dispersed BST/CNF composites. The Vickers hardness value of 101.8 Hv was obtained for the BST/CNF composites.