High-Temperature Structural and Electrical Properties of BaLnCo2O6 Positrodes
Iga Szpunar, Ragnar Strandbakke, Magnus H. Sørby, Sebastian Wachowski, María Balaguer, Mateusz Tarach, José M. Serra, Agnieszka Witkowska, Ewa A. Dzik, Truls Norby, Maria Gazda, Aleksandra Mielewczyk‐Gryń
Abstract
The application of double perovskite cobaltites BaLnCo2O6−δ (Ln = lanthanide element) in electrochemical devices for energy conversion requires control of their properties at operating conditions. This work presents a study of a series of BaLnCo2O6−δ (Ln = La, Pr, Nd) with a focus on the evolution of structural and electrical properties with temperature. Symmetry, oxygen non-stoichiometry, and cobalt valence state have been examined by means of Synchrotron Radiation Powder X-ray Diffraction (SR-PXD), thermogravimetry (TG), and X-ray Absorption Spectroscopy (XAS). The results indicate that all three compositions maintain mainly orthorhombic structure from RT to 1000 °C. Chemical expansion from Co reduction and formation of oxygen vacancies is observed and characterized above 350 °C. Following XAS experiments, the high spin of Co was ascertained in the whole range of temperatures for BLC, BPC, and BNC.