Preparation and Properties of p-Type (Bi₂Te₃)_x(Sb₂Te₃)_1−x Thermoelectric Materials

Abstract

P-type (Bi₂Te₃)_x(Sb₂Te₃)_1−x thermoelectric materials with various chemical compositions (x=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=α²σT⁄κ) 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.