Room‐temperature bulk plasticity and tunable dislocation densities in KTaO$_3$

We report room-temperature bulk plasticity mediated by dislocations in single-crystal cubic potassium tantalate oxide (KTaO$_3$), contrasting the conventional knowledge that single-crystal KTaO$_3$ is susceptible to brittle fracture. A mechanics-based combinatorial experimental approach using cyclic Brinell indentation, scratching, and uniaxial bulk compression consistently demonstrates room-temperature dislocation plasticity in KTaO$_3$ from the mesoscale to the macroscale. This approach also delivers tunable dislocation densities and plastic zone size. Scanning transmission electron microscopy analysis underpins the activated slip system to be <110> {1$\bar{1}$0}. Given the growing significance of KTaO$_3$ as an emerging electronic oxide and the increasing interest in dislocations for tuning the physical properties of oxides, our findings are expected to trigger synergistic research interest in KTaO$_3$ with tunable dislocation densities.