Development and applications of various BiFeO3 structures for fabrication of high-performing devices using industry-ready technologies

Abstract

Production of cleaner energy and the treatment of more and more toxic wastewater are probably the two main challenges humanity will face in the decades to come. Even though tremendous efforts are deployed to bring tangible answers to those problems, a lot of investigations are still needed to find optimal solutions. Among those, ceramic materials and more precisely oxide perovskite are of huge interest. Due to its singular crystalline structure, bismuth ferrite or BiFeO3 (BFO) is today one of the most studied oxide perovskites. In fact, BFO is a unique multiferroic material as it possesses both ferroelectric and ferromagnetic ordering within the same phase at room temperature. Some coupling effects between both orders have also been demonstrated and most of them are still under intense theoretical and experimental investigations. Despite such endeavors, commercial devices based on BFO are still scarce. The framework of this doctoral thesis aims to contribute to the advancement of devices based on bismuth ferrite. In particular, this thesis focuses on the development of BFO nanofibers and powders to fabricate high-performing devices. Following an extensive review of the literature about BFO, we first identify sun-based technologies such as photoelectrochemical water-splitting for production of cleaner energy and photocatalysis for better treatment of wastewater. Then, we fabricate devices using industry-ready technologies such as electrospinning and screen printing to facilitate the integration of BFO. As a result, we create various photocatalytic cells based on BFO nanofibers and particles involving smaller material quantities than previous literature reports. The fabrication methods also enable the syntheses of colloidal-free catalysts, which allow live and automated tracking of the pollutant concentration. This strategy holds great promises to bypass the need for catalyst collection of the treated leachate. For the second part of this thesis, we work toward the integration BFO powder as a highperforming thermistor for the printed circuit board technology. Using screen printing as a deposition method, we report highly reproducible and sensitive thermistors. By mixing and adjusting the graphene quantity added to the BFO powder, we enable room-temperature assessment. We also achieve the highest sensitivity reported for graphene-based printed thermistors for such a large range of operating temperatures. Overall, this thesis yields a favorable way to achieve high-performance devices based on various BFO structures using industry-ready technologies.

Date	5 Dec 2022
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Sylvain G. Cloutier (Supervisor)