Multiferroic bismuth ferrite-based materials for multifunctional applications: Ceramic bulks, thin films and nanostructures

Among the different types of multiferroic compounds, bismuth ferrite (BiFeO3; BFO) stands out because it is perhaps the only one being simultaneously magnetic and strongly ferroelectric at room temperature. Therefore, in the past decade or more, extensive research has been devoted to BFO-based materials in a variety of different forms, including ceramic bulks, thin films and nanostructures. Ceramic bulk BFO and their solid solutions with other oxide perovskite compounds show excellent ferroelectric and piezoelectric properties and are thus promising candidates for lead-free ferroelectric and piezoelectric devices. BFO thin films, on the other hand, exhibit versatile structures and many intriguing properties, particularly the robust ferroelectricity, the inherent magnetoelectric coupling, and the emerging photovoltaic effects. BFO-based nanostructures are of great interest owing to their size effect-induced structural modification and enhancement in various functional behaviors, such as magnetic and photocatalytic properties. Although to date several review papers on BFO and BFO-based materials have been published, they were each largely focused on one particular form of BFO. There have been very few papers addressing the different forms of BFO in a comprehensive manner and providing a comparison across the different forms. As BFO has been extensively studied over the past more than one decade especially in the past several years, there have been new phenomena arising more recently. Naturally they were not included in the early reviews. Here, we provide an updated comprehensive review on the progress of BFO-based materials made in the past fifteen years in the different forms of ceramic bulks, thin films and nanostructures, focusing on the pathways to modify different structures and to achieve enhanced physical properties and new functional behavior. We also prospect the future potential development for BFO-based materials in the cross disciplines and for multifunctional applications. We hope that this comprehensive review will serve as a timely updating and reference for researchers who are interested in further exploring bismuth ferrite-based materials.