Investigation of Dislocation-Controlled Domain Nucleation and Domain-Wall Pinning in Single-Crystal BaTiO₃ by Multi-Stimuli MEMS-Based In Situ TEM

Engineering domain walls at the nanoscale to influence macroscopic functional properties presents significant potential in electromechanics and electronics. This potential is particularly apparent in introducing topological defects into functional materials, highlighting the broad possibilities in this area. However, our comprehensive understanding of defect-mediated domain nucleation and domain wall mobility remains limited.<br/><br/>In this work, we achieved well-aligned dislocations with {100}&lt;100&gt; slip systems oriented in the [001] out-of-plane direction in single-crystal BaTiO₃. This was accomplished through high-temperature uniaxial compression on a notched sample. Utilizing MEMS-based <i>in situ</i> heating and cryo scanning/transmission electron microscopy (S/TEM), we were able to observe the dislocation-mediated domain nucleation and dynamic interactions between domain walls and these topological defects. These observations spanned a wide temperature range, from -175 °C to 200 °C, covering all phases of BaTiO₃ from rhombohedral to cubic, offering high-resolution insights into the electro-mechanical interactions within this ferroelectric material. Furthermore, we explore the direct manipulation of the domain wall motion using <i>in situ</i> biasing TEM. Under various stimuli, we observed the pinning of ferroelastic domain walls by these imprinted dislocations, attributed to the stress fields from the dislocations.<br/><br/>Our findings not only deepen the understanding of domain wall engineering in ferroelectric materials but also introduce a novel approach suitable for both advanced nanoelectronics and bulk applications across various temperatures.