PhD Thesis Proposal: Russell Taylor

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Meeting ID: 929 0743 7304
Passcode: 209378

"Disorder engineering and carrier density tuning for high performance p-type Fe2VAl thermoelectric materials"

Abstract

Even while global electrification increases, the demand for fossil fuels is expected to remain high, and with over 60% of the energy lost as waste heat there is immense opportunity to improve system efficiency through energy harvesting with thermoelectric materials.

Fe2VAl is a promising ordered intermetallic compound that is an eco-friendly, low-cost, and easy-to-process potential replacement for the conventional low-temperature thermoelectric materials like Bi2Te3, which are brittle and use toxic and expensive elements. The disordered and metastable phases of Fe2VAl, of which we have developed a method to quantify, can enhance both thermal and electrical properties. Initial trials indicate phase composition can be optimized for favorable thermal properties with a Joule-heating and rapid quenching process, electro-pulse annealing.

A key factor in achieving desirable electrical properties is the carrier density, which can be challenging to measure in high-carrier density materials like Fe2VAl. Using a method we developed, we propose that we can tune carrier density to an optimal value where peak electrical performance is achieved, without sacrificing the thermal properties. Through a novel "compensation doping" strategy, we aim to introduce n-type doping into p-type materials to reach the targeted carrier densities. Our n-type alloy, Fe2VAl0.9Ge0.1, has achieved a record ZT of 1.2, with a high Seebeck coefficient enhanced by ferromagnetic phase stabilization. However, our best-performing and record p-type alloy, Fe2V0.7Al1.3, has only reached a ZT of ~0.25. By combining off-stoichiometric Al-rich compositions with Ge, we aim to achieve new record p-type efficiencies in compensation-doped Fe2V1-xAl1+x-yGey alloys by leveraging the best properties of both.

Proposed work: 1) efficiency improvement through carrier density tuning in Fe2V1-xAl1+x-yGey compensation-doped alloys, 2) optimization of thermal treatments to improve ZT through electro-pulse annealing, and 3) validation of performance within a thermoelectric generator.

Thesis Committee

• Ian Baker (Chair)
• Jifeng Liu (co-advisor, project lead)
• Yan Li
• Geoffroy Hautier (external)

Contact

For more information, contact Thayer Registrar at thayer.registrar@dartmouth.edu.