Phase interface engineering enables state-of-the-art half-Heusler thermoelectrics

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Phase interface engineering in thermoelectrics reduces thermal conductivity and enhances effective mass but often decreases carrier mobility.
• Single energy barriers are insufficient for effective low-energy carrier filtration across all temperatures.
• Existing methods struggle to decouple interrelated thermoelectric parameters.

Purpose of the Study:

• To address the limitations of traditional phase interface engineering in thermoelectric materials.
• To develop a novel composite phase interface strategy for improved thermoelectric performance.
• To decouple the interdependent thermoelectric parameters in ZrNiSn.

Main Methods:

• Utilized atomic layer deposition (ALD) to create a coherent dual-interface energy barrier.
• Engineered a composite phase interface on ZrNiSn-based thermoelectric material.
• Coated ZrNi1.03Sn0.99Sb0.01 with 40 cycles of TiO2.

Main Results:

• The engineered dual-interface barriers significantly enhanced the density-of-states effective mass across the entire temperature range.
• Carrier mobility was preserved, overcoming a key limitation of previous methods.
• Strong interface scattering of phonons effectively reduced lattice thermal conductivity.

Conclusions:

• The developed coherent composite-phase interface engineering strategy successfully decouples thermoelectric parameters.
• Achieved a record thermoelectric figure of merit (zT) of 1.3 at 873 K.
• This work provides a deeper understanding of composite interface engineering for advanced thermoelectric materials.