fig2
Figure 2. (A) Initial domain structure of 30 nm thick PZT thin film without surface charge and (B) its corresponding double-well total free energy. (C) Evolution of domain at different densities of positive and negative surface charges[47]. (D) Polarization of BFO switched from upward/downward to downward/upward after adsorption of four H and two OH radicals. (E) Density functional theory simulations showing displacement of Fe and O atoms along the Z-axis of the BFO surface with the adsorption of four H and two OH. (F) Scanning transmission electron microscopy images of BFO thin film, including the pristine state and the case of contact with Milli-Q water and an acidic solution[43]. (G) Variations of electrostatic potential difference as a function of armchair and zigzag strains in WSSe monolayer[20]. (H) Variations of electrostatic potential difference as a function of size for WSSe armchair nanotubes[55].
