Dislocation-enabled plasticity in rutile TiO_2−x at room temperature

Ceramics are widely perceived as brittle. Recent research showed that the deformability of brittle ceramics can be improved by introducing defects, e.g., dislocations and stacking faults, into the ceramics using flash sintering. However, many ceramic materials, including TiO₂, have limited room-temperature dislocation mobility. In this work, we explored a potential route to toughen ceramic materials by introducing oxygen vacancies into rutile TiO₂. Nanoindentation method was employed to investigate the deformation behavior of the oxygen-deficient TiO_2−x. Detailed post-deformation transmission electron microscopy analyses revealed a significant increase in dislocation density. The improved fracture toughness is attributed to the abundant dislocation plasticity in reduced TiO₂ with abundant oxygen vacancies. This study provides insight into understanding the influence of point defects and dislocations on the deformation behavior of ceramic materials towards the future designs of ductile ceramics at room temperature.