Mr. Zhiheng Luo - M.Sc. Candidate
11/08/2024
אודיטוריום ע"ש דויד וואנג, בניין מידן, קומה 3
14:30 - Jerusalem time / 19:30 - Beijing time
Freestanding ferroelectric films offer many advantages over traditional substrate-attached thin films such as the enhanced spontaneous polarization and flexibility. Without constraints of the rigid substrate, folding of the freestanding film has been observed experimentally. It was also been found that the film may undergo a folding-unfolding transition under an external electric field, the resulting large electro-mechanical displacements from this transition can be exploited to make devices with superelastic behavior. In this work, a model to explain this folding behavior based on the competition between the elastic bending force of the thin film and the electrostatic force from the surface charges of the
periodic ferroelectric domains is developed. Experimentally observed temperature-dependent folding behavior is qualitatively explained with simulation results. With local curvature dependent surface charge intensity from phase-field method, observed evolution of the folding state under electron beam irradiation in TEM is also reproduced in the model. Hopefully, this model can be used in designing electro-mechanical devices based on the super-elastic folding behavior of the thin film.