Influence of a compressive strain on the high-temperature thermoelectric properties of europium orthoferrite

Abstract

Promising high temperature thermoelectric (TE) potential of europium orthoferrite (EuFeO3) is methodically investigated in this work, wherein the focus is on the influence of a −3% compressive strain on scattering rates and on transport properties. Using Boltzmann transport theory, transport properties such as Seebeck coefficient S, electrical conductivity σ, electronic thermal conductivity κ e and power factor (PF) are obtained with appropriate regard to the prevailing scattering mechanisms present in the materials that affect its electronic transport. Here, we find that polar optical phonon (POP) scattering is the dominant scattering potential affecting the TE properties of EuFeO3 for temperatures from 900 K to 1500 K. The incorporation of a −3% compressive strain suppresses the POP scattering, as evidenced by the decrease in its scattering rates. This result consequently enhances the lattice thermal conductivity κ L—which then has negative impact to the TE efficiency. Nevertheless, we find that the strain largely improves the σ of EuFeO3, and the PF as well. Unstrained p-type EuFeO3 registers remarkable values of PF equal to 167 μW m−1 K−2 at 900 K and 97.7 μW m−1K−2 at 1500 K for when the hole concentration is 1021 cm−3. Under a −3% compressive strain, the PF rises to almost double at 294 μW m−1 K−2 for 900 K and 170 μW m−1 K−2 for 1500 K for the same doping value. Finally, we believe that the methodology and discussions presented in this work well deliver a template relevant in modeling materials fit for high-temperature TE applications.