Effect of Interface Thermal Resistance on Thermoelectric Properties of Acoustically Mismatched Composite

Composite materials can be promising to decouple electron and phonon transport for improved thermoelectric properties. Herein, 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 (κ 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. The embedded WC, owing to its high electrical conductivity (σ), does improve σ of the composite. A high acoustic impedance mismatch between the phases results in a large R int and lowers κ ph . Change in κ ph is further explained using theoretical analysis of Bruggeman asymmetrical model. The correlation between the R int and Kapitza radius is discussed to analyze the reduced κ ph . Synergistic effect of improved σ and lowered κ ph result in improved thermoelectric figure of merit (zT) of 0.20 at 463 K for (1- x )La 0.95 Sr 0.05 Co 0.95 Mn 0.05 O 3 /(x)WC composite. This study shows promise to design thermoelectric composites with the desired phonon thermal conductivity considering the elastic properties between the phases