Effect of interface resistance on thermoelectric properties in (1-x)La$_{0.95}$Sr$_{0.05}$Co$_{0.95}$Mn$_{0.05}$O$_3$/(x)WC composite

TL;DR

This study investigates how interface resistance and particle size affect phonon thermal conductivity and thermoelectric performance in a LaSrCoMnO3/WC composite, demonstrating improved figure of merit through interface engineering.

Contribution

It introduces a detailed analysis of interface thermal resistance effects on thermoelectric properties, linking R$_{int}$ and Kapitza radius using the Bruggeman model, and shows enhanced zT in the composite.

Findings

Increased WC volume fraction improves electrical conductivity.

Higher WC content decreases phonon thermal conductivity.

Maximum zT of 0.20 achieved at 463 K for x=0.010.

Abstract

In this study, the synergistic effect of the particle size of the dispersed phase and the interface thermal resistance (R$_{int}$) between the phases on the phonon thermal conductivity ($\kappa_{ph}$) of the (1-x)La$_{0.95}$Sr$_{0.05}$Co$_{0.95}$Mn$_{0.05}$O$_3$/(x)WC thermoelectric composite, is demonstrated. Further, the correlation between the R$_{int}$ and the Kapitza radius is discussed using the Bruggeman's asymmetrical model. In particular, the polycrystalline La$_{0.95}$Sr$_{0.05}$Co$_{0.95}$Mn$_{0.05}$O$_3$ sample is synthesized using a standard-solid state route. The presence of WC nanoparticle is confirmed from the electron microscopy images. Electrical conductivity ($\sigma$) increases, and the Seebeck coefficient ($\alpha$) decreases with the increase in conducting WC volume fraction in the composite. The simultaneous increase in $\sigma$ and a decrease in $\kappa_{ph}$ with the WC volume fraction results in an increased figure of merit (zT) for (1-x)La$_{0.95}$Sr$_{0.05}$Co$_{0.95}$Mn$_{0.05}$O$_3$/(x)WC composite. A maximum zT $\sim$ 0.20 is obtained for (1-x)La$_{0.95}$Sr$_{0.05}$Co$_{0.95}$Mn$_{0.05}$O$_3$/(x)WC composite for x=0.010 at 463 K. The results obtained in the present study shows promise to design thermoelectric composites with desired phonon thermal conductivity considering the elastic properties between the phases.