Neutron scattering

Electron mobility

Semiconductor

Optics

Physics

Composite material

Ionized impurity scattering

Scattering

Materials science

Thermoelectric materials

Phonon

Condensed matter physics

Optoelectronics

Doping

Thermoelectric effect

Phonon scattering

Thermal conductivity

Thermodynamics

Nature Communications

Chemical doping is one of the most important strategies for tuning electrical properties of semiconductors, particularly thermoelectric materials. Generally, the main role of chemical doping lies in optimizing the carrier concentration, but there can potentially be other important effects. Here, we show that chemical doping plays multiple roles for both electron and phonon transport properties in half-Heusler thermoelectric materials. With ZrNiSn-based half-Heusler materials as an example, we use high-quality single and polycrystalline crystals, various probes, including electrical transport measurements, inelastic neutron scattering measurement, and first-principles calculations, to investigate the underlying electron-phonon interaction. We find that chemical doping brings strong screening effects to ionized impurities, grain boundary, and polar optical phonon scattering, but has negligible influence on lattice thermal conductivity. Furthermore, it is possible to establish a carrier scattering phase diagram, which can be used to select reasonable strategies for optimization of the thermoelectric performance.

Establishing the carrier scattering phase diagram for ZrNiSn-based half-Heusler thermoelectric materials