Dislocation-enhanced electrical conductivity in rutile TiO₂ accessed by room-temperature nanoindentation

Dislocation-enhanced electrical conductivity is an emerging topic for ceramic oxides. In contrast to the majority of present studies which focus on large-scale crystal deformation or thin film fabrication to introduce dislocations, we use a nanoindentation “pop-in stop” method to locally generate 〈011〉 edge-type dislocations at room temperature, without crack formation, on the (100) surface of a rutile TiO₂ single-crystal. Ion beam assisted deposition of microcontacts allowed for both deformed and non-deformed zones to be locally probed by impedance spectroscopy. Compared to the dislocation-free region, a local enhancement of the electrical conductivity by 50% in the dislocation-rich regions is found. The study paves the way for local “mechanical-doping” of ceramics and oxide materials, allowing for the use of dislocations to tune the local conductivity with high spatial resolution.