Preparation and Properties of p-Type (Bi<SUB>2</SUB>Te<SUB>3</SUB>)<I><SUB>x</SUB></I>(Sb<SUB>2</SUB>Te<SUB>3</SUB>)<SUB>1−<I>x</I></SUB> Thermoelectric Materials

Abstract

P-type (Bi2Te3)x(Sb2Te3)1� x thermoelectric materials with various chemical compositions (x ¼ 0:16, 0.20 and 0.24) were fabricated through the zone melting (ZM) method and spark plasma sintering (SPS) technique. The dimensionless figure of merit (ZT ¼ � 2 � T=� ) of the zone-melted crystals increased with increasing the Bi2Te3 content (x). Compared to those of the zone-melted crystals with the same chemical composition, further enhancement by 108–115% in the ZT values was obtained through a combination of ZM and SPS techniques. As a result, the optimal figure of merit reached 1.22 at about 350 K for the composition of 24%Bi2Te3–76%Sb2Te3 with 3 mass% excess Te. The bending strength of the sintered materials was about 65 MPa, which was 5–7 times higher than that of the zone-melted crystals.