Thermal conductivity of ordered-disordered material: a case study of superionic Ag2Te

Area of Science:

• Materials Science
• Condensed Matter Physics
• Energy Science

Background:

• Thermoelectric devices convert waste heat to electricity, crucial for growing energy demands.
• The 'phonon-glass electron-crystal' (PGEC) concept guides the search for high-efficiency thermoelectric materials.
• Ordered-disordered materials represent a promising avenue for advanced thermoelectric performance.

Purpose of the Study:

• To comprehensively investigate the thermal transport properties and underlying mechanisms of superionic silver telluride (α-Ag2Te).
• To explore the potential of α-Ag2Te as a high-performance thermoelectric material within the PGEC framework.
• To elucidate the role of sublattice vibrations and ion diffusion in thermal conductivity.

Main Methods:

• Equilibrium molecular dynamic simulations were employed to study thermal transport in α-Ag2Te.
• Analysis of contributions to thermal conductivity from different sublattices and ion interactions.
• Investigation of the effects of external stimuli like compressive strain and carrier concentration modulation.

Main Results:

• α-Ag2Te exhibits intrinsically very low thermal conductivity.
• The Te(2-) sublattice vibrations are the primary contributors to thermal transport.
• Collisions between diffusing Ag(+) ions and the Te(2-) sublattice significantly reduce thermal conductivity.

Conclusions:

• Atomistic simulations reveal that Te(2-) sublattice vibration and Ag(+) ion diffusion govern thermal transport in α-Ag2Te.
• Compressive strain and stoichiometric modulation can further reduce thermal conductivity.
• Findings provide guidance for optimizing thermoelectric performance in superionic conductors.