Dislocations are usually expected to degrade electrical, thermal and optical functionality and to tune mechanical properties of materials. Here, we demonstrate a general framework for the control of dislocation–domain wall interactions in ferroics, employing an imprinted dislocation network. Anisotropic dielectric and electromechanical properties are engineered in barium titanate crystals via well-controlled line-plane relationships, culminating in extraordinary and stable large-signal dielectric permittivity (≈23100) and piezoelectric coefficient (≈2470 pm V^–1). In contrast, a related increase in properties utilizing point-plane relation prompts a dramatic cyclic degradation. Observed dielectric and piezoelectric properties are rationalized using transmission electron microscopy and time- and cycle-dependent nuclear magnetic resonance paired with X-ray diffraction. Succinct mechanistic understanding is provided by phase-field simulations and driving force calculations of the described dislocation–domain wall interactions. Our 1D-2D defect approach offers a fertile ground for tailoring functionality in a wide range of functional material systems.

Depolarization in ferroelectric materials has been studied since the 1970s, albeit quasi-statically. The dynamics are described by the empirical Merz law, which gives the polarization switching time as a function of electric field, normalized to the so-called activation field. The Merz law has been used for decades; its origin as domain-wall depinning has recently been corroborated by molecular dynamics simulations. Here we experimentally investigate domain-wall depinning by measuring the dynamics of depolarization. We find that the boundary between thermodynamically stable and depolarizing regimes can be described by a single constant, P_r/ε₀ε_ferroE_c. Among different multidomain ferroelectric materials the values of coercive field, E_c, dielectric constant, ε_ferro, and remanent polarization, P_r, vary by orders of magnitude; the value for P_r/ε₀ε_ferroE_c however is comparable, about 15. Using this extracted universal value, we show that the depolarization field is similar to the activation field, which corresponds to the transition from creep to domain-wall flow.