Small-scale plasticity in oxide ceramics at room temperature: Recent progress and future opportunities

This review synthesizes recent advances in nanomechanical testing and atomistic modeling of oxide ceramics, with particular emphasis on the relationship between room-temperature plasticity and microstructure at small length scales. Although the limited plasticity and resultant brittleness of ceramics have long inhibited their structural applications, recent developments in nanomechanical testing, such as nanoindentation and micropillar compression, have enabled the characterization of dislocation-mediated plasticity prior to crack initiation, even at room temperature. Particular attention is given to the relationship between small-scale ductility and the activation of crystallographic slip systems, the resistance of individual grain boundaries to dislocation transmission, and atomistic mechanisms governing dislocation dynamics revealed through molecular dynamics simulations. Emerging microstructural design strategies for enhancing small-scale plasticity and fracture toughness, including dislocation engineering and interface-induced plasticity, are also discussed. These findings highlight new opportunities for tailoring microstructures of ceramics through advanced processing routes, including mechanical treatment and solidification processes, in addition to conventional sintering approaches. By integrating insights from nanomechanical characterization, atomistic simulations, and microstructural design strategies, this review proposes potential pathways toward intrinsic toughening and macroscopic strengthening of engineering ceramics.