Temperature gradients in microelectrode measurements: Relevance and solutions for studies of SOFC electrode materials

Microelectrodes on solid electrolytes, contacted by current-collecting tips, have become increasingly important for analyzing electrochemical properties of electrode materials in solid state ionics. Samples are usually asymmetrically heated from the bottom side. It is shown experimentally, e.g. by thermovoltage measurements, impedance spectroscopy and infrared camera pictures, as well as by finite element modeling that substantial temperature gradients may arise in these experiments. Consequences in terms of data analysis are discussed and ways to alleviate the problem are described. For a complete avoidance of the temperature inhomogeneity problem, a novel symmetrically heated micro-contact set-up was built.