Surface Characterisation of metallic materials and coatings by LEIS

Service description

The Localised Electrochemical Impedance Spectroscopy LEIS allows spatially resolved impedance measurements to be made, combining established principles of EIS measurements with scanning probe technology. The principles of LEIS are similar to those employed in EIS, in that a small sinusoidal voltage perturbation is applied to a working electrode sample and the resulting current is measured trhough the scanning probe to allow the calculation of the impedance. However, rather than measuring the bulk current, the small electrochemical probe is scanned close to the surface, measuring the local current in the electrolyte. The LEIS of this lab is integrated in a M370 system that uses a fast closed loop x, y, z positioning system with submicron resolution, along with a data acquisition system. Localised impedance values on materials with dimensions of 70 x 70 x 70 mm, with a resolution of 8 nm, can be registered. Some of the main applications of this technique whose local impedance variations on surfaces of materials is measured in resistive media, are related to the study of surface modifications, corrosion science, film/coating research and surface contaminations. Specifically, this technique is very useful for the study of the degradation of organic coatings and kinetics of activation and passivation of metals or alloys. This service will provide localized impedance measurements in specific points of the metal surface over a wide frequency range and impedance maps of the area of interest (XY), specifically impedance module and phase angle, at a fixed frequency.