Mechanical tailoring of dislocation densities in SrTiO₃ at room temperature

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 SrTiO₃. By using a millimeter‐sized Brinell indenter, dislocation densities from ∼10¹⁰ to ∼10¹³ 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.