Defects are essential to engineering the properties of functional materials ranging from semiconductors and superconductors to ferroics. Whereas point defects have been widely exploited, dislocations are commonly viewed as problematic for functional materials and not as a microstructural tool. We developed a method for mechanically imprinting dislocation networks that favorably skew the domain structure in bulk ferroelectrics and thereby tame the large switching polarization and make it available for functional harvesting. The resulting microstructure yields a strong mechanical restoring force to revert electric field–induced domain wall displacement on the macroscopic level and high pinning force on the local level. This induces a giant increase of the dielectric and electromechanical response at intermediate electric fields in barium titanate [electric field–dependent permittivity (ε33) ≈ 5800 and large-signal piezoelectric coefficient (d33*) ≈ 1890 picometers/volt]. Dislocation-based anisotropy delivers a different suite of tools with which to tailor functional materials.

Dislocation-tuned functional properties such as electrical conductivity, thermal conductivity, and ferroelectric properties in oxides are attracting increasing research interest. A prerequisite for harvesting these functional properties in oxides requires successful introduction and control of dislocation density and arrangement without forming cracks, which is a great challenge due to their brittle nature. Here, we report a simple method to mechanically tailor the dislocation densities in single-crystal perovskite SrTiO 3 . By using a millimeter-sized Brinell indenter, dislocation densities from ∼10 10 to ∼10 13 m −2 are achieved by increasing the number of indenting cycles. Depending on tip radius and indenting load, large and crack-free plastic zones over hundreds of micrometers are created. The dislocation multiplication mechanisms are discussed, and the work hardening in the plastic zone is evaluated by micro-hardness measurement as a function of dislocation density. This simple approach opens many new opportunities in the area of dislocation-tuned functional and mechanical studies.

This work presents multilayer phase‐field simulation of selective sintering process and the calculation of effective mechanical properties and residual stress of the microstructure using the finite element method. The dependence of the effective properties and residual stress on the process parameters, such as beam power and scan speed, are analyzed. Significant partial melting of powders is observed for large beam power and low scan speed, which results in low porosity of the microstructure. Nonlinear relationship between the effective mechanical properties and process parameters is observed. The increasing rate of effective mechanical properties decreases with increasing beam power, while increases with decreasing scan speed. The dependence of effective Young's modulus and Poisson's ratio on porosity are well established using power law models. Stress concentrations are found at the necking region of powders and the intensity increases with the level of partial melting, which results in increasing residual stress in the microstructure. The numerical results reveal quantitatively the process‐microstructure‐property relation, which implies the feasibility of the subsequent data‐driven approach.

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The paper is focused on the influence of the morphology of barium strontium titanate (BST) thick-films on their effective dielectric properties. Therefore two BST thick-films are made with a minor deviation in sinter temperature, and hence their mean grain size of the films and their sintering necks. By modeling the meso-structure using a Nonlinear 3D Finite-Difference Time-Domain field solver, the assumed effect of the morphology on the effective dielectric properties are confirmed. The simulation results show the potential for a further improvement of the dielectric tunability of BST thick-films.