Thermoelectric properties of (Bi0.25Sb0.75)(2)Te-3 alloys fabricated by hot-pressing method

Thermoelectric properties of the hot-pressed p-type (Bi0.25Sb0.75)(2)Te-3 a lloy were characterized with variation of the hot-pressing temperature and the starting powder size. The roles of the factors which affect the Seebeck coefficient of the hot-pressed (Bi0.25Sb0.75)(2)Te-3 alloy has been elucid ated in this study. The donor-like behavior of oxygen could be one of the p ossible explanations for the higher Seebeck coefficient of the hot-pressed (Bi0.25Sb0.75)(2)Te-3 alloy. Te vacancies formed by mechanical deformation during the powdering process significantly promote the diffusion of second phase Te atoms into their lattice sites so that the matrix Te solubility ap proaches its equilibrium value at a given temperature in a relatively short length of time. Using the Seebeck coefficient at various hot-pressing temp eratures, the micro-phase diagram near the stoichiometric composition of (B i0.25Sb0.75)(2)Te-3 was evaluated. (C) 2001 Kluwer Academic Publishers.