Electrical and microstructural properties of Bi2−xSbxTe and Bi2−xSbxTe2 foils obtained by the ultrarapid quenching process

Abstract

This paper is concerned with the feasibility and reproducibility of the ultrarapid quenching process used to fabricate Bi 2-x Sb x Te and Bi 2-x Sb x Te 2 alloys for thermoelectric applications. Microstructural properties of the materials, obtained in the shape of foils, were studied concerning the phase analysis, cell parameters, texture, and microstructure observations. The Bi 2-x Sb x Te alloys were found to have the (2023) texture. The (2024) texture, with an additional (1 1 2 0) component for x values greater than 0.4, was predominant for Bi 2-x Sb x Te 2 foils. The electrical properties of these materials were then characterized by measuring the Seebeck coefficient, Hall coefficient, and electrical resistivity. It was found that Bi 2-x Sb x Te foils changed from n- to p-type for an x-value of about 1.2. A maximum Seebeck coefficient, |α|, of 36 x 10 -6 V K -1 was measured for Bi 2 Te. In the case of Bi 2-x Sb x Te 2 foils, the change from n- to p-type was observed for an x value of about 1. A maximum Seebeck coefficient, |α|, of 32 x 10 -6 V K -1 , was measured for Bi 1.4 Sb 0.6 Te 2 . Measurements of the temperature-dependent electrical resistivity, Hall and Seebeck coefficients of the foils were carried out and the analysis revealed a semi-metallic behavior.