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MM: Fachverband Metall- und Materialphysik

MM 24: Transport II: Thermal and Electrical Conductivity

MM 24.1: Talk

Tuesday, March 17, 2015, 11:45–12:00, H 0107

Thermal conductivity of half-Heusler thermoelectric materials from first principles — •Lars Bergqvist — Dept. of Materials and Nano Physics, KTH Royal Institute of Technology, Electrum 229, SE-164 40 Kista, Sweden — Swedish e-Science Research Centre (SeRC), KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden

Thermal conductivity and finite temperature phonon properties of half-Heusler thermoelectric materials are presented using large-scale ab-initio molecular dynamics simulations for calculation of interatomic force constants (IFC), including temperature and anharmonic effects, together with the full solution of the Boltzmann transport equation for phonons, as implemented in the newly developed Temperature Dependent anharmonic Effective Potential (TDEP) methodology.

Calculated lattice thermal conductivity, important for thermoelectric performance, show good agreement with experimental data. In particular, it is found that n-type ZrNiSn has lower conductivity than p-doped ZrCoSb, which can be analyzed in terms of the phonon lifetimes and broadening of the spectra from the dynamic structure factor at finite temperatures. Moreover, doping with Hf in ZrNiSn further reduces the thermal conductivity.