  The quest for room-temperature ductile ceramics has been repeatedly fueled by
hopes for large-scale applications but so far has been not successful. Recent
demonstrations of enhanced functional properties in ceramics through judicious
dislocation imprint, however, have been sparking renewed interest in
dislocation plasticity in brittle ceramics. Here, we propose a facile approach
using room-temperature mechanically seeded mobile dislocations with a density
of ~10^14/m^2 to significantly improve the room-temperature plasticity of
ceramics with a large plastic strain beyond ~30%. The seeded mobile
dislocations trigger profuse dislocation multiplication via cross slip and
motion. Hence, they offer an avenue to suppress brittle fracture and harvest
plasticity in ceramics without any additional high-temperature process. We
employ both in situ nano-/micromechanical deformation and ex situ bulk
deformation to bridge the length scales. This finding tackles the pressing
bottleneck of dislocation engineering in ceramics for achieving ductile
ceramics and harvesting both versatile mechanical and functional properties.
