Thermoelectrics. Dense dislocation arrays embedded in grain boundaries for high-performance bulk thermoelectrics

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Thermoelectric technology's widespread adoption is limited by the low conversion efficiency (zT) of bulk alloys.
• Improving zT requires reducing lattice thermal conductivity via phonon scattering, targeting low- and high-frequency phonons.

Purpose of the Study:

• To investigate the effect of dense dislocation arrays on phonon scattering in bismuth antimony telluride (Bi(0.5)Sb(1.5)Te3).
• To enhance the thermoelectric figure of merit (zT) by achieving full-spectrum phonon scattering with minimal charge-carrier scattering.

Main Methods:

• Fabrication of Bi(0.5)Sb(1.5)Te3 with dense dislocation arrays at low-energy grain boundaries using liquid-phase compaction.
• Evaluation of lattice thermal conductivity and thermoelectric figure of merit (zT) at various temperatures.
• Testing a thermoelectric cooler device utilizing the enhanced material.

Main Results:

• Dense dislocation arrays effectively scattered mid-frequency phonons, leading to substantially reduced lattice thermal conductivity.
• The thermoelectric figure of merit (zT) was significantly improved to 1.86 ± 0.15 at 320 K.
• A thermoelectric cooler achieved a maximum temperature difference of 81 K, surpassing commercial Peltier devices.

Conclusions:

• Full-spectrum phonon scattering achieved through engineered dislocation arrays is a viable strategy for enhancing thermoelectric performance.
• The developed Bi(0.5)Sb(1.5)Te3 material demonstrates superior thermoelectric properties suitable for advanced cooling applications.
• This research paves the way for more efficient thermoelectric devices with practical applications in cooling.