Controllable Ferroelastic Switching in Epitaxial Self-Assembled Aurivillius Nanobricks

Layered perovskites with Aurivillius phase have drawn tremendous attention recently, owing to their high ferroelectric Curie temperatures, large spontaneous polarization, and fatigue-free and environment-friendly characteristics. Bi₂WO₆ is one of the simplest members in the Aurivillius family with superior ferroelastic and photo-electrochemical behaviors. The self-assembly fabrication of its nanoarchitectures and strategic modulation of their ferroelastic switching are crucial toward highly efficient nanoscale applications. In this work, Bi₂WO₆ nanobrick arrays were epitaxially grown along the orthorhombic direction in a self-assembled way. Such a nanoscale topology supports out-of-plane and in-plane vectors of ferroelectric polarizations, enabling a perpendicular voltage manipulation of these emerging ferroelectric/elastic domains. Combining the scanning probe technique and transmission electron microscopy, we confirmed the in-plane polarization vectors of 78.6 and 101.4° within the crystallographic axes of the nanobricks with respect to the (110) plane of the substrate. Thus, this work provides new opportunities for ferroelectric/elastic engineering in Bi₂WO₆ nanostructures for a wide range of applications, such as sensing, actuating, and catalysis.