Thermoelectric properties of Bi2.2−xPbxSr2Co2Oy system

Abstract

Polycrystalline samples of Bi2.2−xPbxSr2Co2Oy (x=0, 0.4, and 0.8) with a layered structure have been prepared using a hot pressing technique and their thermoelectric properties methodically investigated. It is found that the substitution of Pb for Bi is a fairly effective means of improving the thermoelectric properties of the Bi2.2−xPbxSr2Co2Oy system owing to resistivity (ρ) decreasing and thermoelectric power (S) increasing simultaneously. The thermal conductivity (κ) at high temperature also decreases markedly with Pb substitution. As a result, for the x=0.8 sample the dimensionless figure of merit, ZT(=S2T/ρκ), increases with temperature and reaches 0.26 at 1000 K, which indicates that this material is a strong candidate as a high-temperature thermoelectric material.