Thermomechanical behavior of promising mixed ion-electron conductors based on co-doped barium ferrite

Mixed ion-electron conductors (MIECs) represent a class of materials that have emerged as promising candidates for various applications in energy conversion and storage fields. These materials, which may demonstrate triple conducting behavior, are especially promising as symmetrical electrodes in protonic ceramic fuel cells or as oxygen-permeable membranes. Notable representatives of these materials include perovskites based on barium ferrite with an ABO3 structure, which might be doped or co-doped with various dopants. This short communication focuses on the investigation of the thermomechanical characteristics of Pr0.6Ba0.4FeO3–δ, Pr0.6Ba0.4Fe0.9Ni0.1O3–δ and (Pr0.6Ba0.4)0.9Fe0.9Ni0.1O3–δ materials. Their phase stability was investigated by high-temperature XRD analysis, while the contributions of thermal and chemical expansions as parts of the total expansion were analyzed between 25 and 1000 °C. According to the results obtained, at temperatures above 500 °C, changes in the thermal dependence patterns of the unit cell parameters for all the samples were observed. This phenomenon may be attributed to dimensional factors resulting from the variation in the ionic radii of the B-sublattice cations upon reduction of the B-cations and oxygen vacancy formation. A comprehensive analysis of the obtained results enables the formulation of conclusions regarding the rational level of co-doping for these materials, with the objective of optimizing their thermomechanical characteristics by reducing the chemical expansion contribution.