Superelastic NiTi Thin Layer Triggering High-Performance and High-Durability Thermoelectric Devices.

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Thermoelectric devices (TEDs) face durability challenges due to operational stresses.
• Enhancing the lifespan and performance of Bi2Te3-based TEDs is crucial for practical applications.

Purpose of the Study:

• To develop a NiTi thin film as a barrier layer for improving the durability of Bi2Te3-based TEDs.
• To investigate the structural and mechanical properties of NiTi/Bi2Te3 interfaces.
• To evaluate the performance and long-term stability of the modified TEDs.

Main Methods:

• Sputtering deposition of NiTi thin films on Bi2Te3.
• Atomic-resolution microscopy for structural analysis (e.g., TEM, HRTEM).
• Mechanical testing to assess superelasticity and strain recovery.
• Performance testing of TEDs under pulsed current aging cycles.

Main Results:

• NiTi barrier layers exhibit coexistence of B2 austenite and B19' martensitic phases.
• NiTi/Bi2Te3 joints demonstrate excellent superelasticity and strain recovery.
• Equimolar NiTi barrier layers show highest efficiency (ηe=52.1%) and durability (ηd=59.3%).
• NiTi/Bi2Te3 TEDs achieve a high cooling power density (3.55 W·cm⁻²).
• NiTi/Bi2Te3 devices show significantly enhanced durability, with half the decay in cooling temperature difference after 10,000 cycles compared to Ni/Bi2Te3 devices.

Conclusions:

• Superelastic NiTi barrier layers act as effective stress buffers, enhancing TED durability.
• The NiTi/Bi2Te3 interface engineering provides a pathway for high-performance and robust TEDs.
• This approach offers a promising strategy for overcoming the operational limitations of thermoelectric cooling technology.