Effect of Mechanical Deformation on Thermoelectric Properties of p-Type (Bi0.225Sb0.775)2Te3 Alloys. (9th January 2014)

• Record Type: Journal Article
• Authors: Jung, Sung-Jin; Kim, Seong Keun; Park, Hyung-Ho; Hyun, Dow-Bin; Baek, Seung-Hyub; Kim, Jin-Sang
• Other Names: Park Chan Academic Editor.
• Is Part Of: Journal of nanomaterials. Volume 2013(2013)
• Publication Date: 2014-01-09
• Subjects: Nanostructured materials -- Periodicals; Nanotechnology -- Periodicals; Nanomatériaux; Nanostructured materials; Nanotechnology; Nanostructures; Nanotechnology; Periodicals; Fulltext; Internet Resources; Periodicals; 620.115
• DOI: 10.1155/2013/868540
• Languages: English
• ISSNs: 1687-4110

Abstract

Abstract : The effect of mechanical deformation and annealing on thermoelectric properties of p-type (Bi0.225 Sb0.775 )Te3 was performed. The ingots were prepared by melting, followed by quenching method using source materials with compositions of (Bi0.225 Sb0.775 )2 Te3 . Rectangular shaped specimens (5 × 5 × 12 mm 3 ) were cut from ingots and then cold-pressed at 700 MPa for 2 to 20 times by changing the press direction perpendicular to previous one. The cold-pressed samples have been annealed in a quartz ampoule at 573 K. The grain size of the samples was controlled by the number of cold-pressing process and annealing time. Fine grain structure with a grain size of not more than 10 μ m is obtained in highly deformed samples. The Seebeck coefficient of the deformed samples were gradually increased with annealing and converged to the similar value of about 225 μ V/K after 30 hrs. The small grain size in highly deformed sample enables a rapid increase of Seebeck coefficient with annealing time ( ~ 2 hrs.), indicating that the thermal energy needed to recrystallize in highly deformed specimens is lower than that in low deformed specimens. Z values are rapidly increased with annealing time especially in highly deformed alloys, and converge to about3.0 × 10 − 3 /K at room temperature. A higher thermoelectric performance could be expected by the optimization of composition and microstructural adjustment. The present study experimentally demonstrates a simple and cost-effective method for fabricating Bi-Te-based alloys with higher thermoelectric performance.