Glass-like phonon scattering from a spontaneous nanostructure in AgSbTe2

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Low thermal conductivity is crucial for thermoelectric and optical phase-change applications.
• Synthetic nanostructuring is a key strategy for reducing thermal conductivity via phonon scattering.
• Producing bulk nanostructured materials remains a significant challenge.

Purpose of the Study:

• To investigate the thermal conductivity properties of crystalline silver antimony telluride (AgSbTe2).
• To explore the role of self-forming nanostructures in suppressing thermal conductivity.
• To provide a microscopic understanding of thermal transport mechanisms in AgSbTe2.

Main Methods:

• Crystallographic analysis of AgSbTe2.
• Phonon mean free path mapping.
• Microscopic characterization of nanostructure formation and its impact on thermal transport.

Main Results:

• Crystalline AgSbTe2 exhibits spontaneously forming nanoscale domains.
• These nanostructures effectively scatter phonons, reducing thermal conductivity to a glass-like level.
• Intrinsic anisotropies in thermal conductivity are linked to the nanostructure.

Conclusions:

• Ground-state degeneracy in AgSbTe2 drives the formation of ordering domains and atomic displacements, scattering phonons.
• This self-assembly mechanism provides a novel bottom-up approach for nanoscale engineering of materials.
• The findings open new pathways for developing efficient thermoelectric converters and phase-change memory devices.