Implementation of In-Situ High-Temperature XAFS Experiments: Case of Praseodymium Oxide as an Oxygen Electrode in Low-Temperature Solid Oxide Cells

Abstract

This article presents  the  initial results  of  in-situ high-temperature X-ray absorption spectroscopy measurements using hard X-ray radiation of oxygen electrodes of solid oxide cells. The ability to perform in-situ measurements, i.e., under conditions close to those of real operation, enables the acquisition of unique information on the behaviour of the material, providing a deeper understanding of the operating mechanisms of the electrodes, which can guide their further development. Praseodymium oxide (PrO_x) was selected as a promising material with potential applications in low-temperature solid oxide cells. The average oxidation state of praseodymium in a 100 nm PrO_x film has been shown to decrease from 3.49⁺ at room temperature to 3.06⁺ at 400°C. These results emphasise the importance of using thin films and highlight the processes occurring at the interface between the electrolyte (ionic conductor) and the oxygen electrode. The studies presented here lay the groundwork for further development in this area of high-temperature measurements, with the goal of establishing operando measurement methodology.