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

This paper is concerned with the feasibility and reproducibility of the ultrarapid quenching process used to fabricate Bi2-xSbxTe and Bi2-xSbxTe2 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 Bi2-xSbxTe alloys were found to have the (20(2) over bar 3) texture. The (20(2) over bar 4) texture, with an additional (1 12 0) component for x values greater than 0.4, was predominant for Bi(2-x)Sb(x)Te2 foils. The electrical properties of these materials were then characterized by measuring the Seebeck coefficient, Hall coefficient, and electrical resistivity. It was found that Bi2-xSbxTe foils changed from n- to p-type for an x-value of about 1.2. A maximum Seebeck coefficient, \alpha\, of 36 x 10(-6) VK-1 was measured for Bi2Te. In the case of Bi2-xSbxTe2 foils, the change from n- to p-type was observed for an x value of about 1. A maximum Seebeck coefficient, \alpha\, of 32 x 10(-6) VK-1, was measured for Bi1.4Sb0.6Te2. 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. (C) 2003 Kluwer Academic Publishers.