Cascading nanodomainization of bulk tetragonal BaTiO3 triggered by mechanical stress of a few MPa

Ferroelectrics enable the interconversion of mechanical, electrical, and thermal energies via control of spontaneous polarization. Here, we report nanodomainization of millimeter-scale bulk ferroelectric crystals induced by a few MPa of mechanical stress, where a tetragonal BaTiO 3 single domain evolves into an aggregate of nanodomains several hundred nanometers in size. The process features striking morphological evolution, including the emergence of domain-wall-related contrasts cascading across the entire surface, while the final visual appearance closely resembles the original pristine state. Owing to this internal complexity, the dielectric responses are significantly altered upon mechanical loading. Notably, small variations in loading conditions give rise to different domain configurations that lead to distinct dielectric responses. This mechanical approach opens a deterministic pathway for engineering nanoscale domain structures and their associated emergent properties in bulk ferroelectrics.