Electronic and Thermoelectric Properties of RuIn_{3-x}A_{x} (A = Sn, Zn)

TL;DR

This study combines density functional theory calculations with experimental data to understand and optimize the thermoelectric properties of RuIn_{3-x}A_{x} (A = Sn, Zn), achieving a high figure of merit (zT) of 0.8.

Contribution

It provides a detailed microscopic understanding of electronic structure changes due to substitution and demonstrates how to tune thermoelectric performance in RuIn_{3-x}A_{x} compounds.

Findings

Electronic structure changes in a rigid-band manner.

Calculated transport properties agree with experimental data.

Achieved a thermoelectric figure of merit zT of 0.8.

Abstract

Recently, we reported [M. Wagner et al., J. Mater. Res. 26, 1886 (2011)] transport measurements on the semiconducting intermetallic system RuIn3 and its substitution derivatives RuIn_{3-x}A_{x} (A = Sn, Zn). Higher values of the thermoelectric figure of merit (zT = 0.45) compared to the parent compound were achieved by chemical substitution. Here, using density functional theory based calculations, we report on the microscopic picture behind the measured phenomenon. We show in detail that the electronic structure of the substitution variants of the intermetallic system RuIn_{3-x}A_{x} (A = Sn, Zn) changes in a rigid-band like fashion. This behavior makes possible the fine tuning of the substitution concentration to take advantage of the sharp peak-like features in the density of states of the semiconducting parent compound. Trends in the transport properties calculated using the semi-classical Boltzmann transport equations within the constant scattering time approximation are in good agreement with the former experimental results for RuIn_{3-x}Sn_{x}. Based on the calculated thermopower for the p-doped systems, we reinvestigated the Zn-substituted derivative and obtained ZnO-free RuIn_{3-x}Zn_{x}. The new experimental results are consistent with the calculated trend in thermopower and yield large zT value of 0.8.