Achieving a High Average zT Value in Sb₂Te₃-Based Segmented Thermoelectric Materials

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Thermoelectric materials convert heat to electricity, crucial for waste heat recovery.
• Indium-antimony-telluride based materials show promise but require optimization for efficiency.
• Enhancing the figure of merit (zT) is key for practical thermoelectric applications.

Purpose of the Study:

• To improve the thermoelectric properties of In$_{0.15}$Sb$_{1.85}$Te$_{3}$ through manganese doping and nanotwin engineering.
• To develop a segmented thermoelectric leg for broad temperature range applications.
• To achieve high conversion efficiency for waste heat recovery.

Main Methods:

• Doping In$_{0.15}$Sb$_{1.85}$Te$_{3}$ with a small amount of manganese (Mn) to tune carrier concentration.
• Constructing nanotwins within the material to scatter phonons and reduce thermal conductivity.
• Fabricating a segmented thermoelectric leg by combining Mn-doped InSbTe with a previously reported low-temperature material (Mn$_{0.0075}$Bi$_{0.5}$Sb$_{1.4925}$Te$_{3}$) using nickel as a barrier layer.
• Employing a simple one-step sintering process for fabrication.

Main Results:

• The Mn$_{0.02}$In$_{0.15}$Sb$_{1.83}$Te$_{3}$ sample achieved a zT value of 1.0 at 673 K.
• The segmented leg exhibited an average zT value of 1.08 across a wide temperature range (303–673 K).
• An Ohmic contact interface was achieved, and the maximum theoretical conversion efficiency reached approximately 12.7% for a 370 K temperature difference.

Conclusions:

• Manganese doping and nanotwin engineering are effective strategies for enhancing the thermoelectric performance of InSbTe-based materials.
• The fabricated segmented thermoelectric leg demonstrates robust performance over a broad temperature range, suitable for medium-temperature applications.
• This work presents a promising approach for efficient waste heat recovery and thermoelectric power generation.