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Spectroscopie d'impédance non linéaire appliquée aux matériaux et systèmes thermoélectriques

Abstract : This Phd work describes the study of the harmonic response of a thermoelectric system in order to extract the physical quantities associated with the thermoelectric coupling. The study of thermoelectric phenomena is of great interest both for the study of transport in materials as well as for applications in the field of energy recovery and temperature control. The amplitude of the response of the system in the harmonic regime allows extracting the different components of the response according to the associated time constants. This technique applied to thermoelectric systems makes it possible to extract several properties simultaneously thanks to an analytical model that we have developed to describe the response. In order to overcome the limitations of the linear electrical response obtained by impedance spectroscopy, we were interested in the nonlinear electrical response in the harmonic regime. The models we have developed take into account different sources of nonlinearities: the Joule effect, the non-linearity of the Peltier effect and the dependence of the properties of the system as a function of temperature. The study of the response as functions of frequency, on model systems such as thermocouples and Peltier modules, has allowed us to extract all the thermoelectric properties of the studied system. To extend this measurement to thin films, analogous to the setup traditionally used for 3w measurements of thermal conductivity. The developed micro device allows a 2w measurement of the Seebeck coefficient of the thin film. We then used this device to perform 2 and 3w measurements on various samples. Finally, we sought to extend the harmonic analysis for the study of coupled flow system other than the thermoelectric system. In particular, the coupling between the flow of magnons and the heat flux in a magnetic insulator gives rise to effects similar to conventional thermoelectric effects. We have therefore studied the response of a YIG/Pt system whose analysis has made it possible to extract a signal from the coupling of the heat flow and the flow of magnons paving the way for a new technique to study these systems.
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Submitted on : Monday, June 3, 2019 - 11:15:39 AM
Last modification on : Tuesday, September 29, 2020 - 4:43:09 AM


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  • HAL Id : tel-02145671, version 1


Etienne Thiebaut. Spectroscopie d'impédance non linéaire appliquée aux matériaux et systèmes thermoélectriques. Science des matériaux [cond-mat.mtrl-sci]. Université Paris Saclay (COmUE), 2019. Français. ⟨NNT : 2019SACLS074⟩. ⟨tel-02145671⟩



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