Mg-Defect Compensation to Realize High Performance at Room Temperature in Mg₃Bi₂-Based Thermoelectric Single...

Area of Science:

• Materials Science
• Solid State Physics
• Thermoelectrics

Background:

• Mg3Bi2-based materials show promise as alternatives to Bi2Te3 thermoelectric alloys.
• High-performance Mg3Bi2 single crystals are crucial for practical thermoelectric applications.
• Suppressing magnesium defects is key, but excessive Mg leads to undesirable secondary phases.

Purpose of the Study:

• To synthesize Mg3Bi2-based single crystals with suppressed Mg defects.
• To investigate the effect of lithium doping as an electron compensator.
• To improve the room-temperature thermoelectric performance of Mg3Bi2 materials.

Main Methods:

• Growth of bulk single crystals with a modified composition (e.g., Mg3.1Bi1.49Sb0.5Te0.01).
• Introduction of lithium as an electron dopant to compensate for Mg vacancies.
• Tuning of Li concentration to optimize electron concentration and thermoelectric properties.

Main Results:

• Successful growth of Mg3Bi2-based single crystals with low Mg content.
• Demonstration that low-concentration Li doping effectively compensates Mg defects.
• Observation that high-concentration Li doping leads to Mg substitution and reduced electron concentration.
• Achievement of a record-high figure of merit (zT) of 1.05 at 300 K for Mg3+xLixBi2-based compositions.

Conclusions:

• Lithium doping is a viable strategy to mitigate Mg defects in Mg3Bi2-based thermoelectrics.
• Optimized Li doping enhances room-temperature thermoelectric performance.
• The developed single crystals offer a promising pathway for efficient thermoelectric devices.