Honoring Guillaume Nataf
The performance of all these devices could be considerably improved if they were combined with thermal switches and diodes.
My aim is to investigate a fundamentally new mechanism for designing compact and efficient thermal switches and diodes.
My strategy exploits, in ferroelectric oxides, the interactions between heat-conducting phonons and spontaneous planar defects called domain walls. These domain walls are easily created, moved and oriented by the application of a voltage, and scatter phonons.
They are therefore perfect interfaces for rapidly and reversibly obtaining large variations in thermal conductivity in controlled directions. These thermal switches and diodes will be compatible with a wide range of devices, and will have an impact in many areas critical to our transition to a sustainable future.
Guillaume Nataf completed a PhD in cotutelle between the University of Paris-Saclay (CEA Saclay) and the University of Luxembourg (Luxembourg Institute of Science and Technology), where he developed new approaches to studying the specific properties of domain walls in ferroic materials.
He then spent 4 years in England, at Cambridge University, for a post-doctorate, where he obtained funding from the Royal Commission for the Exhibition of 1851 and Wolfson College, to study alternatives to the fluids currently used in cooling systems.
A winner of the CNRS 2020 competition, since 2021 he has been a CNRS research fellow at the GREMAN laboratory (a joint research unit under the supervision of CNRS, the University of Tours, and INSA Centre-Val de Loire), where he is continuing his research into functional oxides and their spontaneous nano-structuring, with a view in particular to developing innovative thermal devices for energy efficiency.
A thermal switch. When the density of domains (brown and blue rectangles), and therefore of domain walls, is high, thermal conductivity is low. When the density of domains is reduced by applying an electrical voltage (V), thermal conductivity is high.
