High-Performance and Stable (Ag, Cd)-Containing ZnSb Thermoelectric Compounds

Area of Science:

• Materials Science
• Solid State Physics
• Energy Conversion

Background:

• Zinc-antimony (Zn-Sb) compounds like ZnSb and Zn4Sb3 are cost-effective, earth-abundant thermoelectric materials.
• Previous limitations included low thermoelectric figure-of-merit (zT) for ZnSb and poor thermodynamic stability for Zn4Sb3.
• Overcoming these challenges is crucial for practical waste heat harvesting applications.

Purpose of the Study:

• To simultaneously enhance the thermoelectric figure-of-merit (zT) and thermodynamic stability of Zn-Sb compounds.
• To investigate the effects of alloying cadmium (Cd) and doping silver (Ag) on ZnSb.
• To explore the potential of these modified compounds for efficient waste heat energy conversion.

Main Methods:

• Synthesis of (Ag, Cd)-containing ZnSb compounds.
• Measurement of lattice thermal conductivity, power factor, and thermoelectric figure-of-merit (zT).
• Evaluation of material stability through current stress tests under high current densities.

Main Results:

• Alloying Cd significantly reduced lattice thermal conductivity to 0.97 W K⁻¹ m⁻¹ at 300 K.
• Doping Ag enhanced the power factor to 17.7 μW cm⁻² K⁻² at 500 K and reduced bipolar thermal conductivity.
• A peak zT of 1.2 was achieved at 600 K for Zn0.698Ag0.002Cd0.3Sb, comparable to state-of-the-art Zn4Sb3 compounds.
• The modified ZnSb compounds exhibited excellent stability under electric fields, outperforming Zn4Sb3.

Conclusions:

• Simultaneous optimization of electrical and thermal transport properties was achieved in Ag- and Cd-modified ZnSb.
• The enhanced thermoelectric performance and stability of Zn0.698Ag0.002Cd0.3Sb pave the way for practical waste heat harvesting.
• This research accelerates the application of Zn-Sb-based materials in thermoelectric energy conversion.