Synergistic Approach Toward a Reproducible High zT in n-Type and p-Type Superionic Thermoelectric Ag₂Te.

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Superionic thermoelectrics offer ultralow thermal conductivity and high figure-of-merit (zT).
• Existing materials like Cu2X achieve high zT at temperatures causing degradation, limiting practical applications.
• Silver telluride (Ag2Te) exhibits complex thermoelectric behavior in its superionic phase.

Purpose of the Study:

• To synthesize and characterize superionic silver telluride (Ag2Te) for thermoelectric applications.
• To overcome reproducibility issues in Ag2Te thermoelectric properties.
• To enhance the figure-of-merit (zT) of Ag2Te beyond the phonon-liquid electron-crystal limit.

Main Methods:

• Synthesis of Ag2Te via various methods, including all-room-temperature fabrication for reproducibility.
• Hierarchical nanostructuring to suppress thermal conductivity.
• Measurement of thermoelectric properties (thermopower, electrical conductivity, thermal conductivity) and validation with first-principles density functional theory calculations.

Main Results:

• Achieved reproducible thermoelectric properties in Ag2Te using an all-room-temperature fabrication technique.
• Hierarchical nanostructuring significantly suppressed thermal conductivity.
• Obtained record zT values: 1.2 for n-type and 0.64 for p-type Ag2Te at 570 K, surpassing previous reports.
• Demonstrated high critical current density (>15 A cm-2) for metal-ion migration at 570 K.

Conclusions:

• Nanostructured Ag2Te exhibits significantly enhanced thermoelectric performance.
• The material demonstrates stability and potential for practical thermoelectric applications.
• First-principles calculations support the experimental findings on electronic and thermal properties.