High-Performance p-Type Bi₂Te₃-Based Thermoelectric Materials Enabled via Regulating Bi-Te Ratio.

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Bismuth telluride (Bi₂Te₃)-based alloys are the only commercially available thermoelectric materials.
• Existing Bi₂Te₃ alloys suffer from low thermoelectric efficiency, poor mechanical properties, and high costs, hindering large-scale applications.
• There is a critical need for advanced thermoelectric materials with improved performance and durability.

Purpose of the Study:

• To develop high-performance p-type Bi₂Te₃-based thermoelectric materials.
• To enhance both thermoelectric efficiency and mechanical properties for practical applications.
• To investigate processing methods that improve carrier and phonon transport.

Main Methods:

• Preparation of p-type Bi₂Te₃-based materials using ball milling and hot pressing techniques.
• Optimization of alloy composition, specifically Bi_0.55Sb_1.45Te₃ + 2.5 wt % Bi.
• Characterization of thermoelectric properties (figure of merit, zT) and mechanical properties (Vickers hardness, compressive strength).

Main Results:

• The optimized p-type Bi_0.55Sb_1.45Te₃ + 2.5 wt % Bi achieved a peak thermoelectric figure of merit (zT) of 1.45 at 360 K.
• An average zT value of 1.24 was recorded over the temperature range of 300-480 K, comparable to state-of-the-art Bi₂Te₃ alloys.
• Significantly improved mechanical properties were observed, with Vickers hardness reaching 0.95 GPa and compressive strength up to 94.6 MPa.
• Enhanced electrical conductivity and reduced lattice thermal conductivity were attributed to optimized carrier and phonon transport.

Conclusions:

• The ball milling and hot pressing method successfully produced Bi₂Te₃-based materials with competitive thermoelectric and mechanical performance.
• The achieved properties demonstrate the potential for enhanced industrial applications of bismuth telluride alloys.
• This work provides valuable insights for researchers focused on improving Bi₂Te₃-based materials for thermoelectric devices.