Characterization and thermoelectric properties of p-type 25%Bi2Te3-75% Sb2Te3 prepared via mechanical alloying and plasma activated sintering

In the present work, starting from elemental bismuth, antimony and tellurium powders, p-type 25%Bi2Te3-75%Sb2Te3 thermoelectric materials with high density were prepared by mechanical alloying (MA) and plasma activated sintering (PAS). The single phase 25%Bi2Te3-75%Sb2Te3 alloys were obtained after MA for 12 h. The effect of sintering temperatures on microstructure and thermoelectric properties of the as-PASed samples was researched. Highly compact samples with relative density over 99% could be obtained when sintering temperature was over 653 K. A preferentially orientated microstructure with the (I 10) plane parallel to and the basal planes (0 0 1) perpendicular to the pressing direction was formed, and the orientation factors of the (0 0 1) planes changed from 0.11 to 0.12 at different sintering temperatures. The maximum power factor and figures of merit (Z) at room temperature were 3.10 x 10(-3) W m(-1) K-2 and 2.85 x 10-3 K-1, respectively. The Vickers microhardness reached 112.7 Hv, which was twice that of the single crystal samples prepared by zone-melting.