Fig. 1: Bending behavior of BFO membranes.
From: Enhanced polarization and abnormal flexural deformation in bent freestanding perovskite oxides
a Scanning electron microscope (SEM) image of wrinkled freestanding BFO. Scale bar: 1 μm. b Cross-sectional STEM-HAADF image of a single wrinkle in (a). Scale bar: 100 nm. Inset indicates the unstrained state taken from region 1 (marked by red square), where the spontaneous polarization has an upward out-of-plane component (yellow arrow). c–e STEM-HAADF images (left) taken from the bent regions 1, 2, 3 in (b), respectively. The strain gradients εxx,z are 5.2 × 106 m−1, 2.1 × 107 m−1, and 3.5 × 107 m−1, respectively. Middle STEM-iDPC images taken from yellow trapezoid regions show the position of Bi, Fe, and O atomic columns. The variation of lattice and oxygen octahedral from the internal (IS) to external surfaces (ES) can be conjected as shown in the right schematics. Scale bar: 2 nm. f–h Corresponding mapping results of in-plane and out-of-plane strain distributions in bent regions marked by yellow trapezoids in (c–e), respectively.
