Tailoring Local-Global Structures via Hot Deformation for High-Performance BiSbSe₃ Thermoelectrics.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Improving thermoelectric (TE) materials often involves increasing carrier concentration (n), but this typically reduces carrier mobility (μ), creating a trade-off.
• Existing methods struggle to simultaneously optimize both n and μ, limiting the performance of high-performance TE materials like BiSbSe₃.
• A need exists for novel processing strategies to overcome the n-μ trade-off in TE materials.

Purpose of the Study:

• To synergistically optimize both carrier concentration (n) and carrier mobility (μ) in BiSbSe₃.
• To investigate the effects of combining composite engineering and hot deformation processing on the microstructure and thermoelectric properties of BiSbSe₃.
• To achieve a significant enhancement in the thermoelectric figure of merit (ZT) and mechanical properties.

Main Methods:

• Employed a synergistic approach integrating composite engineering (BiSbSe₃ + CuI + Cu) and hot deformation processing.
• Conducted microstructural analysis to study texture formation, recrystallization, secondary phase precipitation (CuSbSe₂), and atomic ordering.
• Measured thermoelectric properties, including electrical conductivity, power factor, lattice thermal conductivity, and Vickers hardness.

Main Results:

• The dual processing route induced significant microstructural evolution, including texture, dynamic recrystallization, Cu-rich phase precipitation, and enhanced short-range ordering.
• Optimized carrier concentration and tailored transport pathways led to substantially enhanced electrical conductivity and power factor.
• A multiscale phonon scattering network, formed by interstitial atoms, dislocations, and interfaces, effectively reduced lattice thermal conductivity.
• Achieved a peak ZT value of ~1.3 at 723 K, a significant increase from ~0.06 for pristine BiSbSe₃, surpassing previously reported values.
• Concurrent improvement in Vickers hardness was observed in the modified samples.

Conclusions:

• Hot deformation processing synergistically regulates thermoelectric properties by tailoring local-global structural modifications in BiSbSe₃.
• The combined strategy effectively overcomes the carrier concentration-mobility trade-off, leading to superior thermoelectric performance.
• This work provides a robust foundation for the commercialization of high-performance thermoelectric materials through advanced processing techniques.