Tellurium Doping-Driven Material and Device Performance of Mg3(Sb0.3Bi0.7)2-Based Alloys

Area of Science:

• Materials Science
• Solid State Physics
• Energy Harvesting

Background:

• Mg3(Sb,Bi)2 alloys are promising n-type thermoelectric materials for waste heat recovery.
• Te-doped compositions require further investigation for device-level performance.

Purpose of the Study:

• To investigate the thermoelectric transport properties and single-leg device performance of Mg3(Sb0.3Bi0.7)2-xTex with varying Te doping levels (x = 0.007 and 0.03).
• To correlate material properties with device efficiency for optimized thermoelectric applications.

Main Methods:

• Systematic investigation of thermoelectric transport properties (Seebeck coefficient, electrical conductivity).
• Evaluation of single-leg device performance and efficiency (η).
• Application of the cumulative temperature dependency (CTD) model.

Main Results:

• Lightly doped (x=0.007) composition achieved a peak ZT of ~0.87 at 468 K with higher Seebeck coefficient.
• Heavily doped (x=0.03) composition achieved a peak ZT of ~0.96 at 590 K with higher electrical conductivity.
• The lightly doped device demonstrated a slightly higher efficiency (~7%) compared to the heavily doped device (~6.6%) at ΔT ≈ 267 K.

Conclusions:

• Device efficiency is influenced by average temperature-dependent transport properties within the operating temperature range.
• A device-oriented, composition-specific optimization strategy is crucial for Mg3(Sb,Bi)2-based thermoelectrics.
• Efficiency-driven design is paramount for practical thermoelectric energy harvesting.