PhD Thesis Proposal: Tao Fang

"Improving zT values in Fe2VAl thermoelectric material system"

Abstract

Fe2VAl system belongs to the thermoelectric (TE) materials, which can convert a thermal gradient to electricity or inversely convert electricity into a thermal gradient. Compared to other TE materials, like Bi2Te3 or Sb2Te3, Fe2VAl is a low-cost, earth abundant candidate. In our previous work, we improved the figure of merit zT to 0.75 in Fe2VAl system by n-type doping and water quench in fabrication process. We use density functional theory (DFT) calculation to explain the improvement of the zT value. These calculations include the cluster expansion, which reveals the existence of meta-stable states in room temperature. These calculations also include defect formation energy calculation, so Ge dopants will help to stabilize the L21* higher energy state. Inspired by heat capacity calculation, we explore the p-type, Al-rich Fe2VAl sample, which is expected to have a lower phase transition temperature and higher zT value. Preliminary experiments confirmed this hypothesis, but we still do not reach the peak value of the zT. Therefore, we need more study on p-type samples.

Thesis Committee

• Jifeng Liu (Chair)
• Ian Baker
• Geoffroy Hautier

Contact

For more information, contact Julia Abraham at julia.s.abraham@dartmouth.edu.