Tuning Interstitials in Fully Dense β-Zn₄Sb₃ Doubles Single-Leg Thermoelectric Efficiency

Area of Science:

• Materials Science
• Solid State Physics
• Green Energy

Background:

• Zinc antimonides (Zn₄Sb₃) are foundational thermoelectric materials.
• Their use in thermoelectric generators (TEGs) is limited by high-temperature structural instability.

Purpose of the Study:

• To enhance the stability and thermoelectric performance of Zn₄Sb₃.
• To investigate the effects of dilute aluminum (Al) doping on Zn₄Sb₃.

Main Methods:

• Synthesized Al-doped Zn₄Sb₃ (Al_xZn_4-xSb₃) with low Al concentrations.
• Characterized the structural stability and thermoelectric properties (zT, conversion efficiency η).
• Fabricated and tested single-leg TEG devices.

Main Results:

• Achieved a highly stable Al-Zn₄Sb₃ phase.
• Observed an improved peak figure of merit (zT) compared to undoped Zn₄Sb₃.
• Demonstrated a 3% conversion efficiency (η) at a 225 K temperature difference (ΔT) in a single-leg device, a ~200% increase over pristine material.

Conclusions:

• Dilute cationic doping with aluminum effectively stabilizes Zn₄Sb₃.
• Phase diagram engineering and doping enhance thermoelectric performance.
• Zn₄Sb₃ shows significant potential for efficient and sustainable green energy applications.