Electrical and Thermal transport studies of Sr and Mn co-substituted NdCoO3

TL;DR

This study explores how co-substituting Sr and Mn in NdCoO3 affects its thermoelectric properties, leading to improved figure of merit through enhanced Seebeck coefficient and reduced thermal conductivity.

Contribution

It demonstrates that Sr and Mn co-substitution can optimize thermoelectric performance of NdCoO3, achieving a higher figure of merit at elevated temperatures.

Findings

Co-substitution enhances Seebeck coefficient due to localization effects.

Thermal conductivity decreases with co-substitution, improving thermoelectric efficiency.

Achieved zT of approximately 0.038 at 540 K for optimized composition.

Abstract

Oxide thermoelectrics are exciting due to their chemical and thermal stability at high temperatures. However, the efficacy of these materials are limited by poor figure of merit (zT). In this study, the role of Sr and Mn co-substitution on the thermoelectric properties of NdCoO3 (Nd_{1-x}Sr_xCo_{1-y}Mn_yO_3; 0.00 \leq x \leq 0.10; 0.00 \leq y \leq 0.10) is investigated. The Seebeck coefficient decreases with single Sr substitution at Nd site; however, the Sr and Mn co-substitution enhances the Seebeck coefficient compared to single Sr substitution and is attributed to the localization effect. Sr substitution at La site creates hole in the system and results in enhanced electrical conductivity ({\sigma}); however, {\sigma} reduces with Mn substitution at Co site in NdCoO_3. A reduced thermal conductivity for the co-substituted samples is observed and attributed to decrease in phonon thermal conductivity. Simultaneous optimization of TE parameters results in improved zT \sim 0.038 for Nd_{0.95}Sr_{0.05}Co_{0.95}Mn_{0.05}O_3 at 540 K.