Microstructural Manipulation for Enhanced Average Thermoelectric Performance: A Case Study of Tin Telluride.

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Tin telluride (SnTe) is a promising thermoelectric material due to its low cost and non-toxicity.
• Achieving a high figure of merit (ZT) in SnTe is critical for thermoelectric applications.
• Previous attempts to enhance SnTe properties by introducing planar defects faced challenges in quantity and controllability.

Purpose of the Study:

• To demonstrate the successful creation of dense planar cationic vacancies in Sb₂Te₃(Sn_1-xGe_xTe)₈ samples.
• To investigate the impact of these vacancies on the thermoelectric properties of SnTe-based materials.
• To optimize SnTe for high thermoelectric performance.

Main Methods:

• Electron microscopy and X-ray diffraction were used to characterize the material structure.
• First-principles calculations were employed to understand the electronic properties.
• Thermoelectric properties, including thermal conductivity and power factor, were measured.

Main Results:

• Dense planar cationic vacancies were successfully produced in Sb₂Te₃(Sn_1-xGe_xTe)₈ for the first time.
• A significant reduction in lattice thermal conductivity to ∼0.7 W m^-1 K^-1 was achieved.
• An enhanced power factor of ∼2.5 mW m^-1 K^-2 and a maximum figure of merit (ZT_max) of ∼1.3 were obtained at 723 K for x = 0.2.
• An excellent average ZT value (ZT_ave) of ∼0.78 was realized across a temperature range of 323-773 K.

Conclusions:

• The manipulation of planar cationic vacancies offers an effective strategy to enhance the thermoelectric performance of SnTe.
• The optimized Sb₂Te₃(Sn_0.8Ge_0.2Te)₈ exhibits competitive thermoelectric properties, making it suitable for practical applications.
• This study provides a novel approach for developing high-performance thermoelectric materials based on SnTe.