MS Thesis Defense: Apoorva Joshi

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Meeting ID: 982 2415 5363
Passcode: 205696

"Thermal transport tuning via nanoscale hierarchical frameworks for Fe₂VAl  thermoelectric materials"

Abstract

Waste heat represents a vast, untapped energy resource. Thermoelectric materials offer a promising route to harvest this energy by directly converting thermal gradients into electricity. The Heusler alloy Fe₂VAl is a prime candidate for such applications because it is non-toxic and cost-effective. However, its intrinsically high thermal conductivity severely limits performance.  A detailed understanding of thermal transport mechanisms is therefore essential for improving its thermoelectric efficiency. This work examines the effect of atomic disorder on the thermal transport behaviour of Fe2VAl. We use germanium doping to introduce atomic-scale disorder and demonstrate a substantial reduction in thermal conductivity, from 28 W m^-1 K^-1 in undoped Fe2VAl to ~ 4 W m^-1 K^-1 in Ge-doped Fe₂VAl at 400 K. This reduction is attributed primarily to enhanced phonon scattering from antisites and vacancies, with additional contributions from lattice softening and electron-phonon interactions. To quantify these temperature-dependent mechanisms and connect macroscopic transport with atomic-scale structure, we combine low-temperature thermal conductivity measurements, differential scanning calorimetry, and inelastic neutron scattering. Ultimately, these findings map the role of disorder in tuning thermal conductivity and paving the way to optimize Fe₂VAl as a viable high-performance thermoelectric material. 

Thesis Committee

• Ian Baker (Chair)
• Jifeng Liu
• Will Scheideler

Contact

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