Semiconductor-metal transition powers high-efficiency MgAgSb thermoelectrics

Area of Science:

• Materials Science
• Solid State Physics
• Energy Conversion

Background:

• Semiconductor-to-metal transitions are typically avoided in thermoelectric materials due to performance concerns.
• MgAgSb exhibits an alpha-to-beta phase transition with potential for thermoelectric applications.

Purpose of the Study:

• To investigate the strategic exploitation of the alpha-to-beta semiconductor-to-metal transition in MgAgSb.
• To enhance thermoelectric output power and conversion efficiency through a novel material junction.

Main Methods:

• Fabrication of an alpha/beta-MgAgSb junction.
• Experimental and simulated measurements of thermoelectric performance (conversion efficiency, power density).
• Construction and testing of a two-pair thermoelectric module.

Main Results:

• The alpha/beta-MgAgSb junction demonstrated a 150% increase in output power due to reduced internal resistance.
• Achieved high maximum conversion efficiency (>10% simulated, 9% experimental) and power density (>1 W cm⁻² simulated, 0.9 W cm⁻² experimental).
• A thermoelectric module using alpha/beta-MgAgSb and n-type Mg₃Sb₀.₆Bi₁.₄ exhibited unprecedented power density.

Conclusions:

• The semiconductor-to-metal transition in MgAgSb can be strategically utilized to enhance thermoelectric performance.
• The alpha/beta-MgAgSb junction offers significant advantages for high-power thermoelectric applications.
• This work provides a new design strategy for high-performance thermoelectric materials and devices.