Enhanced atomic ordering leads to high thermoelectric performance in AgSbTe₂

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Achieving high thermoelectric performance typically involves trade-offs between optimizing electronic structure and phonon scattering.
• Simultaneous optimization of electronic and phonon transport is crucial for advancing thermoelectric materials.
• Atomic disorder presents a challenge and an opportunity for thermoelectric material design.

Purpose of the Study:

• To develop innovative strategies for simultaneously optimizing electronic and phonon transports in thermoelectric materials.
• To investigate the effect of cadmium doping on atomic disorder in polycrystalline silver antimony telluride (AgSbTe2).
• To achieve high thermoelectric figure of merit (ZT) near room temperature and at elevated temperatures.

Main Methods:

• Systematic doping of polycrystalline silver antimony telluride (AgSbTe2) with cadmium.
• Characterization of atomic structure, electronic properties, and thermal conductivity.
• Analysis of nanoscale superstructure formation and localized vibrational modes.

Main Results:

• Cadmium doping in AgSbTe2 enhances cationic ordering and optimizes electronic properties by tuning disorder-induced localization.
• Achieved a thermoelectric figure of merit (ZT) of ~1.5 near room temperature and a maximum ZT of ~2.6 at 573 K.
• Reduced lattice thermal conductivity through spontaneous formation of nanoscale superstructures and coupling of soft vibrations.

Conclusions:

• Optimizing atomic disorder through cadmium doping is an effective strategy for enhancing thermoelectric performance in AgSbTe2.
• The demonstrated approach simultaneously improves electronic transport and reduces lattice thermal conductivity.
• This strategy holds promise for application in other thermoelectric materials with inherent atomic disorder.