Thermal Conductivity in Thermoelectric Materials

Abstract

Thermal conductivity is a key parameter in identifying and developing alternative materials for many technological and temperature-critical applications, ranging from higher-temperature capability thermal barrier coatings to materials for thermoelectric conversion. The Figure of Merit (ZT) of a thermoelectric material (TE) is a function of the Seebeck coefficient (S), the electrical conductivity (σ), the total thermal conductivity (κ) and the absolute temperature (T). A highly-performing TE material should have high S and σ and low κ. Thermal conductivity has two contributions, the electronic (κE) and the lattice (κL). Various models have been developed to describe the lattice component of thermal conductivity. In this chapter, the models for the evaluation of lattice thermal conductivity will be explored, both phenomenological as well analytical models, taking into account the various phonon-scattering processes, with examples of real materials.