Exceptional Rare-Earth Half-Heusler Thermoelectrics With Sublattice Softening

Area of Science:

• Materials Science
• Solid State Physics
• Condensed Matter Physics

Background:

• Half-Heusler (HH) compounds are recognized for their thermoelectric potential.
• High lattice thermal conductivity (κ_L) in conventional HHs impedes their efficiency.
• Exploring rare-earth (RE) containing HHs presents an opportunity to overcome this limitation.

Purpose of the Study:

• To investigate the impact of sublattice softening on thermoelectric properties in rare-earth containing Half-Heusler compounds.
• To identify novel RE-HH materials with intrinsically low κ_L and enhanced thermoelectric performance.
• To establish a structure-property relationship for optimizing RE-HH thermoelectrics.

Main Methods:

• Computational modeling and experimental synthesis of RE-HH compounds.
• Measurement of lattice thermal conductivity (κ_L) and thermoelectric figure of merit (zT).
• Analysis of lattice dynamics and phonon scattering mechanisms.

Main Results:

• Sublattice softening in RE-HHs leads to increased lattice anharmonicity and phonon damping, significantly reducing κ_L.
• Four RE-HH compounds (DyPtSb, Y_0.7Lu_0.3PtSb, Sc_0.6Lu_0.4PtSb, Dy_0.7Y_0.3PtSb) showed peak zT values over 1.0.
• Dy_0.7Y_0.3PtSb achieved a maximum zT of 1.33 at 875 K, demonstrating exceptional thermoelectric efficiency.

Conclusions:

• Sublattice-softened RE-HHs offer a promising pathway to intrinsically low κ_L and high thermoelectric performance.
• The findings highlight the potential for broad compositional tuning in RE-HH systems.
• This research advances the development of efficient thermoelectric materials for energy conversion applications.