Lessons from a thermoelectric transport trend study on half-Heusler alloys
ORAL
Abstract
The thermoelectric properties of the 4-9-15 (Ti,Zr,Hf)(Co,Rh,Ir)(As,Sb,Bi) and 4-10-14 (Ti,Zr,Hf)(Ni,Pd,Pt)(Ge,Sn,Pb) series
have been studied theoretically [J. App. Phys. 126, 145102 (2019)]. The electronic transport properties were calculated with density functional theory (DFT) and Boltzmann transport equations (BTE) at the hybrid functional level utilizing a recently developed k.p-based interpolation scheme [J. App. Phys 123, 205703 (2018)]. Phonon transport properties were calculated with the temperature-dependent effective potential (TDEP) method, including alloy and grain-boundary scattering.
Our trend study provides a number of key lessons:
1) Electronic band structures show much variation and there is, in particular, the potential for n-type Half Heusler with higher ZT.
2) The predicted thermoelectric properties are quite sensitive to the choice of exchange-correlation potential.
3) The thermal conductivity of a pure material is a poor indicator of the final thermal conductivity once other scattering mechanisms are included.
4) Sub-lattice alloying is generally more effective on the Z site than on the X site.
These findings provide valuable insights for more realistic high-thruput assessments of thermoelectric properties.
have been studied theoretically [J. App. Phys. 126, 145102 (2019)]. The electronic transport properties were calculated with density functional theory (DFT) and Boltzmann transport equations (BTE) at the hybrid functional level utilizing a recently developed k.p-based interpolation scheme [J. App. Phys 123, 205703 (2018)]. Phonon transport properties were calculated with the temperature-dependent effective potential (TDEP) method, including alloy and grain-boundary scattering.
Our trend study provides a number of key lessons:
1) Electronic band structures show much variation and there is, in particular, the potential for n-type Half Heusler with higher ZT.
2) The predicted thermoelectric properties are quite sensitive to the choice of exchange-correlation potential.
3) The thermal conductivity of a pure material is a poor indicator of the final thermal conductivity once other scattering mechanisms are included.
4) Sub-lattice alloying is generally more effective on the Z site than on the X site.
These findings provide valuable insights for more realistic high-thruput assessments of thermoelectric properties.
–
Presenters
-
Kristian Berland
Faculty of Science and Technology, Norwegian University of Life Sciencies, Centre for Material Sciences and Nanotechnology, University of Oslo
Authors
-
Kristian Berland
Faculty of Science and Technology, Norwegian University of Life Sciencies, Centre for Material Sciences and Nanotechnology, University of Oslo
-
Ole Martin Løvvik
SINTEF