Giacomo Clementi : "LiNbO3 films: integration for piezoelectric and pyroelectric energy harvesting"

PhD works of Giacomo Clemeni : "LiNbO3 films: integration for piezoelectric and pyroelectric energy harvesting"

A videoconference solution will be offered for attendance, more information to come about this.

Abstract : This thesis is a part of the Marie Sklodowska-Curie Innovative Training Network (ITN) ENHANCE project (Piezoelectric EnergyHarvesters for Self-Powered Automotive Sensors: from Advanced Lead-Free Materials to Smart Systems), which is related to energy harvesting for automotive applications, specifically for vibrational and thermal harvesting for self-powered sensors. In this thesis, we investigated lead-free LiNbO3 piezoelectric material as transducer for energy harvesting applications, with special focus regarding its optimized material properties and electronic interface. We explored all the possible routes of micro-fabrication for LiNbO3 films, with top-down or bottom-up approaches, in order to achieve high quality LiNbO3 films. We presented both PIMOCVD films which can be grown textured on silicon substrates, and thick films from single crystal LiNbO3 Au-Au bonded to silicon or metal. We optimized the coupling and electro-mechanical properties of the LiNbO3 transducers by finite element simulations and orientation study. Finally, we attained a normalized power density of 371.2μW.cm^-3.g^-2.Hz^-1 by using the proposed composite structure vibrating at resonance frequency, that is among best values even compared to lead-based (and other lead-free) materials commercially available. Furthermore, we fulfilled the objective to provide rectified output voltage in 1-3 V range from Pb-free harvesters, achieving for systems of compact dimensions (< 1 cm^3), a piezoelectric figure of merit of 26.6 GJ/m^3 with considerable mechanical quality factor (> 100), and operational frequencies in the range of 10-500 Hz available in vehicles.

Jury Composition:

Alper Erturk, Professeur des Universités, GeorgiaTech, Reporter

Elie Lefeuvre, Professeur des Universités, Paris-Saclay, Reporter

Francesco Cottone, Maître de Conférences des Universités, UniPg, Reviewer

Paul Muralt, Professeur Emeritus, EPFL, Reviewer

Mickaël Lallart, Professeur des Universités, INSA Lyon, Invitee

Roberto La Rosa, Directeur de recherche, ST-Microelectronics, Invitee

M.me Ausrine Bartasyte, Professeure des Universités, UBFC, PhD Director

Bernard Dulmet, Professeur Emeritus, ENSMM, PhD Co-Director

Samuel Margueron, Professeur des Universités, ENSMM, PhD Co-Director

Localization : Amphithéâtre Émilie du Châtelet, ENSMM, 26 Rue de l'Épitaphe, Besançon