Thermal Conductivity, Thermopower, and Figure of Merit of La_{1-x}Sr_xCoO_3

TL;DR

This study investigates the thermal and thermoelectric properties of La_{1-x}Sr_xCoO_3 single crystals, revealing low thermal conductivity, doping-dependent thermopower, and promising thermoelectric figure of merit for certain compositions.

Contribution

It provides new insights into the spin-state transitions' effects on thermoelectric properties and identifies La_{1-x}Sr_xCoO_3 as a potential thermoelectric material.

Findings

Low thermal conductivity across all Sr concentrations

Strong variation of thermopower with doping

High thermoelectric figure of merit at intermediate doping levels

Abstract

We present a study of the thermal conductivity k and the thermopower S of single crystals of La_{1-x}Sr_xCoO_3 with 0<= x <= 0.3. For all Sr concentrations La_{1-x}Sr_xCoO_3 has rather low k values, whereas S strongly changes as a function of x. We discuss the influence of the temperature- and the doping-induced spin-state transitions of the Co ions on both, S and k. From S, k, and the electrical resistivity rho we derive the thermoelectric figure of merit Z=S^2/(k*rho). For intermediate Sr concentrations we find notably large values of Z indicating that Co-based materials could be promising candidates for thermoelectric cooling.