Electrical properties of Bi2-xSbxTe3 materials obtained by ultrarapid quenching

Bismuth and antimony telluride alloys were prepared using the ultrarapid quenching process route. The electrical properties of these materials were then characterized by measuring the Seebeck coefficient, Hall coefficient and electrical resistivity. It appeared that the Bi2-xSbxTe3 materials changed from the n-type to the p-type at an x-value of about 0.7. For n-type materials, the Bi1.6Sb10.4Te3 foils (x=0.4) showed a maximal Seebeck coefficient with a value of -100 muV K-1. For p-type materials, a maximal Seebeck coefficient was observed for x-values varying from 1.2 to 1.6 with a value of 135 muV K-1. The evolutions of the Seebeck coefficient, electrical resistivity, Hall coefficient with temperature, from 77 to 300 K, showed the degenerate nature of the quenched materials. The evolution of the mobility with temperature indicated that the diffusion mechanism was mainly associated with acoustic phonon scattering. The study evidenced that the Bi,,,,Sb,,,,Te, alloy has optimal electrical properties with a carrier concentration of 3.2X10(19) cm(-3), a Hall mobility of 150 cm(2) V-1 s(-1) and a Seebeck coefficient of 225 muV.K-1 after annealing. (C) 2001 Elsevier Science B.V. All rights reserved.