Nanoscratch in highly oriented FeSe0.5Te0.5 superconductor

Tribological properties of highly oriented lamellar FeSe0.5Te0.5 superconductor samples were investigated. Nanoscratch morphologies and profiles were characterized by instrumented indentation, SEM and AFM. Anisotropies of the scratch morphologies of the ab- and a(b)c-planes were observed. Plowing seems to be the main mechanism of scratch deformation in the ab-plane, with plenty of material pile-up around the scars. Distinctively, microcracking is the dominant deformation process in the a(b)c-plane. Also, the scratch resistance of the a(b)c-plane is higher than the ab-plane, which presented scratch hardness values of 1.5 GPa and 0.6 GPa, respectively. Cracks were observed in the a(b)c-plane parallel to the c-axis. These observations are consistent with the deformation mechanism of cracks running perpendicular to the c-axis in the same a(b)c-plane, produced by indentations.