Mahsa Sadat SAFAVI : "Investigation of thermoelectric properties of magnesium-based metal alloys coatings deposited by sputtering process"

PhD works of Mahsa Sadat SAFAVI : "Investigation of thermoelectric properties of magnesium-based metal alloys coatings deposited by sputtering process"

Abstract  : Thermoelectric materials have drawn global interest, according to their ability to convert directly thermal to electrical energy, thus providing a clean and renewable supply of energy. Mg2X (X = Si, Sn, Ge) and their solid solutions attract more attention due to their thermal stability, low cost, non-toxicity, constituent abundance in the earth’s crust, low density and their potential for providing both n and p-type conductions in a moderate temperature range of applications. Most of the studies focused on these materials are limited to n-type and as a bulk, while for developing a good thermoelectric generator both n- and p-type materials are required. Furthermore, thin film materials are required to reduce the size of current thermoelectric devices in order to address them in miniaturized applications like Micro Electro-Mechanical Systems and Internet of Things.
This thesis aims at developing and improving thermoelectric performances of p-type Mg-based by employing different strategies, including thin films synthesis, magnesium deficiency, doping, and solid solutions. In this work, thin films were deposited by magnetron sputtering and the role of chemical composition and structural modification on their electronic transport and thermoelectric properties were investigated. The influence of Cu-doping on stoichiometry and Mg-deficiency Mg2Sn thin films were studied as a strategy to enhance thermoelectric performances in the Mg2Sn system. Such thermoelectric performances of Mg2Si1-xSnx, were investigated as a function of the film composition and microstructure. The effect of Ge-doping on p-type Mg2Si0.35Sn0.65 was discussed in detail. Mg2Ge and Mg2Ge1-xSnx thin films were synthesized to explore the role of Ge substitution in electronic transport and thermoelectric properties of these compounds. Finally, the thermal stability of the films was studied after annealing in vacuum (10-4 Pa) at different temperatures from RT to 600°C.

Jury Composition : 

Nicolas MARTIN, Professeur des universités, Université Bourgogne - Franche-Comté, PhD Director

Nicole FRETY, Professeure des universités, Université de Montpellier, Montpellier, France, Reporter

Angélique BOUSQUET, Maître de conférences, Université Clermont Auvergne, Clermont-Ferrand, France, Reporter

Bertrand LENOIR, Professeur des universités, Université de Lorraine, Nancy, France, Reviewer

Corinne NOUVEAU, Maître de conférences, Arts et Métiers Sciences et Technologies, HESAM Université, Paris, France, Reviewer

Alain BILLARD, Professeur des universités, Université de Bourgogne Franche-Comté, UTBM, Montbéliard, France, Reviewer

Mohammad ARAB POUR YAZDI, Ingénieur de recherche ; Université de Bourgogne Franche-Comté, UTBM, Montbéliard, France, PhD CoDirector

Localization : 1 Cours Louis Leprince-Ringuet, 25200 Montbéliard - salle Amphi M101