Defective metal oxides as the next generation of lead-free piezoelectrics for ultrasonic actuators

• Grant number: 22/09589-6
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2023
• End date: August 31, 2026
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Agreement: M-ERA.NET
• Principal Investigator: Daniel Zanetti de Florio
• Grantee: Daniel Zanetti de Florio
• Principal researcher abroad: Vincenzo Esposito
• Institution abroad: Technical University of Denmark (DTU), Denmark
• Host Institution: Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil
• Associated researchers: Andre Santarosa Ferlauto ; Fabio Coral Fonseca ; Marissol Rodrigues Felez
• Associated scholarship(s): 24/13678-0 - Defective metal oxides as the next generation of lead-free piezoelectrics for ultrasonic actuators, BP.TT

Abstract

Electromechanically active smart materials (piezoelectrics, relaxors and electrostrictors) change size and shape under electrical stimuli. They have many key applications in sensors, actuators, and transducers, ranging from ultrasound imaging to consumer electronics and biomedical implants with associated energy harvesting. These technologies are thus of great relevance and societal impact. Their use is expected to increase over the coming decade as part of biomimetic systems with self-diagnosis and self-repairing capabilities. Despite the futuristic applications being at the door, the best-performing electromechanical materials are an old technology: lead (Pb)-based piezoelectrics, which are highly toxic and pose a severe environmental threat.Recently, a new class of electroactive materials, "non-classical ionic electrostrictors", i.e., CeO2-based, have been discovered and developed (TRL3). In recent "Science" and "Nature" papers, the proponent and coworkers showed that the electromechanical properties of the materials are radically different from lead-based piezoelectric materials, with large and steady performances. Governed by a mostly unexplored atomistic mechanism, the origin of phenomena is electrodynamic ionic defects in their crystalline structures. The materials are also non-toxic, largely available and inexpensive. However, to transfer this unique mechanism into a practical application, electromechanical functionality must be formalised and quantified at high operating frequencies, especially in the ultrasonic range (kHz-MHz).This project proposes an innovative concept of electromechanical property tuning via artificially designing ionic defects as building blocks and exploring their properties over a wide range of applied frequencies from Hz to ultrasound (> 20 kHz). For this purpose, we will develop ionic electrostrictors based on alternative dopants and composites. Ionic defects in metal oxides have a high degree of tunability via doping. Synergetic effects can be achieved via modified defect chemistry, opening a new window for undiscovered properties to emerge. Furthermore, this new class of materials can be fabricated and shaped with facile ceramic processing methods in various devices and components from the macro to the nanoscale and in complex shapes, e.g. via 3D printing.The project has two primary success criteria:(1) Scientific: modeling the atomistic mechanism of ionic defects configurations on electrostrictive properties for low and high frequencies;(2)Technological: Optimising electromechanical properties at the ultrasound frequencies for bulk ceramics, thin films and complex shapes.As a proof of concept (TRL4-5), we will design environmentally sound lead-free and potentially biocompatible electromechanical multiscale systems, producing high strain (> 1%) and stress (> 500 MPa) in the ultrasound range (> 20 kHz). Such an outcome would significantly impact the European research society through industrial innovation and environmental sustainability, e.g., in ultrasonic imaging and the emerging miniaturised devices, e.g., lab-on-chip, fast adaptive lenses and ultrasonic manipulators. The consortium joins academic and industrial expertise, including chemistry, physics, materials science, ceramic processing, and device design. (AU)