Yan Zong

Year

2018

Degree Name

Doctor of Philosophy

Department

Australian Institute for Innovative Materials

Abstract

For the modern electronic industry, miniaturized, multifunctional, low-cost and easily processable materials are always desired to meet the requirements of integrated devices. For many decades, magnetoelectric (ME) composites that allow magnetic-to-electrical signal conversion have been highly attractive for applications, including sensing, actuating, memory and energy harvesting devices. In these ME materials, such as ceramic composites BaTiO3/Fe3O4 and lead zirconate titanate (PZT)/NiFe2O4, the magnetic-to-electrical conversion is not an intrinsic property of the ME materials but is essentially due to the strain coupling between a piezoelectric (PE) and magnetostrictive (MS) materials. Most significantly, the strain-mediated output voltage of ME composites can be generated at room temperature and is an order of magnitude higher than previously studied single-phase ME crystals, e.g. Cr2O3. Thus, ME composites are considered to be suitable for practical use in electronic applications. Since PE polymers such as poly(vinylidene difluoride) (PVDF) were first introduced into ME composites in 2002, the polymer-based ME composites enabled more flexible and lighter weight candidates to replace the fragile, heavy and toxic ME ceramic composites. Polymer-based ME composites are now proving to be potential candidates in the development of portable, flexible and stretchable electronic devices.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.