Dislocation-tuned electrical conductivity in solid electrolytes (9YSZ): A micro-mechanical approach

Tailoring the electrical conductivity of functional ceramics by introducing dislocations is a comparatively recent research focus, and its merits were demonstrated through mechanical means. Especially bulk deformation at high temperatures is suggested to be a promising method to introduce a high dislocation density. So far, however, controlling dislocation generation and their annihilation remains difficult. Although deforming ceramics generate dislocations on multiple length scales, dislocation annihilation at the same time appears to be the bottleneck to use the full potential of dislocations-tailoring the electrical conductivity. Here, we demonstrate the control over these aspects using a micromechanical approach on yttria-stabilized zirconia - YSZ. Targeted indentation well below the dislocation annihilation temperature resulted in extremely dense dislocation networks, visualized by chemical etching and electron channeling contrast imaging. Microcontact-impedance measurements helped evaluate the electrical response of operating individual slip systems. A significant conductivity enhancement is revealed in dislocation-rich regions compared to pristine ones in fully stabilized YSZ. This enhancement is mainly attributed to oxygen ionic conductivity. Thus, the possibility of increasing the conductivity is illustrated and provides a prospect to transfer the merits of dislocation-tuned electrical conductivity to solid oxygen electrolytes.