Thermoelectric Properties of (1-x)LaCoO$_{3.x}$La$_{0.7}$Sr$_{0.3}$MnO$_3$ Composite

TL;DR

This study investigates the thermoelectric properties of LaCoO3 and La0.7Sr0.3MnO3 composites, showing improved Seebeck coefficient and figure of merit at high temperatures, indicating potential for enhanced thermoelectric materials.

Contribution

It introduces a composite approach to enhance thermoelectric performance of LaCoO3-based materials at elevated temperatures.

Findings

Maximum ZT of 0.09 at 620 K for 5% La0.7Sr0.3MnO3 composite

Seebeck coefficient improves with LSMO addition at high temperatures

Electrical conductivity decreases due to reduced carrier concentration

Abstract

We report the thermoelectric (TE) properties of (1-x)LaCoO3.xLa0.7Sr0.3MnO3 (0 < x < 0.10) composite in a temperature range 320-800 K. Addition of La0.7Sr0.3MnO3 to LaCoO3 in small amount (5 weight %) improves the overall Seebeck coefficient ({\alpha}) at higher temperatures. The electrical conductivity, however, decreases due to a decrease in carrier concentration of the composite. The decrease in electrical conductivity of the composite at high temperature may be attributed to the insulating nature of the LSMO above room temperature. Thermal conductivity (\k{appa}) of all the samples increases with an increase in the temperature but decreases with increasing LSMO content. We also report the local variation of the Seebeck coefficient across the composite samples measured using a precision Seebeck measurement system. A maximum value of 0.09 for the figure of merit (ZT) is obtained for 0.95LaCoO3.0.05La0.7Sr0.3MnO3 at 620 K which is significantly higher than the ZT of either of LaCoO3 or La0.7Sr0.3MnO3 at 620 K. This suggests the potential for enhancement of operating temperatures of hitherto well known low-temperature thermoelectric materials through suitable compositing approach.