Dislocation Introduction via Domain Engineering in Mg₂Sn Single Crystal to Improve its Thermoelectric Properties

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Dislocations are crucial for enhancing thermoelectric properties by scattering phonons more than charge carriers.
• Optimizing thermoelectric materials requires decoupling carrier and phonon transport to improve efficiency.

Purpose of the Study:

• To achieve low lattice thermal conductivity and high power factor in n-type and p-type Mg₂Sn single crystals.
• To explore the combined effects of domain engineering and point defect control on thermoelectric properties.

Main Methods:

• Introduction of dislocation cores via domain engineering in Mg₂Sn single crystals.
• Generation of magnesium vacancies (V_Mg) through controlled point defect manipulation.
• Analysis of carrier transport and phonon scattering at interfaces and within domains.

Main Results:

• Ordered V_Mg domains facilitated efficient carrier transport with minimal scattering.
• High dislocation density at interfaces effectively scattered phonons, decoupling carrier-phonon transport.
• Achieved peak thermoelectric figure of merit (zT) values of 0.83(8) for n-type and 0.42(4) for p-type Mg₂Sn single crystals.

Conclusions:

• The combination of domain engineering and point defect control is a viable strategy for high-performance thermoelectric materials.
• Decoupling carrier and phonon transport through engineered microstructures is key to enhancing thermoelectric efficiency.