Mechanical and piezoelectric analysis of ferroelectric domains in BFO thin films

Recent advances in thin-film engineering have led to the realization of BiFeO3 (BFO) epitaxial films, a new type of mixed-phase system driven by the substrate strain. [1] Under a strong compressive strain (>4%), the most stable crystalline structure can be transformed from the rhombohedrallike monoclinics (R) to tetragonal-like monoclinics (T). Additionally, the coexistence of Rand Tphase can be obtained in the same film with an appropriate strain relaxation through the film thickness. This mixed-phase system can provide a template to reveal the origins of physical properties in relaxor and morphotropic phase boundary materials, such as large piezoelectric response and enhanced ferroelectric polarization. [2] In this work, we present a study of the piezoelectric and mechanical properties of T-R mixed-phase stripes by means of piezoresponse and ultrasonic force microscopies (PFM, UFM).