Flexible thermoelectrics based on 3D interconnected magnetic nanowire networks
(2023)
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- Authors
- Supervisors
- Piraux, Luc
- Abstract
- Interconnected networks of magnetic nanowires are suitable architectures for the development of lightweight and flexible planar thermoelectric devices. These three-dimensional nanowire arrays are fabricated by electrodeposition inside nanoporous polymer films. This method offers great flexibility for the synthesis of homogeneous and multilayer nanowire networks of controlled morphology and composition. The interconnected structure provides excellent electrical connectivity on a large scale, while the polycarbonate membrane ensures the flexibility of the nanocomposite system. In these networks of interconnected nanowires, the electrical and thermal currents, which flow globally along the macroscopic dimensions of the film, circulate on a small scale along the axes of the wires. In multilayer systems such as ferromagnetic metal/copper, the currents flow perpendicular to the plane of the layers, a geometry that favors the observation of giant magneto-transport effects. Ferromagnetic nanowires have very high thermoelectric power factors, comparable to those obtained in bulk materials. Based on the spin-dependent Seebeck coefficients of ferromagnetic metals and alloys (mostly NiFe alloys) that we have determined experimentally, we have designed magnetic field-activated thermoelectric switches based on thermocouples formed from multilayer nanowires and homogeneous nanowires. In addition, the contributions to the thermoelectric power of Fe nanowires arising from diffusion and magnon-drag mechanisms were extracted from an in-depth study carried out on various dilute alloys. Finally, we produced thermocouples consisting of networks of interconnected Fe- and Co-based nanowires with promising properties for active cooling applications. The cooling of hot spots requires high thermoelectric power factors combined with high thermal conductivities, two properties found in ferromagnetic nanowires.
- Affiliations
Citations
Marchal, N. (2023). Flexible thermoelectrics based on 3D interconnected magnetic nanowire networks. https://hdl.handle.net/2078.5/99998