Fig. 3: Phase field model simulation on the effect of mechanical stress and electron beam.
a In-plane strain (εx) distribution and (b) in-plane ferroelectric polarization (Px) mapping in the BTO slab calculated by the phase field model simulation. White arrows indicate the polarization directions. As tensile stress was applied in the BTO slab, the tensile strain and the in-plane domain density increased. The ferroelectric polarizations then switched to out-of-plane directions under surface electrical charging and it caused strain profile go back to the initial state, which can be seen in (c) in-plane strain profile of the top of the BTO slab. d Proposed cyclic behavior of the superelastic and shape-memory responses with schematic representation of the corresponding ferroelectric domain switching. The blue grids represent in-plane domains, and the red grids represent out-of-plane domains. ρ, σ, and ε indicate surface charge density, stress, and strain, respectively.
