Resistance pressing sintering: A simple, economical and practical technique and its application to p-type (Bi,Sb)2Te3 thermoelectric materials

Abstract

In the present work, starting from bismuth, antimony and tellurium granules, p-type (Bi,Sb)2Te3 alloys were successfully obtained via melt spinning (MS) combining with resistance pressing sintering (RPS) technique. The phase, microstructure and composition of the samples were evaluated by X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy during each step in the preparation process, respectively. The electrical resistivity, seebeck coefficient and thermal conductivity of the samples were measured in the temperature range of 323–473K. The effects of the substituting of antimony by bismuth on the thermoelectric properties of p-type (Bi,Sb)2Te3 alloys were analyzed in detail. The relative densities of the samples prepared by RPS technique were all more than 98%. The partially oriented lamellar structure could be observed at some local regions of the samples prepared by MS–RPS process and the monolayer thickness of the lamellar structure was smaller than that of the zone melting (ZM) sample. All evidences about electrical and thermal transport properties suggested that suitable decreasing Bi content could effectively improve the ZT value of (Bi,Sb)2Te3 alloys. The maximum ZT value of 1.17 was obtained for the Bi0.44Sb1.56Te3 alloys at 323K. Different from the conventional hot pressing and spark plasma sintering, the RPS method introduced in this paper was more suitable for industrial application due to its simplicity, economy and high yields.