Cu addition and its role in thermoelectric properties and nanostructuring in the series compounds (InSb)nCum

We have performed a comparative investigation of the series compounds (InSb)nCum to assess the roles of Cu addition on the thermoelectric properties and nanostructuring in bulk InSb. Detailed temperature dependent transport properties including electrical conductivity, the Seebeck coefficient, and thermal conductivity are presented. The Seebeck coefficients of In20Sb20Cu (m:n = 1:20) are increased by 13 percent in magnitude if compared to those of InSb, which is responsible for the 22 percent enhancement in the highest ZT value at 687 K. Although the magnitudes of κL are larger than those of InSb over the entire temperature range, a remarkable reduction in lattice thermal conductivities (κL) was observed with measuring temperature elevation. Such changes are mainly due to the precipitation of a large number of Cu9In4 nanoparticles with the size of smaller than 5 nm, dispersed in the matrix observed using high resolution transmission electron microscopy (HRTEM) images.

► We identified a large number of Cu9In4 nanoparticles dispersed in the compound (InSb)nCum (m:n = 1:20) with the size of smaller than 5 nm.
► This Cu9In4 nanoparticle improves the thermoelectric property through increasing the Seebeck coefficients, and enables the highest thermoelectric figure of merit (ZT) value of 0.39 to be obtained for the compound (InSb)nCum (m:n = 1:20), which is about 22 percent higher than that of the present intrinsic InSb (m:n = 0:1) at 687 K. However, the reduction in lattice thermal conductivity at high temperatures is of great significance.